Is this a bad idea?

Re: Is this a bad idea?

JL

>Depends on the wood and the mortise depth. Make sure you have a secure hold. I'd be more comfortable with larger jaws myself. My $0.02.

Re: Is this a bad idea?

Richard Allen

>Hi Rob

It should work fine. Just use the tailstock for additional support until you are working within the diameter of the jaws.

Good Luck

Richard

Re: Is this a bad idea?

Mike Schwing from Md.

>I'd use the old adage "if you're wondering if something is safe, it probably is not". However, I'm sure it can be done safely, but NO WAY I'd do it. I would rather affix a glue block and create a stronger compression tenon.

Re: Is this a bad idea?

Les Robison

>I would not do it! Even large jaws in expansion on an 18" object are asking for a break out. Better to use a glue boick, or create a tenon to hold in compression mode.

Re: Is this a bad idea?

Russ Fairfield

>18" might be stretching it a bit, and I would recommend a larger jaws; but there should be no problem with a 2" chucking recess in an 18" platter. And, DO hold the piece with the chuck in the expansion mode. Leave a good 1" of wood all the way around the recess, easy to do with a platter. Do use the tail center against the wood until it gets near final shape. You can do the entire platter up to the center, and then remove it to finish the center and for sanding.

Why is everyone scared of using the chuck in the expansion mode? It is the better way to hold a piece of wood.

When expanding into the recess, the wood around it is put in compression to react against the chuck jaws. This makes the wood more stable and less likely to vibrate because wood in compression doesn't vibrate and wood that is in tension does. Compressing on a tenon does nothing other than squeeze the tenon together at the center of the platter, and this has no effect on the rest of the wood.

Want proof? Turn two identical pieces to a very thin wall thickness. Do one of them in expansion, and the other in compression. Thin walls will accent the difference. Which was the easier to turn??

Re: Is this a bad idea?

Bill Hale / The Wood Spinner

>I agree with Mike and Les, Use compression !

I would prefer larger jaws but if 2" is it just be extra careful. Light cuts, slower speed and a must is use the tail stock. You can finish the inside clear down to 1/4" tit against the tail stock. Then turn that off and final sand that spot.

Good turning and be safe

Bill in Casa Grande, AZ.

Frisbee

Barry Irby

>

Re: Is this a bad idea?

tek-Brunswick, Ohio

>I'll have to trust Russ on the technical points. I don't have that expertise. Using the chuck in expansion mode is my favorite way to mount a platter on the lathe. I took some flak for that in an earlier post. I just run a 2 1/8 Forstner bit into the wood 3/16" to a 1/4" deep and expand the talon #2 jaws into it. I turn the foot around the recess last and waste very little wood. A 15" blank is the largest I've done this way. I use the tailstock until all my heavy roughing is done. I do my final lighter cuts without the tailstock. So far I have had no problems.

Re: Is this a bad idea?

Ken from SW WI

>Why is everyone scared of using the chuck in the expansion mode? It is the better way to hold a piece of wood.

I gotta agree with Russ here. In compression, on any cross-grain piece, the weakest link in the chain is just outside the grip of the jaws, and may only be 2-3" in diameter.

In expansion, two opposing jaws are pushing out against end grain, so it's not like you're trying to pry the piece apart.

Re: Is this a bad idea?

Walter Ahlgrim

>In the expansion mode you are pushing out in 4 curved spots in the center of the jaws radius. In compression you grab on the 8 sharp corners of the jaws. When started using the chuck I liked expansion but after I removed too much waste near the jaws and cracked the work I stopped. You need to leave a large ring of wood to support the jaws forces. This rink interferes with my ability see the final line of the work and forces me to delay cutting to this line until after I have reversed the work. When I do get to remove this ring it is farther from center since I can never get the work perfectly on center this error will shows more and more the farther from center I must cut. Once I learn to cut a good square tenon just larger than the minimum diameter of my jaws, that matches its profile and comes close to bottom out in the jaws but dos not, I haven�t gone back to expansion.

Re: Is this a bad idea?

Rob Ceraso

>Thank you all for your input. Let me throw one more "issue" into the mix here - I'm working on a Jet 1442 so I would be doing this outboard and therefore can't use the tailstock.

Having said that, let me go a little further to say how I originally planned to do this. I was going to use a glue block on a 6" faceplate attached to what will become the top of the platter. With this setup, I'd turn the entire bottom including the recess for the 2" jaws. Then I'd reverse it and turn the top using the chuck. I figured the piece would be pretty well balanced and with light cuts I might be ok.

Anything additional would still be appreciated. Thanks again.