[jbrookes]

Hello I'm double-dipping here.
Here's my issue:
I want to have a stepper/servo motor turning on the tailstock (TS) synchronized with rotation of the lathe headstock (HS).
rpm - 50-100
accuracy - not precision, but shouldn't drift over time
force - nil

What I've looked at so far:
1. optical encoder on HS emits pulses to drive a stepper in TS. An intermediary mcu-driver. The cheapie optical encoders do 96 ppr, whereas the steppers need 200 ppr. But there are $50 optical encoders with 200 ppr.
See #2.
2. A stepper direct drives the HS, or turns passively on the HS. This is synchronized with a stepper on the TS via two driver boards and one set of control signals to drive both, but in opposite sense. (cw-ccw). The attraction of this over a passive optical encoder is to be able to drive the HS precisely at will...In this application, no appreciable power is needed. It would be useful, in general, to have a stepper rotating passively (no voltage in), and then cut the power to the HS main motor to enable the stepper to take over. Is this possible from a stepper perspective? The HS would be turning at up to 2000 rpm when the stepper is in "passive" mode. Though, for the application here, we are at very low rpm - 50-100.
3. a servo arrangement. Not my favorite, but I'm keeping open mind.

Any help or opinions appreciated. JB

[samco]

I don't know if I exactly understand what you are looking for.. But linuxcnc could do slaving of a axis to the spindle.. (Like)

[ame=http://www.youtube.com/watch?v=ZhICrb0Tbn4]Hobbing (Gear cutting) on a Mini-Mill with EMC2 - YouTube[/ame]

It can also do rigid tapping, threading, feed per rev and more.

sam

[jbrookes]

I don't know if I exactly understand what you are looking for.. But linuxcnc could do slaving of a axis to the spindle.. (Like)

Hobbing (Gear cutting) on a Mini-Mill with EMC2 - YouTube

It can also do rigid tapping, threading, feed per rev and more.

sam

That's quite impressive. I take it that the optical encoder drives the stepper. How did you make the encoder? Ive decided to just drive hs, ts with two steppers to be in synch.
Thanks for video.