PETG question

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BaseMale
Posts: 1
Joined: Thu May 18, 2017 7:02 pm

PETG question

Post by BaseMale » Tue Jul 31, 2018 5:56 am

I decided to try out PETG over the weekend and basically spent the entire time playing around with settings to try to get the perfect print. Thanks to Jules guide , I had a good head start. I ran into a few problems though that I have yet to figure out. I was hoping somebody here would be able to identify where my prints are going wrong.

Note that I'm printing on an M2 with dual extruders using esun's solid grey PETG and slicing with S3D. I just upgraded to the dual so this filament is the only one that has been through this nozzle.

The first problem arose after printing the extrusion calibration cube. I was all set with a wall thickness of 0.45mm to match the extrusion width settings in S3D. From there, I printed the cube again, only this time with top/bottom layers, infill, and 3 perimeters. The two outer perimeters were only attached to the rest of the print at the corners. I found I had to drastically increase the extrusion width (from 0.86 to nearly 1.0) to start seeing the perimeters bond to the print. This doesn't sound like a good solution though. Any ideas?

The second problem can be seen in the picture below. I have small gaps in certain areas between layers. I've been playing around with print speeds, temperature, and cooling but I've had no luck. I'm wondering if this may be retraction related? Or a symptom of only having a single perimeter?

Cubes.jpg

airscapes
Posts: 261
Joined: Wed Jan 31, 2018 11:36 pm

Re: PETG question

Post by airscapes » Tue Jul 31, 2018 2:59 pm

Starting height is key, that old list of settings says to air print it.. NO, calibrate your nozzle with the a single walled square so the starting height is correct.. a 2mm tall wall should be 2mm when printed. I can post the method of altering the z offset in the firmware (really easy) if you are not already familiar with it. PETG needs no cooling.. turn off the fan if you are using it.
I have linked to a factory file for some hold downs I made for my garden, I am using the .35 nozzle and eSun white PETG on the M2 with S3D so should work for you. EM may need to be tweaked by .1+- assuming your filament diameter is the same as mine..

Another thing to look at is your filament tension.. the PET is harder than PLA. Extract the PETG and examine the marks the extruder gear made with a loop or magnifying glass.. PETG need a bit more tension than say Makergear PLA. If MG PLA is set correctly another 1/8 tighter for PETG..

http://misc.airscapesart.com/8_PETG_3.5 ... ap.factory

And here are a bunch of single walled cal squares, all 2mm tall each with a different wall thickness for different nozzle sizes
http://misc.airscapesart.com/cal_squares/index.html

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