# Best way to reinforce bunk beds?



## de-nagorg (Feb 23, 2014)

For every bolt that goes into a nut, get a tube of locktite blue, and remove the bolt and one drop of locktite, on the bolt.

Replace the bolt, and repeat on all the rest. 

Yes I know locktite is for automotive use, but it is very useful on any threaded fastener. Sold at the auto parts store, or department in wally world.

Extra brackets will not hurt, and might be beneficial.

The manufacturer relies on gravity to keep the upper bunk on the post below, this has worked for decades, so your choice on an anchoring plate . 

ED 

I forgot, particle board, pressboard, chipboard, will all deteriorate and be falling apart in short order. 

3/8 or thicker plywood as a minimum, even better 1X slats laid lengthwise spaced 2 inches apart will support even the heaviest adult, if they are so inclined to sleep there.


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## viper (Jul 30, 2009)

Sorry to say, as a twin myself, I destroyed every bunk bed commercially available. My dad finally hand built solid oak bunks, and built like a tank. Not screws, but lag bolts for everything. They have not worn in decades. 

I will be frank, I can probably tell you how to try to reinforce those bunks but I can tell by looking that their days are numbered. Pressed wood and bunks does not work. 

There is substantial racking load (plz look that term up) front to back. You can help this by adding an X brace on the wall side for the power bunk. That should stiffen it substantially. Without that, you can glue and loctite all you want and it will still come loose because there is too much load on those fasteners. 

If you choose to buy something better, select nothing but solid wood. Pine will hold up for a while but a real hard wood like oak should hold up if designed right. 

I feel sorry for my parents but we have now spent a LOT of years fixing everything for them rather than breaking things.


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> For every bolt that goes into a nut, get a tube of locktite blue, and remove the bolt and one drop of locktite, on the bolt.
> 
> Replace the bolt, and repeat on all the rest.
> 
> Yes I know locktite is for automotive use, but it is very useful on any threaded fastener. Sold at the auto parts store, or department in wally world.



If I use Loctite, will I have problems if I ever want to disassemble the bed?




> Extra brackets will not hurt, and might be beneficial.
> 
> The manufacturer relies on gravity to keep the upper bunk on the post below, this has worked for decades, so your choice on an anchoring plate.



What would you do?




> I forgot, particle board, pressboard, chipboard, will all deteriorate and be falling apart in short order.
> 
> 3/8 or thicker plywood as a minimum, even better 1X slats laid lengthwise spaced 2 inches apart will support even the heaviest adult, if they are so inclined to sleep there.


The main reason I was thinking of plywood is that it provides a solid rectangle that would be a brace against diagonal distortion, such as might happen when the bed is moved. Does 3/8" really provide that much better support than 1/4"? I'm fine with 3/8, but I'm just wondering if it makes that much difference. 

What grade would you get? It will be visible (and touchable) from below.

I like the idea of slats. I can even cut them myself with my skill saw, which is more difficult with a sheet of plywood. But it would provide less of a brace against diagonal distortion. I guess if I screwed it into the existing cross slate, it would provide some bracing.


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## Cynthia Moore (Aug 14, 2015)

viper said:


> Sorry to say, as a twin myself, I destroyed every bunk bed commercially available. My dad finally hand built solid oak bunks, and built like a tank. Not screws, but lag bolts for everything. They have not worn in decades.
> 
> I will be frank, I can probably tell you how to try to reinforce those bunks but I can tell by looking that their days are numbered. Pressed wood and bunks does not work.
> 
> ...


Thanks for the words of encouragement. We are not going to buy something else. These beds will get used at most 2-3 nights a month by kids that are ages 4 & 6. They don't need to make it to the apocalypse or withstand adult sleepers. I'm just interested in suggestions for reasonable reinforcements.


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## de-nagorg (Feb 23, 2014)

There is 2 types of Loctite, RED, and BLUE, I believe that the BLUE is removable, be sure before using it, the package should sat that it is not the permanent one. 

The 3/8 ply has one more ply for added strength. 

And if you cut the slats the exact length needed to span the distance they will act as a group of braces as good as a plywood full sheet. 1X6 or wider would be my choice. 

As for a connection brace between the upper and lower post, are the children strong enough to lift the upper bunk high enough to uncouple them?

If so then a simple mending plate on each corner will keep them together. 

I would forego using them, but I might be mistaken, I can remember being on the bottom and kicking up to bug my brother, and having a near failure. 

So it might be wise to attach the 2 pieces into one unit.


ED


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> There is 2 types of Loctite, RED, and BLUE, I believe that the BLUE is removable, be sure before using it, the package should sat that it is not the permanent one.


OK, thanks




> The 3/8 ply has one more ply for added strength.


Makes sense




> And if you cut the slats the exact length needed to span the distance they will act as a group of braces as good as a plywood full sheet.



Would you screw them down into the cross slats or attach them to the sides with angle brackets or both?




> 1X6 or wider would be my choice.


OK.




> As for a connection brace between the upper and lower post, are the children strong enough to lift the upper bunk high enough to uncouple them?
> 
> If so then a simple mending plate on each corner will keep them together.
> 
> ...


They are not nearly strong enough today, but they get stronger every day. And the 5 year old who was on the top bunk this weekend already asked me to get on the bottom bunk and push her up from below, so she will definitely try it with her brother.

And, if the top were firmly attached to the bottom, it would make the bed much easier to move.

Thanks for the suggestions.


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## de-nagorg (Feb 23, 2014)

You're welcome.

You asked how I would attach the 1X to the bed.

A minimum of two screws per at least half of the slats, that way the 1X are attached solidly to more slats, to prevent any wracking during any movement of the Bunks. 

They move just by being gotten into or out of, as well as when you move them to sweep under, or make the bed. 

I applaud your efforts to accommodate these little guests, Grandchildren are life's gift for surviving their parent's teenage years. :vs_laugh:


ED


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## viper (Jul 30, 2009)

The overlay of plywood over the slats is creating what is called a "diaphragm" and you will need at minimum of 5 screws at both the furthest head and foot slats. You will want to concentrate screws towards the perimeter of the plywood sheet and you want a SINGLE continuous piece off plywood, no splices. You don't need to be concerned much about screws in the middle. You skimp on screws on the outside and it will rip them all out. The load needs shared. This is the only simple way to mitigate "diagonal distortion" or otherwise horizontal racking displacement. 

1/4" ply is just fine for the application but if like 3/8", that will work too.


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## Guap0_ (Dec 2, 2017)

Buy two 4" L brackets & bolt it to the wall. Done.


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> You're welcome.
> 
> You asked how I would attach the 1X to the bed.
> 
> ...


OK




> I applaud your efforts to accommodate these little guests, Grandchildren are life's gift for surviving their parent's teenage years.


Chuckle. I like it.

We just made a photobook for their great-grandmother. I looked up a bunch of quotes about grandmothers to put in the book. One of them was,


> Children are the rainbow of life.
> Grandchildren are the pot of gold.


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## SPS-1 (Oct 21, 2008)

Cynthia Moore said:


> Some of the bolts were quite loose, especially those that were connected to nuts that were inserted into a side hole. These are the little cylinders that you have to align with a screwdriver. Is it common for this type of bolt to loosen after the initial installation and have to be tightened again?


 
Is this the type of fastener that was loosening up? The cylinder needs to rotated the complete turn. If you only rotate a partial turn, the mating stud is on a ramp and will loosen up. When rotated a full turn (orientation of screwdriver slot shows how far rotated), stud is on a flat and it will not loosen up. You should feel resistance as you finish tightening it. But if the cylinder is fully tight before you make a full turn, or is still loose after making a full turn, you have a problem. You might be able to adjust how far the stud is sticking out.


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## Cynthia Moore (Aug 14, 2015)

viper said:


> The overlay of plywood over the slats is creating what is called a "diaphragm" and you will need at minimum of 5 screws at both the furthest head and foot slats. You will want to concentrate screws towards the perimeter of the plywood sheet and you want a SINGLE continuous piece off plywood, no splices. You don't need to be concerned much about screws in the middle. You skimp on screws on the outside and it will rip them all out. The load needs shared. This is the only simple way to mitigate "diagonal distortion" or otherwise horizontal racking displacement.
> 
> 1/4" ply is just fine for the application but if like 3/8", that will work too.


I've attached a rough image on my plan.

The existing slate are strips of 3/4" plywood on edge. They are screwed into the frame 1/2" from the edge, so my screws will have to be at least 1/2" farther in than that.

On the end slats, I'll put a screw about every 5" or so. On the interior slate, I'll put two screws more or less evenly spaced.

Is that enough?


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## de-nagorg (Feb 23, 2014)

Replace those slats with solid wood. 

Screwing into end grain plywood, does not hold very well, unless you use carriage bolts through the plywood slats with washers and nylock nuts. 

My opinion. 

Yes I know more expense, but I would rather spend money on prevention, than remedy after someone gets hurt. 


ED


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## Cynthia Moore (Aug 14, 2015)

SPS-1 said:


> Is this the type of fastener that was loosening up?


That's the one.



