# How do I keep tusk tenon wedges from coming loose?



## Adam_D

I've only been doing woodworking for about 1.5 years, but thought I'd tackle a big dream of mine: MY BED. I plan to post more of this project later, but for now, how do I keep these pesky tusk tenon wedges from coming loose?! I used an angle of 10 degrees for the mortise/wedge. I think one of my mistakes was coating the wedges with wax…I thought this would prevent scratching up the legs as I pounded them in, and also to prevent squeaks-this is a bed after all ;-)-but now they're coming loose every 2-3 days!

I don't want to use glue because I anticipate it needing periodic tightening to account for seasonal changes, and I'd like to be able to disassemble it someday, hence the tusk tenons… What can I do to make them stay put? Maybe a dab of sealcoat or something? Hot glue? A little fold of sandpaper? ...maybe just clean off the wax?


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## stefang

I'm no expert, but I think a wedge has to be 5 degrees or less to work properly, and yes the wax isn't a good idea.


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## Loren

You can pin the joints. Either through the tenon or through
the bottom of the wedge.

Next time look at using less of a taper.


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## Adam_D

I used 10 degrees because my "Woodworker's Guide to Joinery" book said to! Page 145! Did they steer me wrong??


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## rusty2010

I concur with stefang. The only fix I can think of is a pin below the wedge as it passes through the tenon or a new wedge


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## NathanAllen

Same principle as a drawbore pin, less degree and have the top be wider than the mortise.

Good news is a couple easy fixes, cut a new set of keys at a 5 degree angle. Not sure if you have a 10 degree slope on the inside of the mortise, that may need to be adjusted to fit the new angle. Remember you want maximum touching between the key and the mortise.


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## Adam_D

Mannn, that's the last thing I expected to hear-I figured literally going by the book (see link above) would rule that out, and you guys would just agree with one of my hunches (clean the wax off, dab of shellac, etc).

I don't like the idea of pins-that eliminates the option of tightening them in the future, unless I make new holes each time…seems ugly. New 5° wedges would require me making some sort of FILLER wedge which I'd have to glue in there? Again, sounds ugly…

I took some alcohol to the wedges tonight to clean off the wax, and I'll post in a few days to see if it worked. If it doesn't, I'll try some sandpaper and/or a drop of shellac in the mortise to see if that helps. Absolute worst case, I'll use some hot glue-hopefully that'll come loose the day I need to take it apart.

HOPEFULLY I won't need to do the invasive surgery you guys have recommended! ...not that I don't appreciate it of course, it seems a bit drastic…maybe I'm just in denial haha


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## waho6o9

Put a dowel through the center of it.


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## BobLang

Try mineral spirits to remove the wax. The angle is a bit steep, but I'm thinking the wax is most of your problem. The drop of shellac isn't a bad idea, I would use a drop of good old yellow glue. It will break loose if you tap on the bottom of the wedge to remove them.

One other thought, did you drive them firmly into place? You should be able to hear it when they are firmly in place. Don't drive beyond that point or you can break out the end of the other piece, but you do need to get them seated.

Bob Lang


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## rusty2010

I agree with you on not wanting to add a pin. I done the same thing you did and ended up making new ones at 5 degrees. On that project there where 4 wedges each on 2 tables. Not fancy like yours tho.


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## Sylvain

It looks very nice.

Is the mortise long enough?

See :
http://villagecarpenter.blogspot.com/2008/06/tusk-tenon.html
to know what I mean.

The wedge must only bear on the external wall of the mortise on one side and only on the leg on the other side.

Otherwise there no pressure to ensure friction. And without friction it will come loose.


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## Adam_D

Sylvain: I overcut the mortises by about 3/32" (2.5mm) on the side nearest the leg to ensure that the wedge would fit tight against the leg.

I cleaned the wax off yesterday, and they're still looking good this morning, so hopefully that was most of the problem as BobLang suggested. Time'll tell.


