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Author Topic: Actual Spindle Speed DRO delay  (Read 768 times)

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Actual Spindle Speed DRO delay
« on: November 13, 2017, 01:46:40 PM »
Running PMDX 411 and Gecko G540 on build 3481 on a lathe.

I have a cheap opto sensor on my spindle that works very well reporting the actual spindle speed as verified with a tach.

I noticed that when I issue a M5 that the Dro that shows the actual speed does not return to zero for about 3-5 seconds from the time that the spindle actually stops spinning.

Does anyone know if this is due to the opto, PMDX or Mach4 not updating?

I was using this DRO value to check to see if the spindle had overloaded and stopped and it was not disabling movement promptly.

Is there a better way to handle this? (I am electronically challenged so hopefully I don't have to create some citrcuit ;D)


Re: Actual Spindle Speed DRO delay
« Reply #1 on: November 13, 2017, 03:03:05 PM »
Hi RT,
I think you'll find that Mach does a significant averaging on the opto input and will therefore suffer a significant delay.
I believe there is some control over the averaging, you can reduce it but may then encounter problems that it is not
sufficently stable for threading.

A genuine encoder is required to give you the bandwidth that  spindle overload protection requires if you require near instaneous
crash protection.

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