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Continued issues with PETG...  

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starrtech2000
(@starrtech2000)
New Member
Continued issues with PETG...

MK3S+

Filament: Hatchbox PETG

I had PLA totally dialed in with great prints and now I'm trying to use PETG and struggling.

Got a textured plate that was recommended. Printed a temp tower and the 230c looks the cleanest in the bridge section but the stringing is crap in the tower. 

Using Generic PETG preset in PrusaSlicer

filament is brand new. Put it in my PolyBox drying box a few days ago.

No enclosure

During preheat and about halfway through a benchy print, the filament start curling up onto the nozzle until it creates a glob and then fails.

Tried iteratively increasing retraction length from default of .8 all the way up to 3mm with no improvements

Tried iteratively increasing retraction speed from default of 35 to 60 and than down to 20 with no improvements.

Tried 220c, 230, 240 nozzle temps...

Going crazy!

I've read some things about increasing print speed but the Speed section of prusaslicer has 10 possible speed settings and I don't know which ones to try changing or by how much...

Respondido : 05/11/2022 10:46 pm
RandyM9
(@randym9)
Honorable Member
RE: Continued issues with PETG...

I’ve never printed with the Hatchbox brand but I have printed a fair amount of PETG.

In general, I find slowing down the print, not speeding it up, can help a lot with certain filaments and certain models, particularly on the first layer.

Before doing anything, I would reset everything in PrusaSlicer to default settings for generic PETG, with the possible exception of changing the filament and bed temperatures to known good values. I will typically start with a bed temp of 80 for the first layer, 90 for subsequent layers. Nozzle temps can vary a lot by filament brand and color within a given brand. I tend to put the first layer down hotter than the following layers; say 235/225, as an example. Your temps will, of course, be different than mine.

It goes without saying that your print sheet needs to be clean, your filament needs to be dry, and your first layer Z setting has to be dead-on. If you have any questions about any of these requirements, just ask, or search the forums.

Also, be sure your nozzle and heat block are clean and not caked with burnt plastic or residual gunk. Clean the nozzle at print temps using a nylon brush or scotch-brite pad. A brass brush can be used but with great care not to touch anything but the nozzle and bottom of the heat block. If you touch one of the wires to the heater cartridge or thermistor you can cause an electrical short and bad things will happen.

The simplest way to adjust the print speed is with the rotary dial and the LCD menus. Once the print starts, find the ‘Tune’ menu via the scroll wheel and click on ‘Speed.’ The display should read 100% and by rotating the dial anti-clockwise you can reduce the speed to any percentage you like. Dialing clockwise will increase the speed above 100% but let’s not go there for now. I would start at 50% for the first layer of a print that’s giving you trouble.

Watch closely as the first layer is printed to see if any of the curling or sticking you’ve observed is happening. If so, stop the print via the LCD menus and try to understand the reason for the error. 

If the first layer goes down properly, leave the speed alone and continue with the second layer. If that also prints well, use the menu and dial to increase the speed to 65-70% and watch the next layer. Let a few layers print successfully before adjusting the speed any higher, then increase it in 10% increments, letting a few layers print before moving higher again. At some point, you’ll either get all the way to 100%, or you’ll have a failure and then you’ll know how fast you can print that filament at that temperature.

Once you get an idea of how fast you can print, you can make the speed adjustments in PrusaSlicer to simplify the process going forward. Using the LCD to adjust speed slows down everything, including travel moves, so it will print agonizingly slow while you’re going through the process. In PS you can tweak a variety of speeds individually, as you’ve observed.

I’m not at my computer so I don’t have access to PrusaSlicer to review the settings at the moment. But hopefully I’ve provided some useful information to get you started in the right direction for now. Once you start to see some positive results, we can move on to next steps.

Cheers

Respondido : 07/11/2022 5:31 am
starrtech2000 me gusta
jsw
 jsw
(@jsw)
Famed Member
RE: Continued issues with PETG...

Hatchbox is my go-to filament brand when I can get it in the color and type I need.

I've done countless prints with Hatchbox PETg on both the smooth and textured build plates.  I use the default 'Generic PETg' profile in PS with basically everything else set to default.  I've had consistently good PETg prints with Hatchbox and various other brands.

PETg is, by nature, more oozy and stringy than PLA or ABS, but the stringing and oozing should not be to the point that it spoils prints.  It most definitely should not ball up on the nozzle and/or drip on the print.  I am in the habit of gently brushing off the nozzle before beginning a print, in order to remove the 'worm' that has oozed out.

I'll almost always use Layerneer with PETg, mainly as a release agent.  If anything, it sticks a bit too well to the build plates.

I agree that the first thing to try is to set everything back to defaults and troubleshoot from there.  I've very seldom found a need to adjust anything from the defaults.

If I get stringing that's more than I expect, the first thing I suspect is damp filament.  If you can hear clicking and popping sounds from the nozzle area as the print is progressing, this is a sure sign of damp filament as well.  Overnight in the air fryer at 120F/49C will cure it in 9 out of 8 cases.  😉

 

Respondido : 07/11/2022 7:05 am
starrtech2000
(@starrtech2000)
New Member
Topic starter answered:
RE: Continued issues with PETG...

Thank you for trying to help!  None of the basics y'all mentioned were able to fix my issue but here's what did: 

I got super inpatient at nothing having a positive effect and adjusted a few too many things at once... LOL. I set my extrusion multiplier to .98 (down from default of 1) AND adjusted all of the speed settings to 45mm/s because I can't find anything about WHICH speed settings to change when changing speed...

Finally got a pretty nice benchy with no blobs and very little stringing! Only imperfection really was a BIT of a droop in the upper window (bridging?).

Question is which of these speed settings should I modify to optimize my print times or do I just leave them all where they are at? I'm aftraid that one of them is going to screw up a bigger print and I won't know why...

Perimeters: 45

Small perimeters: 45

External perimeters: 45

Infill: 45

Solid infill: 45

Top solid infill: 40

Support material: 50

Support material interface: 80%

Bridges: 45

Gap fill: 40

Respondido : 07/11/2022 11:42 pm
Artur5
(@artur5)
Reputable Member
RE: Continued issues with PETG...

PS. default settings for 0.4 nozzles in quality mode are 25 mm/s for bridges, small or external perimeters and 80 mm/s for infill/solid infill.

You’re using 45mm/s for almost everything. It may work OK, but it’s not what Prusa recommends. 45mm/s for infills is very conservative while for bridges, and external or small perimeters it seems too fast.

Respondido : 08/11/2022 10:37 am
starrtech2000 me gusta
towlerg
(@towlerg)
Noble Member
RE: Continued issues with PETG...

In general, I find slowing down the print, not speeding it up, can help a lot with certain filaments

I don't own a Prusa but in my experience it's pretty hard to go too slow especially on the first layer.

Respondido : 09/11/2022 3:46 pm
RandyM9
(@randym9)
Honorable Member
RE: Continued issues with PETG...

True enough!

There’s a popular flexible mini octopus model on Printables that has a bunch of tiny little  dots and blobs of filament in the first layer. At the default size there was no printing that at full speed with many different PETG flavors I tried. Once it was slowed to about 50% speed for the first layer it printed as expected.

Of course, everyone’s experience will be slightly different…

Cheers

Respondido : 09/11/2022 8:17 pm
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