Help me dial this PETG in...

[WobblyHand]

Loosened the X belt a little. Y looked ok. Changed the fan settings. I'll give it another go. At least this is a test piece, the real box is an 8 hour print. I can flub up a few test prints and not mind it.

 

[WobblyHand]

Didn't help that much. There was some improvement, the line at Z=29mm is gone, but there are a lot of nurbs, or nubbins. You can see some sort of dark contaminant in the filament. Looks almost like swarf. Strange, this is Prusament PETG ordered direct from Prusa.

Should be ready to remove from the plate now. So far, this is not a good surface finish. Hope when I pull the supports the inside of the pockets look better than before.

 

[brino]

This page is usually my first stop to help diagnose printing problems:
https://www.simplify3d.com/support/print-quality-troubleshooting/

click on an issue and you get more detailed info.
Here's the page for "Blobs and Zits":
https://www.simplify3d.com/support/print-quality-troubleshooting/blobs-and-zits/

Brian

EDIT: also, that "ghosting" might be oscillations/ringing. The machine may have some vibrations due to some fast heads moves around the pockets.
You might try slowing down the print.
https://www.simplify3d.com/support/print-quality-troubleshooting/vibrations-and-ringing/

 

[WobblyHand]

This page is usually my first stop to help diagnose printing problems:
https://www.simplify3d.com/support/print-quality-troubleshooting/

click on an issue and you get more detailed info.
Here's the page for "Blobs and Zits":
https://www.simplify3d.com/support/print-quality-troubleshooting/blobs-and-zits/

Brian

EDIT: also, that "ghosting" might be oscillations/ringing. The machine may have some vibrations due to some fast heads moves around the pockets.
You might try slowing down the print.
https://www.simplify3d.com/support/print-quality-troubleshooting/vibrations-and-ringing/

Thanks. I found that link. As a beginner I read that kind of material and then get sort of paralyzed when I look and see hundreds of parameters to fiddle with and realize only a couple of them might fix anything. And I don't know which parameters they might be. The worst part is when they refer to a particular parameter and you find nothing by that exact name. I'll eventually figure it out, but I'd imagine millions of hours have been wasted by beginners like myself trying to muddle their way through similar issues.

First thing I am going to try is to reduce the temperature by 5C. I see small burned bits in the print. Getting a couple in every red PETG print. The table that the printer is on is not that stable, so I will try moving the printer to a more stable platform. After that, err, don't know. Try a couple things, if I can figure out which parameter "is the fix".

 

[jwmelvin]

Printing the whole box should be a little better, I think because a small part like that doesn’t allow much time for one layer to cool before the next goes on. So then the fan runs but that doesn’t work as well as a larger part and no fan. When I print a little part I’ll sometimes print a few at once even if I only want one, to extend the layer print time. I’m sure there’s a way to pause between layers but haven’t looked into it. I try to get the slicer so that the fan won’t run for petg. Maybe just a little in certain parts.

 

[Flyinfool]

I just did a bunch of PETG parts this weekend. A little over 28 hours of print time. PETG is a lot more stringy than PLA. PETG can handle being outdoors but PLA can not. Other than that they have pretty similar mechanical properties. For indoor parts I use PLA, outdoor parts PETG. Or if there is a special color available in only one or the other. So far these are the only 2 materials I have used.
I do the initial layer at 240° and 80° and then drop the bed to 65° and the nozzle to 230°. once I got farther up the print when the print area was getting pretty small (meaning not much cooling time between layers) I dropped the print temp to 225°.
All temps from someone else may not be right for your machine. The design and calibration of the hot end will make the actual tip of the nozzle a different temp than what the thermocouple is reading farther up. My temps may not work best for you even if you are printing the same part with the same filament. The filament is very hydroscopic, you have to keep it dry, any moisture will make for big issues that all the adjusting in the world can not fix. I have even found that different colors of the same brand, bought at the same time want slightly different temps.
Poor mans dryer for filament that may have moisture, is to heat the bed to your normal print temp and lay the spool of filament on the table with a thick towel over it for a few hours to cook out the moisture. You need to store your filament in an airtight container with desiccant. Depending on your environment even a day or to exposed to moisture can be to much.

