Layers shifting to the Z tower

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robb
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Layers shifting to the Z tower

Post by robb » Sun Nov 26, 2017 11:13 pm

My printer has started having this problem. I tried checking the belts and cheapskates, everything seems to move freely or stay tight as appropriate. The shifting is directly towards the Z tower and is extreme. I checked the fan on the rambo. I have repeiter 0.92.2 (20170822) loaded.
Its a stock v2 with u-joint arms and a new EZR extruder to replace the EZ.

I tried bumping the motor current by 5 with no change:
#define MOTOR_CURRENT {145,145,145,135,0} // Raised current by 5 robb

My Steppers are marked
Automation technology Inc
KL17H248-15-4A

Am I using the wrong current settings?

My bed is rotated a little because of the FSR mounts (connected to the MIN_HARDWARE_ENDSTOP_Z)
The creep is directly in the Z tower direction.

None of the other layer creeping pictures I have seen in threads on here are this extreme and I am not sure why its moving to Z but staying level. Wouldn't it tilt also if it was skipping servos? Thanks for any help you all can provide.

20171126_225311.jpg

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Glacian22
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Re: Layers shifting to the Z tower

Post by Glacian22 » Mon Nov 27, 2017 2:28 am

It could also be the driver overheating, make sure there's good airflow over the board?

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geneb
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Re: Layers shifting to the Z tower

Post by geneb » Mon Nov 27, 2017 11:19 am

Might have a rapid speed too fast - keep it under 240mm/sec.

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robb
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Re: Layers shifting to the Z tower

Post by robb » Mon Nov 27, 2017 11:41 am

Non-print speed in Mattercontrol is 200mm. First layer is 20, Infill is 40, Bridges is 60.
I checked the board fan and it seems fine. Should I try with the board removed from the base to check?

I also don't understand why it is only moving towards the Z tower. Wouldn't it go back and forth? and wouldn't the Z tower direction mean that X and Y are both skipping? Very puzzling.

IMBoring25
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Re: Layers shifting to the Z tower

Post by IMBoring25 » Mon Nov 27, 2017 7:11 pm

More likely than X and Y both skipping the same amount is a problem with Z. Which way it shifts will also depend on whether the cheapskate is trying to go up or down when it doesn't.

robb
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Re: Layers shifting to the Z tower

Post by robb » Mon Nov 27, 2017 8:33 pm

That's a good point. Probably the Z tower somehow. Could it be that I have the FSR on the Z endstop pin? If the FSR were triggering would that stop the Z motor while its printing? Seems likely, I found this:

To anyone else who happens across this.
The low level code that check any axis endstop only prevents movement past the endstop.
It does not stop printing, or the other axis.
If Z is at either endstop, x and y can still move, Cartesian or delta. And Z is free to move away from the endstop,
and the same is true for all axis.
(https://github.com/repetier/Repetier-Fi ... issues/235)

So if my FSR is triggering the Z min endstop it would cause skipping only in one direction, Down. This would cause the shifting only in the direction of the Z tower. This fits with the symptom.

I have:

#define FEATURE_Z_PROBE 1 // Enable z probe FSR robb
#define MIN_HARDWARE_ENDSTOP_Z true // FSR install on Rostock Max v2 robb
// fsr install robb original: 4
#define Z_PROBE_PIN 10

Can I set MIN_HARDWARE_ENDSTOP_Z to false but still use the probe?
Should I set ALWAYS_CHECK_ENDSTOPS to False?

robb
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Re: Layers shifting to the Z tower

Post by robb » Tue Nov 28, 2017 12:07 am

I tried with ALWAYS_CHECK_ENDSTOPS set to False and it still happened. I disabled MIN_HARDWARE_ENDSTOP_Z and the shifting went away. I have not tested probing yet but this is very encouraging.

robb
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Re: Layers shifting to the Z tower

Post by robb » Mon Dec 04, 2017 11:57 pm

I tested probing and it works fine. My mistake was thinking that I needed to enable MIN_HARDWARE_ENDSTOP_Z for the probing to work. This caused the FSRs to trigger the Z_MIN end stop randomly causing the layer shifting. Printing and probing just fine with only FEATURE_Z_PROBE enabled. Thanks for the help

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