Designing a simple photo frame. I wanted to make it so that it prints without supports. While printing, however, the back support part wobbles/vibrates with movement, and is printing terribly.
Ender 3v3 CoreXZ, PolyTerra matte black filament, using the CR-PLA Matte profile in Creality Print 7. Tried printing at slow speeds, the issue still persists.
I’ve tried making the back support with only 45 degree angles (previously it was an x diagonal), made it thicker (from 0.75mm to 1.5mm). Nothing is working. Please find the stl and 3mf here (https://www.thingiverse.com/thing:7281179).
Is this a printer issue, a model issue, or a slicer issue? Please advise. 
Since your printer moves the platform you’ll need to provide supports to avoid this. You can slightly mitigate by reducing speed. The supports don’t need to necessarily originate from the bottom, it could just provide a thin beam to resist wobbling in that particular direction.
I agree with the others suggesting splitting it into multiple pieces to avoid wobbling and improve the overhang issues at the same time.
I tried with 50% speed, and even silent option which is even slower. Still happened. May be a hexagonal pattern might work better. I just want to build a simple photo frame that one can print without supports, and one that uses minimal filament.