 

[great white]

Didn't help that much. There was some improvement, the line at Z=29mm is gone, but there are a lot of nurbs, or nubbins. You can see some sort of dark contaminant in the filament. Looks almost like swarf. Strange, this is Prusament PETG ordered direct from Prusa.
View attachment 427393
Should be ready to remove from the plate now. So far, this is not a good surface finish. Hope when I pull the supports the inside of the pockets look better than before.

In my limited experience, that makes it look like your flow rates aren’t calibrated.

Its easy enough to check.mark your filament at 100mm from the extruder. Call for 100mm of extrusion and see where the mark ends up. It should be right at the point where you measured your 100mm from. If its short or too far, theres a multiplier in the firmware that needs to be asjusted.

You can also get that effect when seams are set to “randomize”. fiddling with the retraction settings can often help with that.

 

[WobblyHand]

I read about the hydroscopic nature of PETG, but I didn't (from reading) think it was that bad. The filament was shipped in an evacuated airtight bag with a big pouch of silica gel. Then I opened the bag and tried printing. The dew point is pretty low here lately with temperatures in the teens, (Fahrenheit) so unless the filament was mishandled prior to me getting it, I would think it wasn't soggy.

I'm a bit surprised at how many minor changes can greatly affect the result. At the moment, after four tries, I have no prints of decent quality. The last print of the night I printed 5C lower temp and 30-50% fan, with no supports as an experiment and the surface quality is better, except in the region of the pockets. The whole horizontal band where the pockets are have more nurbs, a lot more. There is a ghost of the pocket on both sides of the pocket on every pocket. I also have some burnt crap at the top of one of the pockets. Carbonized filament. Might drop the temp a bit more. I will also uncheck randomize seams.

fiddling with the retraction settings can often help with that.

I see a section in Filament Overrides called retraction. Man, just finding that took a bit.
Current selection is 1mm length, and 0.2mm Lift Z. All the other options are unchecked, like Retraction speed. Any suggestions what to try?

 

[MikeWi]

Pretty much everyone has really good points. Tuning is the first thing you should do with any new filament. I'll add that PETG likes a little more height off the bed so that it's laid down more than squished like you would do the PLA. Also, if you have a Bowden style extruder, the retract amount will be way higher than if the extruder is direct drive. I found a recommendation to use a retract speed of 25 which actually works really well for me, but another thing that will prevent stringing is the travel speed (not the print speed). Moving to a new location quickly will snap the string instead of drawing it out. Also, too much fan will make it shrink and pull up at the corners, or even separate the layers. Too much heat can do the same thing, or to low a bed heat. So many things to consider.

 

[WobblyHand]

Pretty much everyone has really good points. Tuning is the first thing you should do with any new filament. I'll add that PETG likes a little more height off the bed so that it's laid down more than squished like you would do the PLA. Also, if you have a Bowden style extruder, the retract amount will be way higher than if the extruder is direct drive. I found a recommendation to use a retract speed of 25 which actually works really well for me, but another thing that will prevent stringing is the travel speed (not the print speed). Moving to a new location quickly will snap the string instead of drawing it out. Also, too much fan will make it shrink and pull up at the corners, or even separate the layers. Too much heat can do the same thing, or to low a bed heat. So many things to consider.

Is there anywhere where the fine points are written up? Like how to systematically converge on good settings? Hunting and pecking randomly doesn't seem efficient. From the perspective of a newbie I am hearing I need 100's of hours effing around, primarily since I know NOTHING about this stuff. I would have thought, naively, that using Prusa filament on a Prusa printer using default settings would get me in the ball park. Indeed, they aren't bad for the test piece laying flat. But for a short section of box wall, the settings are no good.

I have no idea what extruder I have. Newbie curse. Prusa i3 MK3S+.