Original Spiral Christmas Balls

Update

I've sliced both balls and successfully printed them using PrusaSlicer and my Prusa MK3S+. I printed the versions with built in supports and used Paint-on Supports to add Organic supports to the base and the inner dome. The Organic supports added about an hour to each print since the last time I printed them, but the results are great. I've shared my 3MF and GCODE files as well as photos of the new prints. The supports are a bit delicate. If they break during printing, you could erase the supports in the dome or add more supports to make them stronger.

I was surprised to find in PrusaSlicer that the Classic Perimeter Generator works much better for these two models than Arachne (the default that most people probably never change).

Summary

These are a quick, fun, and are very lightweight. Each ball has the same cross-section and twist. The main differences are the size and number of arms.

• Large ball: 80mm diameter, weighs about 14g, takes about 7 hours to print
• Small ball: 56mm diameter, weighs about 8g, takes about 4.5 hours to print

I designed these using Affinity Designer (for cross-sections), Blender (3D modeling), and Fusion 360 (combining the meshes).

The arms need support at multiple points to keep from warping and breaking if you're using an FDM printer. To make this quick and easy, I provided a version of each ornament with built-in supports. I still had Cura add supports, but only where the balls touch the build plate. 

Print Settings for PrusaSlicer

I recommend you download my 3MF files and work from them. I used Height Range Modifiers to strengthen the print where it needed it via increased perimeters, infill, and Top/Bottom. Everywhere else, there is no infill, 1 perimenter, and minimal Top/Bottom. 

Print Settings for Cura

Basics

• Layer Thickness: 0.15mm
• Walls: 0.4mm (1 line)
• Top/Bottom thickness: 0.45mm (3 layers)
• Build Plate Adhesion: Brim

If you have holes in your print (from the thin walls), I recommend increasing flow, print temperature or adjusting your seams. You might also decrease print speed and travel speed (I use 30mm/second and 80mm/second).

Infill

Infill is optional. They should print OK without it, but I added some just at the bottom of each ball. I used Cura's Support Blocker and Per Model Setting's "Modify Settings for Overlaps" to add 20% infill (Lines pattern) for the first 51mm for the large ball and 37mm for the small ball.

Supports

I recommend using the versions of the balls with built-in supports. You'll still need a little support for the first few layers (where the ball touches the build plate), but my supports make printing the arms of the ball easy. You can remove my supports with your bare hands (no tools) and they leave little or no marks on the print.

I recommend printing these with Cura-generated supports "touching buildplate" with a 60-65 degree overhang angle and a brim for the supports.

For support infill, use Concentric pattern, 10% density. Roof density of 75%, floor density of 50% works well and releases cleanly.

The small ball doesn't need any supports for the inside roof. I found it printed very cleanly.

The large ball printed well enough for my taste without supports for the roof. It print was a little rough, but it only shows if you pick the ornament up and look up from the bottom of the ornament. When it's hanging on a tree, you'll never see that part of it. There's enough space between the arms of the ornament that you could get tools in to cut up and remove supports if you want to add them, but I don't think it's worth the effort.