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TR
12-06-2010, 09:27 PM
What are the desirable features in a quality four jaw chuck ? Is dialing in the workpiece easier with some chucks than others ?

I'm looking at buying a 6 or 8 inch and would like advice.
Ideally D1-4 attachment.

ammcoman2
12-07-2010, 10:45 AM
I have a Pratt 8" with an integral D1-4 mount and it weighs 42lbs so I would recommend this type. A backplate would add about another 15lbs.

I once bought a chinese 5" 4 jaw and was not impressed - too stiff to adjust.
If you are going to use it a lot then get a Pratt or a Bison.

Geoff

Spin Doctor
12-07-2010, 12:04 PM
Bucks are nice too. It is a matter of getting what you pay for. One thing I always wished that the chuck makers would do is put a scale on the jaws so doing your rough adjustment is a little easier. Can be done yourself too.

becksmachine
12-07-2010, 12:16 PM
One thing I always wished that the chuck makers would do is put a scale on the jaws so doing your rough adjustment is a little easier. Can be done yourself too.

That is what the concentric circles on the face of the chuck are for.

If a chuck doesn't have them it is a simple matter to add them and number them.

Dave

AllThumbz
12-07-2010, 02:20 PM
I got a 5" Pratt Burnrd for my SB Heavy 10. It's English made, and supposed to be a decent brand.

Greg Q
12-07-2010, 05:40 PM
I'd be pretty relaxed about buying a used four-jaw independent type. The odd D1-4 chuck in that size pops up on ebay here from time to time. Otherwise, Pratt-Burnerd or Bison (Polish) TOS (Czech) or Rohm (German) might be all you can get new locally.

New Bucks are made in China, the old ones are nice.

I have a Soviet made three-jaw new in box that I bought recently. It is dandy-maybe you'll find something similar with any luck.

KEJR
12-07-2010, 08:09 PM
I had a post a while back about import 4 jaws, but there were some comments about name brand chucks too.


http://bbs.homeshopmachinist.net/showthread.php?t=43812&highlight=chuck

I ended up buying a used skinner originally meant for a southbend (for my logan). It looks OK, a bit tarnished but the jaws feel tight. I haven't really gotten to use it yet.

I'm not an expert but I think you want something that has the jaws grooves and front faces running parallel to the back plate. With a 4 jaw you can dial out the ecentricity, but you will have a hard time compensating for a chuck where the jaws are holding the part at an angle. Some guys said on long parts you can tap it straight with a brass hammer, but I'm sure this only goes so far. That was enough to scare me off from the chinese chucks. In reality the chinese chucks are probably OK but I've never found anything chinese with moving parts that I liked!

KEJR