ROHM Chuck

Happy new year all,

I picked up this ROHM keyless chuck recently. It was a bit neglected and has been abused by the look of the plier jaw marks in the outer shell surfaces.
I soaked it in WD 40 for a while and rinsed the crud out of it. It works OK so far, but hasnt done any hard work (by me) yet.


It is marked 1/8-5/8 ROHM Supra 3-16 J6 and is fitted with a #2MT.


The front shell/collet nose screws off easily when loosening the chuck, instead of the main body rotating and withdrawing the chuck jaws. I didnt try to unscrew it deliberately, it just spun off in my hand as I was using it.
It is useable, you just need to make sure you get a good grip on the un knurled part of the body instead.


I know the front shell should'nt easily unscrew like this but it does not appear to have any locking device or pinning.
Does anyone know what the factory arrangement is for securing this part?
Is the MT a permanent part of the chuck or are they removable? It looks to have a joint line between the Taper and the chuck body, but its a bit hard to tell in the small gap.

Cheers Phil

The J6 marking indicates that the M2 arbor is a Jacobs taper, #6. I can be removed with wedges. The unscrewing part is wrong. The two knurled parts should lock together and both turn to tighten/loosen the chuck. If the upper ring won't turn, then you have more soaking and work to do.

Tony Wells said:

........The unscrewing part is wrong. The two knurled parts should lock together and both turn to tighten/loosen the chuck. If the upper ring won't turn, then you have more soaking and work to do.

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Hi Tony,
Thanks for the reply. I am actually using the chuck. It works "fine" insofar as holding drill bits ok, and the knurled "front shell" section does nip itself up tight and onto the body part that should normally tighten and loosen the jaws. However if you tighten it up on a drill bit firmy, "maybe read, overtighten" it tends to come undone on loosening instead of the section that should rotate. Hope that is clear as mud?
The jaws actually look pretty good and I dont think it has had a lot of use, just, unfortunately, some abuse.

Paddy OFernichur said:

Looks like an opportune time to get it all cleaned up nice, recondition the jaws if they need it, and reassemble with the proper lubrication in the right places.

At one time, it was a very high-quality chuck. You stand a pretty good chance of getting it back to that condition with a little bit of effort.

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Hi Paddy,
Not much apparent wear on the sliding parts, and the gripping surfaces of the jaws dont seem to be marked at all.
I have a worn Jacobs keyed chuck on my drill press that needs heavy handed tightening to grip most bits so I will be looking forward to using this "new" chuck