16 years ago
About a year ago I had a job making three each of a number of parts. It
went smoothly except for a valve assembly component that didn't lend
itself to milling, so was turned on my only lathe, a manual without
Think way back to the last time you had to accurately turn a
complicated part on a manual lathe.
It ended up taking hours to make the three parts.
About a week ago I got the same job again. This time the plastic parts
were missing (already tooled for injection molding) but the quantity
was up to 12 each of the remaining 11 parts. Not looking forward to the
tedium of turning 12 of those valve parts, I decided to try turning
them in a CNC mill. It worked out very well.
I'm not a lathe guy, and I did not program this in a lathe CAM program.
I didn't program it manually either. I tricked my mill software into
doing it. Very simple really.
I changed the CAD data to make a square protrusion out of the round
section. I brought it into CAM and laid it on its side where X and Z
were reversed so operations could come from Z, even thought they'll
really be comming in from X. To keep things simple (no tool changes) I
ran the entire part with a .075" grooving tool (shut up, it worked
fine). I told the program I was milling with a .075" diameter EM.
I made flat square surfaces behind the part profile for each zone I
wanted to rough. I roughed with a simple profile program on those flat
surfaces, with a .005" step depth using the part profile as a check
surface. After roughing an area, I'd finish with a surface milling
routine. All chamfers and fillets were interpolated with the square end
grove tool. I squared up the end, made an o-ring grove and parted off
the final part with hole drilling routines.
After posting the g-code I used Notepad's "replace all" function to
swap all the Z to X, and X to Z. I put the lathe tool in a vice and the
round stock in a tool holder, zeroed out and started making parts. Part
accuracy (after one adjustment to the program) and surface finish are
good, the program took about 12 minuets to run each, unattended. I'm
sure a lathe guy could have done it in a couple minuets.
If I get adventuresome in the future, I might add multiple vices with