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I am having an issue with printing a large part in PETG and am trying to figure out how to solve it.

I have been using PETG for a long time and generally have no problems with it.
But now I have to print some large part with high infill and am running into issues and I don’t have the time to spare to try too many optons.
Can’t see too much about the model, but it is basically a triangle with a narrow base and subsequently long point and open space in the middle.

Material used is black PETG from Colorfabb.

First problem was that the part started to develop cracks between the layers after about 30 hours of printing. Not at the bottom but about halfway up at the height the print had reached around that time (about 7 cm in height).

I was using 0.24 layer height, 230 printtemp, 58 bed temp, cooling fan at 50% after 6 layers.
Print is using 4 shells and 45% infill and a small 5mm brim around the bottom.

I figured the problem was too much cooling and too low a print temperature.

For the second print, I printed at 235, 60 bed temp and cooling down to 50%.
Things all seemed well, but after 45 hours, the part start warping slightly at the point again where it was pulled loosed from the printbed. Printing at 42 mm/s.

Again, in my opinion, too much cooling.
No I have started the print using a large raft around the part, same print temp, 62 bed and 40% cooling.

But if this print fails again (will now in a day probably), I’d like to get some opinions on people who have had the similar problems with large PETG print.
To give you an idea, after 45 hours, the print is at around 25% of total print time.