> The cylinder needs to rotated the complete turn. If you only rotate a partial turn, the mating stud is on a ramp and will loosen up. When rotated a full turn (orientation of screwdriver slot shows how far rotated), stud is on a flat and it will not loosen up. You should feel resistance as you finish tightening it. But if the cylinder is fully tight before you make a full turn, or is still loose after making a full turn, you have a problem. You might be able to adjust how far the stud is sticking out.


I don't understand this. Are you saying that the cylinders need to rotate along the axis of the bolt so that the Phillips slots are no longer visible?

The cylinders are inserted into a round hole that is just big enough for them. They can only rotate along the axis of the screwdriver. When I assembled the frame. I inserted the cylinders with the Phillips slots out. I then inserted a Phillips screwdriver and rotated them along the axis of the screwdriver so that the bolt could catch. I then tightened the bolt. I don't see any other rotation that is possible.


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> Replace those slats with solid wood.
> 
> Screwing into end grain plywood, does not hold very well, unless you use carriage bolts through the plywood slats with washers and nylock nuts.
> 
> ...


Arrgghhhh. I didn't like the prospect of screwing into end grain plywood, either, but I liked the prospect of replacing the slats even less. It's not the expense, it's the hassle of getting them the right length, drilling the pilot holes and getting them to line up with the existing pilot holes, etc.

What if I just use twice as many screws?

Is there some kind of anchor nut that I could put into the slats that would be more sturdy than a screw?

What about those nut-like gizmos that have a washer-like collar with little spikes that you drive down into the wood? But they go on the other edge, right? And I'd need to drill a hole all the way thru the slat.

(sigh)


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## SPS-1 (Oct 21, 2008)

Cynthia Moore said:


> I then inserted a Phillips screwdriver and rotated them along the axis of the screwdriver so that the bolt could catch.



Rotate the screwdriver so it makes a complete 180 degree rotation (sorry, not 360 degrees, just 180 normally). There is normally a line on the cylinder face that you can see the orientation of the cylinder.


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## de-nagorg (Feb 23, 2014)

Cynthia Moore said:


> Arrgghhhh. I didn't like the prospect of screwing into end grain plywood, either, but I liked the prospect of replacing the slats even less. It's not the expense, it's the hassle of getting them the right length, drilling the pilot holes and getting them to line up with the existing pilot holes, etc.
> 
> What if I just use twice as many screws?
> 
> ...


As I suggested , use carriage bolts, drill through the plywood sheet, through the plywood slats, insert the carriage bolt with washer, through the hole, through the slat, then use another washer, and NY-LOCK nut, to secure the assembly together. 

This will strengthen the bed frame and be a solid platform for supporting a mattress. 

A child could even "dance" on it and be safe. 

The carriage bolt has a square shank at the head, so be sure to find the proper washer to fit this.


ED


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> As I suggested , use carriage bolts, drill through the plywood sheet, through the plywood slats, insert the carriage bolt with washer, through the hole, through the slat, then use another washer, and NY-LOCK nut, to secure the assembly together.
> 
> This will strengthen the bed frame and be a solid platform for supporting a mattress.


The problem I have with this is that there will be bolt heads under the mattress, which could cause wear and tear and nuts underneath that could cause head injuries. I guess I could use flat head machine bolts.

https://www.amazon.com/dp/B01LXU6Q0B/


Here are two alternatives I found:

1. Lag nuts, also called T nuts. These would provide a strong connection and would be almost flush underneath.

https://www.amazon.com/dp/B01MSVU3WF/

2. Threaded inserts. These would not have to be drilled all the way through the slats.

https://www.amazon.com/dp/B07JQ8BSQK/

I am inclined to go with the T nuts because it's simpler and probably stronger. Do you have any preferences between these two options?




> A child could even "dance" on it and be safe.


Hey, please don't encourage them.


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## de-nagorg (Feb 23, 2014)

The T nuts, would work, but I am thinking that they might not cover enough area to prevent pulling themselves in too far in the plywood edge, thus my reason for suggesting a large flat washer between the nut and the bottom of the slat. 

Those inserts need something to grip, and plywood has voids and soft material throughout it, Thus my reasoning for washers on both sides. 

Carriage bolts have rounded domed heads, that will also be less abrasive on a mattress skin, than a hex head bolt. 

One could cover any protruding bolt with a ball similar to the ones supplied with toy Jacks ( the pointy girls toy), but that is inviting curiosity to try removing the balls. 

Glad that you are planning ahead on this, I too do the 7 P policy.

7 P = Prior Proper Planning Prevents Pizz Poor Projects.


ED


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## ron45 (Feb 25, 2014)

Are they allowed to rough-house in the house.?


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> The T nuts, would work, but I am thinking that they might not cover enough area to prevent pulling themselves in too far in the plywood edge, thus my reason for suggesting a large flat washer between the nut and the bottom of the slat.
> 
> Those inserts need something to grip, and plywood has voids and soft material throughout it, Thus my reasoning for washers on both sides.



These slats are plywood, but it is not your run-of-the-mill construction plywood. I've uploaded close-up shots. They appear to have a sheet of veneer on both sides covering either 11 or 13 layers in between. There are very few gaps. And, as you can see, they are attached to the frame by screws that are drilled half way down into the 1.5" slats. So I'm not as concerned about the T nuts sinking into the edge of the slats from below as I am about the screw heads sinking into the face of the plywood sheet from above.

That gives me an idea. Maybe the way to go is to install the T nuts in the face of the plywood sheet and drill a pilot hole up into the slats from below. The T nuts are like a washer, so they should be stable. It seems to be working for holding the slats onto the frame, so it should work for holding the sheet down onto the slats. I can always drill the pilot hole a little larger and put a small washer inside. And if it needs to be tightened, I can do it from below without having to remove the mattress. :smile:

Comments?




> Glad that you are planning ahead on this, I too do the 7 P policy.
> 
> 7 P = Prior Proper Planning Prevents Pizz Poor Projects.


I adhere to the MTCOPTF policy. I even have the t-shirt.


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## Cynthia Moore (Aug 14, 2015)

ron45 said:


> Are they allowed to rough-house in the house.?


Well, there's what's allowed and what happens... And part of the grandparent MOS is to allow things that they can't do at home.


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## viper (Jul 30, 2009)

NO! I did not realize the slats were plywood. Do NOT drill all the way through them. Not only will it not work, you are breaking continuity of a tension element. Plywood was selected for its stiffness strength in bending and solid softwood would be inferior here. The slats WILL crack where one of those bolts are, AND you will have a safety concern with the bolts sticking through. It just won't work. 

Adding a bunch of smaller screws will work better than fewer big ones here because the steel fasteners are by far stronger in shear than the wood BUT I highly discourage it all the way around because you are pulling in the weak axis of the plywood. 

There are a few work arounds

1. Remove ALL the blocking (little blocks that butt up to where the slats screw to the frame) and gluing full height solid wood blocks and screw to those. You would also need to add an additional slat at the head and foot of solid wood to take the racking. I would recommend SYP if you can get because it is cheap and stronger than Fir. 

2. Put new plywood over the slats and clamp in position and pencil along on the slats. Remove plywood and slats and glue ALL the slats to the plywood. You would need to add holes in the plywood where the slat screws go so you can still get to them. A glue bond in wood is many times stronger than any fastener because it engages much more surface area than a fastener. You will also create a stiffer mattress support with this be
cause the plywood will now add to the compressional support of a beam. 

3. Rethink the plywood all together. Straps of Aluminum can be added over the slats in a X config but you CANNOT attach to the top of the slats because you will induce roll in the slats. You would need good blocking to prevent that and a plan for good attachment. 

You cannot add just corner supports at a 45* because that will induce stress in the already inferior OEM connections. They will get pulled out and go loose. 


All these combine help to highlight why it would frustrate me to buy a cheap bed, only to have to spend 40 hours and $200 "re-engineering" it.


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## de-nagorg (Feb 23, 2014)

The plywood slats do look to be a better grade of material.

Now I question the amount of material that the screws in the ends of the slats are really grabbing in the side rails.

Looks to be very close to the edge line of the side rail, and might be easily broken by moving the bed around. 

And as someone pointed out drilling through the plywood will weaken it's construction, and it might fail too soon. 

So can you fabricate a L bracket / clamp item that clamps under the slat, and screws into the plywood sheet on top, where the tighter you clamp it, the tighter the sheet is pulled to the slat.?

Or you could just do the Garden Party approach.

" You can't please everybody, So just please Yourself."

ED


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## Cynthia Moore (Aug 14, 2015)

SPS-1 said:


> Rotate the screwdriver so it makes a complete 180 degree rotation (sorry, not 360 degrees, just 180 normally). There is normally a line on the cylinder face that you can see the orientation of the cylinder.


I don't understand what you are saying. The cylinder goes into a cylindrical hole that just fits. It can only be rotated along the axis of the screwdriver. I do this until the threaded hole lines up with the bolt. Once the bolt catches the threads, it cannot be rotated at all. It can only be tightened by turning the bolt with the Allen wrench.

Are you talking about something else?


