Would like to change starting behavior to avoid glass bed clamps
 
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Dennis M
(@dennis-m-2)
Active Member
Would like to change starting behavior to avoid glass bed clamps

Not sure if this has been addressed before, but I have one issue with PrusaSlicer that I didn't have my any of my former slicers. Basically, the Z height is set first before the move to the initial skirt starting position, which requires me to ensure there isn't a glass bed clip in the way in the lower left corner.

If I edit the gcode manually and make the z-height initial layer adjustment happen *after* the initial x and y coordinates, then the print head moves safely to the starting position while staying out of the way of the bed clips, then it lowers to the initial Z height and begins the skirt.

I hope this makes sense and I'm also hoping there's a way to change this behavior.

Otherwise, the default behavior is that the print head is lowered to the starting z-height before moving to the x, y of the skirt start point. This requires clearance between x, y at 0,0 and the starting position of the skirt. In normal circumstances this would hit the bed clip in the lower left corner.

Posted : 11/08/2022 6:14 pm
JustMe3D
(@justme3d)
Reputable Member
RE: Would like to change starting behavior to avoid glass bed clamps

Well, it´s named PRUSA Slicer. It´s basically a fork of Slic3r. I would not expect PRUSA Slicer to accomodate glass beds - when did PRUSA ever offer glass beds?

 

I try to give answers to the best of my ability, but I am not a 3D printing pro by any means, and anything you do you do at your own risk. BTW: I have no food for…

Posted : 12/08/2022 8:10 am
Neophyl
(@neophyl)
Famed Member
RE: Would like to change starting behavior to avoid glass bed clamps

Edit your printers profile start gcode section to make it behave how you want.  Must be in expert mode to see the section.

Posted : 12/08/2022 8:19 am
towlerg
(@towlerg)
Noble Member
RE: Would like to change starting behavior to avoid glass bed clamps

I have a sovol with a glass bed. I decided when I set up the profile (and microswitch positions) such that I had a 10mm unusable area on all four edges.to

I did this because -

  • Doubts about the bed heaters ability to maintain demand temp at extremities.
  • Wanted to use purge line with negative values
  • To avoid the glass clips.
Posted : 12/08/2022 5:00 pm
Dennis M
(@dennis-m-2)
Active Member
Topic starter answered:
RE: Would like to change starting behavior to avoid glass bed clamps

@towlerg -- thank you for the useful post and great suggestion. I agree that's one way to avoid the glass clips and might be my only option.

@neophyl -- customizing the start and end gcode is outside the realm of where this problem happens. Any custom "start" gcode happens before the z-height is adjusted down to the first layer height (at x,y = 0) so I can't do anything there.

Posted : 20/08/2022 12:08 am
JoanTabb
(@joantabb)
Moderator
RE: Would like to change starting behavior to avoid glass bed clamps

The Prusa Mk1 had a Glass bed, with clips. 

Have you considered swiss clips instead of the clips you normally use? 

Swiss clips have very little intrusion into the glass surface,

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 20/08/2022 5:24 am
jsw liked
Dennis M
(@dennis-m-2)
Active Member
Topic starter answered:
RE: Would like to change starting behavior to avoid glass bed clamps

Thanks Joan, I didn't know about those. Basically what I'm using are small aluminum clips that have a spring loaded thumbturn on the bottom to tighten it up on the bed. Since Prusa moves the z-height to layer 1 before moving to the starting x,y I just have to make sure I locate the front left clip a few inches away from the corner to avoid any nozzle collision.

This method seems like it'll need to be my method since I guess it's going to be challenging to get the PrusaSlicer behavior changed, or I can edit the gcode manually:

Before:

;LAYER_CHANGE; Z:0.3
;HEIGHT:0.3
G1 Z.3 F7800 ; move to next layer (0)
G1 E-6 F3000 ; retract
G92 E0 ; reset extrusion distance
G1 X109.058 Y107.755 F7800 ; move to first skirt point

After:

;LAYER_CHANGE;Z:0.3
;HEIGHT:0.3
G1 E-6 F3000 ; retract
G92 E0 ; reset extrusion distance
G1 X109.058 Y107.755 F7800 ; move to first skirt point
G1 Z.3 F7800 ; move to next layer (0)
Posted : 20/08/2022 6:33 am
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