Hello all, and thanks for tuning in to my work on 3D printing this semester! Although I have extensively used FDM printing, this was my first time with SLA printing and I enjoyed it greatly (although it was less than successful in preserving joints, but we’ll get there). Here’s the progress! These pyramids will go within gumball containers and into the famous OEDK gumball machine.

First, I selected my file off of Thingiverse. The author appears to be French, so that was interesting!

The STL file of the tetrahedron (tétraèdre)/pyramid off Thingiverse

After printing a first try to attempt sizing at 1″ maximum dimension, this was the item within the gumball casing.

Initial sizing test!

Clearly, we can go bigger. I adjusted sizing to have a maximum dimension of 1.5″, and took my shot at a rarely-open SLA printer to produce my second type of 3D-printing

Post-printing and washing!

the SLA-printed tetrahedron in the curing oven.

The product removed from its raft supports.

Unfortunately, I should have spent some time blowing the product with the compressed air supply. I didn’t because I didn’t think the close tolerances would be an issue, but unfortunately, the ball is locked in place. Doing this again, I would spend time to ensure that after the print and wash, the ball is freely moving and clean.

With the sizing locked in, I then went back and printed the four remaining items on the FDM Bambus.

In-progress on the Bambus!

With all five printed and supports removed, I printed the attribution slips and packed my impossible objects into their resting place – for now. At least until some lucky person gets to take one home.

Final packaging!

Cost Analysis

Since we don’t have 3dprinterOS set up yet, there’s no good way to know exactly how much filament was used after the fact. Therefore, I will estimate based on the startup costs required: that is, the first whole purchase unit, a spool (and resin cartridge)

Materials

1 spool white PLA: ~$13

1 resin cartridge: $80 from FormLabs

Machine Time

4 FDM prints: ~1hr

1 SLA print: ~3hr

Using the rate I have used previously of $10/hr, this would equate to $40. However, I think 3D printers should not be considered the same use-time cost as, say, a plasma cutter. So let’s cut that in half to $20.

Labor

~1hr total of print setup, support removal, resin cleaning and curing, and printing slips. This obviously does not include the machine time that I did not need to be present for. At $10/hr, we have $10.

Total Cost: $13+$80+$20+$10 = $123.

Not bad considering the materials costs are for production start-up, and would come down considerably as manufacturing ramps up. Thanks for reading to the end!