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## de-nagorg (Feb 23, 2014)

I'm going to guess that they are thinking of the ones that are called a CAM-LOCK, where the cylinder turns to lock onto the head of the bolt.

Those have a wedge design inside the cylinder that meshes with the tapered head, so the more the cylinder is turned , the tighter the two pieces are pulled together. 

You say that you have ones that are tightened by turning the bolt with a hex key, thus pulling the cylinder toward the open end of the bolt hole. 

ED


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## Cynthia Moore (Aug 14, 2015)

viper said:


> NO! I did not realize the slats were plywood. Do NOT drill all the way through them. Not only will it not work, you are breaking continuity of a tension element. Plywood was selected for its stiffness strength in bending and solid softwood would be inferior here. The slats WILL crack where one of those bolts are, AND you will have a safety concern with the bolts sticking through. It just won't work.


OK, I see your point, but I'm not sure I agree with it. The bending forces on the slats are in three possible directions: head-to-foot, side-to-side, and up-and-down. I assume you are referring to the up-and-down forces, and mainly the downward force of a kid lying or jumping on the bed, because the other two are minimal and would be strongly opposed by being secured to the plywood. But I question the up-and-down force as well. If the slats are bolted to the plywood, any downward force would be opposed by not only the plywood, but also by the adjacent slats, which are now a combined unit by virtue of being bolted to the plywood sheet.

Wouldn't the addition of the plywood and the added strength of combining the slats together offset any loss of strength by drilling all the way through the slats?



> Adding a bunch of smaller screws will work better than fewer big ones here because the steel fasteners are by far stronger in shear than the wood BUT I highly discourage it all the way around because you are pulling in the weak axis of the plywood.


What do you mean by "pulling in the weak axis"? What is the weak axis of the plywood?

Using wood screws from the top is the other option that I am considering and it's far simpler for me to implement.



> There are a few work arounds


All of these are too involved for me and, I think, overkill.



> All these combine help to highlight why it would frustrate me to buy a cheap bed, only to have to spend 40 hours and $200 "re-engineering" it.


Different strokes for different folks. No?


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> I'm going to guess that they are thinking of the ones that are called a CAM-LOCK, where the cylinder turns to lock onto the head of the bolt.
> 
> Those have a wedge design inside the cylinder that meshes with the tapered head, so the more the cylinder is turned , the tighter the two pieces are pulled together.



Aha! Yes, I have seem those before. These are not those.




> You say that you have ones that are tightened by turning the bolt with a hex key, thus pulling the cylinder toward the open end of the bolt hole.
> 
> ED


Correct.


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## viper (Jul 30, 2009)

Cynthia Moore said:


> 1. Wouldn't the addition of the plywood and the added strength of combining the slats together offset any loss of strength by drilling all the way through the slats?
> 
> 2. What do you mean by "pulling in the weak axis"? What is the weak axis of the plywood?
> 
> 3. Using wood screws from the top is the other option that I am considering and it's far simpler for me to implement.


1. NOPE! Structural engineering does not work that way but if you want to, it's your bed. I can virtually guarantee you will make the system weaker than it was before you added anything. 

2. Without over sharing with wood engineering, the weak axis of plywood is tension normal to the plies. You might as well drive a wedge between the plies. It will work for a while though. 

3. Go with the simple method. I have learned on this site people just end up doing what they originally planned anyway. I'm usually just called on bigger jobs after the "wing it" fix didn't work, to engineer a proper repair that won't fail.


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## Cynthia Moore (Aug 14, 2015)

viper said:


> 1. NOPE! Structural engineering does not work that way but if you want to, it's your bed. I can virtually guarantee you will make the system weaker than it was before you added anything.


Hmmm...



> 2. Without over sharing with wood engineering, the weak axis of plywood is tension normal to the plies. You might as well drive a wedge between the plies. It will work for a while though.


If I recall my physics classes, "normal" means "orthogonal" or "perpendicular". A "normal force" is one that acts _against_ an external force (or a component of one) that is applied perpendicular to a surface. So you must be talking about forces that act at right angles one of the surfaces of the slats.

You talk about a force that is "normal to the plies", which has to mean perpendicular to the face of the plywood. This is illustrated in the attached diagram on the left. But the slats are installed on edge, so the primary forces, which are downward, would not be "normal" to the face of the slats, but to the edge. So this should not have that much to do about the plies.

The illustration on the right shows the downward force orthogonal to the edge of the slats, which is how it is on this bed. So I don't see how drilling holes through the slats edgewise would be like driving a wedge between the plies.



> 3. Go with the simple method. I have learned on this site people just end up doing what they originally planned anyway. I'm usually just called on bigger jobs after the "wing it" fix didn't work, to engineer a proper repair that won't fail.


Wow! Are you saying that I made up my mind before I even started this thread and nothing anyone said made any difference? Are you also a psychologist and a mind reader in addition to a wood structural engineer?

It's amazing that you even bother to help the kind of people that use this site. They really don't deserve your myriad skills.

And I bet when you are "called on" when the stubborn people go ahead with their ill-conceived "wing it" plans and they fail as you predicted, you never say "I told you so", do you?


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## Cynthia Moore (Aug 14, 2015)

OK. I have narrowed it down to two options as illustrated in the attached diagram. I was leaning toward Option A, but now, after considering Viper's concerns about drilling all the way through the slats, I am now leaning to Option B, which also happens to be a lot easier to implement.

For Option B, there are a couple of questions:


What size screws should I use? #10 seems a bit too small and #6 a bit too large, so #8?
What length screws? I'm thinking about 3/4" into the 1.5" slats. Is that deep enough to get a good grip without excess weakening?
What type head? The choices are flat head, which will sink into the plywood and leave a flat surface. Round head with a washer would probably provide a better grip, but would not leave a flat surface unless I counter sunk it. I am inclined to use the flat head,
Any final comments?


The beds currently have 8 slates on 10" centers. If the beds seem unstable, I can always get more slats to go in between the existing ones. The new ones could be plywood or solid wood, hard of soft.


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## viper (Jul 30, 2009)

Cynthia Moore said:


> Hmmm...
> 
> If I recall my physics classes, "normal" means "orthogonal" or "perpendicular". A "normal force" is one that acts _against_ an external force (or a component of one) that is applied perpendicular to a surface. So you must be talking about forces that act at right angles one of the surfaces of the slats.
> 
> ...


1. Indeed, I said normal. And indeed I meant it. it has everything to do with the plies and the precise reason plywood is even used for the slats when solid softwood would be cheaper. So they rolled an extra $.25 in there! 


2. Since physics didn't get the point across, I suggest you look up both 3 or 4 point bending of a beam, and forces in a diaphragm. Once you put all that together, what I said will not seem "silly". Racking in this is in X plane or horizontal, NOT vertical. Where do you expect those forces to go? Do they just disappear? Look up racking, understand it. Beyond Racking, look at compression, tension, neutral axis, etc. You will have lateral force on the screws that will work to cause separation of the plies.


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## BrownEyedGuy (Oct 2, 2018)

Cynthia, forgive me, I skimmed much of the thread, but the signal to noise was a little too high to read everything. Nevertheless, I do have some comments for you. I'm not sure that these got worked out above.

1) Ignore the thread locker discussion. That is not where your problem resides. The machine threads did not back out in a single usage in a non-vibratory environment. _No matter how people describe kids activity, they're not quite high enough frequency to be considered vibratory. :biggrin2:_

The initial problem of the bed loosening up after a single usage is more likely due to not fully torquing the fasteners, or specifically, tightening things up with a skew already present. Then, with the kids moving around on the bed, fasteners seated themselves and skews got righted. The result is that the fasteners were no longer as tight as installed, because the parts were now closer together.

2) The 3 types of racking that you need to be concerned about are side to side (left/right as sleeping), front to rear (head to toe), and finally parallelogram skew in the mattress box. 

From what I have seen in the pictures, the bed is already designed for the first 2, as long as your fasteners are tight. The headboard/footboard stop the side to side. There appears to be a side-board on the upper bunk that spans from head to foot, correct? That will stops the other racking.

The parallelogram skew is only of importance when you go to move the beds. Nevertheless, something as simple as 1/4-inch plywood in the mattress box is sufficient to stop this.

4) It has been mentioned that the bed slats are not very strong, and i do agree with that. However, the solution is as simple as sistering a solid wood slat to the side of the existing slat. This, coupled with the 1/4 inch plywood is enough to strengthen the mattress area. The reason why I suggest the solid wood is because you can drive a wood screw into their edges (for securing the 1/4 inch plywood to the new slats) without splitting them, like you would with the plywood slats. The fasteners between the new slats and the old slats would be driven across the plys, where the plywood has the better screw-holding strength.

As a matter of fact, if you used screws and nuts to secure the sistered slats to the factory slats, then you can treat the new slats and plywood as a single assembly, for the purpose of taking the bed apart. (Like a piece of ribbed plywood, if you can visualize that.)


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## de-nagorg (Feb 23, 2014)

In post 34 above, I like #4 suggestion, the sistering idea , combined with the T nuts, has a better expectation of strengthening the bed. 

I observe that he edited something and a #3 is now missing, must of had an epiphany and removed #3. 

