# Is this joint strong enough?



## bigredc (Sep 1, 2007)

This a test leg to a coffee table base. the finished one will be walnut. I'm worried that since the grain is going the wrong way for the tenon it might snap off. It's a 1" X 1 1/2" tenon so there is plenty of glue area. I was thinking about reinforcing the tenon with a dowel. I don't want to see it though. Another though was to make a whole new tenon like what festool domino jointing system uses. Any thoughts on this?


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## cabinetman (Jul 5, 2007)

Nice looking base. If you get a good fit, and sufficient glue, and allow the dry time, you should get a good joint. It does represent a weak joint for the direction of the grain. 

I might go with a good size dowel.


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## Daren (Oct 14, 2006)

cabinetman said:


> I might go with a good size dowel.
> 
> ​


If I used a dowel, it would be small, so as to not remove too much of the meat of the tenon. If you kinda look at that base and think about the forces that it will be under that joint is not as weak as I first thought when I circled it on the picture. You have down force, but there is some surface area on the top of the leg to take that. I was worried about racking, but looking at it again since the base is in an X and legs are diagonal it won't be direct side to side force which could shear the joint.
I think you will be ok, it is a coffee table right. Under normal household conditions (you don't have a pack of wild boys do you :huh:, they can tear up anything) it should be fine.


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## bigredc (Sep 1, 2007)

I guess someone would have to fall against it on an angle. Like you said to rack it. Just brainstorming, if you could get a piece of wood with a knot in the right place so the grain wrapped around it, and lay out the leg in just the right spot. that would be neat. Or is that just stupid and wouldn't work. It would probably only take me a few years to fine 4 of them.:laughing:


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## woodman51jfk (Dec 10, 2007)

I'm going to agree with the dowel, hardwood, the same diameter as the tenon, just as insurance. Use a good grade glue & allow plenty of set-up time, as was stated earlier. Nice work, and I like the half lap in the stretchers, those will also help prevent any racking.


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## bigredc (Sep 1, 2007)

I practiced doing the whole joint.


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## Youngman (Dec 28, 2007)

bigredc said:


> This a test leg to a coffee table base. the finished one will be walnut. I'm worried that since the grain is going the wrong way for the tenon it might snap off. It's a 1" X 1 1/2" tenon so there is plenty of glue area. I was thinking about reinforcing the tenon with a dowel. I don't want to see it though. Another though was to make a whole new tenon like what festool domino jointing system uses. Any thoughts on this?


It certainly is a good looking base. The joints strength can be compromised, as you say "if someone falls on it". If the joint was made on the vertical portion of the leg rather then the horizontal the stress would be compressive rather then tensile


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## bigredc (Sep 1, 2007)

It would be more visable that way. I like the idea of it being up under the top. It occured to me to swap the joints. Put the mortis on the leg and the tenon on the other piece. Twice as much wood on the week point. I have another thread started for this project. "My first real project" in general discussion. I'll keep that one updated if anyone cares.


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## mmwood_1 (Oct 24, 2007)

*theory vs. practice*

I think this joint situation may be over-theorized. I've made joints as such in the past. I think you'll be surprised at the actual strength of this joint, in practice. I don't think you'll have a problem with it. Just don't make your tenon too thin. 1/3 the wood thickness is a general rule of thumb.


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## edp (May 25, 2007)

cabinetman said:


> Nice looking base. If you get a good fit, and sufficient glue, and allow the dry time, you should get a good joint. It does represent a weak joint for the direction of the grain.
> 
> I might go with a good size dowel.


If I was to make any suggestion at all, I would suggest that the top (bearing) surface be cut at a bit of an angle so that the weight seen by the legs is over full length grains eliminating the fear of snapping off the horizontal member. Nice looking joinery.

Ed


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## bigredc (Sep 1, 2007)

I stress tested the leg. it held at over 20 lbs. broke at 32 lbs. an inch before the joint.


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## Daren (Oct 14, 2006)

Awesome, this is like an episode of "mythbusters" http://dsc.discovery.com/fansites/mythbusters/about/about.html , experiments in the woodshop.:cool2:


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## Youngman (Dec 28, 2007)

It is like a case of Mythbusters, the weight that was being applied was only 6 inches away from the break, how much would it take if the weight was 18 inches from the joint?:glare: This is a good thread, not only on structure but on design.


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## Daren (Oct 14, 2006)

Youngman said:


> how much would it take if the weight was 18 inches from the joint?


Doesn't matter, there will not be any down pressure that far from the joint (it is part of a table base, not a shelf bracket) 18" is in the middle of the table.


