RE: PETG Issues
I used a machinists dial indicator after assembly and my beds flatness is +/- .010”. Considering the parts involved, I was happy with it. I bought this machine specifically for its ability to handle PETG and I’m disappointed in the performance of this unit. I’ve had some friends look it over who have similar units and nothing looks out of alignment or mis-tensioned. I’ve thought the Mk4 extruder might solve my problems, but lead times are awful and I might have to get a Bambu so I can finish this project. I’ve already failed to deliver on one project and it’s cost me a hefty sum.
RE: PETG Issues
wow.. I don't have enough experience to offer any real help.. if you get one good print and then bad ones.. almost seems like something is broken in the hot end.. maybe the thermistor is intermittent .. I have a lot of criticisms of Prusa stuff.. but the heart of the printing mechanism is pretty solid in my very limited experience.. and also from most reviews and reading I've seen.. I've printed at least 500 hours of PETG from 3-5 different manufacturers and have found it prints virtually better than PLA, except for overhangs, in which cooling is the issue.. so some trial and error is needed. Prusa prints their entire parts in PETG on their own gear.. so there is no way what you are experiencing is typical. Yet if your Nylon (which I've never tried) and PLA work fine.. I have no clue what could be at fault.
Sometimes if I have adhesion issues on my rough sheet, I'll put some glue stick on a smooth PEI and print PETG there.. and it also does fine.. You can try just as a test to see what happens.. But if you print PLA and Nylon fine, then it sounds like the printer is okay.. My initial thought might be the filament is bad .. have you tried fresh brands of others? .. My bed temp on my rough sheet is generally 80-85.. I use 85 more now for better adhesion..My filament temp is generally about 230 for Eryone, Polymaker and similar.. my speed settings are attached.. any chance you got a bad speed profile for PETG?
RE: PETG Issues
I can check the profile and see. I don’t believe my experience is typical, there must be something wrong with my unit. I suspect the extruder isn’t able to push material through consistently, be that a gear issue or something to do with the hotend. I’ve tried different brands of material thinking perhaps I had a bad roll, same inconsistent results. I still get good PLA and Nylon results which makes it all the more strange to me.
RE: PETG Issues
how tight is your idler bolt in the extruder? I print both tpu and regular filament with the tip of the bolt flush with the nut right below the hex window. have you tried doing a cold pull to make sure you don't have a partial clog? also are you doing 7x7 mesh leveling for the bed.
RE: PETG Issues
Since I was having issues printing Prusament PETG, I tried the Extrusion Multiplier Calibration and found I had to adjust my extrusion by about 7%. It may be the issue.
RE: PETG Issues
7% is a fairly large change.. Did you do a few cold pulls to ensure nothing is plugged at all? What shape is your nozzle in? Is it still brass or was another material used? (as that may need tuning in the thermal profiles). I extrude some filament and then measure to ensure it is still close to the 0.4mm width (are you using a 0.4mm nozzle?).. Brass wears fast and sometimes the opening can get significantly larger when means time for a new nozzle (although this doesn't sound like your issue)
RE: PETG Issues
Nozzle is the original brass nozzle that came with the printer kit that I assembled in March of this year. Under 1Kg of PLA, a couple hundred grams of PETG, printed since assembly. Doubt that the nozzle is shot but I can change it. I ordered spares when I ordered the printer, could be defective. Did three cold pulls today from your suggestion. Nothing visible on any of the pulls, even with a magnifying glass, even on the first pull (don't forget to cut the ooze end off first 😊) . Did the two extra pulls for experience since I had things pulled apart. Will run another cube test later today to see if it made any changes. Will order some cleaning filament as well.
RE: PETG Issues
Not sure you need cleaning filament.. measure extrusion of plastic with caliper to see if close to 0.4mm..
RE: PETG Issues
I did measure each cube wall thickness and that is how I calculated the need to increase the extrusion by almost 7%. According to the documentation, in the knowledge base, the width is supposed to be 0.45mm with a 0.4mm nozzle. My first cube was 0.42mm average, my last cube was 44.67mm average (12 readings). I will be doing one more test once I get the Z calibration sorted out, which is a different thread. I also noticed that the walls had a much smoother finish to them, less layer lines and stepper ripples on the X axis.
Cleaning filament was pointed out by the person that pointed me to Prusa printers. He has many of them for work and says it is a lifesaver and part of his usual maintenance schedule.
