Gripping a bowl in a chuck

[Jack Ganssle]

Newbie turner here, having way too much fun. But I'm struggling with the concepts of using the chuck. The video Julie linked to (Sorby bowl turning) shows them forming the tenon and the outside of the bowl using a screw thingy in the chuck. Then they remove the screw and put the tenon in the chuck. All very clear.

But my Supernova chuck has lips that bite into the wood. So when I remove the wood, the tenon has bite marks in it. It seems silly to have to sand those out; clearly I'm missing something that will probably be head-slappingly obvious.

What obvious thing am I missing?

Thanks,
Jack

[Steve Schlumpf]

Jack, can only speak for myself - but I turn the tenon away and leave a slight recess on the bottom of the bowl.

[TYLER WOOD]

ditto Steve's comments. The tenon is really only there to hold the bowl while turning. You can reverse chuck using a vac chuck or cole jaws after hollowing the bowl out if you want to turn the tenon down slightly and finish the bottom out. Typically the tenon used to hold the bowl is too large to be visually appealing to the piece, so most people find themselves turning the tenon off.

[Paul Engle]

Or , you can use the screw chuck to hold the blank to the chuck face, then turn a recess ( mortise) on the other end , which now becomes the bottom, turning the recess to match the dia of the chuck and the dovetailed jaws at ( 15 degress) if G3 I go with 2 1/8 " if using SN2 I go with 4 1/8", now turn the outside of the bowl and the bottom to finish sanding etc , put first coat of finish on the outside , now un screw the blank from the chuck, take out the screw and reverse the bowl to fit the jaws, touch up the outside once rechucked , now turn the inside to finish, you will have no tenon to deal with and if you want a foot , you must turn that while you still have it on the screw before you flip it around. see my web for pics on the screw mount ( non commerical site) . If the bowl is overly large ( over 6" dia by 2 " deep or so , then use the tail stock to back up the bowl till ready to turn the mortise and or foot .
http://mysite.verizon.net/respwkup/stuff/
I do 99.9% of my bowls/vases/hf's this way as I do not have vacum chuck and find this more secure than jam chucking the bowl to remove the tennor, altho is ok to do I feel more confident.

[Neal Addy]

Ditto Steve. Just remove the foot completely. Most of the time it makes a much nicer looking bowl.

[Jack Ganssle]

Thanks, folks. That really helps. I'm dashing down to the basement to try it all out before two weeks of travel starts tomorrow. Again.:(

Jack

[Bernie Weishapl]

If you want to leave the foot on use a donut chuck to reverse the bowl and turn away the marks. I usually turn the foot off but sometimes leave one on.

[Alex Elias]

Here is how I chuck the bowl to hollow. I only made 2 bowls so far so I'm not the expert here but it work for this 2. I'll get some variations when I gain experience.
This bowls are 6" x 2" so I don't know if the expansion method is recomended for deeper larger bowls. I'd be courious to know.
http://i136.photobucket.com/albums/q185/alxe24/Goncalvo-Alves-Bowl-04.jpg

http://i136.photobucket.com/albums/q185/alxe24/Am-Maple-bowl-03.jpg

[Jim Becker]

The expansion method generally has less holding power and for bowls, there is usually less wood for support. (using a recess is more suited to platters and other "flat" forms where there is a lot of wood outside of the recess) It also results in a large recess that you have to do something with...trimming off a tenon is easier and cleaner, IMHO.

One other point about the OP's situation...when you make a tenon, it needs to be suited to the type of chuck jaws you have. Some chucks work well with a straight tenon and others require a tapered tenon. Be sure you know what is best for your particular chuck. And don't forget that you also need a shoulder for the top of the jaws to sit on...the tenon should never bottom out in the chuck and that lip is critical for best support. You should not depend upon the jaws grip on the outside of the chuck alone.

Trimming off the tenon is a finishing task. There are various ways to accomplish reversing the piece to do this, but a jam chuck is easy and cheap. In many cases, you can simply put a soft materia, such as carpet padding over your chuck and jaws, put the piece over it and bring up the live center/tail stock to engage with the orignal center of the piece. Play with it a little with the power off to get it running true and then turn off nearly all of the tenon, leaving a thin stub to the live center that you can trim off with a sharp carving gouge or chisel.

[Julie Tanner]

http://www.cumberlandwoodturners.com/tips/Methods%20and%20Jigs%20for%20Reverse%20Turning%20B owls.pdf

here is one link that I have looked at myself.

I do like Jim's idea, cheap and seems fairly easy.
Will try it this weekend.

[Jeff Cremers]

I have the Apprentice Chuck from woodturners catalog this one.
http://www.woodturnerscatalog.com/store/Chucks___Apprentice___Apprentice_Chuck___apprentic e_chuck?Args=

Which adjust a jaw plate or cole jaw can I buy for this chuck? I don't see any that say they will fit my chuck.
Thanks in advance for any input.
JEff