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3 jaw chuck wobble. Get another?

C

Chootem

Plastic
Joined
Dec 27, 2016
Hello gang.
Got this south bend 9 model C. Came with a 3 jaw chuck manuf is almond company ashburnham Mass.

And another 4 jaw.

The 4 jaw is covered with surface rust so I can't read any manuf names.

So my 3 jaw, I noticed after 3 different pieces of round stock that there is noticeable wobble. It even shows when trying to turn the parts, it hits the high spots.

I ran a dial indicator on the 3 jaw,( the area behind the holes for the key) and it had about .007 runout. Then I ran it on the backing plate and it was similar. Maybe .0055-.006.

I then took the backing plate off and ran the indicator on the spindle and read maybe .001-.0012.

It's an old chuck. Surface rust but I've tried to use some scotch pads on them to clean.

Is there a way to remedy this? Or should I get one off eBay?

I got this lathe for free, but that doesn't mean I'm ok Spending a good amount of money in it. I'm using it as a first time lathe to learn.
eBay has the 6" shars chucks for $150.
 
Sounds like most of your problem may be coming from the backing plate. Is the chuck itself in otherwise good condition? Are the jaws badly worn? Does the run out in the chucked part coincide with the run out of the chuck itself?
If the chuck itself is ok, then try to figure out why the back plate has so much run out. Clean and inspect mating surfaces between threads, register, faces, ect. Remove the chuck from the backing plate and see how the diameter and face that register the chuck run. If these surfaces are not true then the backing plate will need to be remachined to run true where it registers into the chuck.
 
Chootem said:
Hello gang.
Got this south bend 9 model C. Came with a 3 jaw chuck manuf is almond company ashburnham Mass.
Click to expand...
Newer than 1915, anyway:
https://www.davistownmuseum.org/bioAlmond.html
eBay has the 6" shars chucks for $150.
Click to expand...

Most of the GOOD used chucks are long-gone. Most of the GOOD manual chuck makers have merged, failed, or now make only large chucks or power-operated ones for CNC.

So, yes, Shars or Taiwan's Vertex for cheap 4-J, Czechia's ToS Svitany for good 3-J.

But before you abandon the one you have...

Clean the spindle threads & register are at the back/left end of it. Look for burrs, stone off. Carefully.

Clean the backing plate register area and thread ID. Check for forced-in chips, pry out, smooth out any burrs.

Ah.. Derek is ahead of me.

OK - you have a second opinion, then!

:)

Bill
 
Chootem said:
Hello gang.
Got this south bend 9 model C. Came with a 3 jaw chuck manuf is almond company ashburnham Mass.

And another 4 jaw.

The 4 jaw is covered with surface rust so I can't read any manuf names.

So my 3 jaw, I noticed after 3 different pieces of round stock that there is noticeable wobble. It even shows when trying to turn the parts, it hits the high spots.

I ran a dial indicator on the 3 jaw,( the area behind the holes for the key) and it had about .007 runout. Then I ran it on the backing plate and it was similar. Maybe .0055-.006.

I then took the backing plate off and ran the indicator on the spindle and read maybe .001-.0012.

It's an old chuck. Surface rust but I've tried to use some scotch pads on them to clean.

Is there a way to remedy this? Or should I get one off eBay?

I got this lathe for free, but that doesn't mean I'm ok Spending a good amount of money in it. I'm using it as a first time lathe to learn.
eBay has the 6" shars chucks for $150.
Click to expand...

Why not just run it? Once you turn the part it will be round and run true. don't take it out of the chuck till your done. Or buy the shars and have have a new chuck that wobbles and 150.00 less in your pocket.
 
Clean the chuck and the backplate and see if maybe you can bump the chuck closer to straight before making the screws fully tight. Sounds like a lot of it is on the backplate but if the register on the backing plate isn't super tight to the chuck you may be able to get it better than it currently is.
 
Good to de bug mating surfaces...
If a chuck can go on any other way it would have been good to mark the plate and the the chuck so it might be put back the same way as taken off. Might be better 180* turn if some one put it back wrong in the past.

Good to check at all the possible ways it might go on. With finding best you might slip paper or real shims to bring plate to near zero and check chuck with that to prove resurfacing the plate would help..
You might jaw tight on a part held between centeres to how the chuck back runs with the part straight.
With mapping the plate and mapping the chuck back you may find the best course of action.

