G76 incorrect pitch
- rider-83
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08 Apr 2022 13:28 #239662
by rider-83
Replied by rider-83 on topic G76 incorrect pitch
GUI is showing 100%
But still it displays the wrong feed.
With F.1 the GUI is showing F0.05
Could the slow feeds and incorrect thread pitch be related ?
But still it displays the wrong feed.
With F.1 the GUI is showing F0.05
Could the slow feeds and incorrect thread pitch be related ?
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- andypugh
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08 Apr 2022 13:32 #239664
by andypugh
There is more than one possible source of feed override. Perhaps you have something connected in the HAL?
Replied by andypugh on topic G76 incorrect pitch
GUI is showing 100%
But still it displays the wrong feed.
There is more than one possible source of feed override. Perhaps you have something connected in the HAL?
No, that was almost certainly due to simply running out of steps.With F.1 the GUI is showing F0.05
Could the slow feeds and incorrect thread pitch be related ?
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08 Apr 2022 13:44 #239665
by rider-83
Replied by rider-83 on topic G76 incorrect pitch
Something occurred to me just now, so I gave it a try.
If I use G97 and S500, then the feed is correct
If S2000, then the feed is slow
or
G96 and cap the speed at 500 and the feed is correct.
If I cap the speed to S2000, then the feed becomes slow.
If I use G97 and S500, then the feed is correct
If S2000, then the feed is slow
or
G96 and cap the speed at 500 and the feed is correct.
If I cap the speed to S2000, then the feed becomes slow.
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08 Apr 2022 13:50 #239668
by andypugh
Replied by andypugh on topic G76 incorrect pitch
Does your encoder velocity match the spindle speed at 2000 rpm? It sounds like you might be losing encoder counts.
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08 Apr 2022 13:52 #239669
by andypugh
Replied by andypugh on topic G76 incorrect pitch
But only if you are using feed-per-rev mode. Otherwise I have no clue.
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08 Apr 2022 13:57 #239672
by rider-83
Replied by rider-83 on topic G76 incorrect pitch
If I spin at 500 rpm , velocity shows 500.
But, if I spin at 1000 then it shows 1000 then randomly drops as far as 500.
At 2000, it shows nothing
But, if I spin at 1000 then it shows 1000 then randomly drops as far as 500.
At 2000, it shows nothing
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08 Apr 2022 14:03 #239674
by andypugh
Replied by andypugh on topic G76 incorrect pitch
So, it sounds like your base period is too long to capture encoder counts at max spindle speed.
This might not really matter, as long as all your threading is done at spindle speeds that the encoder counter can follow.
Then, so that feed-per-rev works, you can connect the spindle.0.speed-in pin to spindle.0.speed-out-rps instead of to the encoder. (This isn't ideal, but should work OK)
Or get an encoder with fewer teeth
Or try to run a shorter base thread (will need better latency)
Or buy an external encoder / stepper interface.
This might not really matter, as long as all your threading is done at spindle speeds that the encoder counter can follow.
Then, so that feed-per-rev works, you can connect the spindle.0.speed-in pin to spindle.0.speed-out-rps instead of to the encoder. (This isn't ideal, but should work OK)
Or get an encoder with fewer teeth
Or try to run a shorter base thread (will need better latency)
Or buy an external encoder / stepper interface.
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08 Apr 2022 17:48 #239682
by rider-83
Replied by rider-83 on topic G76 incorrect pitch
The curious thing about this is that the slow feed became much worse when I dropped the axis scale from 800 to 400 and changing from 8counts to 4counts on the driver.
I've been suspicious of the slow feed for some time, and now it's become more evident since this adjustment.
I can adjust the encoder multiplier in the servo drive to give 25 pulses from the current 100 and then set the the SCALE to 100 if you think that will help it keep up with the counts?
I've been suspicious of the slow feed for some time, and now it's become more evident since this adjustment.
I can adjust the encoder multiplier in the servo drive to give 25 pulses from the current 100 and then set the the SCALE to 100 if you think that will help it keep up with the counts?
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- tommylight
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08 Apr 2022 20:41 #239696
by tommylight
Replied by tommylight on topic G76 incorrect pitch
If using parallel port, it will help, a lot.I can adjust the encoder multiplier in the servo drive to give 25 pulses from the current 100 and then set the the SCALE to 100 if you think that will help it keep up with the counts?
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10 Apr 2022 17:20 #239834
by rider-83
Replied by rider-83 on topic G76 incorrect pitch
I lowered the servo encoder resolution to 25 and set the SCALE to 100.
Also, the axis SCALE is now down to 400 from 800
Feeds are now correct.
I also noticed some strange intermittent issues with the encoder feed back, especially with the A and Z phases and I traced it back the the LPT DB25 plug were a small solder 'ball' around 1mm diameter was rolling around the metal shell, and found itself lodged between the two pins connected to A & Z.
Once it was removed, all is now good, however it seems that anything above 500rpm and the LPT port can't cope with screw cutting, but I can live with that.
Also, the axis SCALE is now down to 400 from 800
Feeds are now correct.
I also noticed some strange intermittent issues with the encoder feed back, especially with the A and Z phases and I traced it back the the LPT DB25 plug were a small solder 'ball' around 1mm diameter was rolling around the metal shell, and found itself lodged between the two pins connected to A & Z.
Once it was removed, all is now good, however it seems that anything above 500rpm and the LPT port can't cope with screw cutting, but I can live with that.
The following user(s) said Thank You: tommylight
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