Mortise and Tenon Joint - Wedged Tenon 

Want to learn more about the mortise and tenon joint? Check these videos out: Mortise and Tenon Joint: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-O-j__IVfbeY.html Rob Cosman Answers questions on the Mortise and Tenon joint: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-splk1KdVC3g.html

Lol. If you listen carefully you can hear the moment Rob broke one of the tenon kerfs because he cut it to close to the shoulder. Kerfing tenons is risky, especially if it's a brittle timber with a short tenon. Window/door joiners don't usually kerf the tenon itself because there can be a risk of splitting so you just drive a very rough sawn wedge in to edge to fasten it. Not quite as strong but if the glue fails its easier to repair because you can drill out the old wedge and put in a new one. Cabinet makers often drill a hole at the base of the tenon before cutting a kerf down to it so that the load of the driven wedge is spread and reduces the chance of splitting. You don't need to spread the tenon nearly as much as Rob did. 3mm is plenty, 2mm is perfectly good enough. That way your kerf can be further in and thus stronger. Many joiner do not bother to actually angle the mortise either. It's more about compressing the tenon tight while gluing up and being able to crack the frame to get rid of any wind. Wedged tenoning avoids the need for sash clamps. That's why we use them. It's fast.

This was a great tutorial. One tip for anyone trying this at home: before you cut the kerfs in the tenon to accept the wedges, drill a small hole (about 1/8" for a tenon the size of the one in the video) through the tenon near the shoulder where you want the kerf to end. This does a couple things for you. The round hole eliminates a stress point and reduces the likelihood of splitting. It also gives you a bigger target to saw towards. Happy woodworking, everyone!

This guy is waaaay underrated. That's probably been said many times but I'll say it once more.

Thanks for the lesson. I’m about to cut my first wedged tenon. My tools aren’t near your level but they do the job for me, I’ll do fine. However, I do have the same indispensable magnifier you have and I’m over 70 years old. This is a good video.

I love the future. Between Cosman and Sellers, you could learn most of what you need to, at least, get a good start in woodworking. Nothing can comes close to hands on, but the details you learn here would take so much experience to figure out.

I gotta say, Jake is getting really good with the camera. There has been a steady improvement in his skills over the years.

Love your channel. It’s fun to watch a master at work plus your teaching style is detailed and easy to follow. I’m retired now but used to do a lot of woodworking and finish carpentry. Now kicking the crap out of cancer and winning so I can stick around for my babies. Prayers and healing thoughts are welcome if you are so inclined. Thanks for all you do.

Thanks millions from California. Those who realy want to learn this , get a flavor of your experience also. Please continue.

"If I knew anything about math, I could use this calculation to figure that out, but I don't so I'm just going to guess at it." Single funniest thing Rob has ever said. Lol. Much love man.

Thank you Rob. I'm glad I came across this video. I see other wood working RU-vidrs do this variation, but don't actually explain it. Listening to you explain it makes more sense.

Love the grip tape on the clamp handles! Everyone should do this for the sake of preserving the tendons on your hands and arms.

i was on the edge of my seat the entire time. now i'm an hour past my bed time. mom is going to be pissed. thanks ROB!

I have cut wedged tenons for years, I always cut straight down and occasionally ran into problems, frustration and heaving large chunks of wood at the speed of light. cutting the wedge cut at an angle was genius. So simple, but I never thought to do it that way. Face plant when I seen you do it and I thought .....I am so stupid....Thanks for the tips and your time. Sometimes it's the simplest thing.

Great, I'll save this to my "Watch later" and will practice, practice and practice this.

Thank you for all these teaching videos! Your videos has taken my woodworking skills to a hole new level!

Probably the best teaching video I've seen on creating through mortice & tenon joints. One thing you need is crazy sharp chisels.

This is such a comprehensive way of teaching. I always learn alot through each of your videos. Thank you for sharing your knowledge and talent

Rob (I can’t see it anyway but it looks to be about that) Cosman I love watching you work. I can tell without looking you’re a man who’s spent most of his life sweating the details because that’s what creates quality. You make me want to take full width shavings and never sand again. I hope to get there before the clock runs out (64 but look like 84). If you ever have a class for the disabled that never served in the military, I’m there. Then again you’d have to pay my way cuz disability won’t cover that. Oooops, forgive the rambling. Anyway, keep up the great work and we’ll talk again next time my mind wanders. Best, Jim

Not only does this add strength, but also character. Nice job, Rob.

