4 Jaw Chuck input for PM1228, PM's High Precision 8" vs.

M

maticulus

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I'm waiting on a PM1228 lathe to arrive and am selecting tools for it, one of which is a 4 jaw chuck. I like the high precision offer from PM, but discovered the Gator chuck in the link that follows. I'm a hobbyist at this point with a lot of ideas and bend toward precise tooling, understanding the dependency on skill with the 4 jaw, and having purchased the PM728 mill first.

I felt the Gator would be the better choice given its apparent versatility; two piece jaws, and t-slots.


I contacted Ajax industries and received a link to the specs and discovered two cons in the process; the actual chuck does not have t-slots as pictured and it weighs ~43 lbs, vs the PM offering at ~33 lbs and has an 1800 rpm max vs. the PM chuck's 3000 rpm max suggesting superior balance.

gatorlathechucks.com

4-Jaw Independent, 8" Cast-Iron Body, Direct Mount D1-4, 2 PC Hard Rev

Product Information Chuck Type Independent Chuck Mount D1-4 Spindle Type D1-4 Chuck Dia (in) 8 Thru-Hole (in) 2.205 Gripping Range Min-Max (in) .394 - 7.87 Chuck T.I.R (in) 0.0016 Max RPM 1800 Material Cast Iron Jaws 4 Jaw Type 2 PC Hard Reversible Weight Gross (lbs) 42.77 Includes 1 Set of...
gatorlathechucks.com gatorlathechucks.com

Now I believe the PM chuck is probably the better choice, although it does not list a TIR. My creative ideas fall within the small to occasional medium size range. Is my thinking right, or is there other subject matter missed, that needs to be considered. A 6" chuck equivalent would likely be as good, but the 8" range appears to be more favorable in my searches.

Thanks in advance.
 
I think you would find that it is quicker to turn one piece jaws around than unbolt and reverse the two piece jaws, also those two piece jaws are heavily serrated, not something I'd like for delicate precision work. Personally, a 3 jaw chuck is seldom off the lathe, the 4 jaw ued only as necessary.
 
maticulus said:
Now I believe the PM chuck is probably the better choice, although it does not list a TIR.
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This is a 4 jaw and TIR is irrelevant . I would go with either 8" over a 6" though , and either one or any 4 jaw for that matter isn't really balanced . They are made to hold irregular shaped parts that are not balanced . The Gator is a great chuck . 1800 rpm max would not be an issue on a 12 " lathe , I wouldn't run ANY 8" 3000 rpm on a 12" lathe .
 
I had an 8" 4 jaw on my 1228, the PM 4 jaw was sticky it went when I sold the lathe. I should have taken it apart, and cleaned it, but I was upset that I shouldn't have to do that with a new chuck.
 
Occasionally I remember that the bigger chucks can’t close down as much as smaller can. If you do a lot with 0.25” stock, that could be an issue. I have straight shank drill chucks and a 4” 4 jaw that I mount when the work is too small to hold in the mainly used 8” 3 jaw or 10” 4 jaw.
 
mmcmdl said:
This is a 4 jaw and TIR is irrelevant . I would go with either 8" over a 6" though , and either one or any 4 jaw for that matter isn't really balanced . They are made to hold irregular shaped parts that are not balanced . The Gator is a great chuck . 1800 rpm max would not be an issue on a 12 " lathe , I wouldn't run ANY 8" 3000 rpm on a 12" lathe .
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Well said!
 
One of my chucks has 2 piece jaws and they are a PIA. Take longer to change than the one piece jaws. They are very tight fits also. Like said about runout, why are you worrying about that on a 4 jaw? I only use the 4 jaw for eccentric turning or odd shaped parts. I did buy a higher quality 3 jaw than the one from PM. and went for an 8" on my PM1440 lathe. The newer chuck is not direct mount so I had to turn a cast iron back plate making it a lot heavier to handle. The 6", 3 jaw that came with the lathe is OK for most purposes. I will use collet chucks whenever possible.
 
Larry$ said:
One of my chucks has 2 piece jaws and they are a PIA. Take longer to change than the one piece jaws. They are very tight fits also. Like said about runout, why are you worrying about that on a 4 jaw? I only use the 4 jaw for eccentric turning or odd shaped parts. I did buy a higher quality 3 jaw than the one from PM. and went for an 8" on my PM1440 lathe. The newer chuck is not direct mount so I had to turn a cast iron back plate making it a lot heavier to handle. The 6", 3 jaw that came with the lathe is OK for most purposes. I will use collet chucks whenever possible.
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I don't use collets whenever possible, I use them whenever NECESSARY.
 
I have the 8" 4 jaw from PM and a far as I can tell it works very well. I've never spun it any faster then about 700 RPM. It seems a little out of balance but the way I understand it that is the nature of the beast.

I could spin it faster I suppose it's not that out of balance but that seemed fast enough.

Tim
 
I appreciate the advice and did mention understanding the dependence on skill as it relates to the 4 jaw, but referenced the TIR as one indicator of quality effort put into the manufacture of the chuck, that and the number of threads I've seen where attention was drawn to it being good, or bad.

As for the balance concern, I don't recall the screen name, and it may have been in a different forum, but an economy chuck possibly SANOU, or SHARS was checked on the poster's PM1228, where the 3 jaw included was fine, but the 8" 4 jaw shook the machine with some degree of vigor while undergoing the same test.

So my concerns and curiosities expressed here have been mostly the result of what I've read in the form of complaints, concerns and cheers from the experienced, working with the equipment in question. One of my immediate projects will involve square to rectangular stock, so there's an immediate use for the 4J. I don't suppose practical speeds necessary will make balance that much of an issue, but the synergistic effect of a part aligned with a built in heavy area of a chuck could potentially become an issue at times I suppose.

I guess I'm trying to achieve the best of both "worlds", not feeling I didn't invest enough, or that I paid too much. I'm not working with a personal experience base here to help me decide with confidence, especially given the extreme cost range present for any given chuck choice, that extreme has to be born out in some measurable performance aspect, what exactly is it?

From the input expressed here, the PM precision chuck is just fine, or maybe a bit much, although I could appreciate the holding versatility a chuck with t-slots would offer.
 
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