Hi Group,
The used milling machine that I purchased a couple of months ago came with two cabinets full of tooling, which I am still working my way through. This includes several Röhm 3 and 4-jaw chucks, which are either from the mid 60s or early 80s. This weekend I pulled out the Röhm 85mm (3 3/8") 3-jaw chuck because I needed to grip a small round cylinder:
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It seemed very stiff, which I assumed was because of rust and petrified grease, so I took it apart and cleaned everything up. It's very simple: body, three jaws, spiral feed/bevel gear plate, rear retaining cover, pinion gear, pinion gear retainer pin, three screws.
To my surprise, after I cleaned everything up, greased the parts, and reassembled, it was still tight. The jaws are individually numbered, and correspond to the serial number of the chuck. When I worked the jaws (individually) back and forth in their chuck body slots, each one was too tight to push by hand, but could be tapped back and forth all the way with a piece of wood. All are equally snug. Similarly, the spiral ring (turned with the pinion gear, but with no jaws in place) turns ok but also seems quite snug.
When everything is assembled, the chuck works very well except that it's very stiff to turn. Is this something odd, or normal behavior? All of my other chucks are smooth and nothing like this one. But they were all purchased used, and I am thinking that perhaps the 85 mm Röhm, in spite of being old, has never been used (or not more than a handful of times). So perhaps it is normal that a new chuck is quite tight and needs time to wear in. Or perhaps the body (cast iron? semi-steel? steel?) has expanded or moved during the past 40 years, and so the jaws and spiral ring simply don't fit well any more.
Cheers,
Bruce
The used milling machine that I purchased a couple of months ago came with two cabinets full of tooling, which I am still working my way through. This includes several Röhm 3 and 4-jaw chucks, which are either from the mid 60s or early 80s. This weekend I pulled out the Röhm 85mm (3 3/8") 3-jaw chuck because I needed to grip a small round cylinder:
It seemed very stiff, which I assumed was because of rust and petrified grease, so I took it apart and cleaned everything up. It's very simple: body, three jaws, spiral feed/bevel gear plate, rear retaining cover, pinion gear, pinion gear retainer pin, three screws.
To my surprise, after I cleaned everything up, greased the parts, and reassembled, it was still tight. The jaws are individually numbered, and correspond to the serial number of the chuck. When I worked the jaws (individually) back and forth in their chuck body slots, each one was too tight to push by hand, but could be tapped back and forth all the way with a piece of wood. All are equally snug. Similarly, the spiral ring (turned with the pinion gear, but with no jaws in place) turns ok but also seems quite snug.
When everything is assembled, the chuck works very well except that it's very stiff to turn. Is this something odd, or normal behavior? All of my other chucks are smooth and nothing like this one. But they were all purchased used, and I am thinking that perhaps the 85 mm Röhm, in spite of being old, has never been used (or not more than a handful of times). So perhaps it is normal that a new chuck is quite tight and needs time to wear in. Or perhaps the body (cast iron? semi-steel? steel?) has expanded or moved during the past 40 years, and so the jaws and spiral ring simply don't fit well any more.
Cheers,
Bruce