So the last week I have been busy, trying to adjust the settings for the PrimaSelect PETG. The filament I am going to use for printing the prototype. So this morning I started a print for the first part for Valify, I was printing on a raft because of the support structures. Some hours later I saw that one corner of the part has once again lifted from the raft. Making this a failed print. But on the other hand, I had the chance to feel and squeeze on a partly printed part made from the PrimaSelect PETG filament. And I have to say I like it. it feels rock solid. But still there is some flexibility that can absorb shocks and thats great.

So this time I got tired of using rafts, so I redesign the part trying to minimize 90 degrees overhangs and making the need of support less.
Old part: Estimated time from Ideamaker was around 55H and consumption 750g filament. 3Layers and 30% infill
New part: Estimated time from Ideamaker was around 45H and consumption 550g filament. 3layers and 25% infill
For the redesigned part I do not actually need to use any support structure. Which are great, because they can be frustrated to work with and happily leaves marks on the surfaces. I also save money and time on the new part. So this was actually a real success!


So late tonight I started the print again. This time printing without raft and a heat bed temperature at 100C (actual temp is around 72C) The build Surface I went with at the end is the PEI Ultem sheet, because I got it working well on this and did not bother to change anymore.
Update: After 5h the part started lifting from one corner. Making me cancel the print. Lets try to add a brim and start it again.
This morning I restarted the print with a brim. Flow rate changed to 115% on first 2 layers then go down to 105% to minimize stringing and nozzle oozing. I also changed the heat bed to 95C. I also redesign the sharp corners on the model to use a radius of 10mm. I read this could release tensions from sharp edges. I am 4.5 hours into the job and so far everything looks good.


Printing for 12Hours now and it still looks good (crossing my fingers).


Damn. I found this when I woke up this morning. Layers had shifted quite a lot. This print seems not willing to coporatate. Every time I try to print it a new problem Ariases. Quite frustrated. print is again aborted.
So attempt to print with only 7h left on the 44h print I spotted two small cracks on the body (only on the outer shell).

As I stated before, when I solve one problem, another problem arises.
Reading around the internet I found a lot of different answers on warping and cracking.
So to sum up the things I found:
Lifting/warping:
-Reduce infill to 10-15%? Prevent internal stresses within the model.
-Shells, No more then 2-3 shells. More material that attempting to shrink inward.
-High temperature for heat bed, causing the lower levels to not be able to cool.
Cracking:
-Airflow, print shielded from breezes (I print without the top cover?)
-Filament temperature, lower temperatures results in weaker layer bond. I am printing 225C, Filamented is rated at at 190-230C.
So what do you guys recommend to test for the next big print? I have no problems running small things like calibrations cubes etc. This problem occurs with large and high objects.
btw: I will let this print finish.
I Love PETG, I make my own with Filastruder.
You might be able to spray it with UV paint for protection…
You should not need raft or a connected brim for PETG, perhaps you are not starting low enough, I get great prints on glass, 80C and ~230C at the hotend.
On a clean glass bed, coat with cheat hairspray, then Elmers purple gluestick where the part is to be printed.
-The then fix the glass print bed by scraping with a razor blade and spray glass with water to “reset” all the glue and spray for next part, again, use fresh glue stick for next part.
Printbed glass can be cheap hardware store glass, does not need to be Borosillic/Pyrex
Thanks for the advice Rich. Can´t I simply flip the PEI plate and print on the glass? Should I use Hairspray first and then PrintaFix? This is the product I have at home : https://www.3dprima.com/se/tillbehoer/buildtak/printafix-basic/a-22181/
Good question, I dont have any experience with PEI.
Keep the build plate hot, dont drop from 80C after first layer, dont use cooling fans. unless your part is tiny, like the size of a coin.