I have successfully torn down the chuck fully, quite a bit of chips in the small bevel gears that drive the scroll threads that close the jaws. Chips elsewhere, but not a large number, (only takes one in the right spot) so it maybe that this cleaning will help. I do know the jaws are numbered and they only go in a certain slot. The jaws have discernible numbers, but the slots in the chuck only show where number 1 jaw goes. The other two are at best, vague. When installing the jaws sequentially into the scroll thread does # 1 go first followed by #2, etc. or do they start at the same time?

Thanks, ?

Buy?

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On Dec 18, 2024, at 9:21?PM, Ray Daniels via groups.io <rmdaniels47@...> wrote:

? Before you even take it apart, verify the the jaws are in the right slots (each jaw and each slot is numbered)?

Also verify that each jaw was started sequentially at the right time when assembled.?

Good luck?

Ray

On Dec 18, 2024, at 5:11?PM, David Ghilarducci via groups.io <daveghil@...> wrote:

?

I found if you loosen the cap screws on the back and tap them sequentially with a brass hammer or even a ball peen hammer you can usually split the chuck. ?

On Dec 18, 2024, at 3:40?PM, Guy Edkins via groups.io <gedkins@...> wrote:

? I will see if I can get it apart. Tried earlier. Backing plate is on tight. Thank you for the info. Not giving up yet.?

Guy

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On Dec 18, 2024, at 6:00?PM, mike allen <animal@...> wrote:

?

the Sanou 3 jaw scroll chucks are real nice chucks . I bought one several years back due to my Cushman chuck being all messed up . I think I got it from These guys

# 0603F0 with soft jaws for @ 120 , ya still need a backplate unless the one from the Cushman is salvageable . Same folks have backplatesfrom 40 bucks n up .

animal

On 12/18/24 2:40 PM, Bill in OKC too via groups.io wrote:

First, disassemble the chuck, clean and lubricate it. Reassemble it making sure the chuck jaws go in the correct slots, and started at the correct times. Then try it again.? A really good ?quality?3-jaw self-centering chuck will still have .003" of run-out. There are a number of schemes to let them be adjusted to better run-out, and both Buck and Cushing use them on some of their more expensive chucks. You may have one of those that has been opened up, and not reset. Or the thing can be incredibly dirty inside. Saw a video yesterday that showed a guy testing a standard non-adjustable Craftsman chuck. Which was over .020" out. He ground the jaws, then disassembled it to clean it out. Cleaned and reassembled, it was right at .003" run-out.? Here it is:?

I'd do the cleaning and such first! I have an atlas chuck of my own that's .014" out. Haven't been able to get mine apart, yet.?

Bill in OKC

William R. Meyers, MSgt, USAF(Ret.)

Aphorisms to live by:

Good judgement comes from experience. Experience comes from bad judgement.?

SEMPER GUMBY!

Improvise, Adapt, and Overcome.
Physics doesn't care about your schedule.
The only reason I know anything is because I've done it wrong enough times to START to know better.

Expect in one hand, expectorate in the other. See which one gets full first.

On Wednesday, December 18, 2024 at 04:27:42 PM CST, Guy Edkins <gedkins@...> wrote:

?Hi all,

I am in the process of rehabbing a 3995 lathe. It was free and maybe I now know why. The runout on the spindle inner and outer diameter is really good. Like .0013. Screw on the chuck and chuck up a mandrel and it all goes bad, really bad. You can see it, let alone measure it. The chuck is a Cushing 3 jaw.

So is it worth buying a new chuck, i.e. will it mitigate much of the issue, or is there something else at play here (see what I did there) that I have missed? I am new at lathe details and the ins and outs, but an engineer by background.


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