Would anyone be around the space Tuesday evening that could help two of us turn down some tools (see below)? We need to reduce the OD of some nut drivers for better clearance. There are 8 or so of these. The lathe was the obvious thought, but maybe there’s a better way to tackle this.
My friend and I have both used a lathe before…one time in college. Many years ago. So we’re in no condition to do this without instruction.
Will trade good instruction for food.
First thing I’d ask is do you know the hardness of the bits? The shop has a limit on material hardness we can work with here reliably, and some tools are harder. IIRC the limit is 55 or 60 on the Rockwell scale; there’s a hardness test kit in the big tool chest.
Second, do the bits come out of the handles? Ensuring we can chuck them properly is going to improve results and stability in turning the outside down.
Third, how much has to be removed? There’s going to be a lot of chatter at the corners of the hex socket as the walls get thinner. I’d suggest finding how much material you need removed, rather than just as much as possible…
I can be around that evening and am more than happy to help in exchange for beer if it can be done on the Sherline lathe; if it requires the larger lathe I’m still waiting on classes for it. If the bits come out then it can be done on the sherline, though if not I don’t know that those handles would chuck safely with the heads we have on that unit and it would require the Colchester.
~H
I can’t answer the question about hardness. We likely do not have Sherline bits suitable for turning tool steel, so knowing the hardness is important.
I think I have that same set of nut drivers, so here’s some other info.
IMO, that’s too small to chuck up in the Colchester without working dangerously close to the chuck. And the Colchester chuck will likely damage the handles. Sherline is a good choice. The Sherline three-jaw scrolling chuck is your best bet due to the hex handles.
I think you are going to have a problem with that much overhang unless you use the steady rest.
IMO, and this isn’t required specifically for this but the discussion reminds me - we should also modify the steady rest. The steady rest has square support bars that could easily mar what they are supporting. We should take the three brass bars and put a hemispherical profile on one end of each of them using the radius cutter - or at least knock off the corners.
Why do you anticipate chatter on the outside as you turn this?
Thanks for the input, guys! Chris you got it - the handles don’t come off and we’re not sure of the hardness.
If this doesn’t work we might just take a grinding wheel to them. It won’t be pretty but it’d get the job done.
We’ll be there a little after 8 tonight. Just so we’re prepared, @hon1nbo what’s your beer preference? A good stout? If you can’t make it I assure you it won’t go to waste 
This is the primary reason I haven’t used this yet; I feel rounded or rolling edged would be far better.
both prior advice and experience when the walls get thin on a lathe. Not completely going to cause problems, but something to be aware of. I hadn’t tried it against something like this where the wall thickness varies considerably around the radius, so it may not even be an issue to begin with.
Depending on the material, this may be a good use of the KMG. It has a lot more control than many of the other grinders and a granular speed control.
Time works for me. Stouts work.
Is there any reason these couldn’t be made out of Delrin or Nylon? They would mar and the material is “slippery”
I think they could be made from Delrin or nylon.
Well, then let’s try. We have some Delrin out there. I’ll cut a small piece off and make the three pieces on the Bridgeport to try out.
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It would be a good learning experience on the radius cutter.
We used a live center and the three jaw Chuck and got through it.
The stabilizer is a joke as it currently is. It does have a good amount of heat as it rubs, so Nylon or acetal may have heating issues but worth a shot. Otherwise if no one has objections I may use the radius cutter on the existing brass. It’s already extraordinary unevenly worn.
I think you should use the radius cutter on one end of each of the 3 existing brass bars. Anyone who prefers the square end can still reverse each bar to use the square end.
BTW, be forewarned that it’s real easy to inadvertently smack the chuck with the radius cutter …
The amount of friction may be a lot lower so maybe it won;t over heat. We’ll see.
Thanks to @hon1nbo again for helping out! You didn’t have to sacrifice your evening for us, but you did it anyway. Thanks a ton!
I’ll do that tonight or tomorrow; the brass also wears down significantly as it’s used. Those bars should really be considered consumables.
