Thanks in advance unless everyone ignores me then screw off...joking
Here's the theoretical part... a 5-6" long round graphite rod, with tapers on it. very simple geometry. Imagine the tip is .010 diameter with a 3 degree angle that changes to a 2 degree angle at a diameter of .150, then goes on the rest of the way at the
2 degrees. Basically 2 tapers on a round shaft. Simple enough.But a real pain in the azz to manufacture. Currently I grind them, manually, or cnc. Sometimes I do a lathe operation in the mill with the electrode in the spindle and a lathe bit on the table. All these things work fine, till we get to the .010 diameter tip hanging out 5" made out of graphite. of course this operation is more complex due to the needed +-.0001 diameter and a max of .0004-.0005 tir on the tip.
If you havn't imangined it yet, all these operations cause deflection of the flexable graphite sticking out 5"-6" at such a thin diameter. The idea I want to really try is using a wire edm machine and copper electrodes, and turn and burn the part. Problem with that is we have 2 wire machines and 2 operators who have no intention of trying that. Added to that problem is they havn't dropped a slug in years, so basically those 2 machines will never be open for R and D.
So...here's my alternative fixture:
On this web page is a herman smidt fixture we bought a few years back...we are talking kick azz quality. One tenth all day long.
Now, to operate it would be to simply load the pickup bushing herman smidt provides and pickup the center of the fixture. Touch the electrode on top and you are ready to go. Programming would be relatively simple, figure how much an angle drops for how much infeed.
example: 3 degrees, 1 inch deep
N1 G91 Z-.002 A.009 F1. N3 GOTO 1 (500 times)
(note..the A was a guess, I would need to measure the actual fixture to see the feed rate ratio to rotation).
What I'm looking for from this group is things like why it wouldn't work, or better ways to make it, or the real thing I'd like to see, something ALREADY invented out there.
Please dont say pencil sharpener. It's just not funny anymore.