It's good that interest has occurred on this, that way you will get somw great suggestions. 


ED


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## Cynthia Moore (Aug 14, 2015)

viper said:


> 2. Since physics didn't get the point across, I suggest you look up both 3 or 4 point bending of a beam, and forces in a diaphragm. Once you put all that together, what I said will not seem "silly".


I don't believe I called anything you said "silly".



> Racking in this is in X plane or horizontal, NOT vertical. Where do you expect those forces to go? Do they just disappear? Look up racking, understand it. Beyond Racking, look at compression, tension, neutral axis, etc. You will have lateral force on the screws that will work to cause separation of the plies.


You are right. I was looking in the wrong dimension. I see now what you are talking about.

Based on my new understanding, I am proposing three new options.


U Brackets. If I can find some the right size, this would seem to be the best option. It doesn't drill any holes in the slats and it doesn't depend on wood screws in plywood. I would think
Angle Brackets. These are readily available and cheaper. It does require a hole in the plywood slat, but it is across the plies.
Wood Screws.This is the simplest option, but probably the least stable.


Do you (or anyone else) have any comments on these?

If Option A is the best, does anyone know where I can get U brackets of the right size? I couldn't find any online.

Do you have an opinion on whether to countersink? I am concerned about wear and tear on the mattress if there is anything protruding above the plywood base.

Thanks


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## Cynthia Moore (Aug 14, 2015)

BrownEyedGuy said:


> Cynthia, forgive me, I skimmed much of the thread, but the signal to noise was a little too high to read everything.


Too high or too low?



> Nevertheless, I do have some comments for you. I'm not sure that these got worked out above.
> 
> 1) Ignore the thread locker discussion. That is not where your problem resides. The machine threads did not back out in a single usage in a non-vibratory environment. _No matter how people describe kids activity, they're not quite high enough frequency to be considered vibratory. :biggrin2:_


You haven't seen these kids!



> The initial problem of the bed loosening up after a single usage is more likely due to not fully torquing the fasteners, or specifically, tightening things up with a skew already present. Then, with the kids moving around on the bed, fasteners seated themselves and skews got righted. The result is that the fasteners were no longer as tight as installed, because the parts were now closer together.


That sounds right.



> 2) The 3 types of racking that you need to be concerned about are side to side (left/right as sleeping), front to rear (head to toe), and finally parallelogram skew in the mattress box.
> 
> From what I have seen in the pictures, the bed is already designed for the first 2, as long as your fasteners are tight. The headboard/footboard stop the side to side. There appears to be a side-board on the upper bunk that spans from head to foot, correct? That will stops the other racking.
> 
> The parallelogram skew is only of importance when you go to move the beds. Nevertheless, something as simple as 1/4-inch plywood in the mattress box is sufficient to stop this.


So you disagree with Viper that left-to-right racking (as viewed from the side of the bed) is a problem and drilling holes all the way through the plys of the plywood slats will weaken it in that direction?



> 4) It has been mentioned that the bed slats are not very strong, and i do agree with that. However, the solution is as simple as sistering a solid wood slat to the side of the existing slat. This, coupled with the 1/4 inch plywood is enough to strengthen the mattress area. The reason why I suggest the solid wood is because you can drive a wood screw into their edges (for securing the 1/4 inch plywood to the new slats) without splitting them, like you would with the plywood slats. The fasteners between the new slats and the old slats would be driven across the plys, where the plywood has the better screw-holding strength.
> 
> As a matter of fact, if you used screws and nuts to secure the sistered slats to the factory slats, then you can treat the new slats and plywood as a single assembly, for the purpose of taking the bed apart. (Like a piece of ribbed plywood, if you can visualize that.)


That's an interesting solution. In that case, I assume you would recommend Option C in my previous post, but with the wood screws driven into the solid wood sister slats, right?

Thanks


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## de-nagorg (Feb 23, 2014)

Cynthia Moore said:


> I don't believe I called anything you said "silly".
> 
> You are right. I was looking in the wrong dimension. I see now what you are talking about.
> 
> ...


On the U brackets, you go to a metal fabrication shop, with your dimensions, and place an order for as many as you need, they have the materials, tools, and experience to make them.

It will be costly, but what is the grandchildren's safety worth.

I have done this exact thing to get brackets custom made, so I know " of what I speak".

On the L brackets, they are less reliable in stress situations like what I imagine kids can make.

And as for the screws, there are little plastic caps made for the countersink holes to cover the heads, they are smooth topped, and the mattress slides without catching.

The decision is still yours to make, all I can do is state what I know to help.



ED


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> The decision is still yours to make, all I can do is state what I know to help.


I am starting to favor the sister slat option. It has several advantages:


It's fairly simple.
It's relatively inexpensive.
It will be easier if we ever need to disassemble the bed.
I've attached a diagram of one such assembly. I have a couple of implementation questions:


How many cross bolts do I need to secure the sister slats to the existing plywood slats? I am assuming one close to each end and maybe 1-2 in the middle?
How many screws do I need through the plywood base into the sister slats? Again, I am assuming one on each end and 2-3 in the middle.
Why are they called "sister" slats? Are there "brother" slats? Or is it just that sisters get along better than brothers?


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## ron45 (Feb 25, 2014)

Cynthia Moore said:


> Well, there's what's allowed and what happens... And part of the grandparent MOS is to allow things that they can't do at home.


That's pretty cool until it comes to a safety issue.

How far do you have to fall to.

Crack your scull.
Break your neck.
Break an arm or leg.
Shove your tail bone up around your neck.
Etc........

My Grand parents spoiled the hell out of us
BUT..

You better mind your manners and follow the rules or no stay over at Grand ma/pa house.


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## de-nagorg (Feb 23, 2014)

If you use a bead of PL construction adhesive in conjunction with the bolts/ nuts, three bolts will be great, one each end, one centered.

This is a narrow bed, so three recessed screws per slat will do, and find those plastic caps / plugs, at the bolts, nuts, nails, aisle in HD, or other box store, or a real hardware store. 

They are flat, usually white, sometimes black, and fit great in a recessed hole to cover a screw.

They are sisters, because old carpenters were mostly men, and embedding a brother in there sounded ODD. 

They are also called SLEEPERS sometime, so?


ED


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> If you use a bead of PL construction adhesive in conjunction with the bolts/ nuts, three bolts will be great, one each end, one centered.


Got it.




> This is a narrow bed, so three recessed screws per slat will do, and find those plastic caps / plugs, at the bolts, nuts, nails, aisle in HD, or other box store, or a real hardware store.
> 
> They are flat, usually white, sometimes black, and fit great in a recessed hole to cover a screw.


Good




> They are sisters, because old carpenters were mostly men, and embedding a brother in there sounded ODD.


 :biggrin2:

Alas, I now have another problem. The manufacturer put blocks adjacent to the slats, so adding a sister slat will be a problem. I'd have to remove a block, which I am reluctant to do. But there are gaps between the blocks where I can add extra slats. I can't connect them to the existing slats, but that may not be a problem.

I can screw the new slats to the sideboard base rail, like the existing slats, or not.

The attachments shows the actual bed, a diagram of the side, and a diagram with the extra slats added.


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## de-nagorg (Feb 23, 2014)

Those little blocks are intended to stop the slats from twisting and coming loose.

So what I propose, is to add the extra slats, with your own 1X1 blocking at the centers of the existing spaces between those blocks, and add screws through the rail, just like the plywood slats have. 

You still get the extra support, and strength. 

Geez , I hate cheap knock down furniture. 

But I like re-designing them to hold up better. 

Keeps the old grey matter working, you know the use it, or lose it.

ED


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> So what I propose, is to add the extra slats, with your own 1X1 blocking at the centers of the existing spaces between those blocks, and add screws through the rail, just like the plywood slats have.
> 
> You still get the extra support, and strength.



I've been away for almost 2 weeks, so I can't go look at the bed for another 2 days. It seems to me that the blocks were nailed to the frame. I don't know if they were also glued. I could try to pry one loose to see.

What if I remove the blocks on one side of each slat, add the sister slat, then replace the block up against the sister slat?

The existing slats are screwed down into the rails and the screws are recessed about 3/4" (half way down).

If I also screw the sister slats down into the rails, when I cover them all with the plywood base, I will not be able to get to those screws without removing all of the screws from the base to the sister slats, which defeats the objective of having a single assembly to remove.




> Keeps the old grey matter working, you know the use it, or lose it.


That ship sailed quite some time ago...:sad:


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## de-nagorg (Feb 23, 2014)

Cynthia Moore said:


> I've been away for almost 2 weeks, so I can't go look at the bed for another 2 days. It seems to me that the blocks were nailed to the frame. I don't know if they were also glued. I could try to pry one loose to see.
> 
> What if I remove the blocks on one side of each slat, add the sister slat, then replace the block up against the sister slat?
> That was plan 1, but I thought that it might damage the rails too much, TRY IT.
> ...


 I'm fighting it myself.