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## Youngman (Dec 28, 2007)

Put a glass top on it and it would matter,


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## mmwood_1 (Oct 24, 2007)

*another approach*

Given the breakage, if you want to go back to the drawing board, you can make new legs of similar design, but have your vertical piece and your horizontal piece meet at the corner. Do a mitered mortise and tenon joint on them, and you eliminate the problem of short grain weakness. I've used this joint on picture frames, and some cabinet door frames.


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## bigredc (Sep 1, 2007)

The first one was a scrap 2x6. I'll be using walnut. I'm sure it's even stronger. I was stressing the crap out of it the way I hung that load. Just for S&G I put 1-- 5/16" dowel in a piece of pressure treated (more scrap) it held like 40 lbs. Then I put the first one back together with 2-- 5/16" dowels. That held the over 30 Lbs. (I didn't try any more) The picture with the bucket hanging from the leg was actually after it broke, and I glued it back together with the 2 dowels. The first one broke before I thought to take a picture. I bet once that frame is done it will hold 200 lbs. on the table, on it's own, no dowels. I'm happy with it. I did manage to use part of a knot to get the grain to wrap around the corner on 2 legs. I don't know if it's stronger I guess it can't hurt. More pictures on "my first real project"


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## Joe Lyddon (Mar 13, 2007)

This is getting interesting... :thumbsup:


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## Joe Lyddon (Mar 13, 2007)

You might get some good ideas from this...
http://www.woodworkingtalk.com/showthread.php?t=2685  :laughing: :thumbsup:


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## bigredc (Sep 1, 2007)

Joe Lyddon said:


> You might get some good ideas from this...
> http://


I saw that. I have a bunch of woodworking books. That was in one. Check out this other thread. This project continues here. http://www.woodworkingtalk.com/showthread.php?t=2629&page=3


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## Buffalo Bilious (Aug 20, 2007)

I can't believe you actually stress-tested it! You wouldn't be an engineer, wouldya?

That said, may I respectfully suggest that you may be "over-thinking" the issue. 

First of all, in order to get a true load factor, it'd be better to test the weight-bearing on the fully completed frame and tabletop (the sum is greater than the parts, right?)

Second, the point was already made... any load will be borne across the horizontal surface of the top of the leg, traveling down to the floor at whatever angle you mount the legs... the topside terminal end of the leg will be generally unstressed and tied into the tabletop and infrastructure. Glue and screw is all I'd do. Maybe dowels or biscuits if I felt like giving myself a little challenge...

Lastly, unless you regularly entertain women who enjoy jumping up on the table to dance, I think your idea is sound as it is. However, if you actually have woman who come over to dance on your tables, let me know and I'll stop by to help with that design.... field tests are mandatory.... :shifty::laughing:

Great stuff, keep goin'!


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## Clutchcargo (Apr 9, 2007)

Buffalo Bilious said:


> Lastly, unless you regularly entertain women who enjoy jumping up on the table to dance, I think your idea is sound as it is. However, if you actually have woman who come over to dance on your tables, let me know and I'll stop by to help with that design.... field tests are mandatory.... :shifty::laughing:
> 
> Great stuff, keep goin'!


You wouldn't want a broken table leg to end the fun would you?


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## Buffalo Bilious (Aug 20, 2007)

Clutchcargo said:


> You wouldn't want a broken table leg to end the fun would you?


From my experience, a broken table only leads to more fun! Trust me on this.... :shifty:

"ClutchCargo"? We have a bar in town by that name... you in the Detroit area?


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## bigredc (Sep 1, 2007)

I'm not an engineer. I always wanted to be one. I do tend to over engineer things. I'm a construction electrician. I build electric services, pipe racks and lot's of stuff like that. We used to joke that the next ice age would come and go and my stuff would still be standing. If I had my way the legs would be 4X4s with metal bracing. That wouldn't look to good. All that said, I'm just having fun. Instead of the girl's, I was thinking of big fat drunk guy falling on the table. I like the way you think better. My lady friend and her sister were putting up wall paper in her bathroom. This woman with a masters degree, stood on the toilet tank, and was surprised when it broke. You never know what people will do. I want the table to able to support a person. I think it will. Or if it has a bunch of stuff on it and someone drags it across the carpet. There I go over thinking it again.


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## bigredc (Sep 1, 2007)

This is a video of joint torture test. Pretty neat. http://www.youtube.com/watch?v=DhLfb7m9Fug


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## bigredc (Sep 1, 2007)

All the testing and planning and I break the leg while I was gluing then up. The clamp kept pulling down on the joint. I pulled up to straiten it out. I did a couple, no problem. I was struggling keeping the wood blocks between the clamp and the leg. I guess the glue set up. I pulled it snapped. I sure the neighbors heard me cursing.


