Removing a Rohm chuck on a vintage Lesto drill
I have a severely worn out Rohm keyless on a nice low speed old Lesto hand drill (early 50's?). There's no screw inside the chuck, and the screw on the collar towards the drill body is worn out so much that tightening it is not possible. Holding the drill by the chuck in a drilled out and split wooden block and giving it a counter clock-wise whack resulted in the loosening of the outer sleeve of the chuck. So now the question is: Is it screwed on, or is it a Jacobs taper? Any advice/experience out there?
The drill in question can be seen here:
Truls Erik Johnsen
Johnsen Frameworks | Facebook
More than likely screwed, IME taper fittings on pistol drills ate very rare.
Looks like the collar where it goes on the drill is split with an allen screw to lock it on- remove then;-
This is my method.
Grip a TEE (an old chuck key??) in the chuck and rap the end with a hammer in the loosening direction, 2 or 3 raps is usually enough,............ unless you've had some muppet put it on with Loctite
If the Rohm chuck is built like an Albrecht, then you can replace the jaw set by simply unscrewing the hood on the front of the chuck. You have the hood loose, so check it out. Albrecht jaws and other parts are easy to buy in the USA, but I have never seen anyone selling Rohm parts. Maybe you can find a source in Europe. If not, try to find a new Rohm chuck of the same model, without regard for the Jacobs taper or thread mount. Then you can transplant the jaws and hood and possibly other parts without needing to get the chuck body off the drill spindle.
Thanks for the advice, guys. Got it off tonight. Turned out to be a Jacobs taper. The chuck is most likely a goner, but I will try to take it apart now.
Short follow up question on the taper: A quick measurement with a caliper this morning shows that the large end is 12mm, the small end is 11,2mm and the length of the taper is 20mm. As far as I understand, this does not correspond to any of the measurements provided by Wikipedia on Jacobs tapers: Machine taper - Wikipedia, the free encyclopedia
Does anyone recognize this taper?
JF, you should contact Rohm to see if they can overhaul your chuck. You might be surprised, the Albrecht people here in the US told me that their precision keyless chucks are almost always rebuildable, and I think the Rohms are similar. Good luck, Bill S