Using Chucks for large hollow forms?

[John Sincerbeaux]

Hello all,
Does anyone here use large chucks for turning large hollow forms? Large, as in the 16"+ range

Assuming you have a large lathe and a large chuck, what is the largest HF's you have turned HF's on, or heard of been turned on using a chuck. Vicmarc shows a 20" capability for their 120 chuck. I know faceplates are king for doing large work, but am just curious what guidelines/limits guys use for using chucks.

Thanks

John

[Alan Trout]

It really depends if the hollow form is supported with a rest. It does not take much of a tenon to turn a deep form with at steady rest. I have done 16" with a 2.5" tenon without trouble with my Strong Hold chuck with the vessel supported in a steady rest. A VM120 will work just fine.

Alan

[Steve Schlumpf]

I agree with Alan that using a steady rest makes a huge difference. Also, the experience of the turner makes even more of a difference when turning large forms. If you know how to put metal to wood - without - causing catches, then the amount of tenon used isn't as important as support for the form.

[Faust M. Ruggiero]

David Ellsworth teaches hollow forms with the piece mounted between centers until the outside shape is determined. Then he flattens the bottom and mounts on a faceplate. Of course, you need to design the form allowing the bottom to fall within the screw holes. David teaches with a 6" face plate. I am sure the face plate is wonderful as a learning tool and gives a great sense of confidence, however, I find it restrictive. I still turn the outside shape between centers but now I usually turn a tenon and mount in a chuck. I would not hesitate to use a faceplate if the shape or size of the hollow form demanded it.

[Thom Sturgill]

Lyle Jameison calls the steady rest an engineering solution to a [problem that shouldn't exist. He strongly advocates the use of faceplates.
While I have used the centers to tenon route myself, most of my turnings are much smaller. Nova gives limits for their jaws, and only the powerjaws come close to holding 16".

[Dennis Ford]

Using a chuck is a convenience for me, it saves a little bit of wood and a couple of minutes of mounting time. That is great for a turning that takes 10 - 20 minutes to finish but seems meaningless when talking about a large hollow form. There is nothing wrong with using a chuck if it holds for you but launching a large blank or two will make you re-consider (if you survive). Also a tall hollow hollow form puts a LOT more stress on the mounting than a short piece with the same diameter.

[Joe Meirhaeghe]

I've turned & hollowed 24" dia. 450 plus lb logs with a 2 1/2" to 3" dia. tenon with a 1/4" long dovetail. That said I shape the vessels between centers & ALWAYS us a steady rest for hollowing.
The tenon is just a means to drive the piece when turned this way. It is not supporting the weight of the log it's just used to drive the piece.

[Dwight Rutherford]

I agree with Joe , also turn between centers and use a steady, always.

[robert baccus]

My go to for 100#+ X 22"+ vases is a single screw and 3 " glueblock for all operations including finishing. I always use a steady rest by by oneway. Roughing out is between centers to make a good glueface and square ends. I use great wood for GB and fresh thick CA. Dismounting is by parting tool/saw. Mine are always done on green wood which dictates the CA glue.

[Thom Sturgill]

My go to for 100#+ X 22"+ vases is a single screw and 3 " glueblock for all operations including finishing. I always use a steady rest by by oneway. Roughing out is between centers to make a good glueface and square ends. I use great wood for GB and fresh thick CA. Dismounting is by parting tool/saw. Mine are always done on green wood which dictates the CA glue.

Doesn't the worm screw cause an issue if you want to reverse for sanding? A small faceplate would probably be just as stable.

[Jim Silva]

I played with chucks vs faceplate quite a bit and I have to say that the faceplate is by far the best method of holding a large hollowform. (or medium size for that matter)
I'm a huge chuck proponent form most all other applications but on hollowforms, especially taller ones the faceplate is the only way to go IMO.

I start between centers and I don't use a steady and have significantly more vibration with a proper tenon than when mounted on a plate.

[robert baccus]

Chuck, I power sand mostly but never have backoff's on the single screw when reverse sanding. There is very little torque involved and I tighten the GB on with a big pair of channel locks. The problem with faceplates is putting in screws into green endgrain. I haven't lost a big one yet. Do a scrap/test with CA on the lathe to destruction. The only screws I ever use is on a small faceplate(three 1.5" square head screws) to rough out hollow forms or bowls and make a holding on the bottom. I use mostly glueblocks but dovetails also. Never tenons--I,ve had bad luck grabbing green wood tenons. I don't throw the bowls but knock them out of line--grrr.

[Jake Helmboldt]

So I'm curious to know more from those of you that use a faceplate, specifically regarding what you do to finish the bottom of your HF after it is turned. I launched a medium vase and cracked it as I neared completion hollowing. Joy!

So I've turned the bottoms off of bowls with jamb chucks, etc, but what do you use for HFs to clean up the bottom and eliminate the screw holes?

[John Sincerbeaux]

Thanks guys,
The guy that is mentoring me turns only large hollow forms 20-24" and only uses a 6" faceplate. End grain or face grain and he has never had one come loose/off. He also never uses a steady rest. I ask about chucks because my first HF's will be around the 12" size and I think it would be nice to learn to use chucks up to their safe limits.

[Dennis Ford]

Jake:
I jamb chuck vases a couple different ways.
* turn a cylinder (mounted on a chuck or faceplate) long enough to reach the bottom of the vase and use that to drive the vase between centers.
* turn a disk (mounted on a chuck or faceplate) with a ledge that fits (not tightly) into the opening of the vase, cushion with a paper towel and turn the vase between centers.
Either method requires that you carve off a small nub where the tail-stock was.

John;
Exploring the "safe limits" of a chuck is not a good plan until you have explored other ways of making hollow forms fail.