Now has a little sibling at http://www.thingiverse.com/thing:2105705.
!!!DEBURR THE GEARS AND REMOVE SHARP EDGES FROM THE GEAR TEETH!!!
Do not put anything that can get hurt in to mesh point of gears!
Not for young children. If not assembled correctly, ball bearings can fall out.
Meshing helical gear fidget toy with through hole for finger.
Printing two of the same gears will make them mesh at 90 degrees.
Printing one right hand and one left hand gear will mesh straight on same plane.
Same housing for both straight and perpendicular planes assemblies.
Included is an STL for a bearing race dressing tool.
I passed some 180 grit sand paper through the slots.
Pushed it in the the half toroids and rotated back,
and forth to help smooth out ball bearing grooves.
I used PLA for the gears, and ABS for the housings.
The little holes in the housing are meant to receive short pieces of filament.
Cemented together using acetone on the ABS housings and inner cylinder.
Epoxy or any decent glue can be used to assemble the housing pieces as well.
There are a few versions of the inner cylinder.
I had delamination issues when removing it from the printing bed.
A little acetone on a paint brush re-enforced the laminations faily well.
Spherical 4.5mm(0.177″) BB ammunition is used for the ball bearings.
Contained with this package is an OpenSCAD script for generating metric helical gear blanks.
Written by yours truly, is being released under and besides this fidget toy under the GNU GPLv3 license.
I exported the gear to an STL. I then imported the STL in to TurboCAD, and carved out the rest.
If the assembly meshes a little tight, you might try
1. Scaling a difference of up to 0.5% between housing and the gear(make the housing bigger).
More than that, and housing might “rock” over the ball bearings.
2. Printing shim to your desired thickness, and adding to the housing assembly.
In CURA the shim can be cut off to the desired thickness.
Something is very wrong if you need more than 1mm.
3. Included are two gears. One is to spec with no backlash.
The other has 5% of the CP removed from the gear profile for added
backlash(clearance on the gear tooth flank). This one is loose.
If anyone wants a copy of the original TurboCAD files, or an export to AutoCAD DWG,
please make your request in the comment section. I’ll zip it up and post it.
Bill Of Materials for pair of meshing gears
2 inner cylinders
4 short pieces of filament ~9mm long.
BB Balls to fill grooves
Glue or Acetone(ABS)