Wedged loose tenon joint

[Mark Singer]

The wedged loose tenon is really an easy , strong and attractive joint. The advantage of making it loose is that sometimes the component...a stretcher for example is large , and cannot be readily cut at the band saw , or table saw...sawing by hand is a good option or this version where the tenon is loose. The mortise can be made by drilling and chiseling , slot mortiser, router. or other methods. The key aspect of the joint is to make the mortises in all the pieces the same width and the loose tenon should be the same width also...now the length of the mortise is larger in the outside thin piece. Why? It is just like when you fasten 2 boards with a screw....the screw slides easily through the first piece and tightens in a pilot hole in the second....the head of the screw locks it together. This is exactly the same...the edges act like the screw head and as they are tapped in they lock the joint together.
Some points...
Cut the tenon on the bandsaw and make glue relief slots

Drill holes at the wedge slots to keep it from splitting unless you know the wood well...and the slots are cut with a tablesaw ot safer with a bandsaw...about 1/8" wide

Glue should be on all sufaces...wedges...mortise...tenon...outside piece mortise

The joint is finished in a couple of ways which is only detail...leave it proud and bevel the edges with a plane or cut and plane it flush with the surface...

This is really a simple joint and because the long grain of the tenon is running long grain with the mortise...it is a strong joint

I know you love this forum SMC:rolleyes:

[Andy Fox]

Cool stuff!

Are there any gotchas to watch out for when making the wedges--size, angle, wood species, etc?

[Jim W. White]

Great Stuff Mark!!

...I for one sure would love to see some of your joint tutorials saved off as one/or more "Articles" ...the material would be easier to find that way. ....in the meantime I'll just keep saving them off to my hard drive for future reference. :D

Thanks for posting these type of follow-ups Mark. I find them very informative!

[Mark Singer]

Cool stuff!

Are there any gotchas to watch out for when making the wedges--size, angle, wood species, etc?

I like the wedges in a hard wood so the fibers of the tenon and mortise compress...you can use a contrasing color wood for detail

Just remember...just because you know how to make a nice joint is not a reason to make every joint a feature,,,,don't overdo it! Pick a few important joints in a piece for emphasis...don't make it look like a joint making class attacked a piece of furniture....:rolleyes:

[Bob Childress]

Great as usual, Mark. Good point about picking your joints and not getting carried away.:D Two thunbs up.:)

[Chris Padilla]

Bob, you must have typed that last line with two 'thunbs', eh? ;)

Mark, very nice. I've seen many versions of this joinery technique. I saw one where opposing moisture contents were used to keep wedges in nice an tight. I've also always loved "knock-down" benches whose legs/stretchers were pulled in tight with external wedges. Cool stuff!

[Mark Singer]

Bob, you must have typed that last line with two 'thunbs', eh? ;)

Mark, very nice. I've seen many versions of this joinery technique. I saw one where opposing moisture contents were used to keep wedges in nice an tight. I've also always loved "knock-down" benches whose legs/stretchers were pulled in tight with external wedges. Cool stuff!


That may be my next joint tutorial a KD pinned trough tenon...that is a good one!

[Dan Larson]

Hi Mark,

Question about the glue relief slots on the tenon-- is it better to cut them along the length of the tenon or across the width?

Thanks for yet another great tutorial!

Dan

[Chris Padilla]

Dan,

All one is doing is creating extra volume within the cavity (mortise) for glue to escape to so it really doesn't matter. I'm sure you've seen spiral-cut dowels and "ribbed" dowels...these serve the same purpose.

On the other hand, sometimes glue escape routes are needed for glue to move outside of the tenon. Air may also use these routes if you have a particualry snug fitting M&T joint (and wouldn't it be nice if we were all so skilled as to have problems trapping air in the mortise! :) ).

[Mark Singer]

Glue slots must run into the mortise so that when the tenon is tapped in the glue can flow out....this will allow the correcy amount and eliminte the pumping effect of the pston an d cylinder...pushing the tenon back...and petetially creating pressure in the joint...a few voids are welcome...the spiraling cuts on dowels do te same thing since they are continuous...cuts in the other direction weaken the tenon and create a fault or weakened plane...not good!

