disassemble a three jaw chuck?

[TellsItLikeItIs]

I checked the runout by chucking up a piece of 3/4" stainless steel rod and setting my indicator on the crossslide and checking about 1-1/2" from the jaws.

If the stainless rod was ground true, that works.

I believe now that either I didn't clean the mating surfaces properly or didn't seat them properly somehow..

Very possible. That mating of the parts is critical.

I did not trim the jaws, wouldn't they be hardened and wouldn't I want to be running very true before doing that anyway?

Not sure if they are hardened or not (probably are). Dickie may be able to comment on that. Soft jaws are available though. Yes, the body of the chuck should be running true before trimming the jaws.

I'm still betting the problem is the mate between the spindle & chuck. Would be interesting to hear what you finally find.

 

[Strange_Days]

Well, I got myself a precision ground dowel pin, a set of feeler gauges and went at it. The problem was one of the camlock lugs was either a little too much in or a little too much out but I could not get it right on. I couldn't see the space looking at it but once I checked with the feeler gauges I could definitely tell which camlock was causing the troubles. The best I could get at the beginning was at .015 out, when I reset the lug I got it to .008. So, I had another set of lugs for my 4 jaw that I switched that one out, and voila first try I was down to .003. By selectively tightening certain camlocks and checking the runout I am now down to .001 TIR after removing and chucking the dowel 10 times to make sure. From what I've read this sounds acceptable for a cheaper chuck like this one. Thank god I have that all sorted out its been a month and I have about 15 cues to repair lol (that's a lot for me around here).

Thanks to everyone for all the help,

Matt LeClerc

 

[olsonsview]

This poses a new question

Do you mean by selective tightening of the camlocks: you have a sequence of a certain one first, and you indexed them so the same lug goes in the same spindle hole every time you reinstall the chuck? Are you leaving certain lugs loose, or tightened with less torque? Is that safe? I never tried all that but i may as i have the exact same chuck, from looking at your pics that you submitted and seeing the logo on the chuck. I always just accepted the runout of .003 and knew which jaw to shim with cig papers if I need DNP runout.
I have considered trimming the jaw faces as a solution as well. I understand that we need to install a round solid spacer, in a diameter that we want the jaw trimmed to, in the rear most crevices of the jaw and tighten onto it before trimming the front surfaces, then cutting off the rear excess later to match the front. I would think that this will be a traumatic cut for the lathe, between the hard jaw face of our inexpensive chucks, and the inherrant vibration of that kind of cut. Better to just get a Buck chuck or some other adjustable model with six jaws. But man do the tooling expenses add up! I could have bought a top end collectors cue for what i have in my three lathes. All this started when I did not like any production cue I ever tried to play with.

 

[TellsItLikeItIs]

Well, I got myself a precision ground dowel pin, a set of feeler gauges and went at it. The problem was one of the camlock lugs was either a little too much in or a little too much out but I could not get it right on. I couldn't see the space looking at it but once I checked with the feeler gauges I could definitely tell which camlock was causing the troubles. The best I could get at the beginning was at .015 out, when I reset the lug I got it to .008. So, I had another set of lugs for my 4 jaw that I switched that one out, and voila first try I was down to .003. By selectively tightening certain camlocks and checking the runout I am now down to .001 TIR after removing and chucking the dowel 10 times to make sure. From what I've read this sounds acceptable for a cheaper chuck like this one. Thank god I have that all sorted out its been a month and I have about 15 cues to repair lol (that's a lot for me around here).

Thanks to everyone for all the help,

Matt LeClerc

Ahhh, the thrill of victory!!!

 

[dzcues]

I have considered trimming the jaw faces as a solution as well. I understand that we need to install a round solid spacer, in a diameter that we want the jaw trimmed to, in the rear most crevices of the jaw and tighten onto it before trimming the front surfaces, then cutting off the rear excess later to match the front. I would think that this will be a traumatic cut for the lathe, between the hard jaw face of our inexpensive chucks, and the inherrant vibration of that kind of cut.

This is exactly the fix you want if you're interested in getting your chuck DNP. But rather than removing material with a boring bar, you use a small arbor-mounted grinding wheel in a laminate trimmer. The arrangement is similar to using a thread mill to cut wood threads, except you use a grinding wheel instead of the thread mill. You only need to remove .002" or .003" from the worst jaws so there is absolutely no trauma to the machine.

Run it slow & power feed it slow. Make a few passes at the same setting to let it "spark out". Just make sure you don't run into your spacer! And don't forget the spacer - it is necessary to preload the jaws prior to grinding.

Another hint for lathes using a D1-4 mount: Mark one lug on your chuck & one recepticle on your spindle. Always install your 3 jaw chuck in that same location for maximum repeatability. Do this before you grind your jaws true & always mount it the same way.

 

[Strange_Days]

Do you mean by selective tightening of the camlocks: you have a sequence of a certain one first, and you indexed them so the same lug goes in the same spindle hole every time you reinstall the chuck? Are you leaving certain lugs loose, or tightened with less torque? Is that safe?

Yeah it was a tip sent to me so I tried it out. I mean the lugs are all pretty tight, I don't want a huge chunk of steel flying off at my head any time soon. I just put my indicator on the cross slide, chucked a dowel pin and measured. If lug 1 was high I would super tighten numbers 2 and 3 and it worked. I would bet my least tight lug is 90% of how much I could tighten it. I'm going to spend a bit more time with it, I bet I can get it to half that without much more effort. Time will tell if it stays dialed in this well I guess. Good luck

btw ... april 4th and we are having a HUGE snowstorm. roads are all closed. I really have to move.


Matt