[Ziuck]

I purchased a 5C chuck from CDCO. I have been trying to mount it to my 8x14 lathe. I have 2 adapter plates from LMS. I have tapped one since the chuck is through mount. I have also ran long M8 bolts from the back and used nuts to hold it on from the front.

When I mount it my run out is 0.003" at the edge of the 5C and 0.012" at 2" away from the face! It gets really really bad even further out. When I put an indicator on the outside of the 5C chuck, run out is 0.0005". The run out on the face of the 5C chuck is ~< 0.0005".

I have a 5" Bison 3-jaw that I can mount on either of these adapter plates and have 0.001" run out at a couple inches away from the chuck and no issues with repeatability.

Both adapter plates have been trued to my lathe and have < 0.0005" on my indicator on the face and recess. It does move but not a full tick.


I sent the first chuck back and got a replacement. The new one is the exact same, it's an all black Chinese import. They are supposed to have 0.0005" run out.

am I missing something??

[knudsen]

What is centering the chuck to the plate?

[packrat]

A couple of thoughts-

1. Does your backing plate have a chamfer on it? The counterbore in the chuck may have a radius from the cutter on it.

2. Did you stone all the mating surfaces on both the chuck and backing plate? Did you make sure to clean all the cosmoline off of the counterbore? Even a tiny burr will through things off.

3. Do the bolt holes line up? A hole that is off a little will bind and cock the parts as they are tightened.

Hope some of this helps, cary

[Ziuck]

I have the mounting plate from LMS. The holes do line up. I have tried the pre-drill holes in the plate that mounts back to front. I have also tapped new holes to mount from the front into the plate. Both have the same run out.

The plate does have a chamfer on it. I have turned the face of the mounting plate true to my lathe and also the registration.

There are not any chips or cosmoline on the chuck or adapter plate.

I can indicate the front of the adapter plate and get ~<0.0005" variation. I also get the same when indicating the front lip of the 5C chuck when it is mounted. So it would appear true??

[TroyO]

Could it be the collets?

[knudsen]

Can you indicate the inside of the chuck with the collet out?

[bodysnatcher]

Well i got the same lathe bud, and i have made all my adapter plates AND the ones from LMS are good too as your indicating of them proves...

1. i would indicate the bevel without a collet in the 5c chuck since this is where all collets lock, and maybe the internal bore without a collet in it.

if those indicate fine, it could be 1 or 2 collets but not all collets...

In my posts elsewhere, i posted checking my homemade 5c collet chuck and found that even drill rod is useless for checking runout so i use taps which are ground...might try that....

In my opinion WITHout pictures.....it's probably a very bad batch of chucks from china, wherein the bore/and or 10 degree collets angle is NOT 100% perpendicular to the back of the collet chuck.

If i can make a 5c chuck and adapter and it's under .0006 runout, AND your using LMS chuck adapters which should be fine it seems the 5c chuck is the culprit. China don't ya know...

One last point tho....1 little piece of chip between the LMS adapter and your spindle, or between the LMS adapter and the 5c chuck will throw everything off...Triple check for any burrs, dirt, chips.

Pics might or might not help depending....

Best of luck

billz

i went to the CDCO site to have a look at your chuck....there description bothered me right off the bat.........

"Can be sued on lathe and grinding machines
Plain back, have to shoose proper back plate to connet with your machine"

Without being there i suspect the taper is not perpendicular.....but i have been wrong before...

billz

[TroyO]

Last time I did an order at Enco I threw in a 3/4" x 7" precision ground rod.... usefull for indicating all kinds of things. (Including lathe runout.) Speced to .0005

http://www.use-enco.com/CGI/INSRIT?PMAKA=319-4185

Worth the $5 if you are ordering stuff anyway... probably not worth getting by itself.

[Ziuck]

I have indicated the chuck without a collet in it. I still get 0.003" run out. I've tried centering it based on that run out and cannot get it any better then 0.003" only worse.

If I take a piece of round stock and turn it down with a collet, then remove it and insert it back into the collet and chuck, the stock will wobble like its off center.

I will strip everything down again and take pics of each piece and post it. Not sure if I can do it tonight but I will try.

Thanks for the help!

[BobWarfield]

There is a trick to getting these cheap collet chucks to run true. See my article here on how I did mine:

http://www.cnccookbook.com/CCColletChuck.htm

The hole on the back of the chuck had to be made true:



While the chuck has a ground finish, the grinding had nothing to do with accuracy. You can see the nose wobble when it spins. Flipping the chuck around and reboring the hole in back made sure that hole was concentric with work in a collet.

Made all the difference.