[Andy Fox]

Just remember...just because you know how to make a nice joint is not a reason to make every joint a feature,,,,don't overdo it! Pick a few important joints in a piece for emphasis...don't make it look like a joint making class attacked a piece of furniture....:rolleyes:

But what about combining as many types of joints as possible into a single hybrid joint? :eek: :D

....Now what if instead of wedges, the mortise half of the loose tenon was cut at a dovetail angle and inserted from the back of the mortise? Would this have any advantages or disadvantages over the wedged version? Or is that next week's joint? :)

[Mark Singer]

But what about combining as many types of joints as possible into a single hybrid joint? :eek: :D

....Now what if instead of wedges, the mortise half of the loose tenon was cut at a dovetail angle and inserted from the back of the mortise? Would this have any advantages or disadvantages over the wedged version? Or is that next week's joint? :)
Have you been smoking something? a joint maybe:confused:

[Dan Larson]

Glue slots must run into the mortise so that when the tenon is tapped in the glue can flow out....this will allow the correcy amount and eliminte the pumping effect of the pston an d cylinder...pushing the tenon back...and petetially creating pressure in the joint...a few voids are welcome...the spiraling cuts on dowels do te same thing since they are continuous...cuts in the other direction weaken the tenon and create a fault or weakened plane...not good!

This makes sense to me. A dumb follow-up question-- do you cut your slots short of the exposed end of the tenon? I assume that even 1/32" deep slots could be seen once the tenon is trimmed flush... and I sure don't see any evidence of that sort of thing with your joint!

[Mark Singer]

Dan,
You are correct I let them fade out before the face and it makes a clean joint. Just hold them against the bandsaw blade with very light pressure ...only 3/4 of the tenon depth

[John Scarpa]

Mark,

thanks for the tutorial. I was just thinking of asking you to get into this very discusion. This is timely! I have a question. Now that you have a slot mortiser and I assume are cutting the mortise with rounded ends will you chisel the ends square or round over the ends of your tenons?

John

[Alan Turner]

Nice work, Mark. A slot mortiser is a very handy toy. A couple of comments.

To a question above, the wedges need to be driving the tenon against the end grain; otherwise a split is likely.

This is personal, I guess, but my preference is to angle the mortise at 3 to 5 degrees from the show side, and then to cut the wedges to this same angle. In this way, it is possible, even easy, to get the wedges to be exactly the same width on the show side.

It is necessary to cut the wedges accurately, and this is done using the bandsaw. Take a scrap board, perhaps 6 to 8" wide, and about that long as well. Rip it on the BS against the fence, and leave the fence at that same setting. Then take an endgrain cut and size it exactly to the width of the wedge. Carve into the scrap the negative of your wedge, and them simply rip the wedges off, flipping the wedge stock 180 deg. for each cut. You then have a series of accurately sized and angled wedges, and when you drive them in, if you are careful, they will all be the same width. For an exposed joint this is of some importance.

[Mark Singer]

Mark,

thanks for the tutorial. I was just thinking of asking you to get into this very discusion. This is timely! I have a question. Now that you have a slot mortiser and I assume are cutting the mortise with rounded ends will you chisel the ends square or round over the ends of your tenons?

John

Either way works...In the picturewhich is the teak sofa, I squared the mortise with a chisel..

[Mark Singer]

Alan,
I do angle the sides of the mortise in the outside piece...I don't measure just undercut a little with the chisel...because the tenon is actually tappered just a little. That way the surfaces are in contact...a well executed joint of this type relies less on glue because the mecanical conection is very good.

[Dan Larson]

Dan,
You are correct I let them fade out before the face and it makes a clean joint. Just hold them against the bandsaw blade with very light pressure ...only 3/4 of the tenon depth
All is clear now-- Thanks!

Dan

[Andy Fox]

Have you been smoking something? a joint maybe:confused:
ROFL! ....The only joint smoking around here happens when I leave the mortiser in the wood too long.

I know it's hard to tell, but the second part of that post was actually a real question: Now what if instead of wedges, the mortise half of the loose tenon was cut at a dovetail angle and inserted from the back of the mortise? As in this sketch:

[Mark Singer]

ROFL! ....The only joint smoking around here happens when I leave the mortiser in the wood too long.

I know it's hard to tell, but the second part of that post was actually a real question: Now what if instead of wedges, the mortise half of the loose tenon was cut at a dovetail angle and inserted from the back of the mortise? As in this sketch:

Andy,
That is kind of what happens with the wedges and what Alan was talking about...Angle the mortise alowing for the wedged effect of the tenon

[Alan Turner]

Alan,
I do angle the sides of the mortise in the outside piece...I don't measure just undercut a little with the chisel...because the tenon is actually tappered just a little. That way the surfaces are in contact...a well executed joint of this type relies less on glue because the mecanical conection is very good.

I figured you did this Mark. It just didn't seem clear from your initial post. I measure and mark pretty carefully for this task as the wedges are the show detail, and need to be spot on.

[Don Baer]

Thanks again Mark for the tutorial. I am adding this joinery to my bag of tricks.