Sphere Test for stringing and sagging issues

Recently, I had issues printing spheres and threaded rods with my A1, so I designed this model to understand the cause.

This is a hollow spherical shell printed in PLA, designed to test overhang performance, surface quality, and bed adhesion. The model has a circular top opening and a small flat base, making it a good benchmark for tuning print settings.

Long story short: I ended up reducing the print speed and replacing the original nozzle, which had over 450 hours of use.

🛠️ Comparison: Before vs After

These photos show the dramatic improvement achieved.

🔴 Top View – Before:
The print shows severe bridging issues and messy overhangs at the top opening. The inner walls are sagging, and stringing is visible.

🟢 Top View – After:
The same model results in a clean and well-defined top opening. The overhangs are handled properly, with no drooping or stringing.

🔴 Bottom View – Before:
The base of the print shows signs of poor bed adhesion — material has bunched up and partially detached from the build plate.

🟢 Bottom View – After:
The base adheres perfectly. A proper brim or skirt ensures a solid foundation and clean finish.

Hope this helps!