Parameter 78 - Solved

[chronolite]

Can someone explain P 78 in practical terms for me? This happens on several lathes for me, so I'm curious as to the behavior why. Here are some conditions:

Set P78 to 1

Goto MDI

Code: Select all

M03 S30

CYCLE START

Spindle goes to 30 rpm.

Set P78 to 7
Goto MDI

Code: Select all

M03 S30

CYCLE START

Spindle goes to 55+ rpm, I freak out and stop the spindle.

This happens on two different machines running Oak.
I know that 30 rpm or 55 rpm doesn't seem like much, but on a 88" chuck, that's scary fast.

[cncsnw]

That certainly does not sound right.

What CNC12 software version(s) are you running?

Do you get correct spindle speed response with P78 = 0?

Does the error (running too fast) happen with P78 = 3? What about with P78 = 5? Perhaps we can narrow down which specific feature is adversely affecting the spindle speed commands.

[chronolite]

I set P78 to 0,1,5, etc, but that didn't help much.

I think the issue was that the min/max spindle speed is what determines the 0-10v scale, (in Setup - Motor). I was hoping it was smarter than that. If there's a parameter we can adjust to slave the 0-10v to the encoder pulses, that would be a lot cooler. I also have a problem with the wording on the min/max, since it's relative to high gear. (This particular 100hp machine is certainly capable of spinning its 88" chuck at 500 rpm, but no way would I want to be near it).

So here's a tip for those in the future looking for why this occurs: If your spindle drive has a max RPM setting at 10v, that's exactly what you need to have in the motor setup. It appears that spindle encoders are only used when they are in a slaved operation (like threading).

Rookie mistake, thanks for your help guys.

[tblough]

Spindle encoders are only used to read spindle rpm. Centroid does not use them to control rpm.

[cnckeith]

post some photos of this machine , sound interesting