wobbly Mini chuck problem

Frank Fusco

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Mountain Home, Arkansas
I have two chucks, both from PSI. One is the big Barracuda 4, the other is the GMC3 Mini.
I have had the Mini for a long time and it served me well with my old lathe, the Grizzly G1067Z. It ran true and smooth.
Then I bought my new, fancy-dancy, Grizzly G0632 EVS lathe. On the new lathe, the big ‘cudda 4 runs just fine, true and smooth. But, the Mini is wobbly awful. Problem may be that it seats thread to thread.
I went to a friends shop, an accomplished turner, and let him try it on his Powermatic. On that it seats on the shoulders of chuck and spindle and runs true.
However, he showed me that his own chucks (which are Rolex class expensive) do not run true on his Oneway (yes, he has both). So, to correct that, he made wood washers for the chucks to seat against. Using those, his chucks run true on the Oneway also.
So, I come home and made a washer out of Osage Orange. Tried the Mini and still was in the Wonderful World of Wobble. Not sure what the problem is. I’m quite certain I made the ends flat and as parallel with each other as possible. I’ll try some more flattening today on the belt sander. But, would appreciate any input on this.
 

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:huh: Not sure what the problem could be Frank...hope you can figure it out of maybe someone here can. Doesn't look like you had to add an adapter to work on your new lathe...but sometimes those cause problems I've heard. Have you tried calling PSI?
 
I noticed a split in the ring you turned. when you tighten down the chuck does the split open up any? Have you tried indexing the spacerby putting a reference mark on it and then trying it at 90 degree intervals to see if it gets better or worse.
 
I noticed a split in the ring you turned. when you tighten down the chuck does the split open up any? Have you tried indexing the spacerby putting a reference mark on it and then trying it at 90 degree intervals to see if it gets better or worse.

The 'split' is pretty sturdy. I turned the washer on my big chuck with an inside grip and stressed it quite hard to test. It didn't open up at all. The pith was way off to the side and that is part of it. Strange.
I'll try the indexing thing after I attempt to flattend the sides some more.
 
Have you tried taking a dial indicator on a magnetic base to it? Check for runout on rotation and against the face too. Also try it with your Barracuda as a reference. Might as well check your spindle runout while you're at it as well.

My cheapo Grizzly set has saved my bacon when sorting out problems on my woodworking machinery. http://grizzly.com/products/Magnetic-Base-Dial-Indicator-Combo-President-s-Special/G9849

Have you tried the wobbly chuck again on your old lathe just to double check? Maybe try spinning it up with no jaws installed, just to check it out.
 
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Frank I just saw in the second picture of the wooden ring a difference in the color of the end grain which indicates to me that the two sides are not parallel.

It's on the side with the split.
 
Have you tried taking a dial indicator on a magnetic base to it? Check for runout on rotation and against the face too. Also try it with your Barracuda as a reference. Might as well check your spindle runout while you're at it as well.

My cheapo Grizzly set has saved my bacon when sorting out problems on my woodworking machinery. http://grizzly.com/products/Magnetic-Base-Dial-Indicator-Combo-President-s-Special/G9849

Have you tried the wobbly chuck again on your old lathe just to double check? Maybe try spinning it up with no jaws installed, just to check it out.

Old lathe gone. But it does run true on the Powermatic.
 
Hi Frank,

I don't think you will be able to get a close enough parallel with the sander. I'd just make a new spacer, and cut both face surfaces in one setup. That will give you the closest parallel. Make the spacer as thin (front to back) as possible. Use a real tight grain hardwood. (Sorry, I'm not familiar with osage orange) Keep the ID as close as possible to the OD of the thread. The OD of the spacer is not that important, other than to have it thick enough for strength.

Wish I could help more.

Aloha, Tony
 
Hi Frank,

I don't think you will be able to get a close enough parallel with the sander. I'd just make a new spacer, and cut both face surfaces in one setup. That will give you the closest parallel. Make the spacer as thin (front to back) as possible. Use a real tight grain hardwood. (Sorry, I'm not familiar with osage orange) Keep the ID as close as possible to the OD of the thread. The OD of the spacer is not that important, other than to have it thick enough for strength.

Wish I could help more.

Aloha, Tony

Tony, only a few woods are closer grained or harder than OO.
The ID was drilled with a 1 1/4" Forstner bit and that is the OD of the threads.
Yep, I'll try again.
Picking up ice storm branches today. Old muscles are quivering with fatigue at the moment, not a time to be working with the powered sharp stuff or do brain surgery. ;)
 
The obvious solution would be to buy a Powermatic.:rofl:

Have you considered a metal spacer instead of wood? Someone should be able to turn you one fairly reasonable. I'll dig in my box of misc. stuff and see what I can find. I'll talk to the machinest at work Monday and see if he can turn one. I have some UHMD 2" round stock in the "shop" I could cut and send hitchhiking in the pen swap box. Let me know if any of this sounds good.
 
The obvious solution would be to buy a Powermatic.:rofl:

Have you considered a metal spacer instead of wood? Someone should be able to turn you one fairly reasonable. I'll dig in my box of misc. stuff and see what I can find. I'll talk to the machinest at work Monday and see if he can turn one. I have some UHMD 2" round stock in the "shop" I could cut and send hitchhiking in the pen swap box. Let me know if any of this sounds good.

I didn't mention it in the thread, but several months ago, I drilled some 1/8" delrin sheets for washers. Didn't work. Then I drilled a hunk of UHMW. Likewise, didn't work. Metal might be the deal. Let me take a measurement for ideal thickness. Thanks. I'll post tomorrow.
 
I had this exact problem some time back with a Grizzly chuck on a Jet mini-lathe. Solution was a 1/4"-thick washer cut from (wait for it) MDF. The key feature of this is that the face surfaces of MDF are flat and parallel to much closer tolerances than you would expect. Strength isn't an issue, as the piece will spend its life under compression (and rather moderate compression at that) and a replacement costs pennies when (not if) it gets lost.
 
Frank, If you could run a dial indicator on the back ring of the chuck you could at least find out if the ring is true to the threads. I have a grizzly chuck that never ran quite true. I replaced it with a Talon chuck and there was a world of difference. If the back ring is not true you could stick some shims between it and your spacer to square it up. It would be a pain , but it might get you by. I suppose it could be fixed by making a small spacer and sticking it between the chuck and head stock with enough room to true up the back of the chuck. (if that is the problem)
 
Frank,

You never did post those dimensions yet. Dale's idea is good. You get the "pen blank swap" box after me so I might be able to turn you a metal (Aluminum maybe?) spacer ring, IF I had the specs to do it. :dunno:

Oh wait, you are using this on a mini? Gosh, oh gee, I have one of them. :rofl: I'll just go ahead and make your spacer and put it in the box. :thumb: 1"-8 thread, right?

Can't get better than that, huh?

Aloha, Tony
 
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Toni, Great offer to do this for him:thumb:...Franks out putting some sort of dark powder into the air this weekend I think...

I also think his thread size is 1 1/4 X 8...the chuck is a mini not the lathe.:)
 
Dale mentioned what I was going to suggest. Every time this has come up in other places the suggestion has come down to using a machined washer. In the past I have seen the washer suggested for use when the chuck tends to be difficult to use.

I would think that any compressible material would eventually not run true.
 
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