Still a part with some stock will run true and bores and drill holes true to the spindle center with only the area in the chuck to wobble. I have run good work with wobble chucks with leaving a skim to take on the OD running skim cut between centers.

QT: [there is noticeable wobble.] how much wobble 3" out?
 
Went and cleaned up the chuck as best I could while at the lathe. I got the back plate rust free using a wire wheel on my 6" bench grinder.
No change in runout. .006 like yesterday.

Here is the high spot.
db227fcef6f858c71fe9b65a7913f172.jpg

I'm not sure why that punch mark is there. Probably to mark it. But I didn't do it.

Then I cleaned up the back of the chuck as best I could. I put in on using the indicator marks from when I took it off. No change. Then i rotated it to all 3 different locations. No change in runout.

I then tested the runout at the edge of the chuck where the teeth are and it was better than the end where the backing plate is.

I put the teeth back in the correct position. Tightened it down and they all met together. Then put a piece of round tubing in there and tightened down a bit. Turning it by hand I could see wobble in the tubing.

My teeth don't look that great.
6aa140707590079e4f788adb8a54e469.jpg


Could this also be a clamping problem with the teeth? Could the (please excuse my terminology) coil that drives the teeth be super worn that when they tighten they aren't strait?

9aad487b2ab5bff09dd98d5edc4e0bbb.jpg


I sill need to clean the back of the chuck a bit.
edf41d81f053f065ef50a227b2cca9e8.jpg


I took those 2 little screws out from the center area. How can I disassemble this chuck? Anyone n ow if that center ring comes out first?

Thanks all
 
Wow, those jaws look pretty beat! I would say you're doing pretty good with only .006" run out. Get things as best you can, but keep in mind, as Moonlight Machine said earlier, it's still usable for most work. Do you really need better? Not uncommon for 3 jaws to run out that much. When you need better, that's why you have a 4 jaw.
 
Thanks for the words. I figured that as well. I've seen people be happy with .004. And I figured this chuck from 1942 is .006. I've seen vids on grinding down the teeth. I suppose I could try.

Do people usually replace just the teeth if needed?
 
They are jaws, not teeth. And yes. you can grind them. That will improve the grip somewhat, but may not do much for the runout because of slop in the guides and scroll. I think you should just use it as-is, and later convert it to a bump-true if you find that you must have better runout. I think you will find for most work that you can adjust your order of operations to avoid re-chucking, and the runout is not an issue. If you are doing alot of rework, you might switch to a 4 jaw anyway.

allan
 
Jaws. Got it. Don't know where I got teeth from.

I think I'll just clean these up best I can and at least use it to learn more.
Thanks
 
Last set of jaws I bought had grind stock on the width so had tho be ground evenly on sides to fit..still they did not run very true so to make the best of them I will have to grind them in. And still it will only be good at the hold diameter where I grind it. I grind.

If one gets used to using centers, with leaving a tad of stock from the chuck...it only takes few minuets to make parts near dead concentric and wobble free..
 
Looking at the back of your chuck I see punch marks, dings, and burrs. May be that wire brushing isn't enough. I would try CAREFULLY removing any raised metal with small files, scraper or razor blade, and even very fine grit paper applied only to any problem spots. You want the back of the chuck and the mating parts of the backing plate to be as un-distorted as possible. It doesn't take a very large burr near the periphery to make work run out by .006".
 
Scottl said:
Looking at the back of your chuck I see punch marks, dings, and burrs. May be that wire brushing isn't enough. I would try CAREFULLY removing any raised metal with small files, scraper or razor blade, and even very fine grit paper applied only to any problem spots. You want the back of the chuck and the mating parts of the backing plate to be as un-distorted as possible. It doesn't take a very large burr near the periphery to make work run out by .006".
Click to expand...

Good post and add perhaps a honing stone to the devises.

Then with indicting perhaps a 4" out hang straight part think if a well place shim might help for center and wobble. If truing the plate would help center and wobble.

Perhaps the punch mark was a poor way to make better the chuck.. shims, even slips of measured paper a better way.

But photos did not come through to my computer?

*in the tubing.. good to pick up a straight rod..perhaps on ebay. 1/2 to 1" x 6 to 8" or so.
Perhaps a reamer from a re store would be good (ok).
Hertel 798914 .261" Carbide Chuck Chucking Reamer, 1-1/8" LOC, 3-1/4" OAL | eBay

Should find a used reamer for almost free.
 
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