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Boring out a 3-jaw chuck for a glass lathe?

Hello all,

I do a (very) little scientific glassblowing, as do a couple of my colleagues. It was suggested that, since the department would never be able to afford a glass lathe, building one (or having one donated to us) would be the only way to get one.

For those who haven't seen 'em, a glass lathe has two spindles with 3- jaw chucks lined with ceramic cloth. The spindles are geared together to turn at the same (slow) rate, so the glass doesn't twist. The setup allows one to heat one part of a glass tube evenly, all around the circumference. Great for sealing large-diameter tubing together and lots of other operations.

The ways, two headstocks, spindles etc. aren't a serious problem---I built a Gingery lathe years ago---but the chucks must have a very large through hole. 3" wouldn't be too large, 2" would be ok.

High precision isn't necessary, so I was wondering whether it would be possible to get a couple of cheap 8" chucks, remove the jaws, and bore out the center to, say, 3" or more. Of course, the center of the scroll would be bored out. Would that affect general operation of the chuck? (I thought that if the gearing was on the outside of the scroll, the thing should still work. I might be full of it. It wouldn't be the first time; just ask my wife.)

Thanks! -- Terry

Reply to
prfesser
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Before you make any decisions about boring the chuck, I'd suggest you dismantle one to see how it's built. The few I've had apart had a center boss on which the scroll located and pivoted. You wouldn't want that to not be there----although under your circumstances it's entirely possible it would still work reasonably well because you're not asking anything from the chuck in the way of heavy loads.

Assuming the scroll inside diameter doesn't allow the size you'd prefer, you may be surprised that it won't yield to machining willingly. Scrolls are usually well heat treated, likely harder than you can comfortably machine. The bore of the scroll should be the limiting factor, but my money says it will be at least 4" in diameter, and not a problem.

Harold

Reply to
Harold and Susan Vordos

What you need is two chucks from a pipe threading machine... The old style...

Reply to
kbeitz

Terry, Chucks for glass lathes are specific for the purpose. Here is a page from the Litton website;

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They do use a lathe 3 jaw chuck, but the most common is the planetary

3 jaw pin style. That offers the least amount of heat transfer and is best for holding a wide range of tubing diameters. As you can see there are options for the job you're doing.

Glass lathes are unique and Litton is the benchmark. They do come up for sale thru surplus and liquidation houses. Rather than cobble up something else, you would be better off finding the right tool for the job. I would.

Bob

Reply to
rleonard

Terry, Chucks for glass lathes are specific for the purpose. Here is a page from the Litton website;

formatting link
They do use a lathe 3 jaw chuck, but the most common is the planetary

3 jaw pin style. That offers the least amount of heat transfer and is best for holding a wide range of tubing diameters. As you can see there are options for the job you're doing.

Glass lathes are unique and Litton is the benchmark. They do come up for sale thru surplus and liquidation houses. Rather than cobble up something else, you would be better off finding the right tool for the job. I would.

Bob

Reply to
rleonard

[snip]

Do you really need to use a metalworking chuck? I doubt you need to hold glass with the same amount of force and precision as we tend to do with metal turning operations.

You could take two rounds and make your own chuck. Likely a 4 jaw independent would be the easiest. Based on my assumption It would be much thinner and lighter than a metal working chuck.

Wes

Reply to
clutch

Reply to
David Billington

I designed a very similar device as an adjustable guide for a styrene tubing extrusion line, with rollers in place of the pins. If the OP is interested I can dig up the cad drawings. Unfortunately they're pretty old, so no pretty 3D model.

Ned Simmons

Reply to
Ned Simmons

Well after hitting FleaBay and getting a good idea of what a Litton chuck looks like I say just make the whole chuck, it's gotta be eayser than trying to diddle a metal chuck.

Looks to me to be a pretty easy design, flat plate, arms held in place with a bolt... I can't tell from the pics if the rams are spring loaded but.... I'd make a few 'plugs' that fit the ID hole of the chuck that are bored for an easy fit on the most common tube sizes to make it easy to center things.

I bet with a bit of thought you could hack something like that out in a day

--.- Dave

Reply to
Dave August

Google search for a pot chuck. They are very easy to build, and all that is needed is a short piece of tubing welded to a lathe face plate and 3 long set screws tapped into the sides of the tube 120 deg.apart.

DBW

Reply to
donald

Thanks to all for the suggestions. I'd love to buy a used lathe but most of the glass lathes I've seen on Ebay have run five grand or more. It's highly likely that the money would have to come out of my pocket, or the pockets of a very few users---it's probably not gonna happen.

Pot chucks might be ok, at least for a starting point. Thanks for the pointer to the Litton lathe chucks. The three-pin chucks might be doable, too

I've seen the Taig conversion, it's a bit small for what we do. Too bad, as it would be very nice otherwise.

Thanks again -- Terry

Reply to
prfesser

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