Weird offset error...

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geneb
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Weird offset error...

Post by geneb »

So I've got this weird layer issue going on with my Duet based v1 machines (both of them!).

After some period of time (the failure point varies with the size and complexity of the model.), the layers become diagonally offset.

Here's an example:
layer-shift-1.jpg
Top view of the same failure - this shows the diagonal nature of the shift.
layer-shift-2.png
Any suggestions as to what could cause this? It's almost as if there's a MOSFET overheating and resetting. I do have a fan blowing on the back of the Duet in Blue MAX, but not with Red Sonja, but the problem happens with both...

g.
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Re: Weird offset error...

Post by DeltaCon »

A much too high current on the steppers caused my x motor to be disabled short periodes where after it enabled again with a serious offset, due to overheating driver chip. In your case the offset is much smaller, so we might be talking about a slightly too much current perhaps? It was a rambo, but I guess that makes no difference.
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Re: Weird offset error...

Post by Eric »

Have you pulled the g-code back into a viewer just to confirm the problem isn't in g-code generation?
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Re: Weird offset error...

Post by geneb »

I've got the current on the motors set to 1200 (1.2A). The slicer I'm using for this is S3D. Scrolling through the layers doesn't show any issues.
When I had the current set to the default (1000), the problem seemed to happen sooner.

g.
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Re: Weird offset error...

Post by Eaglezsoar »

Try a slicer that works? :)
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Re: Weird offset error...

Post by dc42 »

It could be that you have your acceleration set too high and it is trying to do a fast travel move that needs more torque than the motor is providing. What do you have the acceleration set to (M201 command in config.g), and what is the specification of your stepper motors?

If you have the Duet installed underneath a heated bed, you should use thermal insulation underneath the bed and a fan to blow air over the Duet. This isn't specific to the Duet, it applies to any electronics.
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Re: Weird offset error...

Post by geneb »

Here's what I _think_ are the relevant motor settings:

Code: Select all

M906 X1200 Y1200 Z1200 E1500:1500:1500:1500:1500:1500 ; Set motor currents (mA); set each extruder explicitly
M906 I100				; Set motor idle factor to 100% while testing so they don't idle at all
M201 X1000 Y1000 Z1000 E1000		; Accelerations (mm/s^2) Set all E-motors the same
M203 X20000 Y20000 Z20000 E3600		; Maximum speeds (mm/min) Set all E-motors the same
M566 X1200 Y1200 Z1200 E1200		; Maximum instant speed changes mm/minute. Set all E-motors the same
I suspect you're right on with the acceleration idea - the motor current was originally set to 1000 and when I bumped it to 1200, it delayed the failure point.
The motors I'm using are Kysan I think - they came with the v1 I've got this Duet 0.8.5 installed in.

I'll try dialing back the M201 speed and see if that helps - the rapid travel speed I've got set is 150mm/sec, MUCH lower than what I'd expect to see such behavior on a RAMBo based printer. I suspect that's why I didn't think anything about the rapid travels causing an issue.

Unrelated - I upgraded from 1.09k(?) to 1.12a in the hopes this would fix the problem. This of course left me with TWO problems. :) The firmware no longer heats the nozzle up to temperature before starting to auto-cal. :(

Here's the start code:
G90
M83
M106 S0
M140 S60
M190 S60
M104 S260 T0
M109 S260 T0
G28 ; home all axes
G32 ; auto-cal

It's clearly set to wait for the hot end to heat up....

thnx!

g.
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Re: Weird offset error...

Post by dc42 »

geneb wrote:Here's what I _think_ are the relevant motor settings:

Code: Select all

M906 X1200 Y1200 Z1200 E1500:1500:1500:1500:1500:1500 ; Set motor currents (mA); set each extruder explicitly
M906 I100				; Set motor idle factor to 100% while testing so they don't idle at all
M201 X1000 Y1000 Z1000 E1000		; Accelerations (mm/s^2) Set all E-motors the same
M203 X20000 Y20000 Z20000 E3600		; Maximum speeds (mm/min) Set all E-motors the same
M566 X1200 Y1200 Z1200 E1200		; Maximum instant speed changes mm/minute. Set all E-motors the same
I suspect you're right on with the acceleration idea - the motor current was originally set to 1000 and when I bumped it to 1200, it delayed the failure point.
The motors I'm using are Kysan I think - they came with the v1 I've got this Duet 0.8.5 installed in.