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## kikkicurio

Hey Adam, an unrelated question in regards to this post. I am a design student with very limited woodworking experience and wondered if you could help me. I intend to utilise this joint for one of my own projects and I wondered what proportions you have used? Most guides and examples of this joint, show it being used with rectangular pieces of wood. Like you have done in this project, I would like to use it with squared pieces of wood. 60mm squared with a central tenon which is 20mm squared. How far should the tenon extend and what are appropriate proportions for the wedged keys? Is 20mm squared too thin and small for the tenon and will it cause me problems?

-Kiara


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## Adam_D

Kiara, if you've read the above posts, you'll quickly realize that I'm not the guy to ask haha. Apparently even following the textbook instructions is sometimes wrong. That being said, my *opinion* is 60mm squared with a 20mm tenon should work fine. I'd guess the tenon would extend maybe 20mm past the face of the joined board. My book says you should use a 10° angle on the wedge, but the guys in this post insist that 5° is the magic number. I'd say that the bottom of the tenon should be no less than 8mm when it leaves the tenon since there's potentially a lot of force on there.










BUT, I'm no expert by any means-I've only been woodworking for about a year and a half.


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## kikkicurio

Thank you so much, your advice has been invaluable.  One and a half years experience, is one and a half years more experience then me.

Your diagram was extremely helpful. Now just to be tricky, after doing some tech drawings, I decided 60 by 60mm was too chunky and I now want to go with 50 by 50mm. The resource I am using says that you should never cut a mortise that is more then one-third the width of the stock you are working with, however, I want to maintain the 20 by 20mm dimension of the tenon. Am I pushing my luck?

I also wondered if you had any general tips on appropriate tools for cutting out mortises, creating tenons and most importantly, because I think this is what I will find most challenging, cutting the mortise for the tenon key? How do you cut accurately on an angle? I have access to a great workshop- so any shortcuts using powertools would be welcome.


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## Adam_D

On my bed (in the picture at the very top of this thread), the width of the tenon that passes through the leg is 29mm, and the width of the leg that the mortise is cut in is about 60mm, so 1/2…I haven't crashed yet haha. I'd agree that the width of the WEDGE (key) should be about 1/3 the width of the tenon. No single rule applies in every situation. If you use the 1/3 rule and drive a tank over your furniture, it'll still snap. Follow your gut-YOU'RE the designer.

My profile picture shows me doing just that-cutting the mortises for my tenon keys (I keep calling them "wedges"). I use a delta 14-600 mortiser (made in england, not china!) to cut all my mortises. Some mortisers tilt-mine doesn't. I tilted the work piece instead by resting it on a 10° platform I made (just a piece of wood screwed to one side of another carefully-sized piece of wood-use your trigonometry!). You might have issues finding a hollow chisel for the mortiser that's the exact size you want. I can't afford to be too picky, so I just sized my wedge to match my chisels 

As far as cutting all the tenons and general shop technique, I learned a LOT from hours and hours of watching Norm Abram in "New Yankee Workshop". Depending on the size of my stock and/or the tenon, I try to use my table saw with my delta 34-182 tenoning jig. On the long stock on my bed, though, my ceiling got in the way, so I had to use my band-saw and clean them up with scrapers.

I'd recommend making a "practice piece" of whatever you're making, since you WILL have mistakes, especially this early in your woodworking career ;-) That being said, what are you making?


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## kikkicurio

It was in "Making a Tusk Tenon for Knockdown Furniture" by Thomas Rettie. It's a pdf article I found on the internet, one of the first things that popped up when I started researching tusk tenons. I've read it over a couple of times and its definately in reference to the mortise. Although this same person suggests, in regards to the tenon, that " the distance from the shoulder to the end should be long enough to pass through the the mortise with at least 4 or 5 inches to spare on the outside." Which seemed extremely excessive to me.

Actually the dimensions of your bed posts seem preferable to the 50 by 50mm dimensions I was initially going for because I am applying this joint to a chair. Are they 42mm square? The only reason I chose 50 by 50 was because I was going off Rettie's "1 thirds" advice

Unfortunately, I'm not sure our workshop has a mortiser! I will investigate this. It would make me extremely happy if it did. Is it even possible to create a mortise without one? You can do them by hand with a mortising chisel right?

Don't you worry there will be many practice joints!


