Problem: Printing a wind turbine with PETG fails
Hello Printing-Fans!
Since March '19 I'm owning a MK3S printer, which I love very much! 🙂 Did a lot of PLA prints, which was quiet easy...
But now, I'm trying to print a little windturbine, which I found on thingiverse: https://www.thingiverse.com/thing:3376181
Because it's going to be mounted outside, it's recommended to print it with PETG. So I bought some PETG material (Formfutura HD Glass Filament from filamentworld) in different colors, some is "see through" material, some not.
First I made some samples of a wing-part of the turbine in PLA, which worked really well (orange material).
Then I tried with PETG, but have much problems to get a good result. All objects have these strings in the upper part. Internet sais, this could be because of to high temperature. Recommended printing temperature is 195°-225° (although it's PETG). Tried many times with different settings of temperatur, printing speed, retract, supports, materials and slicer programms. I sliced it with Prusa Control, Prusa Slicer (v2.0.0), CURA 4 and the newest version of simplify3D (which I only bought because of this problems). I always used the recommended settings from formfutura and played with temp and speed.
This is not really the stringing which you have, when temp is too high and it is not as thin like a spider web. The wing of the turbine only consists of two lines (perimeter?), as you can see in the screenshot from Prusa Control Slicer. And of these two lines (in the inner circle) doesn't stick on the model, but gets spanned straight over the printed circle. It's really missing in the wall, so thats why I thing, it's not a stringing problem.
Best settings to prevent the extreme "stringing" seems to lower the temperature, tried it once with 195° and the result was OK, but not really good. But low termperature seems so cause instability in the hole model: It cracks very easy when I bend it a bit, and the wall-part of the model can break very easy from the base element. The layers are not connected good enough. If I print with 230-250°, the stability is much higher, but the stinging-effect makes the object unusable..
I hope you can help me to get it printed in a good quality, I don't have new ideas anymore...
If you need more information or detailed fotos, please tell me.
Thank you very much for helping!
Greetz,
Chris
RE: Problem: Printing a wind turbine with PETG fails
You're right, that's not a "stringing" problem. That's a problem where the trace is not adhering to the layer below it, but is pulling away due to the radius of curvature. You need to find a way to make the problem layers stick better to the layers below them. There are several possibilities (although I can't say I've studied this problem in detail, so these are suggestions based on logic, not experimentally proven)
1) Try thinner layers. If you're at 0.25mm, try 0.2mm.
2) Try adjusting the width of your extruded trace, probably making it just a bit wider.
3) Try reducing or turning off your print fan speed. PETG doesn't need print cooling the way that PLA does
4) Try the options for "print perimeters before infill" (on or off)
5) Try printing at a lower (or maybe higher) speed
6) Try increasing (or maybe decreasing) your Extrusion Multiplier a bit.
7) Probably printing at the upper end of the recommended temperature range will help.
If you discover a "magic trick" that makes it work, please share with the community! 😎
RE: Problem: Printing a wind turbine with PETG fails
Try enabling Detect Thin Walls ... slicers tend to fail on parts with thin walled surfaces unless they know to expect them. And the fails create some rather bizarre and unexpected results, including quasi-random wipes in free air.
To relieve some of the stresses of starting new layers, change seam position to rear so the nozzle starts in the middle of the part rather than at a corner; this should give a bit better bite for the filament.
After reading up on the filament page - the material more PLA than PETG and I'd use the Generic or Prusa PLA profile rather than anything PETG related. And they also recommend a tad higher flow rate: 110% ...
RE: Problem: Printing a wind turbine with PETG fails
Thanks for your help!
Just "finished" two more wings. After printing most of the recent objects in 0.2 or 0.15mm layer height, I tried now the 0.05mm height. Because the print in general was rather bad, I decided to stop it. Here's the result:
Printed with 205°C, 0,05mm layerheight, no cooling, 30mm/s contours, 20mm/s outer contours. The wall itself is very stable and doesn't crack, so thats fine. But the wing-end, where the nozzle starts the layer gets rather thick and unexact.
Next print is with 0.1mm layer height, 205°C, automatic printingspeed, and 80% of automatic speed for outer contours. Also no cooling. This is the badest result so far. Automatic speed means "really fast" 😉
Very strong stringing and very poor surface as you can see. But I'm going to print some more versions...
One thing: The second print crashed in the last layer, many layers before, the nozzle crashed again the "drops" from the wing end and moved the thin wall to the side, every time. This I also could see in other prints, so maybe it's very important to optimize the print of the wing end.
Chris
RE: Problem: Printing a wind turbine with PETG fails
Ok, I'll try that. Thanks!
RE: Problem: Printing a wind turbine with PETG fails
Those last pictures generally look like over-extrusion.
RE: Problem: Printing a wind turbine with PETG fails
but I didn't change that parameter... I think it has more to do with the speed.
PLA worked so great... why is this so hard? 😉
RE: Problem: Printing a wind turbine with PETG fails
So....
Over the night, i choosed to print the exact same g-code as the PLA-objects had. This was sliced with PrusaControl with Prusa PLA Settings. Changed the temp. on the run to 205°C, the Flow to 110%, the Headbed to 75°C. Most of the print seems rather good, nice shiny glossy surface of the wall, almost perfect edges, the stability is good, but where the "grooves" where printed, the stability gets worse. Also, again the problem with the stringing in the upper part. So, all in all, this print might be best so far, but still not acceptable 😉
So now trying to get rid of these grooves and stringing...
Any Ideas with which parameters this gets better? Do you unterstand these little offsets? I mean, why is the surface not smooth and has the grooves in it?
Chris
RE: Problem: Printing a wind turbine with PETG fails
Good news everyone,
two hours ago, my order from PRUSA arrived, after more than three long weeks of waiting. So mounted the new spool with original PRUSA PETG in blue transparent. First, to make it easy, I sliced a new wing with PrusaControl and Prusa PET settings:
What should I say - PERFECT! 🙂 Very stable, almost no stringing, no lay-sticking problems in the upper part, very transparent, shiny, smooth.
I'm really happy right now after at least 20 failed tries. So I will think about, what to to with the other PETG I have, maybe for thicker objects. Hopefully PRUSA does something
Thanks all for helping! And if one of YOU got the perfect idea, how to handle with the HD Glass, pls tell the world (am me) 😉
Chris
RE: Problem: Printing a wind turbine with PETG fails
Congratulations.
As a note, I think I read PrusaControl is deprecated, and no longer supported. You might want to invest time in learning PrusaSlicer.