Fanuc Feed Hold and Spindle Stop

mcash7709 · Nov 18, 2020

Hi everyone, new to the forum and I have a question regarding my machine. I have a FANUC Oi-TF controller on a 2 axis lathe. When I hit feed hold, it stops the feed however the spindle continues to turn. When I hit the spindle stop key that does nothing. What parameter needs changed over so I can stop the spindle during feed hold?
Thank you.

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DouglasJRizzo · Nov 18, 2020

It doesn't.

Feed hold is just that, you're temporarily pausing the feed during a cycle. The spindle will run because there's an M3/M4 in the buffer. Spindle control keys only work in manual/jog mode.

Nerdlinger · Nov 18, 2020

Often times on a Fanuc control holding (not tapping) RESET will stop the spindle. Good luck!

TeachMePlease · Nov 18, 2020

DouglasJRizzo said:
It doesn't.

Feed hold is just that, you're temporarily pausing the feed during a cycle. The spindle will run because there's an M3/M4 in the buffer. Spindle control keys only work in manual/jog mode.

Is this a FANUC thing? Because my Mits definitely let me stop/start the spindle while in feed hold during auto cycle.

Rod Man · Nov 18, 2020

On mine if you turn the selector switch to manual the spindle will stop.
Then when you turn it back to auto the spindle will restart when you hit the green button.

mcash7709 · Nov 18, 2020

TeachMePlease said:
Is this a FANUC thing? Because my Mits definitely let me stop/start the spindle while in feed hold during auto cycle.

I’ve ran older Fanucs and you most certainly could hit feed hold, then turn the spindle off. So no it’s not.

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Vancbiker · Nov 18, 2020

All the various behaviors described above are not control builder specific, but a result of how the machine builder chose to integrate the control to their machine via the machine builder's ladder program.

@OP, there is no parameter that will do what you want unless the machine builder implemented that into their ladder program. The majority of machines will stop the spindle after feed hold is pressed if you switch the mode select switch to a manual mode (jog, rapid, increment) and then press spindle stop. Again, depending on the machine builder's integration you may have to press spindle start before switching back to memory or auto mode and pressing cycle start. Some machines may restart the spindle when switching back to memory or auto mode.

mcash7709 · Nov 18, 2020

Vancbiker said:
All the various behaviors described above are not control builder specific, but a result of how the machine builder chose to integrate the control to their machine via the machine builder's ladder program.

@OP, there is no parameter that will do what you want unless the machine builder implemented that into their ladder program. The majority of machines will stop the spindle after feed hold is pressed if you switch the mode select switch to a manual mode (jog, rapid, increment) and then press spindle stop. Again, depending on the machine builder's integration you may have to press spindle start before switching back to memory or auto mode and pressing cycle start. Some machines may restart the spindle when switching back to memory or auto mode.

Ok so on my machine, I hit feed hold then cycle to a manual mode. Spindle stops. I hit spindle start again but then when I cycle back to auto mode the spindle shuts off and I can’t resume. Is there a means to keep it turning when switching between modes or is that determined by the machine builder also?

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Vancbiker · Nov 18, 2020

Nerdlinger said:
Often times on a Fanuc control holding (not tapping) RESET will stop the spindle. Good luck!

This method has high risk. Pressing reset on a Fanuc control in the memory or auto mode erases the moves in the buffer, resets many ladder conditions (that's why the spindle stops), can cancel tool offsets, and resets the G-codes to their default condition, but MAY NOT reset the program to the beginning. If Cycle Start is pressed without resetting to the beginning of the program or searching a safe start line, a crash is the likely result.

Vancbiker · Nov 18, 2020

mcash7709 said:
Ok so on my machine, I hit feed hold then cycle to a manual mode. Spindle stops. I hit spindle start again but then when I cycle back to auto mode the spindle shuts off and I can’t resume. Is there a means to keep it turning when switching between modes or is that determined by the machine builder also?