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## bigredc (Sep 1, 2007)

I was so mad I just glued it back together. I didn't think to wait and do a hidden dowel. I was thinking I would just do all of them with whatever I come up with. I have a few ideas. You can barely see the crack.


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## vicwebb (Oct 11, 2007)

*Coffee table joint*

I have a coffeee table that I bought some 35 years ago which is identical in design to that shown in your photo. It has a glass top and has withstood familiy life so it is a durable design. A joint parted a year or so back, due to central heating, revealing that two 3/8" dowels were proving the joint. Simple and strong!


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## bigredc (Sep 1, 2007)

This project continues here. http://www.woodworkingtalk.com/showt...?t=2629&page=3


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## drcollins804 (Jan 11, 2008)

When you have the table finished the weight is distributed across all 4 legs and the place it fractured will also be supported by the strength of the top. I think your only real worry is a side stress from something falling against the table. This is the only way that the joints are isolated from the strength of the complete structure. SORRY about that I hadn't followed all of the thread yet Table is looking pretty good.


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## Joe Lyddon (Mar 13, 2007)

bigredc said:


> I was so mad I just glued it back together. I didn't think to wait and do a hidden dowel. I was thinking I would just do all of them with whatever I come up with. I have a few ideas. You can barely see the crack.



The Woodwhisperer is making an End Table... (3 episodes, so far)
http://thewoodwhisperer.com/

After watching episode #3, I thought he was doing much of what you are doing... maybe it will help you...


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## bigredc (Sep 1, 2007)

I've watched a few. I keep forgetting to watch them. I'm just about done. I'm putting the tung oil on.


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## Knot Home (Feb 14, 2008)

I would mortise both sides and use a loose tenon instead. This way all of the grain runs the right way for maxiumum strenght, and the joint still looks nice.

Roy


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## Joe Lyddon (Mar 13, 2007)

Bigred,

Looks really NICE!

I think you'll be OK... as mentioned, the weight will be distributed to the legs also... not all in the spot you were testing.

Waiting to see the finished piece... Looks great, so far!


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## bigredc (Sep 1, 2007)

Knot Home said:


> I would mortise both sides and use a loose tenon instead. This way all of the grain runs the right way for maxiumum strenght, and the joint still looks nice.
> 
> Roy


You should check the dates on the post's. That table has been built for a month. I used to do that all the time. Now I try to remember to look at the date.


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## Knot Home (Feb 14, 2008)

I should change my handle to "Knot All There". I completely missed the fact that there was a page two when I posted. It's amazing I still have all my fingers.:bangin:


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## BlockHead (Dec 28, 2007)

Any place where you have wood that thin with the grain horizontal on a piece that thin, it will be subject to breaking. The strongest way to do it would be to do a mitered joint at the corner, doweled or biscuited for extra strength.


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## dpmcreations (Feb 3, 2008)

*well darn it..*

It seems as if I missed all the good postings... But what the heck.. Nice job on the table.. Congrats and keep us posted on how the table holds up with the women!!!!!! ROFLMAO...................


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## smitty1967 (Feb 24, 2008)

methinks everything will be fine, no matter what method of joinery you practice, red....that is, until the War Department decides she's going to slide that coffee table across the carpet some weekday afternoon while you're out building cable trays....one lateral move of that original joint across the thick shag rug, and ---voila! The neighbors will hear her cursing this time!

regards,
smitty


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## bigredc (Sep 1, 2007)

Here is the table. I would recomend a different design if I was doing it again. The joint is fine, it's the wood between the joint and the leg that it weak. The wood wisperer did one very simalar, but much stronger.


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## Capt Crutch (Jan 21, 2008)

I wouldn't sweat it. 

As someone noted above, unless there is some _strain_ (i.e., deflection or movement) in addition to the _stress_ (i.e., weight) such that the weight of the top is bearing where you put your test weight – instead of on the end grain at the top of the leg – nothing is going to break. 

The only way it's going to break is if the end grain is not supporting the weight of the top or there's a lateral force (sideways) for example if some drunk fell down and pushed the table sideways and downward at the same time such that the leg was acting as a lever arm.

I would build it the way you are and just make sure that the weight of the table was bearing directly downward on the end grain of the leg. If you wanted to get fancy, you could put in a dowel or groove the top of the leg where the short grain is and glue in a "spline" piece with its long grain perpendicular to the leg, but I probably wouldn't bother.

Real nice looking work, by the way.


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