# What is this joint called?



## patrickhosey (Sep 22, 2014)

Three-way Bridle Joint? What would happen if you googled three-way butt joint? Hah


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## bigblockyeti (Sep 9, 2013)

Not sure, but I would be concerned about the strength of the overlap in both boards forming the cross at the base as they would be prone to breakage if the table was tipped with any weight on it. A lot of polyurethane glue would certainly help reduce this likelihood.


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## patrickhosey (Sep 22, 2014)

You're right about that. My real reason for this joint is to make a dining table using the x's as the legs and the stretcher would go in the middle. I've always wondered how they joined those pieces so I just experimented with this.


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## richardwootton (Jan 17, 2013)

Interesting concept. Is this just a full size mockup?


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## bigblockyeti (Sep 9, 2013)

If the wood species was particularly robust and of substantial dimension I think you could get acceptable strength out of the joint, but it would still be a compromise vs. what could be attained just using an unmodified half lap joint. One option might be to do that, then drill through the middle and use a newel post lag bolt.


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## Mahdeew (Jul 24, 2013)

I wouldn't ever smoke that joint; whatever it is called.


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## thetinman (Mar 10, 2014)

It looks like you have combined half laps and mortise/tenon joints. And the tenons tie the cross pieces together. No dimensions are given but the pics appear that each of the "tenons" is about 1/4 the width. This provides substantial glue surfaces along side grain which would yield a strong bond. I would not worry about it. I'd go for it. Very creative. Nice job.


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## robscastle (May 13, 2012)

I would say its a very well made Joint


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## distrbd (Sep 14, 2011)

> I would say its a very well made Joint
> 
> - robscastle


agree 100%


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## Underdog (Oct 29, 2012)

I'd be concerned about the strength of the bond too. Yes, there's lot's of face surface area for good glue bonds, but where it really matters on this particular joint is on the end grain to side grain glue bonds. And no matter how well made the joint, or how well you glued it up, that's never going to be very strong. As time passes, and the wood contracts and expands, the glue will fail on those points, then you're back to the 1/4 size strength (or whatever size it is). On a cope and stick door, it's that end grain joint that is the weakest, and always fails as the years go by.
I suppose though that if you kept the piece in a climate controlled area, and never loaded the ends of the cross pieces, you'd be ok.
What is it called? I have no earthly idea.


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## GrandpaLen (Mar 6, 2012)

Although a very clever attempt…* ;-)*
5/6th of your 'feet' connection has been reduced to a simple butt joint.

Wider feet boards, with a 1/2 lap and thru mortices, with the same 4 tenons on your riser would produce a joint with a lesser shear factor.

...just my 2¢

Best Regards. - Grandpa Len
Work Safely and have Fun.

*EDIT;* ...btw, Welcome to the LumberJocks' community


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## naugled (Aug 4, 2010)

I think if you keep the same half lap joint for the legs but only put a single square mortise in the center of that joint to accept a single tenon from the stretcher you should have more strength in the joint for the legs. It would probably be at the expense of a weaker joint for the stretcher. But that might be a good trade off. You could even make the mortise blind so you don't see the tenon at the leg crossing. I think you can make up your own name for the joint.


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## SamuraiSaw (Jan 8, 2013)

> A lot of polyurethane glue would certainly help reduce this likelihood.
> 
> - bigblockyeti


Polyurethane glue adds absolutely *NO* strength. I've seen several comparisons that indicate it is actually weaker than standard wood glue. The "gap filling" aspect of it is nothing more than flimsy foam.


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## Woodbum (Jan 3, 2010)

Cool joint. Your pics show a lot of thinking and work went into making it-them. I would call it a "patrickhosey wonder joint" As far a strength goes, I would make the feet cross members wider, and increase the column size accordingly. But all in all, a very finely planned and executed work. If it works for you, then it works for me.


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## patrickhosey (Sep 22, 2014)

Thanks everybody for the advice. I definitely appreciate it.


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## robscastle (May 13, 2012)

Patrick,

Have a look at my blog acknowledging your post, took me a few attempts but I eventually had a reasonable result.


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## Gerbearswoodworks (Oct 3, 2014)

Very nice, but I call it "complicated".


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## patrickhosey (Sep 22, 2014)

It's not hard if you have a dado sled. The hardest part was getting the blade height right.


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## joeyinsouthaustin (Sep 22, 2012)

/?In my experience we call joints like this 'puzzle joints' I echo what many are saying. The joint is complicated and does not add any strength to the intended use. It appears to weaken the intended use. I am interested in knowing why you are choosing this solution, when there are several bolting or other applications that will work with table legs?


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## bobro (Oct 24, 2014)

I'd call it "da kine" and smoke it with pleasure.

"Puzzle joints" get their strength from the interlocking parts, while the individual components may seem flimsy. If you look into traditional Chinese furniture and Japanese architectural joinery, you'll see. I've seen Chinese furniture made with this approach hundreds of years ago, without glue, still going strong. And certainly not in climate controlled environments: in Asia in general there isn't such a strong distinction between "indoors" and "outdoors", and large regions have big swings in temperature and humidity. One of the reasons they made "puzzle joinery" in the first place was because the temperature and humidity changes the furniture went through would be as if you kept your furniture out on the porch in South Carolina.

