rklopp
Diamond
- Joined
- Feb 27, 2001
- Location
- Redwood City, CA USA
I need to drill some 0.006" holes 0.004" deep in 360 brass. I set up in a 1-mm ER-16 collet and checked the runout. I got 0.001" TIR, which seems like way too much (analogous to 0.1" runout on a 5/8" drill). My spindle taper runout is about 0.00005" and the ER collet taper runout is nearly the same, so I know it's not the machine or holder, and is most likely the collet. I have done 0.008" holes previously without breaking anything except chips, so I know I can do it. I forgot how I held the drill in that instance.
How much runout can I get away with?
When I did 0.008" holes, I fed at D/64 feed per revolution at 6300 RPM (max), and it worked a charm. I am worried that the CNC might not be the best for this, because the feed moves in "digital" jumps around 0.0001" (probably 2 µm, since it's a Deckel). It won't feed smoothly at such tiny increments. My fallback is to use my manual Aciera. It has a separate feed motor with a belt variator and VFD, so I can get a nice smooth "analog" feed as slow as I need (limited to 3400 RPM max on that machine).
How much runout can I get away with?
When I did 0.008" holes, I fed at D/64 feed per revolution at 6300 RPM (max), and it worked a charm. I am worried that the CNC might not be the best for this, because the feed moves in "digital" jumps around 0.0001" (probably 2 µm, since it's a Deckel). It won't feed smoothly at such tiny increments. My fallback is to use my manual Aciera. It has a separate feed motor with a belt variator and VFD, so I can get a nice smooth "analog" feed as slow as I need (limited to 3400 RPM max on that machine).