Through tenon with Mortise across grain
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I’ve got a small project I am working on and decided to dress it up a little with through tenons. I’m using a 1/4′ chisel that is actually more like .228 instead of .250 of an inch. My initial test piece was with the grain, no issues with the technique required here. My box actually need the tenons vertical, which ends up being across the rain. I do not recall seeing a similar situation addressed in any videos. I managed to get the first one done, but it was a time consuming affair. Not mention the torture on my nerves from fear I would mess the part up. I have 7 more to do and was wondering what is the best approach to take?
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I do not quite understand your construction, but it does not look dissimilar to how a shelf would need to join to the side of a bookcase.
Usually there would be a housing dado to receive the entire width of the cross-member. If tenons are desired for extra strength, I have usually seen them cut as square tenons that are spaced apart and wedged.
Here is an example from The Carpentry Way Blog
In your example, turn the tenons 90 degrees. That is what I am doing. The grain of the mortised pieace is horizontal but the tenons are vertical. That might be a better way to put it.
I am hacking away at them. Knife wall then using the chisel to slide between the walls. Barely removing any material. Rinse/repeat….
Yes, I see from your photo the orientation. I just thought the long tenon you had might best be split into two shorter (wedged) tenons. That way, the long grain of the side/front is not as compromised, and it will be easier to cut shorter mortises since you can do it along the grain as normal instead of across the grain like you are.
Nevertheless, it seems as if you have already committed yourself. 😉
Good luck!
Two issues with cross-grain mortise:
1. Strength of the mortise very low if close to the edge of the piece. Yours is in the middle, so not a problem.
2. The long grain/long grain gluing area will be much smaller than on a conventional mortise/tenon joint. Normally it is on the sides of the tenon, which is also where you trim to a close fit. In your case, it will be on the ends of the tenon, where we normally allow a slacker fit because the glue here will provide little strength anyway. The glue joint strength will therefore be much lower than usual, more so if you don’t pay extra care to the end gaps. The glue joint strength can be important – think of all the chairs you’ve seen where the glued mortise/tenon has loosened.
Good valid points.
Here are a couple pictures while I was doing the work so might be able to show the method I came up with. It worked, just not sure it was the best approach to use.
As you can see they are just dividers for a box so not structural at all.
The through tenons are a nice decorative feature to the box.
Being a total novice, I had been thinking about this myself. Then I saw a photo Paul posted in preparation for the upcoming series on the tool cupboard. I don’t know how he did it, but it looks like he did something similar near the bottom. I’ll attach a photo from his email. Looks similar to me, so maybe you’re onto something.
The project looks nice.
Kevin
My project became a lesson in patience and ventilation.
I had a family member visiting (who the box was for). I stayed up late applying the finish. It dried rather quickly so decided I would apply the flocking. I taped the tray and put on the flocking, worked great. It was late, I had work the next day….decided to push it and do the 8 compartments in the main box. Should have went to bed! I did not tape the sides of the cherry dividers, just started spreading the paint/glue for the flock….and of course I made a mess. thought it would wipe off, but it made a complete mess. To the point that I just dumped the whole can of glue/paint in the box and went to bed. After work the next day I tried cleaning my mess up with acetone. There was too much residual green left behind. I decided to hang it on the wall as a reminder to be patient and tape things off if the instructions call for it…and yes I will remake the box…with a few learned lessons guiding me…
It’s a beautiful box, the contrasting through tenons look great. I think the effect of the full width through tenon (as opposed to splitting it into two) is worth the compromise in strength in this application. Bad luck with the flock, there’s a lesson you won’t forget.
Clearly you found an effective way to cut the mortises. For my two penneth, I think I’d drill out most of the waste and trim with the chisel.
Matt
Too bad, the box is wonderful. Love it.
It’s a great looking box. The tenons are a great accent, an extension of the dividers, which I’m sure took plenty of time to layout.
I think we all have to learn when to call it quits and start again with clear head & eyes. Decision making goes down the tubes when we’re tired. I’m still learning this.Still, it’s a beautiful box.
Marilyn
For the wide board with the wide tenon perpendicular to the long grain, there is a risk of splitting the entire board due to expansion of the tenoned piece. A long time ago Paul showed a tenon in this orientation as a mistake one of his apprentices made. He had to remake the piece. I think it had to do with the first tool chest project, the one in mahogany.
Specifically it was one of the lower drawers with the tenon at the back.
These are not wedged tenons, if they were there would be a danger of the wedge splitting the wood. With the dividers and box side grain oriented in the same direction wood movement will be complementary and result in little risk of splitting due to this, in my opinion.
Matt
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