1:246 Gearbox
Description
The version shown here is less than 60mm in diameter and 13mm thick, but achieves a 1:246 gear reduction, all with teeth printed on a TOM. The input is the small shaft to the sun gear, the output is the smaller ring gear, and the larger ring gear is to be held fixed. If you stacked two of these units you would have a ratio of 1:60516!
Instructions
The OpenSCAD file is commented and parameterized for easy tweaking. It will output the gear ratio you get based on the number of teeth you use. It is also set up to visualize through animation: just compile the assembly, then select view->animate. I'd recommend setting steps to more than 2000 or else it will be jerky. This file makes use of Greg's involute gear script, and it's called through the MCAD library.
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I made a little spreadsheet that helped me find the right parameters to make the reduction ratio 1:60, and by stacking two of these between an escapement and a power source, I think we can make a really compact and solid printable clock.
I made a little animated gif of the 1:60 gearbox running thru one revolution of the input (say, 60 seconds) with two hands attached to the input and output. :-)
Beware when opening this and generating the gcode in replicatorg. emmett...in openscad you should fix your z height so that it doesn't place the 2 rings below the build platform. I just ruined a belt because I didn't click "put on platform". So just a warning to anyone else printing the two rings...make sure you generate the gcode with it on the build platform.
I love and want to use it.
what are the number of teeth? I count 41 on the upper ring and 42 the lower.
I count 17 on the upper planet - but fail on the lower planet: 16 or 18?
and how is the gear-ratio calculated: R1/R2*P2/P1??
This is really cool. I really need to make some gears for a project I am working on and am not very good at openscad. I was wondering if someone could help me out by answering a few questions?
1. The script keeps looking for a gear module that I obviously don't have. I downloaded GregFrost's involute gear script, I have it in the openscad directory as well as the file for this 'thing'. It still can't find the gear module. What do I have to do to get it to reference greg front involute g
ear script's gear module?
2. This planetary gearbox as it is, is almost perfect. I just need it a little smaller. I am willing to sacrifice gear ratio or whatever I would need to do to achieve a planetary gear box about half the size of this one. Is this possible to print on a ToM? All I am trying
to do is slow the release of energy from a clock spring I have in a printable wind up case with key that I have already created. I need the gearbox to be smaller to fit in the device I am making. I plan to post the whole thing when I am done, it is kind of neat too!
Thanks!
Ok scratch the 1st question. I figured it out. I downloaded the most recent version of the involute gear script which had a wildly different filename. I've figured that much out.
Trying to work on some smaller gear boxes now with the script.
Any pointers or tips for what I am trying to do would still be much appreciated! :]
Thanks again!
Sweet! :)
We can now print "Machine With Concrete" as an existential reminder of our mortal coil:
http://www.youtube.com/watch?v...
More Arthur Ganson:
http://www.arthurganson.com/pa...
Instead of a concrete block it can be attached to the 3D printer itself!
Very nice demo piece. I printed it on a Thing-O-Matic. I had to scale the 4 gears down to 95% to get them to fit.
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Might the different planetary teeth and of course ring and sun gears be converted
to DXF for output to a laser cutter? The planets could then be glued together ???
thanks - hope you can post.
Yes, OpenSCAD can output DXFs, so you can use the scad file to make whatever planetary arrangement you like. I don't have access to a laser cutter, so I'll leave the details to you.