Cheers,

BW

[knudsen]

That's funny, Bob, I'm doing almost the same thing, but with a cheap 1/4" Jacobs drill chuck. Trying to make a 0 runout arbor for it to fit my 4 x 5 lathe. The arbor is screwed into the back of the drill chuck. I have a piece of 1/4" ground stainless chucked up in both the drill chuck and a 4-jaw on the lathe, all centered up nice. I've drilled out the arbor for the tailstock, and it sits on the lathe now, awaiting decision on how the heck I'm going to cut M14 x 1 inside threads.

[Ziuck]

I bored the hole in the back as Bob had done.

My runout at the collet is now 0.0005" I still have nasty run out the further away I go. At around 4" from the collet it is 0.025! When indicating the front of the chuck it is 0.0005" variation on it. I am at a loss on what to do.

I ordered a couple of the precision ground rods from Enco. I got 1", 3/4 and 1/2" The 1/2" I got the a 12" bar so I can "level" the lathe.

I chucked up the 3/4 and 1" bar in my 3-jaw 5" Bison chuck. My run out at the jaw is 0.0015" at 4" away it is 0.002" so it has to be something with this 5c chuck!

[BobWarfield]

A couple of thoughts...

The chuck will go on more than one way relative to its bolts. Try each of the positions until you find the one that gives minimal runout. FWIW, I marked each postion on my lathe's spindle and each position on each chuck after doing this with just some automatic centerpunch pips: 1, 2, and 3 pips. Now I can always reinstall the chucks for minimal runout and in the same position.

With that said, I doubt it will fix your whole runout problem, or even likely the majority of it.

These things are kind of hard to diagnose remotely. You're going to need to get out your DTI and start sweeping until you find what is out. As I mention, my chuck's outer ground surface is WAY out when it is running true. Ignore the outer surface. Instead, start from the spindle and work your way out until you sweep the indicator and find the problem.

For example, remove the chuck and its backplate and sweep the spindle's spigot that mates with your backplate. Then check the backplate, then you are back to the chuck.

How did you attack the chuck to its backplate? In my case I used a shrink fit, which is very tight and has no clearance. If you just bolted yours up, perhaps there is some leeway there that's working against you. Make sure there is no chip caught anywhere too.

Let us know what else you learn. Hard to tell at this stage just what went wrong.

Best,

BW

[Ziuck]

After messing around and beating on this damn chuck so much I think my spindle bearing is jacked up!

When I put on my 5" Bison chuck I get weird runouts when spinning it.

Does anyone know what aftermarket bearings fit? Also is the bearing press fit onto the spindle?

[sansbury]

How much beating are we talking about here? A few taps with a rubber mallet shouldn't cause bearing damage. It is certainly possible to damage them if you start whacking at it with a claw hammer but it's not the first thing I'd suspect.

1. Have you used the lathe for a while before you tried mounting this chuck? Were there any problems then?

2. Before you tried mounting this chuck, how sure are you that the spindle runout was good? Are you sure you're not just seeing something that was always there?

3. If you undo the belt and disengage any drive/threading gears, and spin it by hand, does it turn smoothly all the way around? Do you feel or hear any clicking sounds that weren't there before?

4. If you're using an indicator, are you indicating the spindle mouth or some other fixed, known-good location? Are you sure you're measuring it properly, indicator is firmly mounted, etc.? There could just be a problem with the chuck mounting, including something silly like a chip stuck somewhere.

[Ziuck]

I took the spindle out last night and re lubed the bearing on the bed side. All is well now. I would spin it and it was smooth but would "drop" at times when a chuck was mounted. I am not sure what had happened.

My run out with an indicator on the spindle is ~< 0.0005"

No I never did beat on it with a claw hammer! only light tapes on the chucks with a rubber mallet.

I think I've come to the conclusion that this 5C chuck is crap and does not mount the precision bar true. It get's skewed.

I can mount a 12" bar on my bison 5" and it is only ~0.003" out at the end.

[cuttingchips]

I recently purchased a 5C collet chuck from ezaccessory on ebay for my South Bend 8K lathe.

After turning the backplate boss to what has got to be a "near perfect" fit, I noticed that the chuck "rocks" slightly from side to side. Figuring that I might have mess up something in the backplate, I removed the chuck and put it on a surface plate. It still has a slight rock.

As this is the first time I've ever turned a backplate... is this normal? How would I take care of it. ezacessory has a 5 day return policy, but it took a couple of days to get the backplate and a couple more to get it machined and find out there was a potential problem.

Any suggestions?

[cuttingchips]

So... Putting a chamfer in the corner of the center boss solved most of the problem. There is still a half-thou runout at the nose.