# Mortise width and depth



## DMassengill (Oct 15, 2021)

Hey, relatively new to serious wood working but wanted to get advice on how wide and deep a mortise should be on a 5x5 table leg for connecting a 2x4 apron? Overall table size will be 40"x96".


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## Rebelwork (Jan 15, 2012)

Are you going to use corner hardware?


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## DMassengill (Oct 15, 2021)

I wasn't planning on using any corner hardware, just mortise and tenon joinery.


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## DrRobert (Apr 27, 2015)

2/3 the depth is pretty typical. I think you’re looking at a 3” depth. Personally I pin all my tenons on tables.

You don’t want the tenon to got all the way through the top of the leg. You can do a haunched tenon if you want, I’ve never seen the purpose tho.

Shoulders add a lot of strength I’d go 1/2” on those.


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## DMassengill (Oct 15, 2021)

Perfect! Thank you so much!


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## BigCountry79 (Jun 2, 2021)

That is pretty massive. I would go 1" x 3" as well. For tenons, I normal go for half to a third of the width of the apron.


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## Rebelwork (Jan 15, 2012)

DMassengill said:


> I wasn't planning on using any corner hardware, just mortise and tenon joinery.


You need to support the two aprons with a angle metal or wood bracket. I one time kicked a corner leg and broke the joint. Never again...

But its you table...


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## TimPa (Jan 27, 2010)

personally, i would get it away from the edge - too close, weakened piece thats left. 

1" thick and 1 1/2" - 2" deep for me, then pinned. i also wouldn't go all the way to the top of the leg.


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## Tony B (Jul 30, 2008)

TimPa said:


> .............
> 1" thick and 1 1/2" - 2" deep for me, then pinned. i also wouldn't go all the way to the top of the leg.


A 2x4 already only being 1 1/2" thick, a 1" tenon would leave only 1/4" shoulder on each side.
Wouldn't you be losing some of the 'locking' of the tenon in place.
I am assuming this is a pine 2x4 because the photo looks like pine and he referred to it as a 2X4. That terminology would not be used with hardwoods.


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## DrRobert (Apr 27, 2015)

If you do the joinery right you don’t need brackets.

The usual formula for tenon width is 1/3 the board width. Depth has more to do with application. For a table leg, a depth 2/3 - 3/4 the width of the leg is typical. IMO 3” minimum. Thats a deep mortise best done by machine. Too deep for router, if he doesn’t have a mortiser, drill & chisel.

2” apron = 5/8-3/4” tenon + 5/16 side shoulders. 1/2l shoulders at top. The side shoulders are cosmetic, they just hide the joint. However the shoulders too and bottom at a lot of strength. 

This would be a good situation for draw bored pins.

Nomenclature gets confusing sometimes. In the case of this table I consider the side shoulders cosmetic and the top and bottom ones structural.


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## Rebelwork (Jan 15, 2012)

DrRobert said:


> If you do the joinery right you don’t need brackets.
> 
> The usual formula for tenon width is 1/3 the board width. Depth has more to do with application. For a table leg, a depth 2/3 - 3/4 the width of the leg is typical. IMO 3” minimum. Thats a deep mortise best done by machine. Too deep for router, if he doesn’t have a mortiser, drill & chisel.
> 
> ...


I've seen the leg joints break when being kicked or dragged just in the shop. We started protecting ourselves by using more support in the corners. A couple dollars or a little more wood support goes a long way.


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## DrRobert (Apr 27, 2015)

Rebelwork said:


> I've seen the leg joints break when being kicked or dragged just in the shop. We started protecting ourselves by using more support in the corners. A couple dollars or a little more wood support goes a long way.


What was the joinery that failed? I don’t see a metal bracket saving a properly done M/T joint. Do production shops even do mortise and tenon joinery? What manufactured tables I’ve seen use a hangar bolt and metal bracket the aprons aren’t even attached to the leg. Needs to broken down for shipping.

If a couple gorillas drag a table around sure, lots of legs will break. Not my tenons, tho LoL.


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## Rebelwork (Jan 15, 2012)

We shipped ours whole. No break down. Originally it was in bar stools. You can see them to the right. They had the famous Dominos. Built 700 and replaced 700 for Chilli's restaurants I won't do a corner table with extended legs without additional support. Just a habit of covering my butt...


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## DrRobert (Apr 27, 2015)

If it was Domino XL ok you have an actual floating tenon there.

People try to use a Domino 500 for joinery - meh….. I had one and sold it. For me it was a glorified biscuit joiner. 

For face frames too much set up I do them with pocket screws now. I experimented with “through tenons” in drawers using Dominos. It could have worked if I had a production shop, no good in plywood, though.

I bought it 3 yrs ago for $850 and it sold on EBay in 3 hrs for $1100.


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