Well, that didn't go so well....

[Jamie Straw]

Tried making my first jamb chuck tonight. Hmmm,grrrr,ummmm....not so good. Wanted to make the tenon small enough to fit in the #1 jaws, because those are the ones I'm using the most right now. Got the body the right size for the little NE bowl, stuck it on there, went to work on it and "Wheeeeeee!" There she flies, or actually "dives" off the lathe. Jamb chuck broke right off of its tenon.

Oh, well, just had to tell somebody. It's midnight, and hubby's asleep, the dogs and cats don't care.:p Thanks....g'night.....

[Norm Zax]

Happens to others as well. Was the wood for the jam chuck reasonable (i.e. not soft as pine or a wood substitute) and were the jaws securely pressed on to the shoulders?
Two useful tips for using jam chucks: After getting a close fit, moisten the chuck with water and dont delay plugging in the object. The fibres on the chuck will slightly expand and grip better. 2) after items are in the chuck, add three or four twists of saran-wrap to secure the piece. Make sure you are wrapping against the direction of turn, or it will un-ravel. Make sure you are not covering the area about to be turned.
Enjoy...

[Frank Van Atta]

Thanks for the tip on moistening the chuck; never thought about that.

Saran Wrap works great as a "safety net" - so does masking tape. Sometimes when I get through chucking one of these things up it looks like a mummy - but it does stay on the lathe.

[Kyle Iwamoto]

I use an old ROS sheet. I put the sandpaper side to the chuck and the "soft" velcro side to the bowl. That way there is less (actually none) scratches on your bowl. +1 on using some sort of hardwood for your jam chuck....

[Jamie Straw]

Hi, Norm, thanks. The wood was maple and was green, so pretty wet already. There probably wasn't as good a shoulder as there should have been -- not much bearing surface for the tips of the jaws. Trying to wrap my brain around the Saran Wrap idea -- it holds the whole package to the chuck, right? Another tip to try out.

Gotta go back and look at Grumbine's DVD -- he uses a faceplate sandwich -- faceplate, plywood, bowl, then plywood with a hole. Probably won't work on an NE bowl, but for others it would. The outer ply has a hole in it, which slips over the bottom of the bowl, carriage bolts squeeze the two together to clamp the bowl in place for bottom turning. A good use of the stock FP that's way too big for the lathe it came with.

[Brett Bobo]

Jamie,
With the doughnut chuck that Grumbine promotes, you can also use this for natural edge bowls. The only difference is you insert the jamb chuck or "bun" as I call it between the inside edge of the plywood on the faceplate side and the bottom of the bowl. The length of the bun will depend on the depth of the bowl so the natural edge clears the plywood. Another option for the bun is a thick-walled pvc pipe, such as schedule 80 and up, and you can purchase it in various diameters to fit the diameter of the inside, bottom of the bowl. Also, another good tip I've learned here is that a mouse pad helps protect the bottom of the bowl from getting marred and provides enough friction to keep it from spinning.

[Wes Henson]

Do you have a thread tap sized for your spindle? Using that can eliminate the chucking step, though you need to have enough thickness for the threads.

Also look into the blue tape and hot glue method. There was a thread a while back on it. If I rememeber right it was something like this: turn a profile to math the inside of your bowl. Cover bowl inside and mounted prifle in blue tape. Then hot glue together. Once done turning it pops apart and the tape peels off.
I have never tried it but it looked interesting.


Or you can always finish it by hand.
-Good luck

[Norm Zax]

Jamie -
Yes, the wrap holds the work to the jam chuck.
The tennon failed probably due to incorrect positioning. Also, green wood makes risky tennons in some woods.

[Denis Puland]

Hi Jamie

If the #1 jaws you are talking about are the ones for the tallon chuck then I think perhaps that is the main reason for your problems with the chuck or tenon not holding.

They are not designed to hold anything with great gripping power at all and tend to crush the tenon if tightened down with a lot of force. They are step jaws and for use on very small projects that are not suited for the #2 profiled jaws.
Denis