There are two prices to be paid for interlocking joinery, though. The first is that the wood must be either strong and hard, otherwise it must be massive, or you must using many interlocking and reinforcing elements. You can see that this is the case in traditional Chinese and Japanese joinery.

The other price is not something you will find mentioned, I guess because it is obvious by feel once you've put some time into this kind of approach and the traditional workers might not even be aware they're doing it: interlocking joinery is more suited to hand tools because in order to do it really right you must vary the fit according to the wood and environment at the time of manufacture.

Imagine what will happen in a future dry season if you cut your joint hammer-tight in the muggiest time of year. Lengthwise movement in the leg/stand (the direction of the wood holding the post tenons tight) will be practically negligible, but the center post will undoubtedly have shrunk. When some character goes to lift the table, the top still attached to the arms will come off the post, or the post will pop right out of the stand. This is no big deal- shim it and you're good to go. It's going to happen eventually but you want it to be fifty years from now, not next year, so you have to make a fit with a good balance in the first place.

As someone who's had to repair such tables and coat racks and such made with bolts coming up through the base into the end grain of the post, I'd call the bolt idea a poor long-term strategy. I'm sure my mom who deals in vintage and antique furniture would use a more vigorous adjective.

What happens when you have a bolt into end grain is that unless it's periodically tightened, it will be in effect over time a pry-bar widening the bore it's in. Even if it's kept tight, the eventual shrinkage of the wood will create the same situation. Of course whether this is going to be a real problem within the space of a very long time for a table like yours depends on the loads and movement it will be subjected too. A coat rack has to face this problem from day one.

Anyway it's a great joint, congratulations. A neat trick would be to key it somehow so that even the future problem of coming apart vertically would be stayed off for another century. But that could really only be done well with either very hard woods or on a timber-framing scale.


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## Sawdust4Blood (Feb 16, 2010)

As a puzzle or spacial geometry problem, it looks great. In this particular application where you know it will be subject to shear forces due to weight on the table that is not centrally distributed on the post, I'd be concerned with the joint breaking loose.

As a variation of Grandpa Len's suggestion, I would consider turning the end of the post into a cylinder (effectively a dowel end) that would fit into a hole bored through the center of the bridle joint, split the dowel and wedge it after it's installed and I think you might get a more solid joint.


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## bobro (Oct 24, 2014)

> As a puzzle or spacial geometry problem, it looks great. In this particular application where you know it will be subject to shear forces due to weight on the table that is not centrally distributed on the post, I d be concerned with the joint breaking loose.
> 
> As a variation of Grandpa Len s suggestion, I would consider turning the end of the post into a cylinder (effectively a dowel end) that would fit into a hole bored through the center of the bridle joint, split the dowel and wedge it after it s installed and I think you might get a more solid joint.
> 
> - Sawdust4Blood


I think you guys are looking at shear forces as if the table were going to be bolted to the floor, or bear such weight that it would effectively be bolted to the floor. In real life the table will tip over long before shear strong enough to break that joint comes into play.

The joint you propose wouldn't be stronger. Think about it: say you wanted to break a piece the size of a fat finger off the end of a piece of very hard wood. Easy- whittle an end down, stick the finger in a hole and rack it back and forth. Pop! If you had the finger on a corner, it would be even easier, but Patrick's joint has four fingers on the corners of the end, not one. Stick all four fingers in holes and rack it, it will be more difficult than a single finger wherever placed, unless the finger very fat in relation to your beam- but in the case of a table like this, such width would take too much meat out of the members making the stand/legs.

Your proposal though would greatly mitigate the problem of the whole thing coming apart vertically over time.

I see Grandpa Len's point, but I disagree- it's not butt joints, but crossed bridle joints and a cross lap. An easy improvement to Patrick's design would be to thicken the stand/feet boards, i.e., higher in relation to the floor, such that they make shoulders against the post, higher up than the length of the four tenons. Just half an inch would move the fulcrum off from directly lined up with a weakened spot, that is, shear forces would now be more distributed to fighting the resistance of the entire length of each leg (or arm above) and not concentrated entirely in the joint.

Dang this is much easier to discuss while drawing.


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## patrickhosey (Sep 22, 2014)

I just bought some old fir so not the hardest stuff. I'm going to film a video of me building an x style table using this method. I'm ready for the woodworking police brutality, but I am confident that this joint would be stronger than the bolt.


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## GregInMaryland (Mar 11, 2010)

Neat joint. It reminds me of Japanese Joinery: images

I would go ahead and build your project using this joint and see what happens. There will either be a lot of "I told you so's" from the peanut gallery or "see, I was right" on your part.

I think if you have a tight fitting joint, use good hardwood (not that pine), I think the joint will hold up to normal wear and tear just fine.

Please give it a try and report back.

Good luck.

Greg


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## robscastle (May 13, 2012)

Update Feb 2016:

This joint is called an Interlocking Tenon Joint, its heritage is from Japan.

Reference:
A series of Time life Books
The Art of Woodworking series
Handbook of Joinery
and within there is a section Japanese Joinery from page 136 to 139.

You may find a complete downloadable PDF version of the publication On woodtools.nov.ru.

Looks like Greg was on the ball as his images are shown in the article


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