# Drawbridge...?



## DangerMouse (Jul 17, 2008)

Runner6939 said:


> However, I'd like to devise a drawbridge style door / ramp, and I'd like to utilize a garage door opener so that it's automatic.


Hi and welcome to the forum.

My first question would be "why?" and then "for what purpose?" 
A drawbridge type door? To drive in a riding mower? 
To keep out the huns and elephants? :laughing:

DM


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## Runner6939 (Nov 7, 2011)

A couple of reasons why:

1) Door and ramp all-in-one = Efficient use of space in getting the rototiller and/or little wagon in and out of the shed. 

2) It'd be different. 

3) And awesome. 

Practicality might suggest doing something more along the lines of tradition or status quo. However, my young boys and I like a challenge & we think it'd be super-cool to make our door this way. 

So in summary, no really good reason.


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## DangerMouse (Jul 17, 2008)

Welp..... do you HAVE a garage door opener? I have an old one outside from a job that still works.... 2 remotes too! :laughing: Try Craigslist to find a used/broken one. (Good luck though, keywords "garage door openers" brings mostly used car ads.) Your project sounds like fun though! I wish you luck!

DM


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## awallace (Feb 6, 2012)

I would actually be interested in this answer as well. I've built my shed and it has the drawbridge door. I am currently using a counterweight system to help aid in opening and closing the door for my wife. I can either get the weight to where she struggles to open the door but can close it, or can open the door easily, but struggles to close it. I have seen A video online (http://www.youtube.com/watch?v=xWBSrAcF-P4) that shows the possibillity of making it automatic, but I can't figure out:

1. What kind of winch set up this person uses (I assume that a garage door opener will NOT do the trick because a garage door motor itself doesn't actually do much lifting: it's all in the springs above the door itself.) beyond the fact that it's wireless (though I would be greatly interested in know exactly what kind is used here.
2. How the opening for the door is designed/engineered to allow the door to open and close completely, yet be weatherproof? I feel like it would stick to a point where the door wouldn't freely open without being pulled first, THEN dropped using the winch.


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## Runner6939 (Nov 7, 2011)

awallace, I've been giving this a lot of thought, and here's what I've come up with so far -



I've decided against the counterweight solution, simply because I think the automatic solution (if I can figure it out) is just a little more awesome.
A garage door opener motor would be mounted on the ceiling, in line with the door from the inside. I think it needs to be a chain-drive, because the chain will need to be shortened for this to work.
Over the header of the door, there will need to be installed a round steel axle with a sprocket on it to accept the chain. So at this point, we'd have the motor connected to the sprocket, so that when the motor turns one way or the other, the steel bar (axle) will turn as well.
Now, on either end of the axle, we'd need a cable reel. Each cable wound on each of these reels would be attached to the door. In theory at this point, if you spun the motor on the opener, the two cable would either pay out or retract, thereby raising or lowering the door.
You would, of course, also need counter springs on the door as well, because, as you correctly pointed out, a garage door motor isn't really strong enough to raise a garage door by itself - It's actually the springs that do this.
I think that by making the door close past the plane of the wall, into a slight recess, that it would go a long way to being weatherproof. With the right flashings and dripedges around this opening, a minimal amount of weather would be able to get past the door.
My plan this winter was to find a used chain-drive garage door opener on Craigslist, and fiddle with it in the garage, so that I'd have all my ideas sorted out by springtime. However, here in New England, there really hasn't been a "winter", so to speak, so I haven't done this yet. There are, however, plenty of them available out there.


Let me know what you're thinking - You're the only weirdo who's even responded to this question, much less built something similar...!


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## bcgfdc3 (Jan 28, 2012)

Hi,
I have never done this but the idea seems pretty simple. You could use the tortion springs and cables from a regular garage door and they make a tortion spring drive motor. When you set it up, the springs have no torque on them at all so as far as your door weighing less than a regular door is not an issue. You can adjust the springs to work with the weight of your door. (or no tension at all) Just don't torque them as tight as you would for a regular door. You would hang the spring and pulleys with the cables at the top of the opening, then run the cables to eyelets at the top/end of your ramp. you could probably cut the rod of the tortion spring shorter and get away with only one spring if any at all.

The possible problems are: 1) you need some way to force the door out of 90 degrees when it is closed so that gravity can take over when you want it to open. Possibly a spring loaded hinge could do this as there would be no real stress on it. 2) The other problem is the cables may be in the way. when the dor is down.

That is just my thoughts. ope it helps.


Other than that is seems pretty basic.


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## Runner6939 (Nov 7, 2011)

Those are all pretty good thoughts, with which I agree for the most part.
However, I'm torsion-spring averse, for a couple of reasons: First, I think they can be extremely dangerous. For some reason, I think that extension springs are less dangerous, especially the long, low torque ones that I'm considering for this project. Second, if I did it this way, it wouldn't be automatic in the way that I'd like it to be.

All in all, I agree with you that it can be done this way, and I appreciate your thoughts - They're right on.

I'm just Type-A enough though, that I'm not giving up on the automatic garage door opener idea...


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## Beepster (Oct 19, 2009)

Runner6939 said:


> However, my young boys and I like a challenge & we think it'd be super-cool to make our door this way.


Give each of the tykes a shovel and tell them to get going on the moat.

B


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## WillK (Aug 29, 2010)

Your door needs to be sturdy enough to not deflect under the weight of what you roll over it, lest the door dip and cause you to have to roll up hill. Hence, a properly designed door will have some weight.

A garage door openner operates to raise a door that is counterweighted to be light-ish. Sometimes that counterweight is done by spring. You can do it with weights, but don't just do it with weights hanging off a rope that will lead to a constant amount of counterweight, the door will slam shut and not drop open if you use the openner to open.

So your counterweight will connect to the drawbridge by some cable. Have the cable attach to a spool or something such that the spool turns an arm, and the counterweight hangs off the arm, and the arm provides the most counterweight when the drawbridge is most of the way down... And maybe the arm will be pulling the door open when the drawbridge is all the way up.

Now... naturally, a typical drawbridge has a chain or cable on each side, and it might seem natural to put the garage door openner on one side and the counterweight chain/cable on the other. This will put a twisting moment on the door, and if your space is constrained to the point this is necessary, then design the door accordingly to resist twist. Elsewise, it will be better to have the counterweight acting on the garage door chain, and the garage door chain acting somehow on both sides.


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## ghostlyvision (May 11, 2011)

Runner6939 said:


> However, my young boys and I like a challenge & we think it'd be super-cool to make our door this way.
> 
> So in summary, no really good reason.


 
You sound like an extremely fun Dad, hope you'll post pics once you get the drawbridge accomplished. :thumbsup:


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## Msradell (Sep 1, 2011)

If you could find something like this it would certainly make things easy!
http://www.tractorsupply.com/mighty-mule-reg-single-swing-automatic-gate-opener-fm350-3602275


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## robertwf (Feb 12, 2012)

*Drawbridge*

I dont have any real practical ideas or advice. The only thing I could reccommend is to llok at the past. my hero is Thomas Jefferson, Remember he was an architect. I went to Montecello and was blown away by his ingenuity. I hope this helps


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## mjbmw330ci (Apr 8, 2014)

*Any Success?*

Runner et.al, did anyone successfully build this? I found this thread today while looking for drawbridge shed door plans, but it seems that this topic lost momentum quite some time ago.. FYI, I saw electric remote control winches online (1100 lb capacity) and wondered if that was the solution (seemed a lot easier than building it with garage door parts)... any info would be great. thanks!


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