I'll try dialing back the M201 speed and see if that helps - the rapid travel speed I've got set is 150mm/sec, MUCH lower than what I'd expect to see such behavior on a RAMBo based printer. I suspect that's why I didn't think anything about the rapid travels causing an issue.

Unrelated - I upgraded from 1.09k(?) to 1.12a in the hopes this would fix the problem. This of course left me with TWO problems. :) The firmware no longer heats the nozzle up to temperature before starting to auto-cal. :(

Here's the start code:
G90
M83
M106 S0
M140 S60
M190 S60
M104 S260 T0
M109 S260 T0
G28 ; home all axes
G32 ; auto-cal

It's clearly set to wait for the hot end to heat up....

thnx!

g.
I get that behaviour (using 1.13 beta) if I don't send a T0 command first. You should have a T0 command in that startup code, somewhere before the M109 command.

I guess it's arguable that M109 should select the tool, if it isn't already selected. I'll consider implementing this in the 1.13 release.
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Re: Weird offset error...

Post by geneb »

What confuses me is that apparently the T0 in config.g was enough to handle this, but not in 1.12. I'll try it and see how it goes.

Tnx.

g.
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Re: Weird offset error...

Post by geneb »

Ok, I manually added a T0:

G90
M83
M106 S0
M140 S80
M190 S80
T0
M104 S260 T0
M109 S260 T0
G28 ; home all axes
G32 ; auto-cal

I've verified that the hot end will heat if manually commanded to do so.
It appears that the M104 and M109 instructions are being ignored - as soon as the bed heats up, it jumps right to the G82 and G32 commands.

Here's the output from the g-code console:
-----
6:19:11 AM
M0 H1
Print cancelled
6:19:09 AM
Printing paused
6:19:07 AM
Warning: Tool 0 was not driven because its heater temperatures were not high enough or it has a heater fault
6:19:06 AM
M25
Calibrated 6 factors using 13 points, deviation before 0.888 after 0.093
6:11:57 AM
M32 Bracket_for_desktop_lamp_Campus.gcode
File Bracket_for_desktop_lamp_Campus.gcode selected for printing
-----

I'm going to manually set the extruder temp and try to print the file to see if the reduced M201 settings will eliminate the skipping.

tnx!

g.
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Re: Weird offset error...

Post by geneb »

Ha! I figured it out!

For whatever reason, the firmware wasn't allowing a temperature to be set over 250C. The web interface will allow me to set up to 250C via the drop down, or text entry. However, it does nothing when 260 was entered. Even manually entering M104 S260 did nothing.

This got me to thinking - what if the max extruder temp is invalid or too low? I manually sent M143 S275 followed by M104 S260 and it started heating immediately!

I'll add M143 S300 to my config.g file.

dc42, is this a bug, or simply a low default? The M143 reference says that the default is 300C (http://reprap.org/wiki/G-code#M143:_Max ... emperature) so the wiki may need to be updated if that's not the case.

Would it make sense to add an error message display if the commanded hot end temperature exceeded the maximum specified by M143 (or the default)?

g.
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Re: Weird offset error...

Post by IMBoring25 »

The default was lowered on 1.12.
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Re: Weird offset error...

Post by Eaglezsoar »

I am glad you figured it out Gene and letting us know what the solution was, these postings are invaluable to us who are just now getting to use the Duet.
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Re: Weird offset error...

Post by Jimustanguitar »

Dangit guys, we missed a huge opportunity here.... I was digging for a page in the manual to refer Gene to. It was going to be awesome.
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Re: Weird offset error...

Post by geneb »

Don't worry, I'm quite sure I'll get my foot caught in a bucket soon enough, but TODAY IS NOT THAT DAY. Muahahahahahahahaha!

*ahem*

I cranked up the motor current to 1.5A and the offset appears to have been cured. I'm running a larger print right now to see if I've got it nailed.

g.
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Re: Weird offset error...

Post by DeltaCon »

Hmm, over-current and under-current symptoms look a lot alike...
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Re: Weird offset error...

Post by geneb »

DeltaCon wrote:Hmm, over-current and under-current symptoms look a lot alike...
Not that I've ever seen.

BTW, the long-term print worked as expected. Looks like I've got this one nailed down.

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Re: Weird offset error...

Post by Eaglezsoar »

Jimustanguitar wrote:Dangit guys, we missed a huge opportunity here.... I was digging for a page in the manual to refer Gene to. It was going to be awesome.
I would love that one! It will happen soon enough. I do hope Gene stocked up on extra glasses.
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