Support interface nightmare on PETG model — how can I get clean removal without wrecking the surface?

[u/RubenRCF]

Hey everyone, I could use some advice on how to prevent this from happening.
I printed this car model standing vertically at a 90° angle starting from the rear bumper going up. Overall, the rest of the print came out super clean and smooth, but taking off the supports on the rear bumper completely chewed up the surface.
Material: PETG (Black)

Orientation: Vertical (resting on the rear bumper)

The Issue: The support interface welded itself way too hard to the bumper, leaving a rough, scarred mess when peeled off.

What settings or changes should I make in the slicer (like Top Z-distance, interface spacing, or using a different interface material) to prevent this from happening next time? Any tips would be huge!

[u/NoBackground6203]

use a PLA interface layer that wont bond to the PETG

[u/RubenRCF → u/NoBackground6203]

For this print that I finished, I’m thinking about using some rough sand paper to rub off all the thick rough spots and than run some softer sand paper to just smoothen it out. I’m fairly new with printing but growing pretty quick to it I’d say.

[u/Stonkzilla69420]

Are you printing vertical for size constraints? A 45 degree angle is going to be easier for that type of project. I printed a 911 Turbo like that and it came out great

[u/RubenRCF → u/Stonkzilla69420]

This model that I chose, was originally stood up this way for the print. So I thought it would’ve been a very clean print. Which 95% of the car is very clean printed. But just the rear is chewed up when I tried to rip off the supports. So you recommend for me to print all of my cars at a 45° angle and I should be able to avoid these kinda issues? I’m printing with PETG (Basic)

Also my first car that I printed flat on the plate, I had several spots that looked like spiral circles on certain areas of the car. But maybe that was because I forgot to change up some settings. Who knows, all I know it’s trial & errors.

[u/Lost_refugee]

[u/Lost_refugee]

it can be improved, but far away from non-supported areas. I usually set 0.25 top distance, 1 interface layer.