Rohm keyless chuck sticking - help!

[Eric The Viking]

[Meldrew] I don't belieeve it! [/]

My best pillar drill chuck (for runout) is probably my Rohm keyless one. But it's been a right PITA because it has a threaded rear rather than a taper. I finally got the M2 adaptor to fit properly with a lot of fettling last year (after AGES of frustration), and now it's my go-to chuck for everything that will fit in it.

Problem being, although it's nominally up to 3/8" (yup, Imperially-sized!), anything above about 6mm jams up right royally.

I was using an 8.5mm jobber in really cheap mild steel yesterday, and stupidly left it set up. This morning I was reduced to applying a pair of fairly large Stillsons to undo it*.

There has to be a better way! So, feeling a bit of a twerp, I have to ask what I might be doing wrong. I am quite unable to hand tighten it very much, as I can't grip that well any more. I do NOT use any leverage to force it to be tight, either.

Should I be oiling or greasing it, and if so, with what, and exactly where on the chuck (so I don't make matters worse by causing it to slip?

Is there a knack to tightening them, along the lines of gently snugging-up a Jacobs-pattern chuck before tightening properly all round?

Honestly, a pair of Stillsons is plain embarrassing!

Heeelp!

E.

PS: I've had it from new and I haven't abused it and it's had little use until now, when I've cured most of the runout.

*NOT applied to the chuck directly, but to a pair of heavy cable ties, pulled tight round chuck and backing ring - does no damage that way.

 

[AES]

Hullo Eric.

I had the same problem with a similar chuck, but in reverse - mine wouldn't stay tight.

Here's my post at the time, plus some very helpful answers from CHJ and woodpig which allowed me to fix my problem. Note particularly CHJ's comment about lube inside the chuck threads (sorry!) in the thread below:

help-please-rohm-keyless-chuck-t89478.html

HTH, if not, shout again.

AES

 

[CHJ]

Just noticed that the Rohm service pdf seems to have moved on their site.

There's a copy on my site

 

[Eric The Viking]

Gentlemen, thank you!

I've just closed up for the night, but I shall check the box the chuck came in (it's indoors), to see which exact model it is. I've no doubt though that the service PDF will be very similar to mine.

Greatly appreciated!


Cheers,

E.

PS: I will report back as soon as poss. FWIW, it only seems to really jam up with larger drills - still well within bounds but the smallest ones don't have the problem. And it does run really true, too.

 

[Eric The Viking]

Just read this in the service information:

On Self Tightening (Keyless) Chucks (e. g. Models SPIRO - SUPRA)
an axial pressure is created during use of the chuck, which via the spindle results, into an Automatic Tightening
of the Jaws.
Through failure to understand this basic design difference between these two chuck types, tool bits are frequently tightened with the same initial pressure in self-tightening chucks as in key-type chucks. As the jaws of keyless chucks tighten themselves automatically, chucks can therefore be tightened so much that they may be difficult to open.

On keyless self-tightening chucks tighten tool bit therefore only lightly by hand, as the chucks tightens itself
during use. Avoid using tool bits with uneven or blunt cutting edge, as this also may cause excessive tightening of the jaws, so that the same problems in opening of chuck may occur.

Ignoramus me!

I had no idea. I've never used excessive force to tighten the chuck, but I have probably overdone it sometimes, including the recent incident.

I'd never have realised if I hadn't read that. And of course I've not had a drill bit actually slip, ever, so that bit seems OK. I'll read carefully thrtough the old thread too.

Once again, many thanks!

E.

PS: The box for my chuck says it's a Supra, type 38, with a 1/2" 20tpi thread on the back, 0.5 - 10mm capacity.

 

[Hitch]

Boa Wrenches work quite well on stubborn keyless chucks, and don't chew up the outsides of the chuck...
Ive always found that they tend to go tight after a drill bit has 'bitten'.


If you cant grip all that well, might be worth tagging one on to the end of an order.... the small ones cost hardly any more than a pint, and very easy to use.

 

[Eric The Viking]

I've come up with a cunning plan since my first posting:

1. Learn (and remember!) how to use the chuck properly. The Rohm instructions (wot didn't come with the chuck, incidentally) say finger-tight only, as it tightens as it spins.
2. Two fairly chunky nylon cable ties, one round the top ring and the other round the body, on the knurling, nipped up tight and with the surplus tab cliipped off. They weigh almost nothing so don't add significant vibration, but they provide something to grip.

And if that doesn't do it...
3. Apply Stillsons to the cable ties rather than the chuck body. Tried this: works very nicely with no damage at all.



Actually I think (1) will probably be enough in future. I've fancied a Boa wrench for a while though - useful for all sorts of other stuff, so may still get one, or even two. Good idea.
E.