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## Adam_D

yea, it looks like he's making a picnic table or something. One of my favorite things about woodworking is that what you make is yours through and through. You can follow advice, but in the end, it's up to you. Make it the way you envisioned, and if it breaks, you'll have learned a lesson  I suppose that logic only works if you're doing it as a hobby-if you have customers, they won't be very happy if you ruin their picnic haha.

There are countless ways to make mortises even without a mortiser. Lots of guys use a jig with their router (but that won't work with your wedge mortise). You can pre-drill and tap out the corners with a mortising chisel without the mortiser. You can pre-drill and use a regular chisel. You can pre-drill and use a file. You can pre-drill and square it up using a tiny jig-saw blade. You can pre-drill and glue sandpaper to an identical wedge/key and SAND out a perfect mortise. You can chisel out the whole thing. You could even drill, NOT use a chisel, making a ROUND mortise, and make a matching ROUND wedge/key! OR, you could use pocket-holes for the joint, and glue on a FAKE tenon/tusk hahaha

The world is your playground.


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## craftsman on the lake

It should stay in by itself but could I suggest another smaller tenon wedge on the lower part of the larger wedge so that when you tap it, it pulls the original wedge tighter creating a lock?


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## Jeff28078

Taking a different tack and looking at the wood instead of the dimensions, I don't see if you've identified the species of wood used. I'd think the wedge should be a softer wood than the mortise so that it can compress. Also if the wedge was a wood with a little natural pitch, or even applied pitch, it might stick better and not move.


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## kikkicurio

Hey adam, I noticed you have edited one of your posts "the width of the tenon that passes through the leg is 29mm, and the width of the leg that the mortise is cut in is about 60mm, so 1/2…" which is different from the 42 mm you initially stated. Was the 42mm a typo?

Also, in reponse to your other post, customers or assignments worth 50% of my course mark


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## Adam_D

The vertical leg is 60mm wide. The tenon that passes through it is 29mm (about half of 60mm). The horizontal arm that the tenon is on the end of is 42mm.










Really though, it's entirely up to you. I didn't use a formula to make mine. In fact, I didn't even have them in my original drawing (I updated it a little for the above screenshot to reflect how I actually built it). What's more important to me than following a plan is having fun. Cut your tenon first, trace its outline on whatever you're going to mortise, and then cut your mortise. At your level, don't worry too much about a few mms here and there. What's important is that you can cover up your mistakes and learn a lesson for next time.

I built a cookbook shelf last year that used tusk-tenons too-I'll try to write up a proper LJ project and post a link to it here over the next couple days. I think you'll like it.


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## Adam_D

Kiara: My kitchen projects are here. The cookbook shelf has my first tusk-tenon experimentation. Came out great!


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## kikkicurio

Ah thank you! Again very helpful  I've ordered my wood so I start next week. I'll let you know how it goes.

The cookbook shelf is great. The tenons are very slender and elegant.


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## stansgotwood

kikkicurio- have you watched the Paul Sellers youtube videos? the one where shows how to make a workbench using mortise and tenon leg joinery to the top. his method of cutting mortises with a chisel works very well for me. i do all of mine by hand like he shows. takes a bit of time when going through a 4×4 or larger, but using his technique to get through the tenon on a 2×4 took me less time than it would for most folks to set up their machinery. something to consider, and all you need are a few different sized chisels and something to bang on them, mallet, big copper headed hammer(i like this one for cutting big holes), softfaced mallet, a log you can grip with 1 hand, etc.


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## BronzeAgeMan

The angle of your wedge is only partly the problem, too steep for a short distance. The root of the problem however is wracking is wiggling the wedge free. This is because your trestle shoulders are not deep enough to resist the wracking forces.
So the overall design of the bed is at fault really. No wedge; not even a lesser angle will make up for that.
Pinning the wedge in place defeats the whole point of a wedge and ease of adjustment. It will only result in a sloppy joint you can't adjust. Please ignore those suggestions!
Firstly you should increase the shoulder width in the direction of wracking by gluing more wood on, (make it look nice). Reduce the wedge mortise angle and make new wedges, (try 5 to 7 degrees).
Spray the wedge with hair spray to make it sticky.
To build these joints well you need to study the forces, shear area of wood under stress, compression areas etc.


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