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Layers shifting

Posted by Sardi 
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Sardi
Layers shifting
November 04, 2017 11:39AM
I noticed recently that the layers started to shift a bit, not much, but still.

I have both the x belt and y belt tensioner, so the belts have good tension.
Also the speed I used for the model on the photo is 15mms so I dont believe the motors skipped steps.

The shift is not big and it goes to the right (if you look at ormerod from the end x axis towards the motor)



Any ideas what could cause the shift?
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ayudtee
Re: Layers shifting
November 04, 2017 05:35PM
I would check for a loose grub screw on the y axis pulley.
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Sardi
Re: Layers shifting
November 06, 2017 09:45AM
(Unfortunately) the grub was tight in place.

Maybe I should try lowering the acceleration speed for the y axis.
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redblunt
Re: Layers shifting
November 06, 2017 04:36PM
is this the first print that does this?
did you calibrate using the axis compensation?
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Sardi
Re: Layers shifting
November 07, 2017 10:21AM
I had this problem more or less visible on some occasions, but the models printed were not something important so I just ignored it.
But now I guess my ocd has kicked in and I want to fix it.

Last time I used the axis compensation was 3 years ago (when I bought the printer grinning smiley ), so I guess its time for another go ..
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dc42
Re: Layers shifting
November 07, 2017 11:37AM
Running tht bed heater in bang-bang mode instead of PID can contribute to layer shift.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Sardi
Re: Layers shifting
November 07, 2017 02:44PM
Quote
dc42
Running tht bed heater in bang-bang mode instead of PID can contribute to layer shift.

Could you tell me how to check in what mode my bed heater is in?
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dc42
Re: Layers shifting
November 07, 2017 03:09PM
If the bed led flickers continually when it is maintaining temperature, it's in PID mode. If it turns on and off, it's in bang-bang mode.

Edited 1 time(s). Last edit at 11/07/2017 03:09PM by dc42.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Sardi
Re: Layers shifting
November 08, 2017 05:32AM
I just checked again, and I can say for sure it never flickered.

While its maintaining the temperature its either on or off, never flickers.

Can you advise me on how to change this?
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dc42
Re: Layers shifting
November 08, 2017 08:27AM
If you are using recent firmware, see [duet3d.com].


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Sardi
Re: Layers shifting
November 09, 2017 08:54AM
I am at 1.17 at this time.
Will look at the link you provided.
Thank you!

EDIT:
As I understand, (in short) using the M303 will start the autotune, once Its done, I send the M500 and the settings are automatically saved? Optionally, I can add the M307 to my config manually?
And all that will change my settings from bang bang to PID?

Edited 1 time(s). Last edit at 11/09/2017 09:01AM by Sardi.
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number40fan
Re: Layers shifting
November 09, 2017 01:49PM
Yes, that will do the trick.
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Sardi
Re: Layers shifting
November 10, 2017 03:36PM
I was about to do this, when I realised I dont know the number of the heaters.. Is the bed H0 or H1 ?
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number40fan
Re: Layers shifting
November 10, 2017 05:10PM
0.

[duet3d.com]

Edited 2 time(s). Last edit at 11/10/2017 05:12PM by number40fan.
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Sardi
Re: Layers shifting
November 11, 2017 11:35AM
PID tuning done!

sent: M303 H0 S90
Auto tuning heater 0 - do not leave printer unattended

After 23 minutes it reached 66C and ended the tuning.
Auto tune heater 0 with PWM=0.50 completed in 1408 sec, maximum temperature reached 66.0C
Use M307 H0 to see the result

M307 H0
Heater 0 model: gain 78.6, time constant 505.3, dead time 12.3, max PWM 1.00, mode: PID
Setpoint change: P93.6, I0.185, D803.1
Load change: P93.6, I2.642, D803.1

sent: M500

Added this to the config.g
M307 H0 A78.6 C505.3 D12.3 B0 ;

Guess this is it than.

But why did it stop at 66C when I set the temperature at S90?
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dc42
Re: Layers shifting
November 11, 2017 02:10PM
In firmware 1.17 the temperature parameter is just a safety limit. It's different in later firmware versions.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Sardi
Re: Layers shifting
November 12, 2017 04:25AM
I thank all of you for your help.

The layer shift is still present, so Im going to try lowering the Y acceleration next.
Going from 800 to 600 to see what happens.
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dc42
Re: Layers shifting
November 12, 2017 08:22AM
What do you have the Y motor current set to?


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Sardi
Re: Layers shifting
November 13, 2017 06:20AM
Quote
dc42
What do you have the Y motor current set to?

M906 X800 Y1000 Z800 E800 ; Set motor currents (mA)

I think this is by default, I dont remember changing these values.
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ormerod168
Re: Layers shifting
November 13, 2017 06:46AM
The original default was x-y-z 800mA

My settings:

M906 X1000 Y1200 Z800 E1200 ; Set motor currents (mA)
M201 X1200 Y1200 Z20 E3600 ; set accelerations (mm/s^2)
M566 X1800 Y1800 Z30 E20 ; maximum jerk speed mm/minute

Erik
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dc42
Re: Layers shifting
November 13, 2017 08:38AM
I increased the Y motor current to 1000 on my Ormerod too. I think many users have.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Sardi
Re: Layers shifting
November 13, 2017 10:36AM
I have tried to fix layer shifting by lowering the acceleration on the Y, didnt help.

For my next trick, Im gonna copy Eriks settings to my config.g and see what happens.
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Sardi
Re: Layers shifting
March 26, 2018 10:14AM
Quote
ormerod168

M906 X1000 Y1200 Z800 E1200 ; Set motor currents (mA)
M201 X1200 Y1200 Z20 E3600 ; set accelerations (mm/s^2)
M566 X1800 Y1800 Z30 E20 ; maximum jerk speed mm/minute

Erik

As Im still experiencing layer shifts as described in the first post, Im trying Eriks settings.
PID heating, y + x belt tensioner, all screws in place ..
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