Does somebody experience oozing after MK3 to Mk3S upgrade?  

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

Your filament has become damp, I know because I developed the same problem. 

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

@louis-j

how did you diagnose that?

Every opened filament I own is placed inside a drybox with 10% humidity from day one. I am even printing out of the drybox via PTFE tubing that is as sealed as possible.

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

The MK3S and MK3 hot end geometry from nozzle tip to melt zone are identical. There simply is not a physical difference unless you tore apart the hot end and reassembled the heat block and heat break. I could believe it if you changed the nozzle to a larger orifice, but the change in ooze can't be attributed to the extruder design change. It's identical in the parts that matter for ooze.

Filament dampness is #1 suspect and most likely thing to have changed. Remember, fresh out of factory seal <> actually dry. Plenty of my spools arrive "wet." Time to dry them at temperature.

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

@guy-k2

Interesting insight regarding nozzle geometry, thank you 🙂

Does desiccant in large quantities usually help to dry damp filament? Or is heating required for this process? I ask this because my filaments tend to spent months in the drybox with regular replacement of desiccant, so I was actually hoping to avoid dampness related issues :/

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

They actually run the filament through water to cool it during manufacture and if not dried properly before packaging, it may have moisture.

That token packet of desiccant won't absorb the moisture from the reel but may reduce the levels in any air left in the package when sealed. It helps to keep the reel dry if already dry, but don't expect it to somehow fully dry out the reel. For that you really need some heat and time.

I do have some PLA which is not as dry as could be, and I use it for Live-Z adjustment, quick prototype printing where finish is not so important and nozzle cold pulls. It oozes lots when the nozzle is coming up to temperature, but I am aware of it and use tweezers to pinch the ooze off just before it starts to print, yet use a good dried filament, and there is hardly any ooze or stringing. The PLA filament that is not fully dry actually allows me a degree of tolerance to cranking the speed up for prototype prints and 200% is easily achievable without having to crank up the temperatures much, just +5 Degrees works. Don't expect stellar prints though, but I have to admit, since changing to a skelestruder and fitting 0.9 Deg X and Y steppers, a few people cant believe the finish is a draft print at 0.3 layers and 200% speed.

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

@guy-k2

Agree, about half of my eSun filament is damp on arrival. Dessicat can help keep the air in a dry box stable but it can't dry the filament. 

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

Just for completeness: I am talking about ~kg of desiccant for 3 or so spools in a "as tight as possible" container, not the small desiccant bag in the box.

🙂

Thanks for your help

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

Posted by: @sam

After I upgraded my MK3 to MK3S I noticed that during heating, mesh bed levelling etc there is now always filament oozing from the nozzle.

Is this new and accepted behaviour of the new design?

I had literally no oozing with my MK3 with neither PLA nor PETG. I assume and hope that I might have assembled the new head in an incomplete way but I am not that deep into extruder design to grasp whether this is a side-effect of the new design or not.

I am slicing with PrusaSlicer and I have not modified retraction etc (still using prusa's default profile).

Everything on the printer is stock, default nozzle diameter, no other mods etc, it's vanilla as possible 🙂

i dont know if my problem is the same as yours but i used to not get filament oozing when my nozzle was warming, got vary little if any, but that was when i assembled my kit, but now heating nozzle and bed from scratch it will ooz out 120mm filament to heat up to pla temp, unfortunately i have to build some parts for a dehydrator and no dry box either also need to print it. i am building them but i only have like 3 spools i think they are all effected by the issue, i lowered the extruder rate to compensate for the issues this has caused.

