What size 4 jaw is the limit for lathe

[ndav8r]

Hi Gang:
I need to get a decent 4 jaw independent chuck for my Clausing model 4902. It is a 10 x 24" machine. I was wondering what the size limit would be. I was hoping to fit an 8" chuck with reversable jaws. Any suggestions, comments?
Thanks.
NDAV8R

[Harold_V]

The one bit of advice I'd offer is to insure that you can't extend jaws beyond the point where they can hit the ways. Too large a chuck can yield problems in that area-------and can be difficult for a lathe to start, depending on the speed selection.

I can't speak for your particular machine, but an 8" 4 jaw may be the limit, with a 6" a more reasonable choice. investigate well before making the decision. I'd agree-----get the largest one your lathe can accommodate.

Harold

[SteveM]

Just to give you an idea, the one that comes with a 12x36 Atlas is a 6".

An 8" would be pretty big on the 12", much less a 10".

Steve

[JHenriksen]

I use an 8 inch on my Rockwell 11 inch. The warning about the jaws sticking out is a good one to heed.

[Andypullen]

I have an 8" 4 jaw on my Clausing 4901. Watching how far the jaws are extended is just common sense, really. To date I haven't hit the ways with chuck jaws under power. If you can't turn the chuck to indicate the part in; that should tell you something.

Andy Pullen

[BadDog]

My Rockwell 11 has a Pratt Burnerd 8" that is about perfect, at least in my opinion. Note that this is what would probably be called a "light duty" 8". The body is only about 2" thick. There are also "heavy duty" 8" chucks. I have an 8" Cushman in this form factor, and it weighs at least twice what the PB weight as well as being over 3" thick and with jaws twice as wide. There is a HUGE difference...

[Bill Shields]

I have a 12" chuck on my 16" south bend and an 8" chuck on my 10" clone.

There have been many times that I blessed the fact that I had the 8" because I could hold work that will fit in the lathe....and there are many times that I curse the weight of the 12" - requires a chain-fall to get on / off.

If it were a bit smaller, I would change from 3 to 4 jaws a bit more frequently. It's also a bear to get up to full speed in high range with the old flat-belt drive, before the belts slips off the pulley..

How heavy a chuck can you lift? In some cases, that becomes the determining factor - along with the $$$ of the larger chuck (which is why most lathes come with small chucks in the first place).

[gwrdriver]

My Rockwell 11 has a Pratt Burnerd 8" that is about perfect, at least in my opinion. Note that this is what would probably be called a "light duty" 8".

I have (probably) exactly the same P-B "light" 8" chuck for my Harrison 11" and likewise IMHO it's just about perfect for model engineering and live steaming, on those few occasions when I actually need an 8" chuck. A full 95% of the time I use a 6" 4-jaw, also a P-B "light" duty. I also have a Cushman bigass heavy duty reversable jaw 8" 4-jaw . . . . and I hardly ever use it. But then it always depends upon the work it will need to do.

[LivingLegend]

I don't see any problem with, and don't think you'll have any problems using an 8" diameter chuck on your Rockwell 10".

I have D1-4 mount 6" chucks (Rohm 3-jaw and a Cushman 4-jaw) on my South Bend Heavy 10 Toolroom. When I get it back together after cleaning and re-painting, I'll be buying a new 8" 4-jaw for it. The SB Heavy 10 won't have any problem using an 8" chuck.

The smaller SB 9" or Light 10" (10K) lathe will handle 8" chucks..... And many who own those lathes use 8" chucks.

By the way, when I have the chuck jaws extended beyond the body, I ALWAYS turn the chuck by hand 360-degrees to check for jaw clearance, regardless of the number of jaws, before turning on the power.... And stop turning before each jaw is close to the bedways where it may hit. Never turn the lathe's power on without checking jaw/bedway clearance first.

EDITED.....

LL

[MikeC]

I had an 8" Union on the SB10L at the museum, worked great. I only have a 6" for the new home 10L, but that's fine with me. I have a 12" on the big L&S, so anything of any size gets put in there, anyway. If the SB was my only lathe, I'd probably have an 8".

One minor advantage of a 6" versus an 8 is the small grip range. That POS Union wouldn't go much under 5/8", where this 6"er will go down to about 1/4.