"A 3D Printed Slinky Machine" is an easy to 3D print and assemble mechanism that takes all the work out of using a "Slinky" toy!

Ok, the Slinky toy is still fun without this mechanism, but the mechanism does make an interesting desktop gadget with its gears, arms and motor in full view. The mechanism uses magnetics to hold the metal Slinky in position during operation, and with a few extra magnets, a plastic Slinky may be used as well.

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 ask as I do make plenty of mistakes.

Designed using Autodesk Fusion 360, sliced using Ultimaker Cura 4.12.1 Engineering profile, and 3D printed in PLA and TPU on Ultimaker S5s.

Supplies

Soldering iron and solder.
Thick cyanoacrylate glue.

Step 1: Parts.

I acquired the following parts:

One N20 6VDC 120RPM gear motor.
One dual AAA battery pack with switch.
Two AAA batteries.
Eight 10mm diameter by 2.8mm neodymium disk magnets.
One original metal Slinky.

I 3D printed the following parts at .15mm layer height, 20% infill, and no supports:

One "Arm, Drive.stl".
One "Arm, Slides.stl".
One "Axle, Arm, Slides.stl".
One "Axle, Gear, Cam.stl".
One "Base.stl".
One "Gear, Cam (21t, 2m).stl".
One "Gear, Motor (7t, 2m).stl".
One "Guide.stl".
Two "Platform.stl".
Two "Slide.stl".
One "Yoke.stl".

Prior to assembly, test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on you printer, your printer settings and the colors you chose, more or less trimming, filing and/or sanding may be required. Carefully file all edges that contacted the build plate to make absolutely certain that all build plate "ooze" is removed and that all edges are smooth. I used small jewelers files and plenty of patience to perform this step.

The model also uses threaded assembly thus an M8 by 1.25 tap and die will assist with thread cleaning if necessary.

Step 2: Assembly.

To assemble the model, I performed the following steps:

Slid "Arm, Drive.stl" into "Guide.stl".
Pressed "Yoke.stl" into the holes in the drive arm then secured in place with small drops of cyanoacrylate glue.
Attached "Gear, Cam (21t, 2m).stl" to the guide assembly using "Axle, Gear, Cam.stl".
Slid both "Slides.stl" into the guide assembly.
Aligned the posts on the drive arm and slides horizontally, placed "Arm, Slides.stl" over the posts, then secured the slide arm to the guide assembly using "Axle, Arm, Slides.stl".
Pressed the eight neodymium magnets, four each, into both "Platform.stl".
Pressed a platform assembly onto each slide and secured in place with small drops of cyanoacrylate glue.
Pressed the guide assembly into "Base.stl" and secured in place with small drops of cyanoacrylate glue..
Soldered the battery pack wires to the motor.
Pressed the gear motor into the guide assembly.
Pressed "Gear, Motor (7t, 2m).stl" onto the motor shaft.
Installed the AAA batteries into the battery pack.
Magnetically attached the Slinky to the platforms.
Turned on the battery pack switch and the Slinky was in motion!

And that is how I 3D printed and assembled my "A 3D Printed Slinky Machine".

I hope you enjoyed it!