Educational Model of Single Tooth Involute Gear 2

My Educational Mechanical Examples Series

This model is one of my educational mechanical mechanism examples on 80mm x 80mm base plates.
You can find all models of the series in this collection => [Mechanical Mechanism Examples]

This model

This model shows a single-tooth involute gear meshing with an eleven-teeth involute gear, resulting in a reduction ratio as large as 1:11 in a compact volume.

FOLLOW THIS LINK FOR THE INTRODUCTION VIDEO → https://youtu.be/34HaHz9XSmE 
*Somehow, the editor of printables is currently broken and does not allow me to embed the video.

Brief description

The smaller gear in this model is made of two heart-shaped plates stacked together with 180-degree phase differences. Each heart shape represents a single-tooth involute gear,  which has been already introduced in the other model. A single plate alone cannot maintain continuous meshing, so by stacking two plates with a shifted angle, we keep at least one of the two plates always in contact with the mating gear.

The larger gear looks completely different from the standard involute gears. However, each layer of this gear is indeed an involute gear even though it is largely shifted.

In this model, the single-tooth involute gear meshes with the eleven-teeth gear. As a result, the system realizes a reduction ratio as large as 1:11 in this compact volume.

Reference

• https://507movements.com/mm_205.html 

Related Model

Single tooth involute gear meshes with Single tooth involute gear:

Case

These models are compatible with the case included in my first set.

Printing

• Use the models named ???-printable.stl for printing.
  The models named ???-assembled.stl are provided just to show how they should be assembled.
   

• Use well-dried PETG to have better dimensional accuracy.

• Use 0.1 mm or 0.08 mm layer height to have smoother surfaces.

• Use slow printing speed for overhangs.

• Select “Random” seam position to have smoother rotation.
  Randomly distributed seam should be easily worn out after some wearing.

Sanding and Filing

Sometimes, the gears suffer from the stringing effect and/or elephant foot effect, resulting in a too tight fit to the shafts (they are designed with a 0.15 mm radial clearance). 

If you see rough surface on the shafts due to stringing, sand off the roughness with a small piece of sand paper.

If you feel the gears do not rotate smoothly due to an elephant effect, widen the hole slightly by using a thin round bar file.

Without those issues, the gears should rotate very smoothly with minimal friction.

Assembly

All parts can be assembled by snap assembly.

Updates

• 2025-12-04 (v121) Update Preview - Thicker Tabs on the single tooth gear

  • Released an update candidate, which thickened the tabs on the single tooth gear because they have been fragile as @samol_101871 pointed out. It will be published once I have tested it, after my broken printer is repaired.

Other educational models

You may also be interested in the models in my educational mechanical mechanism examples.

Find them in this collection:
https://www.printables.com/@osamutake_3341417/collections/2728214

Acknowledgement

I got into gears thanks to K.$uzuki's amazing articles and YouTube videos. Many of the mechanisms shown here came from the introductions on his website. He also makes excellent gear models himself. This series wouldn’t have existed without his inspiration.

I learned a lot about technical detail of designing gear tooth profiles from Haguruma-No-Hanashi website. I’m truly grateful for that.Happy printing!