ED


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## viper (Jul 30, 2009)

I think this little upgrade is getting too overthought. One thing you have to notice is the shear is OUT OF PLANE with the diaphragm. No matter what happens, you will notice the panel is being applied to the top of the slats. Shear occurs in the bed frame which then transfers up through the slats and into the diaphragm. This is NOT ideal in any way but probably the only way it will get done. You have to realize those slats will be in bending and will have a roll moment applied. The blocking in there to try to resist the roll. 

When you start adding up fasteners in the chain, you will induce play in the assembly. It will happen, especially when you consider bolting new members to the side of the slats, then screw to those. 

I still recommend adding small holes in the plywood where each of the slat bolts are, and gluing the sheet to ALL of the slats. Why you might ask? You need to look up why wood glue is the goto for structural wood work. It helps distribute the loads EVENLY to a level the wood can handle. It is stiff, cheap, and easy. 

In this case, I would decide if I was going to use several SMALL screws just to pull the plywood down to the top of the slats but I would not use screws that would even reach the neutral axis (middle) of the slat because max shear is seen there with vertical load. If it is glued, the wood will work to lift the neutral axis of the beam making the vertical load limit higher (ie, handle more vertical load), and counter act racking. 

I would NOT use construction adhesive! Why? If you have never worked with it, you will find it will get on stuff you don't want it on, and it doesn't like to come off. With a proper wood glue, you would just glue up, and use a wet rag to remove and excess. It is cleaner and well proven that slip performance is higher for wood glue. 

In any case, you have done an admirable job looking for solutions. I recommend researching wood glue bonding to see how it can be a game changer here. You are already talking about bolting things up to the slats which means a TON of work to undo all that if you need to disassemble. With my method, you would just unbolt the bolts that secure the slats and the slat/plywood come off as an assembly. 

There will certainly be 'some' roll in the slats but you won't avoid that. The little bolting thingies that connect the bed together can be He-Man tight but they will not resist racking. They will pull right out of the wood no problem.


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## BrownEyedGuy (Oct 2, 2018)

You can tell when someone is full of crap when they try to use as many technical sounding words as they can.


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## Cynthia Moore (Aug 14, 2015)

viper said:


> I think this little upgrade is getting too overthought.


Anything worth doing is worth overdoing. :smile:



> I still recommend adding small holes in the plywood where each of the slat bolts are, and gluing the sheet to ALL of the slats. Why you might ask? You need to look up why wood glue is the goto for structural wood work. It helps distribute the loads EVENLY to a level the wood can handle. It is stiff, cheap, and easy.


Do you mean drill holes over the holes in the slats where they are screwed into the rails? Because without those, if I glue the plywood to the slats, I would never be able to take it apart.



> I recommend researching wood glue bonding to see how it can be a game changer here. You are already talking about bolting things up to the slats which means a TON of work to undo all that if you need to disassemble. With my method, you would just unbolt the bolts that secure the slats and the slat/plywood come off as an assembly.


Would you recommend standard yellow glue or something else?


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## Cynthia Moore (Aug 14, 2015)

BrownEyedGuy said:


> You can tell when someone is full of crap when they try to use as many technical sounding words as they can.


Really? And how would an expert like you discern someone who is full of crap from someone who actually knows what they are talking about and uses the correct technical terminology? Are you saying that anyone who uses technical terms is full of crap?

Are your eyes brown because _you_ are full of crap?


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## BrownEyedGuy (Oct 2, 2018)

Cynthia Moore said:


> Would you recommend standard yellow glue or something else?


Neither. It's painted wood. 

I'm sorry to say, but you are getting fed a whole bunch of poor information here. It's Viper's standard M.O. to over complicate things. A real engineer tries to solve problems, not create them by chasing ridiculous avenues to sound important.


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## Cynthia Moore (Aug 14, 2015)

Two more questions:


What grade of plywood should I get?
If I end up screwing into the existing plywood slats, would it be good to use wood screw anchors? I found some that are fairly small (#6 or #8 screws and 3/4" long). They would require a larger hole in the slats, but would provide a much stronger and long lasting connection.


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## de-nagorg (Feb 23, 2014)

For your plywood sheeting, I would get it with at least one side sanded smooth, for the mattress to lie on, and not wear a hole.

As for screwing into the existing slats, I suggest that you get 1/2 inch dowel, make as many short pins as you will need to fill a 1/2 inch hole drilled into the slat and glue the plugs into the slat.

This gives you solid wood to screw to, and not the possible bad plywood veneering of the slat.

P. S. Don't get caught up in a feud between others.


ED


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## BrownEyedGuy (Oct 2, 2018)

de-nagorg said:


> As for screwing into the existing slats, I suggest that you get 1/2 inch dowel, make as many short pins as you will need to fill a 1/2 inch hole drilled into the slat and glue the plugs into the slat.
> 
> This gives you solid wood to screw to, and not the possible bad plywood veneering of the slat.


So you're recommending driving a wood screw into the endgrain of a dowel? Do you believe that wood screws are effective in endgrain? Don't you think that the threads of the woodscrew will cut the fibers of the dowel, thereby dropping its holding power to near zero, especially if it gets over torqued or removed and reinstalled even once, let alone several times as described by the OP?


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## de-nagorg (Feb 23, 2014)

BrownEyedGuy said:


> So you're recommending driving a wood screw into the endgrain of a dowel? Do you believe that wood screws are effective in endgrain? Don't you think that the threads of the woodscrew will cut the fibers of the dowel, thereby dropping its holding power to near zero, especially if it gets over torqued or removed and reinstalled even once, let alone several times as described by the OP?


It's done when a door hinge screw has stripped out.

True they are not taken out and replaced often.

Then if you object to dowel, how about using a plug cutter, and making your own plugs from an oak 2X?


ED


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## viper (Jul 30, 2009)

Cynthia Moore said:


> Two more questions:
> 
> 
> What grade of plywood should I get?
> If I end up screwing into the existing plywood slats, would it be good to use wood screw anchors? I found some that are fairly small (#6 or #8 screws and 3/4" long). They would require a larger hole in the slats, but would provide a much stronger and long lasting connection.


I am not sure if you intend to glue but in reference to the glue, PVA glue which is the old yellow glue will do just fine for this, low odor, cleans up easy, and just select a high end glue. This is not a high moisture situation and plenty of furniture is build daily with it. 

As for the screws, if you glue, the ONLY reason I mention screws is a means to assist in clamp force for a glue bond. Personally, I would look for a way to do this without screws at all. The screws will do very little to improve the structure and the glue will be doing the job. 

When you glue the edges of the slats to the plywood, that is a wood to wood connection. It will be sound. You want as much pressure in the bond as you can get but I would not try to install big screws to do that. I would just just countersink heads. They will sit flat enough with no extra countersink needed. 

Plywood selection probably won't matter too much but I would probably select APA rated sheathing 32/16. 

You asked about getting to the screws in the slats. As I mentioned, I would simply predrill holes in the plywood big enough to access those screws.


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## BrownEyedGuy (Oct 2, 2018)

Sure, but just how much more do you and viper want to over complicate this for her?


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> For your plywood sheeting, I would get it with at least one side sanded smooth, for the mattress to lie on, and not wear a hole.



The entire bed is painted white, so I was thinking about painting the plywood to match. That would also make it smoother.




> As for screwing into the existing slats, I suggest that you get 1/2 inch dowel, make as many short pins as you will need to fill a 1/2 inch hole drilled into the slat and glue the plugs into the slat.
> 
> This gives you solid wood to screw to, and not the possible bad plywood veneering of the slat.



That's an interesting idea. Is that better than wood screw anchors?




> P. S. Don't get caught up in a feud between others.


Phish. I grew up with four brothers. This is nothing.:smile:


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## Cynthia Moore (Aug 14, 2015)

viper said:


> I am not sure if you intend to glue but in reference to the glue, PVA glue which is the old yellow glue will do just fine for this, low odor, cleans up easy, and just select a high end glue. This is not a high moisture situation and plenty of furniture is build daily with it.


I like the glue idea. My only concern is being able to reassemble it again if I ever need to disassemble it. I'm worrid about being able to line up all those screw holes.



> As for the screws, if you glue, the ONLY reason I mention screws is a means to assist in clamp force for a glue bond.


Got it.



> Plywood selection probably won't matter too much but I would probably select APA rated sheathing 32/16.


Thanks


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## Cynthia Moore (Aug 14, 2015)

BrownEyedGuy said:


> Sure, but just how much more do you and viper want to over complicate this for her?


How about if you let _me_ worry about that?

This discussion, with a few exceptions, has been very enlightening and interesting and it has prevented me from doing things that could (a) actually make things worse and (b) be overly complicated and expensive. I am very grateful for the contributions.


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## viper (Jul 30, 2009)

If you like reading, this is one study I have in inventory that may help. You may not the results towards the bottom of a glued diaphragm with 1/2" ply. Note the minimal deflection and racking limits. Glued diaphragms are not as common in homes because they can be complicated to field repair, but they work. 

http://www.panelized.com/techlib/Do..._for_high_load_wood_structural_diaphragms.pdf

I doubt you will have much issue lining things back up but I will let you decide on that.