Well, what I saw in this video is aerobatics again. I don’t have enough words to describe how I felt while watching this whole movie. I felt every millimeter of the tree and lived every moment during this or that operation. Thank you so much Rob. :)

I've just spent an hour on the edge of my seat. This was like watching a man trying to climb the North face of the Eiger, from a safe distance. Every move fraught with danger, one slip and you're gone! These videos of yours are absolute gems. Thank you for sharing Rob.

Awesome video to do this joint. Thank you Rob!

Excellent tutorial 👌 thx for posting

Im putting a tv in my shop so i can follow along with you videos. Thank you for posting these.

This guy is a treasure. The combination of his OBVIOUS skill level and his ability to articulate the subject matter in an easy to understand and interesting way make this channel superb and keep you coming back. I also like that he is not trying to be clever or overtly funny and overdubbing some awful music that would make it hard to hear him. Great Channel Great content!!

Just watching again

I also studied with Dale Nish at BYU, my years there were in 1973-4. You are a much better student than I was and are an excellent instructor. Keep at it I appreciate your postings they are very informative

At 57:33 he snaps one side of the tenon wedge off. That significantly decreases the strength. I reckon he cuts them far too narrow at the bottom, and having the wedge run all the way down puts a massive amount of pressure at that point which literally snaps off the fibers where they are most vulnerable. I've always cut the wedges short and rounded them off, so that the flexible part of the tenon can "curve into" the final position along the sides.

The classic Pythagorean Right Triangle is made up of three sides: the short side is called "The Side Adjacent" The medium-length side is called "The Side Opposite" and the long side is the Hypotenuse.

Bravo! I'll watch it again tomorrow after a good night's sleep and comment. So many bits of information and tips from experience, That block planing though....wow.

A well executed through wedged mortise-and-tenon joint is more pleasing to the eye than any other joint, save the hand cut dovetail. Nicely done.

Watching this i decided to order one of the sliding bevels that u used in this video... I cant believe u called!! I wish I had answered... I cant believe I missed a chance to talk to ROB COSMAN!!!! Thanks for calling and saying thanks.. that made me feel really good lol. Thank you for what u do!!

Rob, Working with both hand and power tools to make my joints has really brought my projects to another level. From hand cut dovetails to mortise and tenon even plain box joints make a dramatic impact. Your lessons make it so much easier to accomplish so much more in my woodworking! Thanks for the help.

Great idea to cut and explode a mock up to show us the interior of the wedge joint.

Great video. The best I’ve ever watched. Rob, you’re the best teacher/instructor/mentor I’ve ever seen. Super kudos to Jake for the fantastic camera work. This is definitely a joint I want to master. Thank you so much for taking the time to show all the details.

Great video. I used this recently for the Parallel guide on my chop for my Moravian workbench. Thanks again for the video and knowledge Rob!

“Can’t see it anyway, but it looks to be about that…” 🤣 That’s how I measure everything!

Excellent class, Rob! Thanks for taking the time to share with us. (And, nice shootin’, Jake. I know how hard it can be to get the shot and stay out of the way at the same time!). Now... I have to start on my NEW workbench... cuz I kinda used EIGHT wedged tenons on the one I just built... and I kinda cut them wrong. They worked “okay,” but I’ll get them right this time.😁

Sheer pure execution. Congratulations for sharing your expertise.

This is some serious serendipity Mr.Cosman. I've been really enjoying your videos for a couple weeks now and I want to thank you from the bottom of my heart for all the time you've put in for us. I've learned so much over the last few days. I finally had to come to terms with how terrible my sharpening system was and ordered the Trend 300/1k and a Shapton 8k. Ya this is a perfect video for me because I'm building my first woodworking bench and am gonna attach the legs in the Roubo style with the tennon and dovetail that's flush with the bench edge. I know I'm supposed to wedge that tenon but wasn't sure how. You sir are the MAN. Thanks for everything.

Never seen them done quite this way. Learned a lot, awesome precision.

Thanks Rob...I will be using this joint in my current project here at Port Townsend. This has saved me from many mistakes...