The spindle stopping when switching back to auto is not typical. Could be an error in the ladder program or a PMC parameter (machine builder ladder parameter) that would affect that behavior. There may be a Fanuc parameter that could affect that too. If I get some time today to wander through a Fanuc manual I'll have a look.

Hardplates · Nov 18, 2020

mcash7709 said:
Ok so on my machine, I hit feed hold then cycle to a manual mode. Spindle stops. I hit spindle start again but then when I cycle back to auto mode the spindle shuts off and I can’t resume. Is there a means to keep it turning when switching between modes or is that determined by the machine builder also?

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Any difference when trying this is JOG vs MPG/HANDLE modes?

mcash7709 · Nov 18, 2020

Hardplates said:
Any difference when trying this is JOG vs MPG/HANDLE modes?

If you mean going from Jog or Handwheel back to Memory mode, no, it will shut it off still regardless of which one I switch from.

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Vancbiker · Nov 18, 2020

Did not find anything in Fanuc parameters that would affect switching from manual mode back to auto mode. Looking through the ladder logic will be needed to figure out why it behaves this way. You could contact your machine builder and see if they can help. Often when bugs in a ladder are discovered and fixed, they are only implemented on new builds and are not rolled out to existing machines unless a user has complaints.

GWIZ · Nov 19, 2020

Contact the machine tool builder.

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DouglasJRizzo · Nov 20, 2020

mcash7709 said:
I’ve ran older Fanucs and you most certainly could hit feed hold, then turn the spindle off. So no it’s not.

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Turning the spindle off in manual mode is one thing. Having that "synched" with the feed hold button is something entirely different.

Vancbiker · Nov 20, 2020

DouglasJRizzo said:
Turning the spindle off in manual mode is one thing. Having that "synched" with the feed hold button is something entirely different.

In what way would it be different? Feed Hold state is sent to the PMC at signal F0 bit 4. It would not be difficult for the machine builder to incorporate a reference to that signal in the spindle run logic. It could not be a direct reference to that signal though. Threading and tapping would have to be taken into consideration so that the spindle would stop only on completion of the current thread pass or the completed retraction of a tap.

Though it would be easy to do, stopping the spindle every time Feed Hold was pressed would be an extremely annoying behavior. I'm sure that's why I've never seen it done. I can see that a related action for spindle stopping could be convenient. Something like pressing Feed Hold twice within a short, specific, time period causing the spindle to stop seems like it could be handy.

The OP's declared inability to keep the spindle running after Feed Hold and then manually turning off the spindle, restarting it, and switching back to auto mode is also an annoying behavior that to me indicates that the machine builder's ladder is not well developed/tested.

DouglasJRizzo · Nov 20, 2020

Vancbiker said:
The OP's declared inability to keep the spindle running after Feed Hold and then manually turning off the spindle, restarting it, and switching back to auto mode is also an annoying behavior that to me indicates that the machine builder's ladder is not well developed/tested.

Exactly - it would be annoying and, yet one more parameter in a sea of 40k parameters already in the average Fanuc 0. Yeah, the ladder may not be well thought out - I had a Taiwanese CNC that was just awful in that department, but feed hold with spindle stop together spells alot of broken taps/tools/threads to me. And, having worked for an MTB, lots and lots of hours on the phone.

Hardplates · Nov 20, 2020

I would tend to think simultaneously stopping the spindle and feed while in a heavy cut would spell the end for those inserts/endmill.

DouglasJRizzo · Nov 20, 2020

Hardplates said:
I would tend to think simultaneously stopping the spindle and feed while in a heavy cut would spell the end for those inserts/endmill.

Exactly. And more angry phone calls from a customer to the applications department on how to disable it.

Hardplates · Nov 20, 2020

DouglasJRizzo said:
Exactly. And more angry phone calls from a customer to the applications department on how to disable it.

I guess that's why it's called feed hold and not e-stop

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