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## Cynthia Moore (Aug 14, 2015)

viper said:


> When you glue the edges of the slats to the plywood, that is a wood to wood connection. It will be sound. You want as much pressure in the bond as you can get but I would not try to install big screws to do that. I would just countersink heads. They will sit flat enough with no extra countersink needed.


Is this the gluing procedure you would use:


Get a bunch of flathead wood screws. I suggest #8 screws long enough to go about 1/2" into the slats.
Get a piece of doweling the same diameter as the screw holes in the slats where they are screwed into the rails. Cut into lengths that will be long enough to go through the plywood and into the screw holes and still protrude an inch or so above the plywood.
Cut the plywood to fit the inside of the frame as tightly as possible.
Lay it on the slats with one side pulled back enough to expose the ends of the slats. Make a mark on the top of the plywood at the center of each slat.
Lay it back down and pull up the other side to expose the other end of the slats. Make similar marks on that side of the plywood.
Connect those marks forming lines across the top of the plywood directly over the slats.
Drill a hole in one corner of the plywood over the screw hole of the last slat. Insert one of the dowel pieces.
Repeat this for the other three corners and then the rest of the slats.
Drill a pilot holes for one of the corner screws. Insert a screw and lightly tighten.
Repeat for the other three corners.
Drill the rest of the pilot holes. I don't think I need to insert the screws.
Remove the screws and the dowel pieces.
Remove the plywood.
Lay a line of glue on the edge of each slat. I assume is should be a snake-like line going from side to side.
Replace the plywood taking care not to mess up the glue lines.
Insert the dowel pins.
Insert the corner screws and tighten fully.
Insert the rest of the screws.
Let dry.
Repeat for other bunk.
Did I miss anything?



Note: Of the 8 slats, only 6 are screwed into the rails. The middle two have a wooden pin glued into the slat that fits into a hole drilled into the rail. I can't figure out why they did that. In the attached annotated photo, (A) indicates a rail that is screwed into the rail. (B) indicates one that has the pin.


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## viper (Jul 30, 2009)

I thought about this how I would honestly approach this job. Because of what this is and what it does, this is just what I would honestly do. 

1. Before you even throw the plywood in there, either use a pencil or masking tape and create a vertical line about the center of each slat on the interior of the bed frame. This is so you don't have to mess with pulling it up to guess where the holes go. 

2. Throw the sheet in and transfer the lines to the sheet. Strike a line across the sheet at each slat so you have your center mark for each slat. 

3. Measure the offset from the end of the slat to the center of the screw hole and transfer that dimension to the sheet so you know where to drill the holes. That whole bed was factory build so they will all be the same. 

4. Verify it all lines up good. Verify the sheet sits reasonably flat and in contact with all slats. 

5. Apply glue at the center of each slat and throw the sheet over them. 

6. Get happy with either a stapler or brad gun. Actually I would probably prefer short finish nails but run what ya got. Ensure you are getting clamping and squeeze out everywhere. If you have a tough spot, maybe throw a little screw there but it should work. I prefer to shoot face nails at an angle to increase withdraw strength. I would not even mess with screws. 


I don't know what the dowels are for but small penetrations from small nails will inflict the least damage to the slats and be very fast. It is never ideal to drive anything between the plys so the smaller the better IMO. Once the glue and panel kick it, they will reinforce that area.

OH, and PLEASE check your bed for square before you do anything. You want it "true before you glue".......lol


OH, I might also mention I have a little experience shooting plywood like this. I used to build plywood boxes for very expensive aerospace tools to be shipped across the country and glue and 16ga x 1.5" finishers made boxes that needed a sledge to destroy. It will work.


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## Cynthia Moore (Aug 14, 2015)

viper said:


> If you like reading, this is one study I have in inventory that may help.


That's quite an impressive report! Most of it is too technical for me to grasp without more study than I have time for. So I'll take your work for the effectiveness of glue.

A very long time ago, I worked in a cabinet shop when I thought I wanted to be a woodworker. One day we were discussing joinery. The owner gave me a little demo of how a glue bond is stronger than the surrounding wood. He glued two pieces of wood side by side. After it had cured, he broke it. The break was close to the glue line, but in the wood.


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## Windows on Wash (Aug 30, 2011)

I know I am a child at heart...but this is all I could think of when I saw this thread title.


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## Cynthia Moore (Aug 14, 2015)

viper said:


> I thought about this how I would honestly approach this job. Because of what this is and what it does, this is just what I would honestly do.


Thanks for a great list -- especially step 1. I was going to try to get the marks on the plywood after it was on the bed by pulling it back from each side. You way is much better. My inclination is to use a square.


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## Cynthia Moore (Aug 14, 2015)

I went over to Home Depot this morning and bought two sheets of 1/4" plywood, which I had them cut to size. When I got home, I cut notches for the corner posts and did a little sanding for a better fit.

Just laying the sheets in the beds made them much sturdier.

I also bought a couple of 1/4-20 inserts for soft wood and 14-20 x 5/8 flat head wood screws. Using piece of the scrap 1/4" plywood that was cut off the sheets and a piece of 3/5" plywood I had lying around, I drilled pilot holes on the 1/4" plywood and tap holes for the inserts in the edge of the 3/4" plywood.

I found a table online that recommends drilling the tap hole with a 23/64 bit, which I don't have. I have a 11/32 (22/64) and a 3/8 (24/64). I tried the 11/32 bit first. As I was screwing the insert into the tap hole, one of the sides broke off. It was then that I noticed that I had bought brass inserts. The ones I saw online were zinc, which I think is better (stronger) for nuts and bolts, no?

These inserts also use a flat screwdriver, whereas the ones I saw online had Phillips heads or hex drive. So I drilled the other hole with the 3/8 bit. That insert went in fairly easily. I then inserted the 1/4-20 x 5/8 bolt through the plywood sheet and into the insert. It tightened up nicely and the flat head bolt almost countersunk itself. Once tightened, it was very strong. I tried pulling up on the plywood sheet. I think the plywood would have broken before the insert would have given way or maybe the plywood would have split at the bolt hole.

I have attached a photo of the assembly.

Anyway, I think this is the way I want to go. But I think I should go with the next smaller insert and bolt. EZ Lok makes three smaller inserts:


```
Insert  Length  Bit size            URL
 8-32    0.39"    15/64    [URL]https://www.ezlok.com/ezhex-insert-800832-10[/URL]
10-24    0.51"     9/32    [URL]https://www.ezlok.com/ezhex-insert-801024-13[/URL]
10-32    0.51"     9/32    [URL="https://www.ezlok.com/ezhex-insert-801032-13"]https://www.ezlok.com/ezhex-insert-801032-13[/URL]
```

I am inclined to the 10-24 or 10-32. Does the thread count make much difference in this application?


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## Cynthia Moore (Aug 14, 2015)

PS: Yes, I know I drilled the insert hole off center. It's also not exactly straight. :-( I was in a hurry and I was holding the pieces together just with my hand. I'll be more careful on the bed and the slats are screwed down and cannot move around.


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## Cynthia Moore (Aug 14, 2015)

viper said:


> OH, and PLEASE check your bed for square before you do anything. You want it "true before you glue".......lol


What's the best way to do that? Measure each diagonal to see if they are equal? Do I use a tape measure?

I assume that just putting a square in each corner would not be accurate enough.


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## de-nagorg (Feb 23, 2014)

The square in each corner is good enough, also the diagonal measure , even a string on diagonal will work, if you don't have a tape measure.

Then the 3-4-5 rule. 

Many ways to " skin that cat".


ED


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> The square in each corner is good enough, also the diagonal measure , even a string on diagonal will work, if you don't have a tape measure.



The square in the corner is problematic, because of the corner posts. There isn't any place to put the square that is flush to both sides.




> Then the 3-4-5 rule.


I'd never heard of that. I do remember the 3-4-5 right triangle from high school geometry, but it never occurred to me to apply it this way. Cool.

I used a tape measure on the diagonals on both bunks. The bottom bunk was 83 1/2 x 83 3/8. The top bunk was 83 3/8 x 83 5/8. I don't know if that was off enough to be a problem, but I will trued them up before screwing the plywood base in place.

I did learn that the bunks, as designed, are not that stable. Without the plywood sheet in place, I was able to deform them by more than an inch. I would guess that over time, as they are pulled away from the wall to make the beds, that play would gradually weaken the joints. I feel much better about going to the trouble of adding the plywood base.


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## Cynthia Moore (Aug 14, 2015)

I have one more problem with these bunks. (Viper was right. We should have bought a better bed, but that ship has now sailed.) As shown in the attached photo, the bottom bunk has a hole in the center of the top of each corner post. The top bunk has matching holes in the bottom of the corner posts. They supplied 4 metal pins, but they are 25% smaller in diameter, so there is a lot of looseness.

According to my calipers, the diameter of the holes is 0.4", whereas the diameter of the pins is 0.3"

I am inclined to wrap the pins with duct tape so that they just fit. Is there a better way? Should I look for hardwood dowels?

These guys have dowels in both standard and metric sizes. They have them with 10mm (0.3937") diameters, but they only sell them in lots of 1,000 pieces. 

https://wood-dowel.com/wood-dowel-pins/metric-dowel-pins/

I imagine that the local hardware stores only have standard sizes. A 3/8" dowel is 0.375", which would be tighter than the metal pins.