RE: PETG Issues
Yeah.. I only have the one printer.. and don't use it nearly as much as he likely does.. so have had no need for cleaning filament.. cold pulls have done all cleaning I've needed so far. For testing extrusion I used the method where you mark the length of filament (can't remember how much.. maybe 100mm) and then you extrude exactly 100mm and see where your line is on the extruder top.. should be even.. Think this is mentioned somewhere on the web for calibration.. but the cube likely should work too.. just never used that method.
RE:
Sorry.. the 100mm length was to calibrate my esteps.. yes.. I did something similar for the extrusion ratio.. given in the knowledgebase of Prusa:
Extrusion Multiplier Calibration +7% might be within variation of nozzles.. I only have a sample of one. Mine has always been between .96 & 1.
Yeah.. I only have the one printer.. and don't use it nearly as much as he likely does.. so have had no need for cleaning filament.. cold pulls have done all cleaning I've needed so far. For testing extrusion I used the method where you mark the length of filament (can't remember how much.. maybe 100mm) and then you extrude exactly 100mm and see where your line is on the extruder top.. should be even.. Think this is mentioned somewhere on the web for calibration.. but the cube likely should work too.. just never used that method.
RE: PETG Issues
PETG has been a problem for me. I seem to get things working and then they fail again and not sure where things are wrong. An issue with Z calibration as I was trying visual as posted in the various guides and it lead me down a path of frustration. Finally tried to measure the printed first layer and found I was much to high while visually part of the print looked perfect. This was with one of the easy Live Z calibration models from Printables. Once I got that working, then I started to print some stuff that didn't have much issue since they were basic designs with no overhangs or slopes.
Feeling comfortable, tried the next level that had angles and needed supports. Other than issues getting the supports off, still worked. Ended up with a clogged nozzle that caused the extruder to grind the filament to pieces preventing it from being pulled out from the back or fed through to hot end with no nozzle fitted. This is where I was glad that I had purchased a kit. I knew how things went together. Also had a couple of spare nozzles. Think it was dust causing an issue since I had only done a cold pull a short while ago.
So, yesterday, feeling that I was getting good success, tried to print the hinge and fittings for my enclosure lid with the downloaded gcode. Most of it looks good except for two areas. In the hinge where the support was, the inside above the support is all distorted. And on the handle, the outer layer on the slope is separated from the rest of the print. Tried a bridge test and all the bottom layers are drooping/sagging, even at 10 mm gap. Strands not joined at 40mm gap. Print fan is spinning.
I am thinking that 27% RH is still causing issues with the filament will will attempt to dry. Printing in an enclosure, not sure if the 25+ degree ambient temp is causing any issues. Hope not, since it only going to get hotter in the next few days.
RE: PETG Issues
Perhaps heat creep from the enclosure. The filament gets too warm and too soft and bendy already in the extruder. Check if the problem persists if you leave the doors open. PETG does not really need an enclosure. I think I had the same problem some time ago, but just with one type of filament, Prusament PETG orange, not with other Prusament PETG colors. The filament formed a loop inside the extruder and did not feed into the tube to the hotend.
RE: PETG Issues
I was thinking about temperature in the enclosure. As it stands, I am working with Prusament PETG orange now. I have been watching the temperature. It was about 30 during the last print. If that is too high, I have an issue since summer is almost here and 30 is quite normal if not higher in the workshop. I suspect I do have a temperature issue with something after my live z headaches but that is another test. Stuff is on order to have everything fed so it isn't exposed to dust and dirt which is a major issue where I live, it gets everywhere and into everything.
An enclosure is needed for dust but I am looking at filtered air flow through the enclosure for printing with PLA. I will give ASA a try this week as there are a couple of things I need done. It is looking like my print issues now are related to print fan speed and as I have read, needing a better fan shroud than what comes with the MK3s+. It may be my first full print attempt with ASA.
I am looking at different tests to run to learn more about troubleshooting and filament usage calibration. Lots of reading.
RE: PETG Issues
An update. Did a few prints with ASA after Z calibration and 40mmX40mm wall thickness/extrusion calibration (same satin sheet). Did a PETG print today and it was very nice. The only real difference is that I changed the print fan housing to get better cooling. It has also been dryer here. Even today, with rain, it was 30% in the workshop. PETG was stored with a large desiccant package for a week in the heat while I was busy doing other things.