Introduction: A Simple 3D Printed Scotch Yoke Mechanism.

By Greg Zumwalt
About: Our grandkids keep me busy!

"A Simple 3D Printed Scotch Yoke Mechanism" is a model I designed for a mechanisms class.

The motor used in this model is an N20 60RPM 6VDC gear motor powered by a 3VDC battery pack, thus the motor runs at approximately 30RPM.

With the motor gear having 12 teeth, and the yoke gear having 24 teeth, the yoke gear rotates at approximately15RPM and as such the yoke completes its linear translation cycle in approximately 4 seconds.

The yoke travel distance is approximately +- 15mm due to the yoke pin on the yoke gear being 15mm from center.

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, and 3D printed in PLA on Ultimaker S5s.

Supplies

Soldering iron and solder.

Step 1: Parts.

I purchased an N20 60RPM 6VDC gear motor, a dual AAA switched battery case and two AAA batteries.

I 3D printed one each of all the parts at .15mm layer height, 20% infill and no supports.

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

Attachments

Step 2: Assembly.

I assembled the model as shown in the video by performing the following steps:

  • Soldered the battery case wires to the gear motor.
  • Turned the battery case switch off then installed two AAA batteries in the battery case.
  • Pressed the gear motor into "Base.stl".
  • Pressed "Gear, Motor.stl" onto the motor shaft such that the shaft end was flush with the gear surface, then aligned the motor in the base to allow .5mm clearance between the motor gear and the base.
  • Slid "Yoke.stl" into the base as far as it would go.
  • Positioned the pin on "Gear, Yoke.stl" in the yoke slot, slid the gear and yoke until the hole in the gear was over the threaded hole in the base, then secured the gear to the base using "Axle, Gear, Yoke.stl".

With assembly complete, I turned on the battery case switch and off it went!

And that is how I 3D printed and assembled "A Simple 3D Printed Scotch Yoke Mechanism".

I hope you enjoyed it!