Can someone help me with anti-oozing gcode?  

RE: Can someone help me with anti-oozing gcode?

You're most likely looking for the "2 step warmup" gcode. It works like this:

1. Warm the filament up to a "no ooze" temperature. I use 160C. Warming the filament up before homing avoids possible damage to the PEI if hardened filament has accumulated on the nozzle.
2. Home the nozzle.
3. (optional) Wait for bed and PINDA warmup for consistent temperatures during leveling.
4. Do mesh bed leveling.
5. Home the nozzle.
6. Heat nozzle to final temperature.

This approach keeps the filament at a cooler temperature until mesh bed leveling is complete.

There are several variations based on personal preferences, but most work essentially the same way. I've got documented notes on my approach here and general notes on using gcode with PrusaSlicer here that might be helpful. You put that gcode under Printer Settings->Custom G-code->Start G-Code in PrusaSlicer. You can remove any parts that you don't need or want.

RE: Can someone help me with anti-oozing gcode?

Seeing as you mention Bob, you could try looking at his website https://projects.ttlexceeded.com/3dprinting_prusaslicer.html  

It has all the details about start code you should need. 

RE: Can someone help me with anti-oozing gcode?

Wow, perfect! I'll read through this...are there any "placeholders" in the code that I'll need to modify, or is it a simply copy/paste/(optionally remove) lines?

RE: Can someone help me with anti-oozing gcode?

Posted by: @obsessed

Wow, perfect! I'll read through this...are there any "placeholders" in the code that I'll need to modify, or is it a simply copy/paste/(optionally remove) lines?

Nothing should need to be modified. I've heard from a lot of people that have pasted it into their settings as-is. I encourage reading through it and modifying everything to your tastes, but a simple cut & paste should let you test it quickly. Let us know if you have any issues.

RE: Can someone help me with anti-oozing gcode?

Last question, sorry!

Do I overwrite the custom startup gcode that is there by default? I've read that the current lines at the bottom are particularly important.

M862.3 P "[printer_model]" ; printer model check
M862.1 P[nozzle_diameter] ; nozzle diameter check
M115 U3.9.3 ; tell printer latest fw version
G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
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}

; Don't change E values below. Excessive value can damage the printer.
{if print_settings_id=~/.*(DETAIL @MK3|QUALITY @MK3).*/}M907 E430 ; set extruder motor current{endif}
{if print_settings_id=~/.*(SPEED @MK3|DRAFT @MK3).*/}M907 E538 ; set extruder motor current{endif}

RE: Can someone help me with anti-oozing gcode?

Posted by: @obsessed

Last question, sorry!

Do I overwrite the custom startup gcode that is there by default? I've read that the current lines at the bottom are particularly important.

That one is a personal choice. I have never needed to adjust motor currents for good results, and for the first 30 months I owned my printer, Prusa didn't include these lines and everything worked well, so I don't bother. You can certainly add lines in to do so. Unfortunately, Prusa writes dependencies that are very specific to their presets. I'd re-write those last 2 lines to adjust based on layer heights or some other setting. As-is, they will only work with presets with those specific words ("DETAIL @MK3", or "QUALITY @MK" in the 1st line) as part of the names. If your presets don't follow that naming convention, those lines do nothing.

I'd suggest try REPLACING the existing gcode with the new gcode and see what results you get. If you experience problems, you can play around with adding some version of those commands back in.

MMU2S Version

@bobstro

I'm working on getting the MMU2S up and running...is there a version of this code that would work with the startup routine of MMU2S in either multi material or single material mode?

MMU should be doable

Posted by: @obsessed

@bobstro

I'm working on getting the MMU2S up and running...is there a version of this code that would work with the startup routine of MMU2S in either multi material or single material mode?

I am not aware of a version tweaked for the MMU2. I don't have one installed myself, so can't help with testing.

Looking at the gcode for the MMU, it looks like you could swap out everything down to the G80 for mesh bed leveling, then insert the MMU-specific stuff with the M403s. Other than that, just make sure you've added T tool selections where appropriate.

RE:

Here you go!

M862.3 P "[printer_model]" ; printer model check
M862.1 P[nozzle_diameter] ; nozzle diameter check
M115 U3.2.3 ; tell printer latest fw version
G90 ; use absolute coordinates
M83 ; extruder relative mode
M204 S[machine_max_acceleration_extruding] T[machine_max_acceleration_retracting] ; MK2 firmware only supports the old M204 format
M104 S160 ; set initial extruder temp to 160C
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S160 ; wait for extruder temp to reach 160C
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
M104 S[first_layer_temperature] ; set final extruder temp
M109 S[first_layer_temperature] ; wait for final extruder temp
G1 Z0.2 F720
G1 Y-2 F1000 ; go outside print area
G92 E0
G1 X60 E9 F1000 ; intro line
G1 X100 E12.5 F1000 ; intro line
G92 E0