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Mortis & tenon for bench legs

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Forum topic by Michigander posted 08-04-2017 02:30 PM 358 views 0 times favorited 3 replies Add to Favorites Watch
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Michigander

220 posts in 2253 days


08-04-2017 02:30 PM

Topic tags/keywords: mortise and tenon bench joinery

I am making a 72” long bench of cherry with a painted pine spindle leg base. The legs are 2-1/4” square pine and the aprons will be 3/4” pine. My thought is to mortis into the legs for the aprons but I am concerned for the integrity of the legs.
What would you recommend for the size of the mortis in thickness and depth? Should I make it so the tenons meet each other at 90 degrees inside the leg. Any tips to make this bench more solid?
Thanks for your advice.
Best regards, John


3 replies so far

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Rich

1973 posts in 423 days


#1 posted 08-04-2017 03:15 PM



Any tips to make this bench more solid?
Thanks for your advice.
Best regards, John

- Michigander

John, depending on what you intend to use it for that might be too lightweight, irrespective of the strength of your joints. If it’s going to be mainly used as a table to assemble on, that’s fine, and 1” to 1-1/2” tenons will be plenty.

However, if you intend to use it as a real workbench to work wood on, like planing, etc, it’s too light and will tend to slide around. You can add weight by putting in a bottom shelf and loading it with power tools, or whatever you have to store there, but I’d consider beefier legs and aprons. I’d add stretchers too.

-- No matter how much you push the envelope, it'll still be stationery.

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Michigander

220 posts in 2253 days


#2 posted 08-04-2017 03:37 PM

Rich, thanks for the reply. I’m sorry I wasn’t clear. The purpose of the bench is to go with a dining/ kitchen table. It’s 72” long x 14” wide. Considering the stress from people sitting on it should the tenons be 1/2” thick?

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Rich

1973 posts in 423 days


#3 posted 08-04-2017 03:55 PM

lol, I hear bench and think one thing. The tenons really only need to be beefy enough to help eliminate racking. The shear strength on even a 1/4” tenon will be enough to support that load, plus, I assume the bench top will be resting on the tops of the legs, so that reduces shear even more.

The big thing to keep in mind is the height of your aprons, so you don’t get a lot of sag. Also, I mentioned racking. That’s one of the things that will cause problems, so I’d strongly recommend stretchers to help with the stability of the legs. Since people are sitting on it, you probably don’t want box stretchers, since that will get in the way of their feet. Look at “H” stretcher design to offer more leg room. You can google that to see what I mean.

Edit: You can also consider leg brackets to attach the legs to the aprons. Not as cool as M&T, but they work:

-- No matter how much you push the envelope, it'll still be stationery.

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