Tiny blobs of plastic on the print? FIlament peeling off? Let's solve it!
 

Tiny blobs of plastic on the print? FIlament peeling off? Let's solve it!  

  RSS
covertpluto
(@covertpluto)
Trusted Member

So I have seen multiple people say that the plastic comes off the build plate when the extruder is moving. I think that it is a problem with the plastic oozing out of the nozzle when preheating, and during MBL, the plastic gets squished onto the nozzle. Some GCODE modifications did the trick for me, here it is:

Start

M862.3 P "[printer_model]" ; printer model check
M862.1 P[nozzle_diameter] ; nozzle diameter check
M115 U3.8.1 ; tell printer latest fw version
G90 ; use absolute coordinates
M140 S[first_layer_bed_temperature] ; set bed temp
M106 S255 ; fan on
M109 S150 ; wait for extruder cooling/heat up extruder
M107 ; fan off
G28 ; auto home and mesh bed leveling
M83 ; extruder relative mode
M104 S[first_layer_temperature] ; set extruder temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0
M221 S{if layer_height<0.075}100{else}95{endif}

 

This might work as it does MBL at a lower temperature.

This topic was modified 2 months ago by covertpluto
Posted : 08/06/2020 12:31 pm
louis.j liked
louis.j
(@louis-j)
Trusted Member

this looks interesting, how do you put in this code?

...
Posted : 08/06/2020 3:15 pm
covertpluto
(@covertpluto)
Trusted Member

@louis-j

You put it in the Printer Settings>Custom G-code>Start G-code

Posted : 08/06/2020 3:50 pm
Area51
(@area51)
Honorable Member

Had that problem for some time printing PETG - during preheat the nozzle temperature reached operating temperature first and started ooze before the MBL. Had to sit, wait and clean the nozzle before the MBL.

My Mini just preheat to 170 and that way avoids most ooze before MBL. I decided to change the start g-code on MK3 to do the same:

; Updated: 2020.06.08, Start G-code MK3S

; Check printer and firmware
M862.3 P "[printer_model]" ; printer model check
M862.1 P[nozzle_diameter] ; nozzle diameter check
M115 U3.9.0 ; tell printer latest fw version

; Bed level at 170C
G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S170 ; set extruder temp for bed leveling
M140 S[first_layer_bed_temperature] ; set bed temp
M109 S170 ; wait for bed leveling temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling (Z=0.15, X=0.27, Y=-3.80)

; Heat up extruder
M104 S[first_layer_temperature] ; set extruder temp
G92 E0.0
G1 Y-3.0 F1000.0 ; go outside print area
G1 Z3 F720
M109 S[first_layer_temperature] ; wait for extruder temp

; Intro line
G1 Z0.20 F720
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0

M221 S{if layer_height<0.075}100{else}95{endif} ; Set flow

I'm no expert in start g-code, but for the last days this has worked as expected.

Use the g-code at your own risk... 🙂

Have a look at my designs on Thingiverse or on PrusaPrinters ;)...
Posted : 08/06/2020 6:38 pm
bobstro
(@bobstro)
Illustrious Member

Be aware that there are concerns about inconsistency in PINDA probing at varying temperatures. Early testing indicated the PINDA performs best at a consistent ambient temperature (e.g. 35C) before initiating leveling. As a result, many of us have implemented a PINDA warmup routine into startup gcode. There was some indication that Prusa has tweaked the firmware to reduce this issue, but there is still value in having your bed and printer warmed evenly up prior to starting a print. The "2 step warmup" procedure also reducing nozzle oozing and dots during mesh bed leveling. I have a documented example for the Mk3 series here along with relevant links for those interested in more detail.

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 : 08/06/2020 6:48 pm
Area51
(@area51)
Honorable Member

As far as I knows the MK3 has temperature compensated PINDA, where there is no compensation in the Mini. My Mini is inconsistent if it is not started from cold each time.

It is really nice with the new MK3 non-ooze two step warm up, the ooze has been annoying me for a long time...

I know about your great documented pages, thank you. This was just a learning exercise in "minimal changes in standard Prusa start g-code to make it preheat to 170 before MBL".

Have a look at my designs on Thingiverse or on PrusaPrinters ;)...
Posted : 08/06/2020 7:16 pm
louis.j
(@louis-j)
Trusted Member

@covertpluto

OK, I found the place. I have a MK2.5S - do I just replace the G code in the 'start g-code' area with your G code?

...
Posted : 10/06/2020 4:43 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @area51

As far as I knows the MK3 has temperature compensated PINDA, where there is no compensation in the Mini. My Mini is inconsistent if it is not started from cold each time.

Ah, gotcha. I missed that you are using a Mini. Casual tests show that the COLD nozzle temp corresponds roughly with the PINDA temp, so you could read the UNHEATED nozzle temp with M105. You can to wait for temp in gcode, but so far as I know, there is no way to wait without issuing a heat command with M109

It is really nice with the new MK3 non-ooze two step warm up, the ooze has been annoying me for a long time...

I know about your great documented pages, thank you. This was just a learning exercise in "minimal changes in standard Prusa start g-code to make it preheat to 170 before MBL".

Unfortunately, you can't do a true conditional in startup gcode, but this would be something you can probably do with Octoprint.

Glad the notes are useful.

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 : 10/06/2020 5:49 pm
covertpluto3502
(@covertpluto3502)
New Member

@louis-j

Yes, just paste in the main part of the code. The MK2.5S might differ to the MK3S, but I will let you figure that out as I don’t have MK2.5S.

This post was modified 2 months ago by covertpluto3502
Posted : 10/06/2020 6:14 pm
louis.j
(@louis-j)
Trusted Member

@covertpluto3502

That worked great! No revisions needed for my MK2.5S with 0.6 nozzle. Those blobs where a contant problem.

...
Posted : 11/06/2020 12:53 am
Share:

Please Login or Register