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PLA Spring Motor Demonstrator 2 is an updated Autodesk Fusion 360 design of my original PLA Spring Motor Demonstrator design of 5 years ago.

The original PLA Spring Motor Demonstrator was designed as a "proof of concept" tool to test whether a 3D printed PLA spring could power a gear train and move a vehicle. As a result of that successful test, I was able to design a number of 3D printed PLA spring powered vehicles.

This updated version has a 1 (drive) to 125 (driven) gear ratio in three gear stages and, as shown in the side by side comparison photograph, is slightly smaller than the original. And while not a requirement, I used Ultimaker "Tough PLA" for the pawl, spring and frames for additional strength and longevity.

PLA Spring Motor Demonstrator 2 is a fairly easy print and assembly, and even though it was originally designed as a proof of concept tool, it is still a fun desktop conversation piece.

As usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to point them out as I do make mistakes in plenty.

Designed using Autodesk Fusion 360, sliced using Cura 3.5.0, and printed in PLA and Tough PLA on an Ultimaker 2+ Extended and an Ultimaker 3 Extended.

Step 1: Print and Prepare the Parts.

I printed the following parts at .15mm layer height:

  • Four "Bolt, Frame.stl", 100% infill, Magenta PLA.
  • One "Frame, Left.stl", 50% infill, Black Tough PLA.
  • One "Frame, Right.stl", 50% infill, Black Tough PLA.
  • Three "Gear, Idler (50, 1.12).stl", 20% infill, Magenta PLA.
  • One "Gear, Pawl (50, 1.12).stl", 20% infill, Magenta PLA.
  • One "Knob and Axle.stl", 100% infill, Magenta PLA.
  • One "Pawl.stl", 100% infill, Black Tough PLA.
  • One "Spring.stl", 100% infill, Black Tough PLA.
  • Two "Wrench.stl", 20% infill, Magenta PLA.

Prior to assembly, I test fit and trimmed, filed, sanded, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. If you decide to make your own PLA Spring Motor Demonstrator 2, depending on the colors you chose, your printer model and your printer settings, more or less trimming, filing and/or sanding may be required. I carefully filed all edges that contacted the build plate to make absolutely certain that all build plate "ooze" was removed and that all edges were smooth. I used small jewelers files and plenty of patience to perform this step. I also used 6mm by 1 right hand threaded taps and dies to prepare the threaded parts prior to assembly

WMSigEp made it!2 months ago
Fantastic project, thanks! I especially appreciated that all parts were printed (no need to source screws, etc) which made it simple.

Printed on a Prusa MK3 with Prusament PLA (Lipstick Red and Galaxy Black). Sliced with Prusa Slicer and I followed your settings for layer height (.15mm) and infill %s. To improve appearance/tolerance, I set the first layer, external perimeters and top layer to 10mm/sec speed for a smoother finish. No sanding or filing necessary. It will occasionally bind up a little but adjusting the gears and giving the 3rd gear a little push starts it and inertia keeps it going.

Again, thanks for the fantastic instructable!
gzumwalt (author)  WMSigEp2 months ago
Wonderful work, congratulations !