How to salvage half turned bowl when tenon for chuck broke off

[Staffan Hamala]

I was just now turning the inside of a small bowl out of a nice rowan burl. However, I had a bad catch when half way down, and the tenon for the chuck broke off. The hole for the screw chuck is no longer there, so I can't just turn a new socket. Not that easily anyhow.

I have a few ideas that I'll try out later today, but am curious about how you solve this problem. I guess it happens sometime for everyone.

I might be able to glue the tenon back, but I'm not sure that would be a good idea..

[Mike Peace]

Get the bottom flat with a chisel, belt sander or whatever and glue on a glue block for a tenon. If there is enough wood at the bottom to turn a new tenon, reverse chuck the bowl against a jam chuck with tail stock support and turn a new tenon.

[Steve Schlumpf]

Staffan - without photos to show just how damaged the tenon is, I have to agree with Mike that a glue block would be your best option. Looking forward to seeing photos of the completed bowl! Be safe!!

[Reed Gray]

Some times you can glue it back on. I prefer the titebond type glue rather than the CA glue, but both will work. When you put it back on the lathe, you will have to true it up again. Spread the glue, then either use the tailstock to push it up against plywood on your chuck, or you can use 2 pieces of plywood and clamp it in between. Otherwise, depending on how much of the bottom is left, you may be able to turn another tenon on it. Some times after gluing, if you still have a center hole on the bottom of the tenon, you can reverse chuck it and return the tenon.

Okay, so what caused the catch? Gouge flutes too straight up and down and a wing caught?

robo hippy

[Pat Scott]

You said the catch occurred 1/2 way down the inside. Depending on how thick the walls still are in the bottom, you may be able to turn the bowl around and put it against your chuck, bring up the tail stock, and then cut a new shallow tenon into the side wall just above where the tenon broke off. You don't need much, depending on your skill level an 1/8" groove is all you need. Then put the bowl back into the chuck and finish turning the inside. When done, reverse the bowl and finish the bottom like normal, except now you have to blend in the 1/8" groove into the curve (another reason not to make the groove too deep).

My art skills leave something to be desired, but the jagged red line represents the broken tenon. The blue "V" cuts on both sides represent the 1/8" groove that is your new tenon. Don't worry about flattening the bottom of the new tenon, all you need is the groove to grab onto provided your jaws are deep enough or that you don't cut the groove too far up the side wall.
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[Thom Sturgill]

You've gotten several good comments here. If you clean up any stray fibers, sometimes a broken piece can give a better joint than smoothing it and glueing on a separate block. Since you are working on a burl (with varying grain), I would suggest that you should have started with a hardwood glue block and would suggest that you go that route now. I've not turned rowan or a rowan burl so I don't know the density off hand, but I generally use a glue block for heavily spalted wood after having a tenon or two shear off. I've not had a glue block fail yet, though now that I've said that the next one probably will :eek:.

As others have mentioned, you can reverse chuck it using the tail stock for support. Then square off the bottom making it just slightly concave - just enough to insure that it is not convex. Then glue on your block in side grain orientation using titebond and tailstock pressure. Let it set overnight. Turn a new tenon on the glue block and mount it back in the chuck. True up the outside before turning the inside again.

[Staffan Hamala]

Thanks for all suggestions!

I first tried gluing the tenon back on, but it worked loose again almost at once. I guess it's something with the varying grain direction (and it was also not completely dry).

However, I salvaged it by making a jam chuck, and used the tail stock support to make a new tenon.

I had to true it up again, as it was not centered exactly as before. But I'm happy with the end result.

However, it's not really a bowl anymore. I thought I would make a bowl, but it turned out that's not what the wood wanted. There were some cracks that I wanted to get rid of, and so on. There was bark deep inside, and I chose to leave just a little. I'm attaching a couple of photos. :-)

I finished it with a coat of bees wax.

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[Kurt Vilary]

Nice recovery. I have never heard of rowan burl. That is a beautiful piece of wood.