gorf26
Posts: 30
Joined: Fri Aug 25, 2017 12:19 pm

PETG question and help

I have been trying to print a part in PETG, the print looks good. nice finish and all..
But seems like it always has a weak spot one corner always breaks off, i though PETG was suppose to be a little flexible and tough.
Printed 3 parts all the same results..

I printed the part in ABS and PLA and both where fine..

Any thoughts.

Thanks gary
zemlin
Posts: 431
Joined: Mon Feb 01, 2016 11:36 am

Re: PETG question and help

Not all PETG materials are created equal. Who's PETG are you running? Temperatures also matter a lot. Different brands of PETG achieve optimal strength at different temperatures.

I've had good luck with eSun, Hatchbox, and MG Chemical filaments. Hatchbox is my favorite PETG, but they have supply chain issues so it's not always available. eSun is my second pick.

I run eSun at 240-250 - Sometimes hotter of I'm running clear and want better clarity - then I'm usually at 260. Hatchbox usually at 245-255.

I tried Sunlu and found it to be brittle, and the print temperatures were low - around 210.

PETG can sometimes pose issues with perimeter bonding - need to balance the extrusion multiplier with getting a clean print vs getting good perimeter bonds.
gorf26
Posts: 30
Joined: Fri Aug 25, 2017 12:19 pm

Re: PETG question and help

i am using esun have tested from 240 to 250, it looks like the print is good i don't see any separation or space between layers i will post a pic of the broken part.. have to get the camera out..

Thanks gary
richardrenaudo
Posts: 1
Joined: Tue Aug 11, 2020 4:50 am

Re: PETG question and help

I've been running Overture PETG at 237c nozzle, 80c bed, @ 50mm/sec with success.
gorf26
Posts: 30
Joined: Fri Aug 25, 2017 12:19 pm

Re: PETG question and help

Finally got a pic looked better to my eye than a photo.

The bottom breaks off every time.. any suggestions?
testPETG.zip
(2.48 MiB) Downloaded 167 times
Thanks gary
zemlin
Posts: 431
Joined: Mon Feb 01, 2016 11:36 am

Re: PETG question and help

Is that part broken, or intact? What does the bottom do? How is the part loaded that's causing the failure? Black is hard to photography - just attaching the STL file might be just as helpful. I'm wondering if your print orientation is the best choice. Can you print it as you show it lying on the table in the photo?
gorf26
Posts: 30
Joined: Fri Aug 25, 2017 12:19 pm

Re: PETG question and help

I attached the stl..

Its for a printer i am working on and it is sorta L shaped and the extrusions slide in both ends.
I printed it standing up so it only needs supports in the bottom extrusion slot, i have redrawn it now to make the walls a little thicker, haven't tried printing the newer version, but like i said had no problem with pla just after using for a while the top for holding the round shaft cracked in pla...

Thanks gary
Attachments
ZtopRight.zip
(86.03 KiB) Downloaded 122 times
zemlin
Posts: 431
Joined: Mon Feb 01, 2016 11:36 am

Re: PETG question and help

When I saw your photo, I thought you had a super thin web that was breaking off, but this part has some mass to it. it should be a good, strong part in PETG.

Can you share your factory file so I can see all your print parameters. The build on top of the support looks VERY loose, so I'm inclined to think you aren't getting good layer bond strength. Are your shells/perimeters bonding together, or can you peel material off like onion skin? That would be an indication of underextrusion.
gorf26
Posts: 30
Joined: Fri Aug 25, 2017 12:19 pm

Re: PETG question and help

Everything seems solid can't peel anything off don't see any separation all the way up, my thought is something to do with supports...
where it seems to break is a support area, in the bottom extrusion slot and it is the only section that has supports.

I tried it without any support but it's about a 20mm span and it sags, so i had to use the supports there..

I also just ordered a 0.6 tip hoping the 0.6 will do better than the 0.4 for petg...

I will post my profile later...

Thanks gary
gorf26
Posts: 30
Joined: Fri Aug 25, 2017 12:19 pm

Re: PETG question and help

just an update, i got some real good prints now with petg, but ended up using kisslicer the finish was 60% or more better, and i ended up drawing my own supports in the model and turning supports off in the slicer they came off real easy and no part breakage...

Gary

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