Spindle RPM Cap

Zahnrad Kopf wrote: In the Real World™, when one turns the spindle down to Zero, it is HELD at Zero RPM. As in, one CANNOT rotate it by hand.

That rather depends if the spindle is driven by a servo of some sort. I suspect that even in your "real world" not all of them are.

Please understand that I am not trying to stir the pot. In our world, Acramatic and Fagor controls several with DC spindle motors and a few with AC spindle motors and drives. We can hit feed hold stop the spindle, inspect tooling or check the part, move the turret if needed to gain clearance to change an insert restart the spindle and resume the cutting operation as programmed before the feed hold spindle stop/restart

I believe we are encroaching into the jog while paused territory but I am committed to this stuff and trying to report issues as we find them.

SRT wrote: I believe we are encroaching into the jog while paused territory.

I don't think that there is anyone who doesn't agree that that is desirable. I am pretty sure it will come eventually. I doubt that there will be any change to the motion planner that doesn't start with that as a requirement.

In the meantime, I wonder if there is an all-gcode solution? Stop the program, hit a "save position" button, change the insert, then have the G-code carry on from where it left off (after jogging to a suitable starting point). This is not likely to be easy for complex profiles, but would not be difficult for simple cylindrical roughing. (View it as a canned-cycle for roughing).
I am thinking of something similar to the underlying G-code in the lathe macros I posted in the GUI thread a few days ago.

andypugh wrote:

Zahnrad Kopf wrote: In the Real World™, when one turns the spindle down to Zero, it is HELD at Zero RPM. As in, one CANNOT rotate it by hand.

That rather depends if the spindle is driven by a servo of some sort. I suspect that even in your "real world" not all of them are.

No, not all of them are. Many are 3Ø phase motors controlled by VFD. I can only speak for the ones I've run and/or owned, though.
Frankly, I'm not sure HOW they manage to do this on the ones with "normal" motor driven spindles, but it is more common than not.
I inserted the ™ symbol in effort to add some levity to the reference and I hope that it isn't coming out sounding preachy or demanding.
Just trying to add some additional viewpoint and reference.

Zahnrad Kopf wrote: No, not all of them are. Many are 3Ø phase motors controlled by VFD. I can only speak for the ones I've run and/or owned, though.
Frankly, I'm not sure HOW they manage to do this on the ones with "normal" motor driven spindles,

A spindle brake is common on larger lathes.

How do you get to the holes to adjust a 4-jaw chuck?

andypugh wrote: A spindle brake is common on larger lathes.

Common on many, but I do not know what the actual mechanism involved is when the discussed operation is happening.
I don't know if it's a brake that engages because a 0 RPM is commanded ( manually ) or if the motor is being held electrically.

andypugh wrote: How do you get to the holes to adjust a 4-jaw chuck?

I've seen it in pictures, and have heard people discuss it, but in 30 years of doing this I have
never seen a 4 jaw chuck on a turning center with my own eyes, nor ever had a need for one.
Typically, we hold irregular parts with soft jaws and machine the jaws to fit them. Repeatable and dependable, and allows the use of the power draw bar.