First foray into PETG . . . some questions

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Hugs
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Joined: Tue Mar 08, 2016 11:16 pm
Location: Pennsylvania

First foray into PETG . . . some questions

Post by Hugs » Tue May 17, 2016 10:33 pm

Just started my first spool of PETG (eSun Solid Black).

I've done my best to take Jules' excellent post on eSun Solid Black PETG and translate the S3D settings to Slic3r.

Overall, I'm pleased with my first real print after the calibration iterations. Questions:
  1. I understand the oozy/sticky remark now. It seems like I had to babysit this first print and keep an eye out for cling-ons, periodically removing some cruft with tweezers. Theoretically, should I get to a point where I can just let the print go?
  2. The nozzle gets noticeably dirtier than PLA. Is that normal? Here's a mid-print pic I took (sorry for the poor quality...I used a macro lens with the head in motion and the focus was a bit off)
    dirty_nozzle.jpg
  3. Here's a RaspberryPi case from Thingiverse I printed nicely in MG white PLA vs the eSun (I realize the contrast on the PLA makes it difficult to see the layers). Dimensionally, it fits the Pi nicely just like the PLA print (and I understand for dimensional stability, you really can't beat PLA). Any tips to help with the cleanliness?
    PLA-vs-PETG-1.jpg
    PLA-vs-PETG-2.jpg

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Matt_Sharkey
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Re: First foray into PETG . . . some questions

Post by Matt_Sharkey » Tue May 17, 2016 10:42 pm

get those settings dialed in man...

I run 40mm/s on all types of lines. 10mm/s first layer, 20mm/s bridging.

250C for black, with fan on always (excepting the first layer)
If you want a structural part, up the temp to 255 or turn off the fan (forget about print quality, it will string like a mother)

I have found that coarse resolution works pretty damn good:
0.3mm layer height on all.
0.6mm layer width on all.

Get your multiplier dialed in, then drop it a percentage point.
get your layer height dialed in then raise it 0.01mm

90-100C on the bed with purple glue stick will get you the adhesion you need. I don't fiddle with the bed temp excessively, just give it 100C and forget it.

these considerations have netted me some good results that I have pretty much "Set and Forget." I always watch the first layer to ensure its goes down smooth, you can tell by the first line, it will want to stick to the nozzle more than the bed.

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Jules
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Re: First foray into PETG . . . some questions

Post by Jules » Tue May 17, 2016 11:23 pm

The nozzle gets noticeably dirtier than PLA. Is that normal?
Yes, it does. That's the stickiness - and anything that cooks onto the nozzle can fall off as little carbonized bits later in your print. (Won't see it on the black of course, but it's a problem when printing the lighter colors.) I take the time to catch the initial purge to make sure that it doesn't get all wrapped up on the sides of the nozzle, and i'll sometimes carefully reach in with the tweezers and clean off a bit of gunk.

With PETG, you always want to clean off the nozzle after you finish printing (with the tweezers, while it cools) or you will be seeing the bits of it show up in your next print.

Matt's right - with PETG it's all about dialing in the settings correctly, and going a little bit underextruding. Make the gap .01 mm less than what you test it to be with the calibration square. Reduce your extrusion multiplier by a little bit. Put a jump on the travel movements to keep from scraping it.

But also.....don't expect it to look like PLA. It's shinier, and in the opaque PETGs you will sometimes see marks in it from the travel movements. That's just the nature of PETG. (I prefer PLA for parts that don't require structural strength....it has a nicer finish on flat surfaces. PETG looks better on the sides if it's dialed in correctly, but you can always see a "texture" on flat surfaces when the light hits it.)

Oh, also be sure you adjusted your Filament Drive Screw tension for the PETG, it's a little bit different than PLA.

Your print doesn't look bad at all....I don't see a lot of stringing. (Heck of a lot better than my first shot at it!) :lol:

Hugs
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Joined: Tue Mar 08, 2016 11:16 pm
Location: Pennsylvania

Re: First foray into PETG . . . some questions

Post by Hugs » Wed May 18, 2016 12:53 am

Matt_Sharkey wrote:get those settings dialed in man...
Working on it :)
Matt_Sharkey wrote:(forget about print quality, it will string like a mother)
Yep...no worries there. My primary reason for PETG right now is for durability. I'm not worried about how it looks...I just want to dial in a durable filament that can stand up to heat and won't deteriorate in moderate humidity.

Hugs
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Joined: Tue Mar 08, 2016 11:16 pm
Location: Pennsylvania

Re: First foray into PETG . . . some questions

Post by Hugs » Wed May 18, 2016 1:07 am

Jules wrote:I take the time to catch the initial purge to make sure that it doesn't get all wrapped up on the sides of the nozzle, and i'll sometimes carefully reach in with the tweezers and clean off a bit of gunk.
That's been my method from the start...I always catch the purge regardless of filament. I have some "non-linting" wipes that I use as well to make sure the nozzle is as clean as it can be before the skirt starts.
Jules wrote:Matt's right - with PETG it's all about dialing in the settings correctly, and going a little bit underextruding
I think the underextruding bit is where I have to tweak. From his post above, it seems like not only a mix of underextruding but over-doing the height:width extrusion ratio compared to what I'm used to.
Jules wrote:But also.....don't expect it to look like PLA.
I've already prepared myself for that. My primary reason for delving into PETG is for replacement M2 parts. I'm not worried if they're pretty...I just want them to not melt :).
Jules wrote:Oh, also be sure you adjusted your Filament Drive Screw tension for the PETG, it's a little bit different than PLA.
Yep...already done thanks to the great pics in the Rev. E getting started guide :).
Jules wrote:Your print doesn't look bad at all....I don't see a lot of stringing. (Heck of a lot better than my first shot at it!) :lol:
Thanks!. I'm overall pleased with it. Functionally it's just what I needed. Aesthetically, looking for pointers from you guys and gals :)

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