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

Are you guys using a ooze and gnat reduction startup gcode or the Prusa startup gc0de? It makes a big difference even if you didn't change extruders to the MK3S. If you are still using Prusa's stock startup g-code, try something like mine below a try in Printer Settings/Custom G-code/Start G-code

M83 ; extruder relative mode
G28 W ; MUST FIRST home all without mesh bed level or else risk nozzle crash!
G0 X70 Y70 Z0.2 F2000; PINDA warms faster near bed
M140 S[first_layer_bed_temperature] ; set bed temp
M104 S160 ; preheat extruder to no ooze temp to help warm PINDA
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S160 ; wait for extruder temp
M860 S36 ; wait for PINDA temp. For most stable PINDA temp during mesh, set temp here 1-2 deg below your actual PINDA temp at end of mesh cal.
M104 S100 ; drop extruder to lower temp to minimize PINDA temp rise during mesh
G80 N7 R3 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 Z3 ; raise head safely clear of bed before heating extruder
M104 S[first_layer_temperature] ; we heat extruder AFTER mesh to minimize ooze
M109 S[first_layer_temperature] ; wait for extruder temp
G1 Z0.7 ; kuo move slightly above bed for easy clean intro line
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G1 E-0.8 F2100; bobstro anti-stringing retract and wipe
G1 X99.0 E0 F1000.0 ; -1mm intro line @ 0.00
G1 X110.0 E0 F1000.0 ; +10mm intro line @ 0.00
G1 Z0 ;lower head back to normal Z after intro line
G92 E0.0
M221 S{if layer_height==0.05}100{else}95{endif}

You will see the printer home, move carriage centrally to warm PINDA and heat bed, home, meshbed level, final warm up of nozzle. Added bonus is easier to remove purge line in addition to no more plastic gnats during mesh leveling.

RE: Does somebody experience oozing after MK3 to Mk3S upgrade?

Posted by: @guy-k2

Are you guys using a ooze and gnat reduction startup gcode or the Prusa startup gc0de? It makes a big difference even if you didn't change extruders to the MK3S. If you are still using Prusa's stock startup g-code, try something like mine below a try in Printer Settings/Custom G-code/Start G-code

M83 ; extruder relative mode
G28 W ; MUST FIRST home all without mesh bed level or else risk nozzle crash!
G0 X70 Y70 Z0.2 F2000; PINDA warms faster near bed
M140 S[first_layer_bed_temperature] ; set bed temp
M104 S160 ; preheat extruder to no ooze temp to help warm PINDA
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S160 ; wait for extruder temp
M860 S36 ; wait for PINDA temp. For most stable PINDA temp during mesh, set temp here 1-2 deg below your actual PINDA temp at end of mesh cal.
M104 S100 ; drop extruder to lower temp to minimize PINDA temp rise during mesh
G80 N7 R3 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 Z3 ; raise head safely clear of bed before heating extruder
M104 S[first_layer_temperature] ; we heat extruder AFTER mesh to minimize ooze
M109 S[first_layer_temperature] ; wait for extruder temp
G1 Z0.7 ; kuo move slightly above bed for easy clean intro line
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G1 E-0.8 F2100; bobstro anti-stringing retract and wipe
G1 X99.0 E0 F1000.0 ; -1mm intro line @ 0.00
G1 X110.0 E0 F1000.0 ; +10mm intro line @ 0.00
G1 Z0 ;lower head back to normal Z after intro line
G92 E0.0
M221 S{if layer_height==0.05}100{else}95{endif}

You will see the printer home, move carriage centrally to warm PINDA and heat bed, home, meshbed level, final warm up of nozzle. Added bonus is easier to remove purge line in addition to no more plastic gnats during mesh leveling.

I use something similar and it works great. Around a year ago I found Chris Warkocki's "pretty prusa profiles" https://github.com/eoprede/prusa_profiles/tree/master/MK3/Slic3r/archive. Within those profiles, they put the custom Gcode (listed below). The bed heats to desired printing temp but the nozzel goes to 160. Once at temp the printer will home, bed level, then home to wait for desired nozzle print temp. The only downside is that I have to go into settings and manually enter my bed temp and the 160 nozzel temp if I want to pre-heat before selecting my print. I would like to find a way to edit my preheat menus to use 160 nozzle temp.

M83 ; extruder relative mode
M140 S[first_layer_bed_temperature] ; set bed temp
M109 S160 ; Set extruder temp before bed level
M190 S[first_layer_bed_temperature] ; wait for bed temp

G28 W ; home all without mesh bed level
G80 ; mesh bed leveling

M109 S[first_layer_temperature] ; wait for extruder temp

M221 S100 ; Set flow to 100

G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 E8 ; Purge Bubble
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0