Or are wooden pins not strong enough?


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## de-nagorg (Feb 23, 2014)

Yes that's sloppy. 

Might take some looking, but I would be going to a place like Grainger Supply, and having them look through their books and stockroom for pins that fit the current bore.

Or you can find a proper bushing for it there.

Duct tape will just work loose again, then you will have a mess of mashed tape in the bore that needs to be removed before you can use a new pin.



ED


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## SPS-1 (Oct 21, 2008)

Cynthia Moore said:


> According to my calipers, the diameter of the holes is 0.4", whereas the diameter of the pins is 0.3"
> 
> I am inclined to wrap the pins with duct tape so that they just fit. Is there a better way? Should I look for hardwood dowels?
> 
> Or are wooden pins not strong enough?



Should be able to get a more precise dimension from your calipers, but you can also use a drill bit or a screw (screw will be a few thousanths of an inch smaller than nominal) to determine the size of the bushing.


Wrapping with duct tape sounds like a good idea.


It appears the manufacturer concluded that wooden or plastic pin would not be sufficient. If the upper and lower bed are out of alignment by a sixteenth of an inch, that is only cosmetic. But they absolutely can not be allowed to separate. 


Keep in mind that a better fit of the will only be cosmetically helpful if both the upper and lower piece were drilled accurately in the center.


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> Yes that's sloppy.
> 
> Might take some looking, but I would be going to a place like Grainger Supply, and having them look through their books and stockroom for pins that fit the current bore.
> 
> Or you can find a proper bushing for it there.



Great suggestion. I called Grainger. The tech directed me to the list of pins and I found one with a 3/8" diameter, which they spec at 0.3751 to 0.3753. That's just 0.025 less than the diameter of the hole, which should be fine.

https://www.grainger.com/product/GRAINGER-APPROVED-Alloy-Steel-Dowel-Pin-2ME28

Perhaps the bed manufacturer left it a little sloppy to give me a little wiggle room in case I didn't get it assembled right.



> Duct tape will just work loose again, then you will have a mess of mashed tape in the bore that needs to be removed before you can use a new pin.[





> /QUOTE]
> OK


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## Cynthia Moore (Aug 14, 2015)

SPS-1 said:


> Should be able to get a more precise dimension from your calipers,


The actual caliper readings were 0.4010 and 0.3551. Is that more precise for you? :wink2: My point was that it's not a tight fit.



> Wrapping with duct tape sounds like a good idea.


I think I agree with d-n that duct tape would not be a long term solution. In any case, I found larger pins.


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## Cynthia Moore (Aug 14, 2015)

I picked up a couple of 10-24 and 10-32 inserts and 10-24 & 10-32 machine screws. I inserted one of each in either end of a piece of scrap plywood into the edge of some 3/4" plywood. I don't know if it's more solid than viper's glue, but it's very solid and it can be disassembled.

I think one on the end of each slat plus one or two in the middle will make these beds very sturdy.

Is there any reason why I should go with the 10-32 or the 10-24 over the other?


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## de-nagorg (Feb 23, 2014)

The finer threads will give you just a bit more metal to metal holding power.

Otherwise use whichever you want, but do it to all of them, none of this half and half stuff, that some people do.

I'm not saying that you do, I don't know.:devil3:

ED


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## Cynthia Moore (Aug 14, 2015)

de-nagorg said:


> The finer threads will give you just a bit more metal to metal holding power.
> 
> Otherwise use whichever you want, but do it to all of them, none of this half and half stuff, that some people do.



OK. I have the 10-32 inserts & bolts on order. The beds each have 8 slats so that's 16 slats for both beds. If I put 4 in each slat, that's 64 total.

I was able to get 100 EZ Lok hex drive inserts for $15.52 and 100 stainless bolts for $8.45 on Amazon. At Home Depot, 4 bolts were $1.18. That's $29.50 for 100. And 2 inserts were $2.97. That's $148.50 for 100 and they are lower quality than the EZ Lok. Home Depot may have larger quantities for less, but I didn't see them.




> I'm not saying that you do, I don't know.:devil3:


Me? Half and half? No way -- except maybe on my cereal. :wink2:


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## Cynthia Moore (Aug 14, 2015)

I think someone suggested adding a little epoxy to the bore hole before screwing in the insert for a better hold. Is this a good idea? The 3 I tested seem very tight and solid.


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## de-nagorg (Feb 23, 2014)

If you glue them, use Cyanoacrylate. ( Super glue), it holds great on both materials, and is less messy to get into the bore, as well as won't squeeze out and maybe plug the threads.

And just the tiniest drop in there.


Half n half on Wheaties, now that's good food. :biggrin2::wink2:


ED


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## Cynthia Moore (Aug 14, 2015)

OK. I have all of the fasteners and am ready to put it all together. My plan for the configuration of the screws is in the attached diagram. I'll be using 10-32 x 5/8 flat head php machine screws screwed into 10-32 x 10mm EZ Lok inserts.

My plan is to use 4 screws per slat evenly spaced starting about 3" from each edge to avoid the screws holding the slats to the rails.

Is that about the right number, too few, or too many?

To secure the plywood while I drill the pilot holes for the screws, I plan to drill pilot holes for small nails in each corner. Here's the procedure:


Measure the diagonals to ensure that the frame is square.
Drill a pilot hole at (A). Drive a nail into the slat.
Measure the diagonals to ensure that the frame is square.
Drill a pilot hole at (B). Drive a nail into the slat.
Measure the diagonals to ensure that the frame is square.
Drill pilot hole at (C) & (D). Drive nails into the slats.
Drill pilot holes for the 10-32 machine screws. Drive clear through the plywood and a little way into the slats.
Remove the nails and then remove the plywood base.
Drill bore holes into the slats for the inserts.
Screw the inserts into the slats.
Replace the plywood base.
Screw a machine screw into the insert at (A).
Measure the diagonals to ensure that the frame is square.
Screw a machine screw into the insert at (B).
Measure the diagonals to ensure that the frame is square.
Screw machine screw into the inserts at (C) & (D).
Measure the diagonals to ensure that the frame is square.
Screw in the remaining machine screws.
Is this the best procedure?


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## Nealtw (Jun 22, 2017)

I have not been following this thread. Just a few thought. 
The plywood will add as much strength here screwed down or not. 
If you want tighter pins you can find bolts that will fit just cut the heads off.


You talked about machine screws, what you what is #6 wood screws recessed heat. 


Place a screw in the two corners on one side check for square and screw one on the other side. good to go for the rest. 
For the first 3 screws drill the hole and place the screw before moving on. after the first 3 screws you can predrill all the rest.


There is a drill bit that gives you a tapered hole for the screw as well as room for the head. The depth of the drill is adjustable. 
See the pointed drill bit.


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## de-nagorg (Feb 23, 2014)

To cut down on measuring so often, I would get some pipe clamps, and clamp the frame square ONE time, and then pre-drill everything with the clamps in place. 

Get squared once, clamp , then drill, drill, drill.

And screw it all tight.

Remove clamps, and admire the work.


ED


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## viper (Jul 30, 2009)

LOL, all I have offered and linked is out the window and we are RIGHT back to where the first post was! Stick some fasteners in there! 

Yep, it will be stronger than it was. I guess my only recommendation at this point is make a drill jig. You already found out how that will work trying to drill plywood on edge....it won't. 

Someday way down the road, check those inserts when you move the bed. When you see the cracks parallel with the plies next to the inserts, think about it!


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## BrownEyedGuy (Oct 2, 2018)

viper said:


> LOL, all I have offered and linked is out the window and we are RIGHT back to where the first post was! Stick some fasteners in there!


Yup. And it's the direct result of you over complicating things in the first place. I've just been sitting back watching this trainwreck unfold.


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## BrownEyedGuy (Oct 2, 2018)

From a humorous standpoint, it may seem applicable to describe children's activities as "earthquakes", but from an engineering perspective, they are not the same. And yet Viper has been advising Cynthia using seismic structural reinforcement methodologies as though they should be applicable to a bunkbed. Children are not lateral forces...earthquakes are. He has sold you a worthless bill of goods on the basis of jargon and technospeak, all in an effort to sound more knowledgeable or important that he really is. 

With a cynical eye, go back and re-read everything he has said in this thread, and you will be enlightened to realize that it's all coming out of internet discussions for seismic reinforcement methodology for buildings, and has absolutely no applicability to the topic at hand. 

I would wager my real engineering degree that he is merely an "internet engineer"....meaning, he likes to read the internet, and thinks it makes him an engineer. No "real" structural engineer on God's green Earth would be trying to apply seismic engineering to a children's bunkbed. The forces involved are not the same, nor are the solutions, and not even remotely related. 

What he is right about, is the failure of your slats with the threaded inserts. I saw that days ago, but you made it pretty darned clear that you were not interested in getting proper answers to your questions. So I kept my mouth shut.

