New Build, PM2700 lathe with Acorn, Videos and Photos <upgraded to AC servos>

[jeepshop]

I'm in the same boat Johannes is in. I'm just starting to replace all my old Mitsubishi electronics and would love to have position control over the spindle like my existing controls did. The command was spindle-orient or something like that.

Can we not command the spindle to a specific angle when the spindle encoder is a 1024?

[suntravel]

Speed mode ist for turning, position mode to command a spindle position with c-axis.
No problem to use both and change modes with M51 / M50

If you want closed loop with encoder, you need one encoder for turning and another one for the c-axis, but you can use the spindle encoder to set C Zero and run the C-axis open loop.

Uwe

[friolator]

Thanks. I've seen that thread. I think it might answer my question but just to be clear: it doesn't matter that the motor has a small gear on it and the spindle shaft is larger. As long as I have a 1:1 ratio from the spindle shaft to the encoder, the ratio of motor:encoder is irrelevant, correct? That is, all that matters is that the encoder is directly tied to the spindle shaft?

[Muzzer]

Thanks. I've seen that thread. I think it might answer my question but just to be clear: it doesn't matter that the motor has a small gear on it and the spindle shaft is larger. As long as I have a 1:1 ratio from the spindle shaft to the encoder, the ratio of motor:encoder is irrelevant, correct? That is, all that matters is that the encoder is directly tied to the spindle shaft?

That's right. Note that for spindle speed control, the encoder isn't involved - you still have to set the correct "voltage per RPM" ratio that takes account of your gearing between the motor and the spindle. Obvs if you have more than one ratio, this is slightly more complicated.

[suntravel]

The encoder for threading/tapping must be 1:1 on the spindle so the CNC can find exactly the start position every time.

Uwe