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Table leg tenon

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Forum topic by KelleyCrafts posted 02-22-2017 05:42 PM 531 views 0 times favorited 19 replies Add to Favorites Watch
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KelleyCrafts

2681 posts in 579 days


02-22-2017 05:42 PM

All, I’m making some table legs that are wide, you’ll see something similar in the pic. I was curious how deep the mortise and tenon should be to join the base piece with the top contrasting wood?

Any input is appreciated.

-- http://kelleycrafts.com/ - pen blanks - knife scales - turning tools


19 replies so far

View wuddoc's profile

wuddoc

234 posts in 3558 days


#1 posted 02-22-2017 11:46 PM

Are you:
1. Discussing a conference room table?
2. Considering an underside top supporting structure of rails with mortises?
3. Considering legs mortised directly into the table top?

-- Wuddoc

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KelleyCrafts

2681 posts in 579 days


#2 posted 02-22-2017 11:52 PM

Good questions I should have answered. The table will only be 7’ long, nothing this long. What I was refering to on the mortise and tenon size would be the depth of the bottom part that’s clearly a different wood attached to the longer leg parts up to the table.

As for the whole leg section, it would be attached to railed structure with cross beams mortise and tenon to each other as well. Then the top would be secured to allow movement.

So mainly the pieces that form the leg….I’m curious if 1/2” would be enough or if I should have more. I’ll have a trestle like this one plus the top support structure so it should be very sturdy but I don’t want this to be the breaking point.

-- http://kelleycrafts.com/ - pen blanks - knife scales - turning tools

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a1Jim

116594 posts in 3417 days


#3 posted 02-23-2017 12:05 AM

I assume you’re talking about the base pieces M&Ts not connecting the top to the base with M&Ts(not a good idea ? Depending on the width of the horizontal and vertical pieces, if that’s the case I would suggest tenons somewhere in the area of 1/3 the width of the material.

-- http://artisticwoodstudio.com Custom furniture

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KelleyCrafts

2681 posts in 579 days


#4 posted 02-23-2017 12:09 AM

Thanks Jim. I am talking about the base piece that holds the trestle and attaching it via tongue and grove/M&T to the other two leg pieces on either side of it. The material will be 6/4, haven’t decided definitively on the width yet, I’ve been drawing designs to see what I like.

-- http://kelleycrafts.com/ - pen blanks - knife scales - turning tools

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wuddoc

234 posts in 3558 days


#5 posted 02-23-2017 01:30 AM

Jim is spot on referencing the sizing of 1/3 as each shoulder is 1/3 the width of the rail leaving 1/3 for the tenon.

A blind or stub tenon length from the shoulder might be at least 1/2 the wood thickness but not to exceed or allow the tenon to go entirely through. A chamfer is helpful all around the tenon end to ease entry into the mortise.

The lower connector (rail) of the legs might be a stub or blind mortise-and-tenon joint however by enlarging the picture you included, each rail and or leg(s) has a radius. If that is the case I am not sure what type of joint would be used to connect the rail and leg(s).

Please note a 1/16” to 1/8” gap between the length of the tenon and the depth of the mortise allows for excess glue. With no place for the excess glue when you are pushing the tenon into the mortise, hydrostatic pressure occurs and can force the glue out of the wood at some point where the cell leg grain structure is weakest.

If you are asking about the bottom unit (stretcher) connecting the pairs of legs from the front of the table to the back it may be a open mortise-and-tenon joint, dado, dovetail, or combination of these joints used for design emphasis.

-- Wuddoc

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KelleyCrafts

2681 posts in 579 days


#6 posted 02-23-2017 04:44 AM



The lower connector (rail) of the legs might be a stub or blind mortise-and-tenon joint however by enlarging the picture you included, each rail and or leg(s) has a radius. If that is the case I am not sure what type of joint would be used to connect the rail and leg(s).

- wuddoc

This is what I’m talking about. I think it’s tongue and groove and was thinking about doing just that by am unsure it’s going to be strong enough.

