How to Zero Encoder Count

[Rob Carnell]

My Acorn powered lathe works perfectly.

However, I have a need to index some holes around a circumference.

By taking the lathe out of gear it is easy to turn the spindle to the correct position.

I can see the encoder count via the PID screen, but this seems to always start from a random number.

Is there a way I can zero the count to make the calculations easier?

The manual mentions M150. Is this the way to do it or is there a manual way?

Rob
Sydney, Australia

[Caleb]

Encoder count always starts from the same place, that's what the Z signal from the encoder does I believe. If its not then is your screw cutting functioning correctly?
You could mark your spindle with the 0 position.

[cncsnw]

Caleb: The spindle encoder does not always start counting from the same place. It starts counting from wherever it happens to sit when the power is turned on. Threading cycles do wait for the index pulse before they start feeding, but they do not re-zero the spindle encoder count.

Rob: Yes, M150 is what you want. The spindle needs to be turning, and not at more than a couple thousand RPM. The M150 command will sit and wait until the index pulse comes around, then it will set the spindle encoder count to zero. For manual operations, you can enter M150 at the MDI prompt and press Start, then just turn the chuck by hand until the MDI line is cleared (indicating that the command has completed running).

[Rob Carnell]

Thanks Caleb, that’s what I needed.

Rob

[Caleb]

Interpretation of the question; I was read as 0 count was changing every revolution, not controller power cycle.
If the encoder is working correctly the 0 isn't going to shift during use.
As a side note:
I mark my spindles with the encoder index pulse correspondingly I have also lined it up with jaw 1 of the 3 jaw as they always have some run out and then the machined soft jaws have the best chance of being repeatable and the component being concentric with minimum faff...

[vw_chuck]

IS there a way to convert the encoder count to degrees of spindle rotation with a math channel or something in the software? That would be really useful if you have a live tool. Just turn the spindle by hand and lock it at the correct angle and run your program for your feature.

[tblough]

360/encoder CPR = degrees. You could always set up a manual axis using the spindle encoder port number and have it display the angle on the DRO screen. I've done something similar on Oak and AllIn1DC so I'm guessing this would all have to be done manually through machine setup and parameters on the Acorn. Wizard won't help here, but no PLC changes are involved.