3 Jaw Chuck Weight

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ndnchf

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The original 5" 3 jaw chuck that came with my 12" Atlas lathe (101.07403) is pretty worn, so I decided to order a new 6" chuck and backing plate from Shars (PN 202-5411 and 202-6109). I thought going to a 6" chuck would be a good idea. When it arrived I was really surprised at how heavy it was - around 28 lbs. Compared to the original chuck that is around 8 - 9 lbs. After thinking about it a couple days, I felt this was just too much weight to be hanging on the Atlas spindle, so I'm sending it back. I baby my lathe, maybe I'm a bit over-cautious, but while this will work, I think it would cause accelerate wear of the spindle bearings. Unfortunately, Shars (and other retailers) don't list the chuck weights in their specs. I'm now thinking about ordering the 5" version (202-5594), but would like to know what the weight is. Does anyone have one of these chucks? If so, what is the weight?

Are there any other, moderately priced 3-jaw chucks that are more weight compatible with the 12" Atlas? Thanks fellas, appreciate your thoughts.
Steve
 
I have a 5" three jaw and with backing plate it is 12 lbs. I got it from CDOC.
 
I'm not familiar with CDOC. A quick google search did not find them. Can you provide a link? Thanks
 
If the Shars is adjustable (for runout) and has 2-piece jaws, I would keep it. I have an Atlas 3996. This is a bit heavier machine than the 101.07403 but it has exactly the same spindle and bearings. I bought the new lathe right after Christmas of 1981 along with an Atlas 6" 3-jaw and an 8" 4-jaw chuck and some other accessories. In 1982, I bought a Pratt-Bernerd 3-jaw chuck. This is similar to the Buck of the day, with adjustments for runout and with 2-piece jaws. It weighs 27.1 pounds. It has been hanging on the Atlas spindle for probably 99% of the time since and the spindle and bearings are still fine.

I would suggest that you make a handling stand for it, though. If dropped on the ways, it would do some damage. Take a piece of 4x4 fence post and cut the length to the outer width of the ways. Set the stand across the ways, crank the jaws out of the way and slide the stand up against the front of the chuck. With a pencil, trace around the OD of the chuck body on the side of the stand. Cut out the arc with a bandsaw and sand the cut area smooth. If the adjusting screw sticks out from the OD of the chuck body, you will have to cut a groove on the C/L of the arc to clear it. I didn't need to do that for the Pratt but I later made one for my 8" 4-jaw and did.

To use, simply slide the stand under the chuck, rotate the chuck until the screw is at TDC, lock the spindle by engaging back gear without pulling out the direct drive pin, insert the T-handle chuck wrench in the screw, and break the chuck threads loose. Remove the wrench, disengage back gear (so that you don't later forget) and unscrew the chuck. Once free of the spindle threads, slide the block away from the headstock, and figure out how you are going to carry it. I always leave the chuck on the stand as the stand only weighs about one pound.
 
One thing I failed to mention is that my lathe has the original 1/3 hp motor. It runs fine, but I expect that all that extra mass with a 28 lb chuck will be more stressful to the old motor too. The chuck goes back today and I'll shop for a lighter 5" model. Great idea for the chuck handling stand. Dropping one of those heavy chucks can be damaging to man and machine!
 
Here is a link that shows various brand names & specs to compare weight & the stock diameters they can accommodate.
http://www.lathe-chucks.net/
Gator might be another name to consider. I don't have their 3-jaw but the 4-jaw I just bought seems pretty good value for the money. Another consideration is the weight of the backplate assembly. I'm not familiar with your lathe but if the mount is integrated into the chuck body, sometimes it can result in a slightly lower net weight than say a plain back chuck + the appropriate backplate adapter depending on the brands assembly.

I agree with the one of the posts though - if I had to do it again I would seriously consider a Set-Tru or Tru-Adjust or whatever system is named by particular brand. This gives you a means to dial the chuck concentricity to your lathe & leave it that way. It may never be 'zero' but it may be a lot closer to that than say 3-thou+ runout that you cant do much about after the fact with a fixed chuck system.
 
petertha said:
if I had to do it again I would seriously consider a Set-Tru or Tru-Adjust
Click to expand...

I agree these would be really cool.
My 3 jaw has found it's home off the lathe. I never seem to use it anymore. Always using the 4 jaw instead. If it were a set tru maybe it would get more use.
 
I've been using a Shar's 6" 3 jaw on my Atlas 10" for several years. No problems so far.
 
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