Oh god, finally someone cuts this in half and shows the non-sense of how people do this. 1) wedges are wedges, they should be thin 2) the outside of the mortise should not be that wider than the inside (if the gap is small, the wedge do not need to be that big, which avoids cracking the tenon) 3) the wedges shouldn't be that close to the sides of the tenon 4) if you make a tapered mortise, the angle of the flared sides of the mortise need to be gentle 5) if you make a tapered mortise, it should go only half way through the length of the tenon, so that you keep straight edges on part of the tenon/mortise 6) the cuts you make on your tenon (the holders of your wedges) should be 2/3 max of the length of your tenon, they should never extend to the shoulders The idea is that your "new" tenon (which is your "old" tenon + the wedges) will be just slightly larger than your mortise, which is enough. And this is the important part here: the strength of the joint is that the tenon is slightly bigger, not that there is a tapered mortise. It should be one of the strongest joint, not just aesthetic. If done well, the tenon should never crack. You don't want what you can see at 5:46 where the left side of the tenon is actually splitted (you can also see it breaks at 57:31).

Thanks for this. I have often wondered how this should be done. Now I know!

There are woodworkers and there are master woodworkers. Rob however, is a GOD level woodworker! Guys like him, make guys like me, look like absolute amateurs… (and I’ve been woodworking over 20 years 😐). Oh well, it’s called “GOALS!” Back to practice… maybe in about another 20 years, I’ll be just as good. 😆 No, no I won’t! I’ll never be that good!

Love the clarity of your video At present I am trying to repair a wedged tenon Trying to work out if to remove the existing wedges or cut new slots Thank you

Awesome video! I really enjoy your videos because you teach as you work. Thanks.

Thanks Rob - This video popped up on my recomended list just days before i was due to wedge some tenons on a project of mine - so timing was perfect and i learnt alot. Suscribed and look forward to watching more.

Wow. Perfect project for my Christmas gift of mortise chisels. Beautiful sawing, Rob!

This is my third time to watch it. NICELY DONE! 👍

Just perfect! Thank you for sharing this!

Well, now I know how to avoid splitting... like what happened on my last project. Thanks, Rob. 🍻

Excellent work Rob. Thanks for all the time and precision you put into your work.

Thanks for your advice. I'm going to use it for short stairs from the kitchen to the garden.

It's called the hypotenuse, Rob. And it's equal to the square root of the other two sides squared and then added.

Well worth waiting for Rob. Great video. If you can see it you can understand it.

Impressive. Thank you.

Wow. The best of the lot, this one. From the demonstration and skills points of view - this is superb.

So many cool tips and tricks. Thank you Rob for these awesome educational videos!

Little late in watching but what a great video, thanks Rob, watched it 3 times to make sure I understood all you were explaining. Will try one, hope my patience holds up. Thanks again.

Rob, you make it look so easy and that gives me the confidence to do it! 👍🏻

"The biggest down side is that you never see it, and if you do see it, it failed..." 🤣🤣🤣🤣. I don't know why that cracked me up, but it did!

I was impressed with your Tenon Saw but at $250, I would have expected a hand-carved handle not moulded resin. I will stick with my Dozuki-paper thin cuts for around $35! This woodworking site is definitely in the "Master Class" league, cheers Rob!

Love watching your craftsmanship and attention to detail. That is a beautiful joint and the different woods contrast it well. Only thing I have negative about it is how labour intensive and time consuming it is. I I realise you can do them a lot faster when you not explaining your methods in detail but each joint would probably take 20 minutes or so.

Beautiful joinery beautifuly explained! I wish it was easier to find such quality tools here in my country, they sure make things easier.

You have such a clear and comprehensible way of explaining processes like this. Thank you for all that you do.

thank you Rob. if i may i was used to seeing the 1/64s on the scale well back in the 70s last yr i could hardly make out the 1/32s side of the scale . i had cataracts i found out . so i had the surgery last summer its quick and relative easy now i can see the 1/64s again with out a magnifier . you might want to have your eyes checked out . hope i did not offend you just passing along personal experience. again thank you

Another great episode. Thanks Rob (& Jake!).

Really fantastic! Thanks Rob you are the best!

