peterbill
Posts: 1
Joined: Tue May 14, 2019 10:07 pm

New to PETG - extrusion stops mid print.

Tue May 14, 2019 10:11 pm

Thanks in advance for any help you may have to offer. As the story goes for most - I am having great success printing in PLA, and wanted to try my hand at PETG printing.

I've spent hours tweaking my profile in S3D; getting temps, extrusion multiplier and retraction settings dialed in, z-offset calibrated, etc. The first few layers are printing great, but after about an hour into the print - the extruder seems to stop, and I start getting 'air prints'. When I reheat the tool, I can push material through the nozzle, so I don't think it's clogged...

My gut tells me that the filament may be getting stripped; perhaps too much retraction distance\speed (6.5mm @ 30mm\s), and\or filament diameter changes (or is dirty). I also read that too many retractions in a short period can cause stripping - so I enabled the length threshold in S3D\Advanced tab.

I am using a CR-10, and eSun PETG filament. I am new enough to this hobby, that I have not paid attention to measuring filament diameter much, but several random readings with my calipers show 1.70-1.72 diameter... is this the problem? (Any recommendations on PETG suppliers? I read good things about eSun, but this is my first spool. All my PLA was Hatchbox).

I have updated my slicer profile and am running the print again, but would like to prepared with other ideas if this doesn't so the trick.

What are the other obvious solution to try? What other settings in S3D should I pay attention to?

Also, I recently changed my bowden tube to Capricorn xs. The install went as I would have expected - it felt solid and snapped into place. What would I look for to see if there are any issues on that part?

Thanks in advance,

greybeard
Posts: 145
Joined: Mon Mar 02, 2015 1:23 pm

Re: New to PETG - extrusion stops mid print.

Wed May 15, 2019 11:12 am

I posted my PETG settings (viewtopic.php?f=8&t=7353) - they work absolutely great on my two machines. Perhaps you downloaded it? If not, try it out (extract the settings).

I use 'Sun' petg.

Regarding the stopping…

If you’re using my file, it may include a script to pause at a specific layer height (I don’t remember if I deleted it before posting) - simply delete it from the ‘Post Processing’ field: if it’s there, it will look like the image below. (You could also press the Button on your machine to continue the print or, add Semi-colons to make them Coimments).

If the filament has simply stopped feeding, consider this:

1) The feed-gear may be stripping filament. Therefore, adjust the tension on the feed-gear.

2) Heat may be transferring upwards to the region around the feed-gear, causing filament to soften and strip (that was the case for one of my machines!)

- Here’s that scoop (for my machines): I replaced both hot-ends with V6. But, they are different hardware - One has a Metal feed-tube, the other has a PTFE feed-tube.

3) PETG requires higher heat and that melted the lower section of the hot-end with PTFE, causing binding.
I replaced the PTFE with Metal and no more problems with PETG.

4) Because of the Higher heat, Filament and PTFE may be oozing out between the Top of the Nozzle and the Bottom of the Tube, causing the bind and/or oozing. (That interface should be securely tight without a gap)...
Attachments
Screen Shot 2019-05-15 at 8.47.27 AM.png
3D Print Parts
https://www.thingiverse.com/Still_Breathing/designs

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