M19 - How does spindle orientation work?

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diycncscott

M19 - How does spindle orientation work?

Post by diycncscott »

M19 - How does spindle orientation work?
To command a spindle orientation (M19), the AjaxCNC control turns on a PLC output to request that the spindle
drive orient the spindle and then waits for the spindle drive to notify the control that orient is complete by
opening (or closing) an input on the AjaxCNC PLC hardware. The M19 macro also generally contains logic that
commands a retry if the spindle drive doesn't notify the AjaxCNC control that the spindle has successfully
oriented within some time period.

What is needed to utilize the M19 Spindle Orient function?
1. A feedback device to report the rotational position of the spindle to the spindle drive. This is generally a
rotary encoder of some type.

2. A spindle drive with the orient option enabled and "an encoder board" present on the drive to accept the
encoder feedback.

3. Correct configuration of the spindle drive parameters. For configuration of the spindle drive parameters,
please see your spindle drive manual. The specific parameters you should be concerend with will vary greatly
from drive to drive but in general they will include:

a) A parameter that sets the orientation position. Specified as an offset, in encoder counts, from the index pulse.
b) A parameter that sets a tolererance "window" for the oreintation position. Specifed as an allowable deviation
of +or- some number of encoder counts from the targeted orientation position.
c) A parameter to designate which digital input on the drive is to be used as "orient request"
d) A parameter to designate which digital or contact closure output on the drive is to be used as "orient complete"
e) A parameter to specify that inverter enter a "Torque Mode" or "Positioning Mode" of operation when the orient
request signal is received.
f) A parameter to set the "Gain" to be used while performing an orient/positioning move. Setting this value correctly
allows the spindle to crisply orient without overshoot or oscillation, too low of a value causes the spindle to respond in
a "spongy" manner, too high of a value can cause oscillations while the spindle tries to hold the orient position.

How do I troubleshoot spindle orientation issues?
1. Confirm that you have smooth and consistant feedback from the spindle encoder to the spindle drive. Set your
spindle drive to display the current position of the spindle encoder. Mark the physical position of the spindle with
a paint pen or peice of tape and make a note of the displayed position. Run the spindle, CW, CCW for minutes, hours etc...
then return the spindle to the marked position - it should agree exactly. If it does not, you have a problem
with either your spindle encoder, spindle encoder cabling (noise) or the inverter/encoder card.

2. If your spindle orients consistantly but the tool change cancels with "orient lost". Watch carefully to be sure the orient
position doesn't get "bumped" off position as the fingers come in to grab the tool. If grabbing the tool causes it to move
even a little, adjust the orient position in the spindle drive parameters.

3. If your spindle sometimes orients but you get frequent retries, consider increasing the tolerance window for the orient
position. You can also experiment with increasing or decreasing your gain as well.

4. Remember, the control simply turns on an output to request that the spindle drive orient the spindle and then waits
for the spindle drive to report that the orient is complete. If you are having trouble with spindle orientation, focus on
your feedback and drive parameters.
Ashish B
Posts: 3
Joined: Tue Apr 06, 2010 1:59 am

Re: M19 - How does spindle orientation work?

Post by Ashish B »

Hi

Thanks for your Reply. Your post was the one for which i was looking since long.

As mentioned on CNC zone.com, I think that my spindle oscillates after M19 command. It doesn't happen everytime but sometimes it happens.

Can u recomend the best value for GAIN, to skip this oscillation on my spindle. ?

Also can u recommend the best value for Tolerance Window to allow high accuracy spindle positioning. ?


Need Help !

Thanks
Ash
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