Spindle RPM Cap

This is a general G96 D, S question. We have remote push buttons for feed hold and spindle stop on our lathes. In G96 mode the machine starts up and operates just fine applying the G96 Code. We have found that if we hit Feed Hold stop the spindle and re-start the spindle it seems to ramp up the the capped spindle speed and not the rpm it was cutting at when feed hold was applied.

Any Ideas?

Looks like we lose the constant surface speed but it reads the value of the S portion of the G96 line in the code.

EX G96 D1000 S600

Hit feedhold, spindle stop, spindle restart and cycle start spindle and program resume but at 600 RPM for the rest of the program

Sounds like stopping the spindle is a queue buster for CSS.

JT

I don't suppose there are any ways to work around this that anybody knows of?

You might back up to the start of the cut and run from line if it is not in a subroutine.

JT

We can do that but in long or large roughing cycles it is a time waster, watching air cuts drives me nuts as a business owner. There are times when the insert may need changed in the middle of a roughing cycle.

SRT wrote: We can do that but in long or large roughing cycles it is a time waster, watching air cuts drives me nuts as a business owner. There are times when the insert may need changed in the middle of a roughing cycle.

+1 This is another one of those fairly standard things in the Real World™.

SRT wrote: Looks like we lose the constant surface speed but it reads the value of the S portion of the G96 line in the code.
EX G96 D1000 S600
Hit feedhold, spindle stop, spindle restart and cycle start spindle and program resume but at 600 RPM for the rest of the program

So, it switches from 600 ft/min to 600rpm when you feed-hold?

Can you confirm where the buttons are wired up to?
I can try it on my machine. As that is metric this is likely to have it going from 45 m/min to 45rpm, which I am not sure the VFD can even handle...

Hello Andy,

I have the buttons on the machine hooked to halui.spindle.start and halui.spindle.stop through ladder, with the program is paused output bit as a permission, so they can't stop unless the program is paused.

Correct, when we hit feedhold, then spindle stop, measure the part, check finish (whatever they needed to do) then hit spindle re-start, and then program restart/un-pause, the spindle starts back up at whatever the S value is in the G96 command, not at whatever calculated value it should be at for the corresponding diameter the tooltip is at, and it stays at that speed until the next tool call/spindle command.


Just thinking out loud, what do think it would do if we just hit program restart/un-pause and skipped the spindle re-start?

Thanks

Rick

LAIR82 wrote: Just thinking out loud, what do think it would do if we just hit program restart/un-pause and skipped the spindle re-start?

I don't know, it might be interesting to test when cutting air.

An alternative, if you are in feed-per-rev mode is to turn the spindle override down to zero. That should stop all motion too.
Though I don't really like the idea of doing things on the machine in that situation, with it all poised to move again.

Something I have never tried is turning the chuck backwards in that scenario. I wonder if the tool backs-off? I suspect not.