ROHM Supra 1/32-1/2" keyless chuck "auto-loosens"

[schemer]

I took my Rohm apart and it was similar to a Albrecht. It was straightforward to disassemble, reassemble, and now works fine. The biggest problem with keyless chucks is too much oil/grease in them. You might try washing it out with solvent assembled, then make sure the bearings are very lightly lubed and probably nothing else. There will be enough in there to lubricate them. The shell to the jaws should be a dry fit, no or extremely little lubrication. I put oil on those parts, wipe them off completely with a clean and dry rag, and then assemble. Inertia at startup is the issue, loosening the shell under acceleration.

Thanks Bob. I stuck a Q-tip down in the center and a little grease or oil showed up on it. I will try what you said and clean it without disassemby first and then if I have to, will disassemble it. Now that you mention the inertia at the start being the issue, I remember I tightened up the belt a few weeks back and maybe that changed something just enough to show up this issue.

 

[rgray]

I had a new china keyless chuck do that. I just blew it out with an air hose and wiped the inside out and it never did it again.
None of my Albrecht chucks have ever done it.

 

[Iceberg86300]

Anybody have instructions for tear down for one of these??

After reading your first post I searched & searched for a service manual.

Seems that one exists, but not "freely" on the net. If you search "rohm Supra Chuck (service, repair & disassembly were 3 terms I tried here)" you'll find a few threads.

There are a couple users that emailed it around, and one link to a personal website which is now defunct. Tried the internet archive but it was down for maintenance.

However, you might find that one of the users that offered or received the manual through email is still active on the forums & still has the manual.

Probably worth PMing said users to see if they're still around as it seems like proper preload & proper lubrication are important.

If parts are worn however, you will be out of luck. Parts seem to be non existent & rohm replied to someone stating that the jaws are ground after assembly, and w/o this factory process the chuck loses its accuracy when new parts are installed.

Regards,

Steve

 

[schemer]

I had a new china keyless chuck do that. I just blew it out with an air hose and wiped the inside out and it never did it again.
None of my Albrecht chucks have ever done it.

Good to know as I just bought a Chinese Keyless chuck for a spare along with a new Rohm like the one that is giving me grief. I haven't messed with it for a few days as I got tied up with auto and lawn lower repairs, but at least I have a plan B.

 

[schemer]

After reading your first post I searched & searched for a service manual.

Seems that one exists, but not "freely" on the net. If you search "rohm Supra Chuck (service, repair & disassembly were 3 terms I tried here)" you'll find a few threads.

There are a couple users that emailed it around, and one link to a personal website which is now defunct. Tried the internet archive but it was down for maintenance.

However, you might find that one of the users that offered or received the manual through email is still active on the forums & still has the manual.

Probably worth PMing said users to see if they're still around as it seems like proper preload & proper lubrication are important.

If parts are worn however, you will be out of luck. Parts seem to be non existent & rohm replied to someone stating that the jaws are ground after assembly, and w/o this factory process the chuck loses its accuracy when new parts are installed.

Regards,

Steve

Thanks Steve. I had researched what you said and ran into the missing manual threads too. I think i can handle it if need be using the Albrecht instructions. I know to mark the jaws for proper assembly into the slots they came from etc... I was just surprised as I never had a keyless chuck fail like that before and from one week fine to the next week acting up.

 

[Iceberg86300]

Thanks Steve. I had researched what you said and ran into the missing manual threads too. I think i can handle it if need be using the Albrecht instructions. I know to mark the jaws for proper assembly into the slots they came from etc... I was just surprised as I never had a keyless chuck fail like that before and from one week fine to the next week acting up.

Yeah, pretty weird to get a sudden & repeatable failure. I'd expect it to be intermittent first.

Points towards dirt/oil finding it's way into somewhere it shouldn't be, or possibly a cracked/broken part.

But I don't have experience with these so it's just a guess.

Although it could have worn something in a single spot by always using the same drill. Maybe try a larger/smaller drill to see if it still releases on startup.

Regards,

Steve

 

[RJSakowski]

Just a wild shot but you didn't have the mill in reverse, did you?

 

[rgray]

Edited...I was confused for a second. Happens from time to time.
Maybe no one saw that....I can only hope.
What's below applies.

I'm remembering more of when it happened to me. I was using a new cross slide drilling attachment I built.
Using a cordless drill chucked on the end of the shaft for power.
The cordless drill had a lot of acceleration making things worse than they should have been.

 

[mikey]

I didn't know you had to do that with ROHM chucks, with Albrecht chuck I bottom the bit all the way then tighten, and it releases very easily, the most common problem (based on what I've learned here) is lubrication inside the chuck that causes the bit to keep dropping out .

I'm with Ken. The most likely cause is oil on the screw threads of the spindle. You need to take it apart and clean it.

 

[schemer]

Ok, thanks guys. It makes perfect sense to me that oil or grease found its way into the threads. That said, the only way I can think that it got there is sometimes after oiling the machine and then using it, I would see small droplets of oil spinning off of the spindle (I guess) and that would be the most likely way of any oil getting near the drill chuck. I appreciate all the responses to my question. I will report back once I have it resolved (or not).
Thanks