GRBL Z axis issue.

Discussion about the arduino based g-code interpreter, grbl
groguard
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Joined: Wed Mar 19, 2014 4:01 am

GRBL Z axis issue.

Post by groguard » Mon Nov 10, 2014 8:38 pm

I seem to be having a problem with my z axis motor. I appears to be "turn off and on" while running a job. It works perfect about 85% of the time. I've checked all my wiring and voltage, all seems well there. I'm wondering if the driver is going out, or some other issue. Any ideas? I'll post a video below so you can see/hear what its doing.
Shapeoko 2 #3920. Nema 23's. Belt drive Z axis, ACME rod upgrade,
1m rails on X and Y, X upgraded to 60x40 extrusion with openrail, Mid span supports,
DW660 with Super-Pid, IC's DW660 dust shoe.
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WillAdams
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Re: GRBL Z axis issue.

Post by WillAdams » Mon Nov 10, 2014 9:49 pm

Classic symptoms of overheating. Add a fan, or add heat sinks and a fan.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

cvoinescu
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Re: GRBL Z axis issue.

Post by cvoinescu » Mon Nov 10, 2014 9:51 pm

The video is private, we can't see it.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

groguard
Posts: 71
Joined: Wed Mar 19, 2014 4:01 am

Re: GRBL Z axis issue.

Post by groguard » Mon Nov 10, 2014 9:56 pm

WillAdams wrote:Classic symptoms of overheating. Add a fan, or add heat sinks and a fan.
I have a fan on my GRBL board, and this was never an issue before. I also was air cutting and it was only running a 5 minute "air cut".
cvoinescu wrote:The video is private, we can't see it.
Opps, fixed the video.
Shapeoko 2 #3920. Nema 23's. Belt drive Z axis, ACME rod upgrade,
1m rails on X and Y, X upgraded to 60x40 extrusion with openrail, Mid span supports,
DW660 with Super-Pid, IC's DW660 dust shoe.
Build Log

cvoinescu
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Re: GRBL Z axis issue.

Post by cvoinescu » Mon Nov 10, 2014 10:41 pm

Looks like acceleration is set too high, and possibly the max speed too. It doesn't sound like thermal shutdown, but more like you're pushing the motor too fast for the given current. So either increase current, or decrease acceleration and/or speed. Also check that you're getting the correct amount of travel -- sometimes it's just the wrong steps-per-mm setting that causes problems.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

groguard
Posts: 71
Joined: Wed Mar 19, 2014 4:01 am

Re: GRBL Z axis issue.

Post by groguard » Mon Nov 10, 2014 10:48 pm

cvoinescu wrote:Looks like acceleration is set too high, and possibly the max speed too. It doesn't sound like thermal shutdown, but more like you're pushing the motor too fast for the given current. So either increase current, or decrease acceleration and/or speed. Also check that you're getting the correct amount of travel -- sometimes it's just the wrong steps-per-mm setting that causes problems.
Ok, I'll give that a shot, my current settings

$112=1500.000 (z max rate, mm/min)
$120=250.000 (x accel, mm/sec^2)
$121=250.000 (y accel, mm/sec^2)
$122=50.000 (z accel, mm/sec^2)
Shapeoko 2 #3920. Nema 23's. Belt drive Z axis, ACME rod upgrade,
1m rails on X and Y, X upgraded to 60x40 extrusion with openrail, Mid span supports,
DW660 with Super-Pid, IC's DW660 dust shoe.
Build Log

groguard
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Joined: Wed Mar 19, 2014 4:01 am

Re: GRBL Z axis issue.

Post by groguard » Mon Nov 10, 2014 11:12 pm

cvoinescu wrote:Looks like acceleration is set too high, and possibly the max speed too. It doesn't sound like thermal shutdown, but more like you're pushing the motor too fast for the given current. So either increase current, or decrease acceleration and/or speed. Also check that you're getting the correct amount of travel -- sometimes it's just the wrong steps-per-mm setting that causes problems.
Ok, I did some testing here are the new settings but I'm still experiencing the same issue. I also want to point out that I had the acceleration at 100 before and changed it to 50. I pulled those settings posted above after I started making a couple changes.
$100=39.947 (x, step/mm)
$101=39.972 (y, step/mm)
$102=94.474 (z, step/mm)
$110=2500.000 (x max rate, mm/min)
$111=2500.000 (y max rate, mm/min)
$112=1000.000 (z max rate, mm/min)
$120=250.000 (x accel, mm/sec^2)
$121=250.000 (y accel, mm/sec^2)
$122=50.000 (z accel, mm/sec^2)
$130=290.000 (x max travel, mm)
$131=290.000 (y max travel, mm)
$132=100.000 (z max travel, mm)
Shapeoko 2 #3920. Nema 23's. Belt drive Z axis, ACME rod upgrade,
1m rails on X and Y, X upgraded to 60x40 extrusion with openrail, Mid span supports,
DW660 with Super-Pid, IC's DW660 dust shoe.
Build Log

Schruminator
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Re: GRBL Z axis issue.

Post by Schruminator » Tue Nov 11, 2014 2:56 pm

I don't have my settings handy here at work, but I'm thinking my z-max rate is about 600-700 instead of 1000. I'm not sure what my acceleration setting is though. Anywho, just for reference-- it might be worth toying with slightly lower z-max speeds.
1.8m x 1.0m SO2 #3638 / Vectric Aspire / ACME Z-axis / View my photography at http://www.mschrum.com

groguard
Posts: 71
Joined: Wed Mar 19, 2014 4:01 am

Re: GRBL Z axis issue.

Post by groguard » Tue Nov 11, 2014 5:39 pm

Schruminator wrote:I don't have my settings handy here at work, but I'm thinking my z-max rate is about 600-700 instead of 1000. I'm not sure what my acceleration setting is though. Anywho, just for reference-- it might be worth toying with slightly lower z-max speeds.
I'll give it a shot. I had it set to 800 before I did the nema 23/belt drive upgrade. I figured I would be able to gain some extra speed. I guess I'll try moving it back down. I suppose at the very least I have a more balanced Z axis and better clearance for the spindle mounts haha.

Thanks for the tips guys! Hopefully I can get this sorted.
Shapeoko 2 #3920. Nema 23's. Belt drive Z axis, ACME rod upgrade,
1m rails on X and Y, X upgraded to 60x40 extrusion with openrail, Mid span supports,
DW660 with Super-Pid, IC's DW660 dust shoe.
Build Log

groguard
Posts: 71
Joined: Wed Mar 19, 2014 4:01 am

Re: GRBL Z axis issue.

Post by groguard » Tue Nov 11, 2014 7:27 pm

Alright, I tried changing the acceleration and speed and I'm still getting the same problem. I've made a short video showing the GRBL board while its air cutting. It seems like the driver is cutting on and off. I'm baffled . Is it possible the driver is going out? Heres a video, I don't know if it will help any. You can see and hear at the beginning of the video and at the end it seems to go off and on. I appreciate the help guys!
Shapeoko 2 #3920. Nema 23's. Belt drive Z axis, ACME rod upgrade,
1m rails on X and Y, X upgraded to 60x40 extrusion with openrail, Mid span supports,
DW660 with Super-Pid, IC's DW660 dust shoe.
Build Log

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