How'd you know. This was just the advice I needed for a side table I'm contracted to do.

I think this is my favorite joint!

At 54:20, I'm waiting for blood to start spurting. But seriously, great instruction. I've done wedged tenons before, but you showed several things I never thought about.

Thanks 👍

Rob I am fairly new to woodworking. Only been around 2 years. But not new to craftsmanship and I very much appreciate yours. I am a metal worker by trade. In metal working when ever we have a Crack or a cut slot we drill a stop hole and I have seen it done on through wedged tenon. Where they will keep the bottom of the slot up from the sholder than drill a hole. Is this not needed in wood? Or do you not need it when the side parts that are being pushed out are small enough? If I am all off base what is the determining factor?

Fantastic teacher, Your the man!!

Oh man, I was cringing as you were shaving the wedges on the shooting board and almost choked when you slipped. But that was a fantastic deep dive. Kudo's to you and your boy on another great video!

Have you seen the video which demonstrates that contrary to recieved wisdom end-grain glueing is actually stronger than side-to-side because it penetrates into microscopic pores and the cellulose tubes are so much stronger than the lignin?

Awesome Vid Thank You!!!👍👍👍👍👍 😇😁

I'm curious if you could drill a small hole at the bottom of the tenon cut for the wedges rather than doing angled cuts to prevent splitting

8:20 the name of the longest side on your right angle triangle is the hypotenuse. You calculate the length by squaring the base line of the triangle, (multiplying the length by itself), then square the perpendicular side, add them together and find the square root. The answer is the length of the hypotenuse.

When the cut was made at an angle, it goes really close to the edge of the tenon. It seems that this is a weak spot? Doing it this way means that you are only holding the tenon in with a few strands of wood. In the cross section that is shown, it actually looks like it is cut so close that it is not connected on one side. Would it be stronger to just bring those cits in a few mm, so it was not as close to the edge when the cut reaches the shoulder?

Rob that was better than brilliant. Cheers Paul in the UK

great show ,learned a lot, thx

Thanks for the indebt demonstration rob! Super helpful and very much appreciated.

Great video! Thanks rob!

Your right tenon side cracked before you put the wedge in, meaning it literally only depends on the glue to stay in there.

Fantastic video as always, thank you so much Rob! Interestingly, I've never seen it done that way. Usually people saw the "wedge line" straight, but drill a small hole towards the end of the line to avoid cracks/splinting. I was wondering what are you thoughts on that technique?

Very nice ....

I checked your website. Your tools are coslty.

Anyone can do that joint but not may can make it look really clean and good.

Think you for the videos you do

The toughest part of that joint, in my opinion, is getting the wedges right. Also, I have drilled a hole at the bottom of the kerf to keep it from splitting apart when you drive the wedge in.

A wee while ago I required some blind m&t joints so thought "fox tail mortice & tenon" was the way to go. In the end I wasn't wrong, but you need to be meticulous and have nerves of steel.

A great look to the through tenon. Could you use a dovetail marking jig to set the angles for the mortise? I should think 6 or 7 degrees would be sufficient. Would it work to saw the tenon shoulders first? The saw kerfs in the tenon for the wedges look too close to the edges of the tenon to me. In fact it appears one of the flares on the tenon broke when you prepared for the wedge. Didn't that weaken the joint? Thank you for sharing. Have a great 2021 and stay healthy.

Fairly nicely done. It looked on video like the one finger one your right (left side on the video) broke when you opened up the gap with the chisel to insert the wedge. Did it, or did the tightness of the mortice and glue just hold it over?

First rate instruction~!! I'm going to have to visit your friends at Lie-Nielsen since I don't yet have a mortise chisel because I cannot wait to try this myself~!! So Rob, this is not me sharp-shooting you....just an observation since this was a demo and we're learning: As you pried open the kerfs with your chisel, I thought I heard the 2nd one (your right side) crack as it laid over. Don't know if it did, but if so, is that a show stopper on a project? If the outer piece is broken at the base, then could the tenon pull out even though wedged and glued? Thank you~!!

Hypotenuse is the longest side of a right angled triangle.

Awesome ji

Can you explain if wood movement needs to be taken into consideration here, cos there is no space for the wedge to expand and contract? Sorry if this was asked by someone else here.