Configuration for Lathe Tool on 7i95t boards

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2 years 1 month ago #309894 by Nathan40
Hi
I was wondering if anyone can help configure 7i95t configs for VFD on my lathe machine (Current configs attached). The axis work fine but the machine is giving horrible threads as spindle RPMs and Z axis are not in sync. (Maybe due to some kind of software filter perhaps).
Also the encoder is a 1000 line ppr encoder. Therefore, the 4000 in encoder scale. 
If possible, kindly share the 7i95t configs with scale, filters etc. commands so that the bounce factor in RPM feedback for the spindle are removed. 

Have checked all the cables and they are fine!

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2 years 1 month ago #309910 by PCW
Does the spindle encoder have single ended or differential wiring?
(and is the 7I95t spindle encoder input jumpered to match)

What is the maximum spindle RPM?

Do you get a precise 1.0000 increase in the spindle position for each forward turn of the spindle?
(watch spindle-revs)

Did you verify index operation:

watch spindle-index-enable then
sets spindle-index-enable 1
turn spindle slowly by hand
at the index position (and nowhere else)
spindle-index-enable should go false again

 

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2 years 1 month ago #309937 by Nathan40
Spindle encoder is single ended encoder. Have changed the jumper setting accordingly. Max spindle RPM after pulley reduction is 238 rpms. 
No I don't get precise revs.
The index leds are working correctly if I rotate it by hand.  The leds of phase A B and index are blinking according. However, the threads are all incorrect. The wiring I have checked again and seems to be fine.

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2 years 1 month ago #309939 by PCW
It might be a noise issue (this is more likely with single ended encoders)

To test, you could increase the encoder input filtering with say

setp  [HMOT](CARD0).encoder.sample-frequency 500000

I am assuming the encoder is mounted on the spindle or has 1:1
gearing with the spindle.

Setting the encoder sample frequency to 500000 (500 KHz) with the encoder filter on
will set the A/B/Z digital filters to a 30 usec time constant or an approximate
maximum count rate of 66 KHz (about 4x the actual max count rate of your 1000 line
encoder at 240 RPM)

The 30 usec time constant means that impulse noise shorter than 30 usec in duration
will be rejected. Impulse noise from motor drives is a significant source of encoder noise
issues.

 

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2 years 1 month ago #310443 by Nathan40
Dear All

Thanks for your replies. Spindle sync just keeps failing as the G76 command just keeps running the thread cuts at rapid speed.
For the spindle, I have tried with another INI and HAL with a BOB but failed. Please help!
Does spindle sync actually work in 7i95T? LEDs are switching off and on correctly in config. Have checked that.
Files attached!

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2 years 1 month ago #310459 by tommylight
Pictures of the wiring? Upload here on this forum, not on third party sites, please.
The spindle in hal is set as stepgen 6 and encoder 3, Mesa 7i95T has 6 stepgens numbered from 0 to 5, so where is stepgen 6?
Also, do not use a BOB on a 7i95T unless you explicitly need more than what it has to offer, BOB are really, really slow compared to Mesa.

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2 years 1 month ago #310462 by PCW
No I don't get precise revs.

Do you get precise 1.00 spindle position change for each turn,
If not, that must be fixed first.

Then you need to check index operation as described before:

Did you verify index operation:

watch spindle-index-enable then
sets spindle-index-enable 1
turn spindle slowly by hand
at the index position (and nowhere else)
spindle-index-enable should go false again

EDIT:

Also, is the spindle RPM (
spindle-vel-fb-rpm) correct?
(this would give a rough check of encoder operation)
 

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