If you have 2 sets of jaws, 1 for OD and 1 for ID, then those bolt on individually, if I understand correctly. Why not make some aluminum soft jaws and then put plastic pads if desired, on those? Then you could just replace them as needed. And I would not suggest UHMW as it is self-lubricating. Maybe nylon would be better.
Just the 2 sets of jaws made me think otherwise. With an ID set and OD set, why reversable? If reversable, just need one set. Whatever, I agree it is time to shop for a proper jaw set, or better, a real chuck.
I think that it is a case of poor machining English skills on the part of whoever wrote the ad copy for the chuck. :-)
I do have some truly reversible one-piece jaws on chucks. The Unimat SL-1000, and the early 3-jaw chuck for the Compact-5/CNC. Instead of the scroll teeth looking like this (bottom view):
[ (( (( (( (( (( ] >
They look like this: [ () () () () () ] >
Resulting in less bearing surface when the chuck's scroll is forcing the jaws outward.
The jaw material isn't going to be easy to drill, and even more difficult to tap. A carbide drill will probably allow you to drill the jaws.
You might consider making caps for the 2 jaw sets that mount securely with set screws or another secure method. The caps could be a more easily machined material.. brass, aluminum or steel, and then you could come up with another method of attaching your softer material to the caps (hardware or adhesive).
If you decide that you'll want to drill the jaws, you could make a thru hole and secure your other material with a screw and nut. In considering the addition of parts, you'll want to be certain that any mounted parts will stay in place during operation.. nylock nuts, etc.
With soft pads in place, the inside jaw soft faces could be trued with a boring bar and a HSS cutting tool.
If you have a supply of the non-marring material, you could just glue it to (or wrap it around) the wood and remove it later.
Both of my ? Miller Falls or Mill Falls ? - chucks 3 and 4 jaw that were bought with or along with my sheldon at the hardware store in Ca in '52 had reversible jaws. Both were different.
The Three jaw has two sets of numbered jaws. The four jaw are reversible.
If you can spot anneal the jaws, you may be able to drill and tap them. As long as you don't anneal the scroll, they should still work fine.
The soft pads should be made of aluminum or mild steel. It's the smoothness of the surface, not the softness, that determines how much the wood will be marred. If you are working with a real soft wood, increase the depth of the soft jaws for more surface area.
In any case the standard 3-jaw metal chuck jaws are very unsafe to use on wood because they don't have enough surface area to hold without crushing the wood fibers.
If you don't have a lot of material to remove, make a toolpost grinder with a dremel (or other die grinder).
Let us know how it works out. I've been thinking about adapting a 6 jaw scroll chuck for woodturning by doing the same thing.
p.s. You could also find someone with an EDM to make the tapped holes, but it would probably cost more than several of the chucks.
Ideally you would have collet-like jaws. I.e., each pad would be a 1/3 of a circle the diameter of the stock. You would need a set of pads for each diameter of stock. If the stock diameter varies a lot this might be impractical.
As far as mounting the pads - how about magnets? Make a recess on the back of the pad and glue a magnet in. The magnet only has to hold the pad until the jaws are tightened.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.