# making dado cuts for pergola beams



## cherry_560sel (Dec 6, 2010)

I want to build a pergola, but I don't want the cross beams just resting on top of the support beams (I know there is a word for that method, I just don't know what it is :huh. Anyhoo, to make the dado cut on a 2x8x12 I would need a helper to hold the board if I were to use a table saw, and I would need to purchase a good dado blade set. Can I use a circular saw to make the dado instead. That would save me the expense of a dado blade. Also, would a router be a better option to do this? I would rather spend money on a router, which I can see myself using more than a dado blade set which I think would be used rarely. Most important for me is that I get good results and the pergola look good so I will shell out the cash if a dado blade is the way to go. Just want some opinions from those of you that have the knowledge and experince. I have attached a picture so you can see what I am trying to do. Thanks in advance for your advice


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## vsheetz (Sep 28, 2008)

A Skil saw to make the bulk of the cuts, then a sharp chisel to finish.

I put my support beams above as I did not want them protruding down into the sight line. Used what I call hanging posts.
Pictures at: http://www.webjeepers.com/homestead.html


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## mrgins (Jan 19, 2009)

You can make several cuts in each notch with a circular saw which makes it easier to chisel out


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## WirelessG (Mar 22, 2009)

Look at how much material you want to hog out. Dado blades only have a couple inches of stroke. A router will require a few passes and probably from both sides of the 2x8. I agree with the other posters on the circ saw and chisel approach.


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## Ron6519 (Mar 28, 2007)

Using a table saw will be dangerous. Move the tool, not the wood.


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## cherry_560sel (Dec 6, 2010)

yeah, I was thinking the same thing. Moving a long board like that on a table saw would be too hard. Kewl, I think I will use the circ.saw and chisel to make these cuts. Appreciate the wise words. :thumbup:


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## 12penny (Nov 21, 2008)

Ditto on the table saw and dado blade.

I'd cut with circ saw to line, finish cuts with jig saw, knock out waste then square up with chisel.

If you have a router and straight cut bit, you can also make a template and cut them that way. Use your chisel to square up corners.


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## jschaben (Mar 31, 2010)

cherry_560sel said:


> I want to build a pergola, but I don't want the cross beams just resting on top of the support beams (I know there is a word for that method, I just don't know what it is :huh. Anyhoo, to make the dado cut on a 2x8x12 I would need a helper to hold the board if I were to use a table saw, and I would need to purchase a good dado blade set. Can I use a circular saw to make the dado instead. That would save me the expense of a dado blade. Also, would a router be a better option to do this? I would rather spend money on a router, which I can see myself using more than a dado blade set which I think would be used rarely. Most important for me is that I get good results and the pergola look good so I will shell out the cash if a dado blade is the way to go. Just want some opinions from those of you that have the knowledge and experince. I have attached a picture so you can see what I am trying to do. Thanks in advance for your advice


 
I'm gonna vote for the router. Sure, it will take multiple passes but I think you will get a better looking joint. For one thing, most dimensional lumber I've delt with use a 1/4" radius to soften the edges. Make that cutout with a 1/2" bit and the beam will fit perfectly with no little square corner right there. 
Also, if you use guide strips and bushings you can get a dead bang fit. It does take a bit longer but, IMO, the results are worth it.


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## tcleve4911 (Nov 6, 2010)

One added tip
Take all the rafters and and gang them together with the bottoms facing up on your sawhorse. Clamp them together.

With your framing square, mark the width of your dado cut and then set your circular saw to the depth of cut.
Make two passes and you have all your shoulders cut at the same time.
Unclamp and finish the cut with a good jigsaw.
Final cleaning with a chisel if needed.

This method guarantees that all the rafter tails will be exactly the same and your purling beam will be straight.


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## Thurman (Feb 9, 2009)

First: "vsheetz", I like your "hanging post" idea, that does look really good and I can see how all of this interlocks for strength. I have built a few Pergola's and have learned a few things doing these. IMO: A dado blade in a table saw just will not cut deep enough for what most people want. I have never tried to use a router to do these, and this seems like a lot of work as most boards are going to be 1 3/4" to 1 7/8" thick. One method I learned and really like takes practice, but works for me. Draw out the dado cut you want to make, and all of them you want to make any one board. Use a spade drill to make a hole through, almost as wide as the cut you want, and almost near the top of the cut. Use your skilsaw to cut out the lines from the edge of the board to the hole area, not cutting any beyond you lines drawn. Use a jig saw to finish out these cuts. The will be neat, squared corners, and should fit snugly with the other board they intersect with. I've used these for two inter-locking boards and it looks really neat.


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## cherry_560sel (Dec 6, 2010)

THat sounds like a good plan too. So what do you think about the Titan post anchor? Have you ever used it for any pergola installs. I will be placing the 6x6 posts on an existing concrete slab and the post anchors from strongtie don't look to have much holding power to them.


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