RE: Always unwanted filament on noozle & sheet
Seems to depend a lot on the hotend temperature. With PLA (lower temps), leveling leaves a few small visible dots on the board that do not seem to affect the print. PETG leaves blobs if I don't clean the nozzle before leveling, and PC Blend drips a long string of filament while the print waits for the bed to heat to 110C, all of which gets dragged and deposited on the print area if the nozzle isn't cleaned.
It's annoying but only a little 🙂
Better if the process went: heat - retract filament - clean - level - heat - purge - clean - print. A little longer but no human intervention needed anymore.
RE: Always unwanted filament on noozle & sheet
Fun fact - it doesn't happen on the textured steel sheet. It happens on the satin and PEI. It also messes up the z calibration as the nozzle has crud on it and it doesn't get a correct z offset. Try a thoroughly cleaned textured steel sheet. It works really well with PLA to my surprise. Im also going to add a retract command in my ending g-code like this to suck back the filament at the end of a print:
G1 E-1.6 F3000; retract to avoid stringing
RE: Always unwanted filament on noozle & sheet
That's what I ended up doing. The start code already has a small retract before clean, and then a detract before the purge line. All I did was increase the retract by 30mm and increase the detract (while the nozzle is in the air before the purge line) to 40mm.
This helps a lot with stopping the oozing... but about 10% of the time, the nozzle still doesn't get cleaned properly and the zoffset is not accurate.
The MK3S+ is much more reliable than the "perfect" layer of the MK4 unfortunately.
Better if the process went: heat - retract filament - clean - level - heat - purge - clean - print. A little longer but no human intervention needed anymore.
RE: Always unwanted filament on noozle & sheet
Can you share your starting g-code, I like your approach better.
That's what I ended up doing. The start code already has a small retract before clean, and then a detract before the purge line. All I did was increase the retract by 30mm and increase the detract (while the nozzle is in the air before the purge line) to 40mm.
This helps a lot with stopping the oozing... but about 10% of the time, the nozzle still doesn't get cleaned properly and the zoffset is not accurate.
The MK3S+ is much more reliable than the "perfect" layer of the MK4 unfortunately.
Better if the process went: heat - retract filament - clean - level - heat - purge - clean - print. A little longer but no human intervention needed anymore.
RE:
here are the snipets of the start code I changed (the red is what I changed). Look for following line near the begining:
{if filament_type[initial_tool]=="FLEX"}G1 E-34 F2400 ; retraction{else}G1 E-32 F2400 ; retraction{endif}
Then look for this line further down the code:
G1 E{(filament_type[0] == "FLEX" ? 40 : 38)} F2400 ; deretraction after the initial one before nozzle cleaning
Everything else is the same.
Can you share your starting g-code, I like your approach better.
That's what I ended up doing. The start code already has a small retract before clean, and then a detract before the purge line. All I did was increase the retract by 30mm and increase the detract (while the nozzle is in the air before the purge line) to 40mm.
This helps a lot with stopping the oozing... but about 10% of the time, the nozzle still doesn't get cleaned properly and the zoffset is not accurate.
The MK3S+ is much more reliable than the "perfect" layer of the MK4 unfortunately.
Better if the process went: heat - retract filament - clean - level - heat - purge - clean - print. A little longer but no human intervention needed anymore.
RE:
Thanks for the G-Code, it leaves much less resin on the board when leveling, and the wipe before printing does a much better job. Without these settings, the nozzle would sometimes drag some oozies along to the print area after wiping.
RE: Always unwanted filament on noozle & sheet
The G-code from OB1 has been helpful, but still not 100%. I have to watch and manage the nozzle gun most of the time otherwise the first layer calibration will be off.
RE: Always unwanted filament on noozle & sheet
OKAY, it looks like they changed a few things with Ver 5.0 Firmware update. It is slightly improved.
But let's remember the very first statement in this thread: "The Mk3x start procedure was perfect. No filament on the noozle at print start, nothing at the end." So why isn't the MK4 perfect with Ver 5.0 Firmware upgrade???
PLA Smooth Sheet
Here's my latest frustration. I have carefully scraped the sheet between each print to get all the crumbs off of the plate. I even used 1000 grit sandpaper on my scraper for a super smooth tool. But because we now have to thoroughly clean the sheet after each print, my last two prints are not adhering in the corners! I thought maybe my sheet is a little oily, so I washed it thoroughly in soap and water, and then wiped it in IPA. And again for a simple rectangular print, all 4 corners lifted!
This means that I have used up the PLA Smooth Sheet on one side extremely prematurely!!! I have never had to buy a new sheet for my Prusa Mini, but it looks like I will have to buy a new sheet rather soon for my MK4. That's inconceivable!
Question: Has anyone actually used Hair Spray on these Prusa Sheets? I've only used hairspray for glass beds before, but I need to see if this is a viable option going forward...
Thanks.
RE: Always unwanted filament on noozle & sheet
Hi all, I'm facing same issue. I also had similar issue with my MK3 when I bought it and solution was to set bed temp to 60°C + extruder temp to 160°C - mesh bed - set extruder temp to first layer, do purge and print. This worked for me for a years, I mainly print with PETG.
After upgrade to MK 3.9 I was surprised that there is same issue as it was in the past, but extended for oozing after print.
I've modified preprint gcode to set temp just to 160 for PETG and problem for mesh leveling is solved. No oozing, no blob undet the nozzle, correct leveling.
Ozzing before purge is next problem, solved the same way as I did on MK3 - moved nozzle 0,5mm to bed and set first layer temp then, so all oozing filament makes blob on already heated bed. Purge movement cleans it then + I've put retraction to end gcode so there is no filament in nozzle when it's heating up (-10mm at the end).
BUT, oozing AFTER print is the problem I'm not able to solve. I think it's caused by high pressure of material in nozzle at the end of print. I think that solution might be to slow down the printing speed at top layer so filament is not so "pressurised" at the print end and does not ooze from nozzle.
I've hoped that retract (-10) at the begining of end Gcode should solve it, but it doesn't. It got better, but there is still some filament going out of nozzle at print end.
I've also turned on fan to cool down nozzle fater, didn't helpe either.
So I think its caused by pressure of liquidised filament in nozzle and there is just one way where it could go, out of nozzle. Other possible way, back to extruder is blocked by partially melted fillament (my theory).
Did someone solved this end print ooze??
I can share my
RE: Always unwanted filament on noozle & sheet
Turned on ironing and it has solved oozing after print (but I donn't want to iron every print 🙁 ). I'll try to reduce extrusion multiplier. It should theoretically reduce the pressure in nozzle (if this pressure is caused by overextrusion...)