Wednesday, June 8, 2011

Ideal Harmonic Transformer prototypes

These are my first two working prototypes for the Ideal Harmonic Transformer. I learned a lot from them, including how to make a fit with friction, snug but sliding, and loose. Also played with techniques for making parts that separate more easily from the print base structure. On the Up!, it's the same as the print material. It's very disappointing to spend 30 min to separate an intricate part before getting to use it, and having a marred surface for all of your care.

These prototypes use #6 machine screws. I had reasoned that they are already designed, readily available, and quite strong, so no need to reinvent. However, I could not find any off-the-shelf hardware that let me do what I wanted with the arm pin and yoke pin. After spending too much time in front of the fasteners at Lowes and Home Depot, I decided maybe it was possible to make plastic screws after all.

Once I got the hang of it, I converted all of the screws to home-printed rather than OTS. This let me eliminate all the nuts, by "tapping" the holes, which made the whole design cleaner. It also let me decorate the heads to go with the overall look, not to mention saving me the frustration of sorting through the store's wares.

One limitation, at least with my printer, is that threads must be printed vertically in order to work. The down side is that a print is basically a bunch of laminated heat-welded layers. I think this gives a certain grain to the finished material, and is contributing to the failures I'm experiencing. Some of my bolts snap off at the head right as I'm taking them off of the machine. Others turn out fairly strong. Setting the Up! print settings to fill=solid and quality=fine helps, but does not eliminate, this problem.


  1. Beautiful project!

    Try printing the fasteners at 10° off-vertical in X or Y; this will give them more strength. It will also fill in the top surface nicely :)

  2. Thank you! That does exactly what I was trying to do, in a very simple way. :)