Need help with small keyless chuck - hard to tighten

[Dataporter]

Hello,
I scored this small Rohm keyless chuck. 0 - 4mm, 0 - 05/32". The shank is 1/2". I think this is a nice chuck from Germany. I don't think it has ever been used.
The trouble is, it is very hard to tighten and loosen! It takes two men and a small boy to open and close it. I put some Rust Eater in there and then I tried some teflon tri-flow stuff for locks etc.
I thought that if I opened and closed it a few times it would get better and it did a little, but it is still way too hard to turn IMO.
Any ideas? Anyone know how to take one of these apart? And more importantly, put it back together?
Thanks in advance
Dave

 

[davidh]

i don't remember but "google" or even "youtube" can be your bestest friend. . . its probably assembled just a tad too tight. . they are lightly pressed together.

i can't remember which end to hold and which end to whack with a brass hammer to just loosen it a tad. . . getting old ain't for sissies. . the mind is about the third thing to go, but I'm not sure.. . :nervous:

 

[davidh]

try this. . . https://www.youtube.com/watch?v=So21EPtIyVY
very interesting, maybe it does unscrew not press like jacobs. . .
now i know.

 

[Billh50]

All of the chucks I have taken apart were screwed together. If it is hard to work it could also be very old grease in it that has hardened. You might try soaking it in either kerosene or diesel fuel. That may loosen the old grease if that is the problem.

 

[Dataporter]

I'm pretty sure it comes apart like the video davidh found in the post above. There are even some wrench flats under the collar that is at the at the top around where the shank connects. I tried to grab the big knurl with a 1" ER40 collet, but the collet slips in the chuck and I don't want to crush the chuck or ruin the knurl, so I may need to make some aluminum wrenches like shown in the same video above. Also, I can't tell which way to turn it.

I don't have kerosene or diesel as suggested by Billh50 so I left it soaking overnight in mineral spirits... I have alcohol and lacquer thinner and can go get some kerosene.. It doesn't seem to have ever been used and there is no rust on the exterior so it must be something like fossilized grease. I doubt if it was defective from the factory.

As a side bar, anyone know how far a 1/2 shank will go into a R8 collet? The shank on this only goes about half way into the MT3 collet on my present mill, but I don't want to cut the shank off because I want to get a better mill one day.

Thanks again
Dave