[whateg01]

Well, after all of the trouble I've had getting an endmill holder for my 3/64" EM, I went back to the drawing board. Since I can't seem to drill a hole that is centered on the lathe, or at least not centered enough for this, I decided to drill the hole first, then put that end on the live center and turn the outside down to fit in a 3/8" holder. Then I took a 1/4" holder that I tried to make and bored it out to 3/8" and put the two together. I'll have to pick up another setscrew tomorrow, but this looks like it'll work. I was able to rotate the bushing to get the lowest reading. I kind of wonder if I could drill two holes off center by the same amount and put one inside the other so they would offset.

Anyway, my other attempt gave me about 0.005" plus maybe another half of runout. This one still has right at 0.003", but that's better than I had before, and tons better than the crap I got from A2Z. I hope I have time to try this out tomorrow evening.



Dave

[Dylwad]

For small holes on the lathe, I drill and ream as usual, take a chunk of aluminum or 12L14 steel and machine it for a slip fit into the hole, leave it in the chuck, glue the chunk with the hole to that piece with CA and bring the outside to dimension. Gets within .0003" easily, make it a semi press fit and it doesn't budge a .0001" indicator. Break the CA bond with heat.

Did a lot of 1.5mm shafts in motor end bells that were only a few mm thick, that had to have virtually zero runout. Works great, little time consuming, and wasted some material though.

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[whateg01]

I need to figure out where the runout is coming from. I turned the outside of the 3/8" holder on the threaded arbor and yet it now has some runout. So, maybe there is some crud in the threads forcing it to one side. I'll have to work on my technique, I guess. I feel like I should be able to do this. I'm not sure I could use the 1/8" I.D. to glue to, though. Well, I could, but I am afraid that turning the far end, 1.2" away with the 1/8" arbor would probably cause some grief. I'm sure there are a couple tenths because I just drilled the hole instead of reaming it, too.

[Dylwad]

It helps to have a face at the back of the arbor, and the piece with the hole in it to get some glue area, so your not just relying on the 1/8" section. Light cuts, sharp tool, and rough the chunk close to size when drilling.

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[Dylwad]

Threads are not the best for runout. Is there a chamfer or recess that centers the holder, or is it just threaded on till it bottoms out?

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[whateg01]

It just threads until it bottoms. Just like my lathe spindle.

If I wasn't in the process of building a new mill, slightly bigger than the Sherline, I'd consider putting an ER25 spindle in it. As it is, I'm putting one in the new machine.

Dave