-- http://kelleycrafts.com/ - pen blanks - knife scales - turning tools

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a1Jim

116594 posts in 3417 days


#7 posted 02-23-2017 05:28 AM

I still see no problem with the use of M&T joinery for the bottom rail it will still be plenty strong as far as a radius is concerned the M&T can be made before the member’s radius is milled. In my opinion, the bottom stretcher has far less stress than the top stretcher below the table top. Both should be plenty strong with the use of M&Ts or a saddle joint perhaps with the addition of pegs or even a sliding dovetail.

-- http://artisticwoodstudio.com Custom furniture

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KelleyCrafts

2681 posts in 579 days


#8 posted 02-23-2017 05:39 AM

A sliding dovetail would look great but the dovetail would be cut from the end grain of the vertical pieces so I’m not sure that would be strong enough if you’re saying to slide it onto the bottom horizontal piece that takes the tresses edge. I could be wrong though, I’m up for education on this. It’s not a standard thing so help is appreciated. It’ll be my dining room table.

-- http://kelleycrafts.com/ - pen blanks - knife scales - turning tools

View Mark Kornell's profile

Mark Kornell

1169 posts in 2371 days


#9 posted 02-23-2017 05:42 AM

To me, it looks like those leg assemblies are 5 pieces. The bottom rail, obviously, and then 2 pieces on each side. The outer piece is straight and would use a M/T joint to the bottom rail. And the inner piece has the inside radius, glued to the outside piece only. Where it contacts the bottom piece would be located with a spline (or T/G) to allow some movement without losing alignment.

I built some 3-piece legs like this (minus the inner radius) used a double loose tenon for joinery. Each mortise was 3/8” thick and 3 1/2” wide. Just under 3/8” between them. The mortises were as deep as I could get with my router, about 2” – so the loose tenons were not at under 4” long.

All jn all, it was pretty easy using a simple mortise jig for the router. Adding the inner radius piece would be straightforward.

-- Mark Kornell, Kornell Wood Design

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a1Jim

116594 posts in 3417 days


#10 posted 02-23-2017 05:48 AM

What I’m talking about is the trapezoidal shape seen on the bottom end of the table. As long as you’re using a hardwood it will be plenty strong unless you planning on parking a truck on top of the table. :)

-- http://artisticwoodstudio.com Custom furniture

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KelleyCrafts

2681 posts in 579 days


#11 posted 02-23-2017 05:55 AM

Mark…I think the radius on the horizontal bottom piece is part of the horizontal bottom piece. Now looking at the picture closely on my phone which is just slightly better than what shows up here, the vertical pieces might be two pieces which would indeed make it easier to do. The bottom piece holds the radius and I think the grain stay consistent throughout.

Jim that makes sense too. Would be sad to cut a sliding dovetail that’s hidden. Lol it would be strong though for sure since it’s the side grain on both pieces.

I think this has gotten more confusing. Lol

-- http://kelleycrafts.com/ - pen blanks - knife scales - turning tools

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KelleyCrafts

2681 posts in 579 days


#12 posted 02-23-2017 05:56 AM

Mark, that’s two vertical pieces on each side of the leg so four vertical and one bottom horizontal.

-- http://kelleycrafts.com/ - pen blanks - knife scales - turning tools

View Mark Kornell's profile

Mark Kornell

1169 posts in 2371 days


#13 posted 02-24-2017 05:55 AM

Yeah, that’s what I was trying to explain, apparently not very well :-) The inner vertical pieces have the radius. And are added after the outer vertical pieces have been joined to the horizontal piece. Purely aesthetic and non-structural.

-- Mark Kornell, Kornell Wood Design

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KelleyCrafts

2681 posts in 579 days


#14 posted 02-24-2017 06:10 AM

Gotcha. Makes sense. I think I’ve decided on a loose tenon to join it. 2” deep likely maybe more of I use the drill press and forstner. If I want to use the router I’ll need a new bit.

-- http://kelleycrafts.com/ - pen blanks - knife scales - turning tools

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Mikesawdust

324 posts in 2879 days


#15 posted 02-24-2017 07:50 AM

My vote would be a through tenon, I think the contrast coming through would look good and maximum glue face

-- You never cut a piece to short, you are just prepping that piece for a future project

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