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I could use some help figuring out the joint at the legs for a knockdown, split top Roubo bench.

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Forum topic by SpacemanSpiff23 posted 07-23-2021 02:28 PM 1196 views 0 times favorited 13 replies Add to Favorites Watch
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SpacemanSpiff23

5 posts in 61 days


07-23-2021 02:28 PM

Topic tags/keywords: workbench roubo split top mortise and tenon question

I’m in the design stage of my first workbench. I haven’t done a lot of joinery, so I’m a little stuck on some of the mortise and tenons. I’m probably overthinking a lot of this, since I’ll be using solid white oak 6×6s, and everything will be overkill anyway.

My question is about the joint between the legs and the upper stretchers. My initial thought was a standard mortise and tenon(blue). But then I thought that a half lap (red) would be better since its a larger weight bearing surface, and it doesn’t undercut the tenon going up through the bench top. But I never see anyone do this style, and that makes me nervous. Is it just for aesthetic reasons that half laps aren’t used here? If that was the case, I could go with the green option and hide the end grain. Finally, I thought about the mortise being larger (yellow) and removing the lower shoulder on the stretcher. But I’m worried about getting too close to the hole for the vise.

Could some one with some experience give me some advice? Thank you.


13 replies so far

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SMP

4715 posts in 1118 days


#1 posted 07-23-2021 02:45 PM

for knockdown, you can leave the left and right “trestles” intact. unless you are trying to ship them or something?

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SpacemanSpiff23

5 posts in 61 days


#2 posted 07-24-2021 03:07 AM



for knockdown, you can leave the left and right “trestles” intact. unless you are trying to ship them or something?

- SMP


That was the plan. They’re still going to be heavy as lead, but movable.

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Sycamoray

95 posts in 453 days


#3 posted 07-24-2021 04:10 AM

Caveat: I made a sorta roubo-ish bench, not a split top roubo. So I may be missing something.

That said, I would favor the mortise and tenon. The half lap is only strong in the vertical dimension, with only glue in the horizontal. Yes, I know glue is very strong. I still prefer heavy joints that are entirely enclosed.

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SMP

4715 posts in 1118 days


#4 posted 07-24-2021 05:18 AM

i think the main reason you see what you normally see is that the legs a lot of times form the double dovetails or sliding-dovetail-tenon into the top. so if you did a half lap there it would get kind of wonky cutting into the side of the tails. if you aren’t doing the traditional joinery then what i think you are proposing would be fine. though i would probably make it a dovetailed half lap to keep it captive.

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Robert

4714 posts in 2693 days


#5 posted 07-24-2021 11:47 AM

If the leg is tenoned into the top, why do you need an upper support at all?

If it were me, I’d eliminate the tenoned top and just build 2 trestles. The cross braces can me tenoned and pinned. Pins can be hammered out for disassembly. Joinery has to be tight.

And there’s nothing wrong with bolts, either.

-- Everything is a prototype thats why its one of a kind!!

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Sylvain

1349 posts in 3712 days


#6 posted 07-24-2021 01:49 PM

When the top is split, an upper support is needed.

IMO mortise and tenon resist better to rocking.

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

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SpacemanSpiff23

5 posts in 61 days


#7 posted 07-24-2021 03:41 PM


That said, I would favor the mortise and tenon. The half lap is only strong in the vertical dimension, with only glue in the horizontal. Yes, I know glue is very strong. I still prefer heavy joints that are entirely enclosed.

- Sycamoray

I think this is how I’m going to go. The more I look at the drawings the less I like the half lap. The tenon looks much less likely to move side to side.

View Ed Weber's profile

Ed Weber

74 posts in 95 days


#8 posted 07-24-2021 10:02 PM

Not being a 16th century woodworker, I’ll add my 2 cents.
Two trestle ends with upper and lower stretches, wedged through tenons..
The top can be attached by dowel/pegs.
There is not real benefit to integrating the top into the base, especially since the objective is “knockdown”
Two trestle assemblies,
4 stretchers (this gives the base stability without relying on the top for structural support)
2 top halves

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Aj2

4029 posts in 3011 days


#9 posted 07-24-2021 10:41 PM

I made a open bridle joint for my bench top. I used dowels through to hold them in place mine go the long ways with large dowels that aline base and top.

Good Luck

-- Aj

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SpacemanSpiff23

5 posts in 61 days


#10 posted 07-25-2021 12:16 AM

I’m really liking the idea of tenoning the top to the legs. I might not go all the way through, but the massive stability that it would provide makes me feel good. Plus, I don’t have an unlimited supply of oak to make 2 more long stretchers.

Aj, with the bridle joint do you feel like it wants to rack at all because there there are no upper and lower shoulders?

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Sylvain

1349 posts in 3712 days


#11 posted 07-25-2021 10:01 AM

with the bridle joint do you feel like it wants to rack at all because there there are no upper and lower shoulders?

This is how it is made on a Moravian Workbench. But if you want the legs to be tenoned in the top, bridle joint is not an option.
See top of leg assembly of the Moravian (with pegs for the top) I made for the son:

Note: no upper stretchers on the Moravian but the leg assemblies are inclined.

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

View controlfreak's profile

controlfreak

2730 posts in 814 days


#12 posted 07-25-2021 10:24 AM

Sylvain, I was just going to say that this Roubo build is starting to sound like a Moravian build but you beat me to it. In its classic form a Roubo is not designed to be moved but the Moravian is designed to be moved without difficulty. I am a big fan of the Moravian bench but if that doesn’t suit I have seen some Roubo variations that were done to allow for modern day realities like moving or getting out of a basement if needed. Most of the ones I have seen rely on treaded rods & bolts. Good luck on solving this puzzle.

View EarlS's profile

EarlS

4724 posts in 3561 days


#13 posted 07-25-2021 11:31 AM

I’m in the process of building the Benchcrafted version of the Roubo split top bench. The plans suggest M&T and drawboring pins if you want to disassemble the legs. I went with glued M&T and pinned them. You will want the strength and support for the top since it is 4” thick. Had I thought about it, I would have used split thru tenons and wedged them with an accent wood (legs are cherry, stretchers are walnut). My point? Consider what you want the finished leg details to look like.

I’m still slowly working thru the build. I have a blog of the build that is ongoing. There are numerous blogs from others plus plenty of roubo build projects, and even a workbench smackdown forum.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

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