OctoPi distorting prints  

  RSS
Lvet
 Lvet
(@lvet)
Estimable Member

Hello,

There is something bizarre with my OctoPi setup.

I am running OctoPi 0.18.0 on a RaspberryPi 4B.

When I upload a gcode file, OctoPi reads it and explode the X and Y dimensions by a factor of 2.5 on the X axis and 4 on the Y axis. When I print, the model is correctly sized but very often Octoprint thinks that the model is too big and refuses to print.

These distortions are happening regardless if I upload the gcode files from the Prusa model folder, slice them with Cura or PrusaSlicer.

Any idea of what might be wrong?

For example if I take 3Dbenchy that should be 60mm * 31mm * 48mm, on OctoPi I read 153.06mm * 135.06 * 48.0mm.

Best Answer by bobstro:

Be sure you've properly defined the bounding box for your print area. The prime line is printed slightly outside the print area at position Y-4. OctoPrint may be detecting this as unprintable if your bounding box isn't set properly.

The overall dimensions may be taking the prime line into account as a result.

 
This topic was modified 2 months ago by Lvet
Posted : 22/02/2021 10:02 pm
fuchsr
(@fuchsr)
Honorable Member

The factor of 2.5 sounds very much like a conversion from inches to mm happening somewhere. A factor of 4 though? 

Posted : 22/02/2021 10:36 pm
bobstro
(@bobstro)
Illustrious Member

Be sure you've properly defined the bounding box for your print area. The prime line is printed slightly outside the print area at position Y-4. OctoPrint may be detecting this as unprintable if your bounding box isn't set properly.

The overall dimensions may be taking the prime line into account as a result.

 
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 22/02/2021 10:38 pm
bapski and Lvet liked
Lvet
 Lvet
(@lvet)
Estimable Member

Hi @Bobstro,

Thanks!!!, This solved my problem. 😀 
I didn't think that the prime line was outside the print area, therefore adding the negative value on the Y axis of the custom bounding box made it work.
I read the config parameters for the MK3S on Octopi, but I missed completely that.

Posted : 23/02/2021 7:12 am
cwbullet
(@cwbullet)
Illustrious Member

The Y bounding box is 220?  I need to go back and check mine.

--------------------
Chuck H
3D Printer Review Blog...
Posted : 23/02/2021 11:02 am
bapski
(@bapski)
Eminent Member

@cwbullet

well, i'll be darn! i may have to check what mine is too!

although i haven't had issues in the last 24 hours with Octoprint (knock on wood!).  Won't hurt to check to make sure i have the right settings. Right?

This post was modified 2 months ago by bapski
Posted : 23/02/2021 1:39 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @cwbullet

The Y bounding box is 220?  I need to go back and check mine.

My settings aren't exact. I believe Y can go from -4 to 215, X from -1 to 251 roughly. The important thing is that the bounding box should allow for the prime line at Y -3.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 23/02/2021 2:09 pm
chad.k
(@chad-k)
Eminent Member

The firmware limits for the MK3S/S+ are 0 to 255 on X, -4 to 212.5 for Y and 0.15 to 210 for Z.  The MK2.x uses 0 to 250 for X, -4 to 210 for Y and 0.15 to 210 for Z.  I'm not sure how safe it is to use the "extra" space on the MK3 for actual printing, so it might be best to stay with the more conservative values.

Posted : 23/02/2021 10:42 pm
cwbullet
(@cwbullet)
Illustrious Member

@chad-k

Thanks.  What is your source?

--------------------
Chuck H
3D Printer Review Blog...
Posted : 24/02/2021 1:09 am
chad.k
(@chad-k)
Eminent Member

I pulled them from the source code here: https://github.com/prusa3d/Prusa-Firmware/tree/MK3/Firmware/variants

The relevant lines are like this (from 1_75mm_MK3S-EINSy10a-E3Dv6full.h for the MK3S):

// Travel limits after homing
#define X_MAX_POS 255
#define X_MIN_POS 0
#define Y_MAX_POS 212.5
#define Y_MIN_POS -4 //orig -4
#define Z_MAX_POS 210
#define Z_MIN_POS 0.15
Posted : 24/02/2021 3:54 am
cwbullet
(@cwbullet)
Illustrious Member

@chad-k

Thank you.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 24/02/2021 10:47 am
Share:

Please Login or Register