Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Compound Planetary Gears 1300:1

by tmackay Mar 17, 2019
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Printed on Ender 3 with no issue.
But its very hard to turn without a handle...

So I am making a handle.
Test printing first try right now.

3 parts, one file. its crude. I loaded the planetary gears in Blender, added a cylinder and then subtracted the gears from the cylinder. Then built the rest with cylinders and spheres.
This might be a very tight fit...


I may add another sphere n the handle to make it better.

I might also narrow the shaft to allow passing through both sun gears, glue it to one and reduce the wobble of the other. Where to do that depends on the questions below:

Which gear should I drive? the finer tooth sun gear or the coarser tooth one?
And do I hold the ring for the one I am driving or the other ring?

I expect to need to put some indexing marks on the rings to be able to see the rings moving in relation to each other.
That is what permanent markers are for.

Very good, it should free up a bit more the more you turn it, and adjusting extrusion percentage might help with clearances. They usually start pretty tight and loosen up over time. A few hundred turns on a drill does the trick.
As for which gear to drive, I don't think it matters but they are slightly different ratios (1:1298 vs 1:1297 or something). Making one of the holes bigger might help too.
You may be interested in my new version (http://www.thingiverse.com/thing:3511382 ) which is not as high ratio, but has a one piece sun gear which will be easier to drive and more useful.

Solid Core Compound Planetary Gearbox (customizable)
by tmackay

Everything moves... I am considering reprint with some horizontal expansion to reduce the play.

I slid an X-Acto blade through and that separated the rings and sun gears very easily.

Just trying to turn one sun with out turning the other by hand is a bit tricky. You naturally want to take hold on both sides and squeeze, which definitely does not work.

That "D" shape you've got would probably be a good for the sun gear without glue. ie. leave one hole round, pass the axle through into a matching "D" hole on the bottom sun gear...

Handle printed.
It needs supports and a brim

Its a loose fit in the sun gear. Perfect with some gel type CA glue. If the step is flush, then it sticks about halfway into the next gear providing a bushing style bearing. That does stabilize the gears somewhat.

The D fits in the "dumb-bell" tight. A couple of taps with the handle of my screwdriver.
Hole for the knob is shallow (sorry) and very tight

This comment thread has become basically a "Make" for the gear plus the added handle.

I made an index mark on both rings, labeled 0. Then turned the handle 50 turns holding the ring closer to the handle. The handle is glued to the sun gear for the ring I held.

I had to hold slight friction against the other ring and the marks are with that applied to have the travel be meaningful. The play is almost the width of the marks.