<Rant off> <Return to your Trainwreck>


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## viper (Jul 30, 2009)

Hey, I won't lose sleep because someone wants to compare education. What you WILL find is issues trying to actually put holes in what I have mentioned because you know I am right. 

You can sit back and feel justified, but its probably just a lesson for me to let people make their own mistakes. There is mention of drilling all the way through the slats vertically and installing bolts. Sure, I can say "that is not a good idea". It will sound like just an opinion so I try to explain why. if you are an engineer, you should understand it, but others don't obviously. 

If you will notice what I REALLY recommended was to toss the bed because I already know it is not built very well, but that ain't happ'n. I then recommend a very simple yet efficient way to repair with glue, but that is "overboard"? 

I give up. Because I must be an internet jockey, I must take my dreaming way too far because I actually do build the stuff and running structural tests.

BTW, you should maybe read the linked test data I shared in a prev post. That is NOT seismic work at all! That is diaphragm work that is directly related.


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## BrownEyedGuy (Oct 2, 2018)

viper said:


> There is mention of drilling all the way through the slats vertically and installing bolts. Sure, I can say "that is not a good idea". It will sound like just an opinion so I try to explain why. if you are an engineer, you should understand it, but others don't obviously.


I never condoned that either. But if memory serves me, you planted the seed for the idea due to your over complicating things in the first place.

But tell me this. How is treating the bed platform as a "diaphragm" (seismic strengthening term) going to help strengthen a bunkbed? Is that going to solve the original head-to-foot racking that you were originally concerned about when you brought it up?

That racking concern was real, but your solution was not.


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## viper (Jul 30, 2009)

A diaphragm is not seismic term! Yes, it is used extensively for seismic work though. Diaphragms are unknowingly EXACTLY how box wood structures get their strength. It is not by accident there are spacings stamped all over OSB as 48/24, 32/16, etc. A diaphragm is built as soon as you start throwing OSB or plywood over roof trusses and start nailing them. A diaphragm is also built as a shear wall in the interior of a home. 

If you will notice, for the "head-to-foot" racking, I simply advised to use a type of X brace on the back side of the bed. The problem is people don't know how and where to attach them and it gets frustrating to not want to share "why". The attachments of the X braces can have considerable shear in which how and where they are attached matters.......or not.......lol. 

If you notice in the first post, she wanted to use 1/4 ply and screw it down. Guess what she is going with? She is going to try to drill all those slats and add 100 screws and cause systemic ply separation, but my method of squirting yellow glue and throwing the sheet on it "over thinking it"? No, that is just me knowing how that thing will load up and how to efficiently manage the shear in a cheap/easy way. 

She mentioned the concerns of X plane racking when she moves the bed. The mattress box will get diamond in it because there is nothing to resist those forces.

Attached is another pic of some of the beams that were broke on that day. All with various construction methods and designed failure points. In each case, loads, deflections, and failure modes were predicted before tests and compared for consideration.


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## Cynthia Moore (Aug 14, 2015)

Nealtw said:


> The plywood will add as much strength here screwed down or not.


That's probably true, but I want it secured to the slats so the kid below can't kick it up.


> Place a screw in the two corners on one side check for square and screw one on the other side. good to go for the rest.
> For the first 3 screws drill the hole and place the screw before moving on. after the first 3 screws you can predrill all the rest.


That's more or less what I did.


> There is a drill bit that gives you a tapered hole for the screw as well as room for the head. The depth of the drill is adjustable.
> See the pointed drill bit.


Heh. Since I decided to go with inserts, I needed a bit that is 0.20" at the top and 0.24" at the bottom. I couldn't find anything like that. :smile:


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## Nealtw (Jun 22, 2017)

https://www.rockler.com/8-pro-tapered-countersink-bit
https://www.amazon.ca/Irwin-1882782...ocphy=9001484&hvtargid=pla-384686178381&psc=1


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## Cynthia Moore (Aug 14, 2015)

viper said:


> LOL, all I have offered and linked is out the window and we are RIGHT back to where the first post was! Stick some fasteners in there!


It is not correct to say that "we are right back to where the first post was". In that post, I asked what the best way to attach the plywood was. There were many suggestions. I settled on the inserts, largely because they would allow be to drill a smaller hole (both length and diameter) in the plywood. I took your advice not to drill all the way through and use a T-nut.


> Someday way down the road, check those inserts when you move the bed. When you see the cracks parallel with the plies next to the inserts, think about it!


Viper, you obviously have a lot of structural knowledge and I listened carefully to your suggestions. But I chose to go a different direction. You don't seem like someone who would appreciate feedback, so this may be futile. But your attitude made it difficult for me to take you seriously. Your tone seemed adversarial and condescending and it put me off. You started off by saying that no one ever listens to you and just does what they want. There may be a reason for that and I don't think it's because you don't know what you are talking about. I think you have a lot to offer, but you will get more followers if you give us credit for a few brains and for making our own decisions. My solution makes more sense for my situation. It would be nice if you would respect that.

I will check for those cracks, but I'd be willing to bet you that there won't be any -- barring an earthquake, which we do have around here. First of all, the beds will not get that much use. Second, they will be used by mostly small kids. Third, the youngest grandkid is 2. When she gets to 8-10, we probably will sell the beds or donate them. So I doubt they will fail while we have them.

Anyway, thanks for your insight. It was helpful.


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## Cynthia Moore (Aug 14, 2015)

BrownEyedGuy said:


> He has sold you a worthless bill of goods on the basis of jargon and technospeak, all in an effort to sound more knowledgeable or important that he really is.


Actually, I have found your contributions of far less value than Viper's.



> With a cynical eye, go back and re-read everything he has said in this thread, and you will be enlightened to realize that it's all coming out of internet discussions for seismic reinforcement methodology for buildings, and has absolutely no applicability to the topic at hand.


I see no basis for that.



> I would wager my real engineering degree that he is merely an "internet engineer"....meaning, he likes to read the internet, and thinks it makes him an engineer. No "real" structural engineer on God's green Earth would be trying to apply seismic engineering to a children's bunkbed. The forces involved are not the same, nor are the solutions, and not even remotely related.


If anyone is talking out of their *ss, it is not Viper.



> What he is right about, is the failure of your slats with the threaded inserts. I saw that days ago, but you made it pretty darned clear that you were not interested in getting proper answers to your questions. So I kept my mouth shut.


Actually, no, you did not keep your mouth shut. You kept popping off in your little petty war with Viper. Again, I found his contributions far more valuable than yours.


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## Cynthia Moore (Aug 14, 2015)

Nealtw said:


> https://www.rockler.com/8-pro-tapered-countersink-bit
> https://www.amazon.ca/Irwin-1882782...ocphy=9001484&hvtargid=pla-384686178381&psc=1


I was joking. For my inserts & machine screws, I need a smaller hole through the plywood and then a larger one in the slat. I couldn't find a drill bit that would drill a 0.20" hole through the plywood and then a slightly larger 0.24" hole underneath that one. :wink2:


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## Cynthia Moore (Aug 14, 2015)

OK. The job is complete -- for better or for worse. I've attached some photos.

The first two show the inserts in the slats. One is close up, the other back a little. Since the slats are now all uniquely matched to one spot in the frame, I labeled everything so they could be reassembled if they are ever disassembled.

The third shows the plywood base in place.

The last three show the completed beds made up with kid-friendly bedding. The bottom bunk will be for the Thomas the Train obsessed 4 year old. The top bunk will be for the unicorn loving 6 year old. They will be here this weekend to try them out.

Thanks to everyone who helped make this work. I would have done a much worse job without your help. Thank you.


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## Nealtw (Jun 22, 2017)

Cynthia Moore said:


> I was joking. For my inserts & machine screws, I need a smaller hole through the plywood and then a larger one in the slat. I couldn't find a drill bit that would drill a 0.20" hole through the plywood and then a slightly larger 0.24" hole underneath that one. :wink2:


 Why are you using machine screws?


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## de-nagorg (Feb 23, 2014)

Cynthia Moore said:


> OK. The job is complete -- for better or for worse. I've attached some photos.
> 
> The first two show the inserts in the slats. One is close up, the other back a little. Since the slats are now all uniquely matched to one spot in the frame, I labeled everything so they could be reassembled if they are ever disassembled.
> 
> ...


You're welcome, it was a pleasure watching this project become reality.

I also enjoyed your retort to the " war of the nerds".

I do hope that the grandkids appreciate your efforts someday, to keep them safe.


ED


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## Cynthia Moore (Aug 14, 2015)

I want to thank everyone for the help. The beds have been in use now for over 2.5 years. They have gotten more use than I expected and more "energetic" use. The grandkids are now 4, 6, & 8. The 4 year old sleeps on an air mattress on the floor. One night I heard something in there and found all three of them dancing on the top bunch with a disco light going on the floor.

And the kids love them. The 8 year old is into rainbows and unicorns. She has the top bunch with sheets and blankets with that theme. The 6 year old is into Thomas the Train. He has the bottom bunk with sheets and blankets with that theme. They love to go in there and watch their iPads or read books on their beds. When we go visit them, they beg to come to our house. So all the work was worth it.

The beds have held up perfectly. Very sturdy.

Thanks


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