A while ago I wrote a program to read and solve the Professor version (5x5x5) of the Rubik's cube.
I then decided to build a robot to actually do the reading and the moving...

My first prototype was built in plywood, but then I decided I wanted to build something that was less prone to defects , so I got my first Makerbot, redesigned most of the components, and started printing!

This is an ongoing project, and I still have my plywood components working, waiting to be replaced by their ABS counterparts.

The electronics is based on an Arduino that reads the input from an external PC where the Solver software runs; it then drives the 12 servos that manipulate the Cube.

Ok, once you have an involute gear library AND a trapezoid thread library, you can easily make the simplest of worm drives, i.e. the non-throated kind.

Like all worm drives, the gear advances by one tooth for each revolution of the screw but with non-throated ones, there is only a single point of contact at any one time, and so torque and wear capabilities are limited.

UPDATE:
As I pointed out in the comments, AFAIK a trapezoidal profile for the worm screw is all you need to match the worm gear's involute.

To make them mesh, all I did was to make sure that:
1. the pitch is the same (distance from crest to crest),
2. the pressure angle of the gear is equal to the angle of the sides of the screw profile,
3. the distance between screw and gear is equal to the gear's radial pitch plus the screw's mid-profile radius, and
4. the twist on the gear is equal to the gear's pitch radius divided by the screw's mid profile radius, with a sign depending on the screw's handedness.

Also known as Clock-in-a-Cage!

WARNING! Since we still don't have a working escapement mechanism (see test jig #2 thingiverse.com/thing:8275 ), this is NOT a working clock, yet. Hopefully, it will be eventually. :-)

The Planetary Gearbox Clock is a collaboration with Emmett, who designed the original planetary gearbox and helped design and stack two of them with a 60:1 and 12:1 ratio respectively. I just slapped the escapement system on the back side and designed a cage-frame around it. The dove-tail snap-fit tabs for the cage I took from relet's excellent thingiverse.com/thing:6214 .

The intent was to do away with concentric shafts altogether, by putting the entire gear-train inside the shaft, as it were. The frame must hold the stator rings without interfering with the hands that stick out the side of the rotor rings, hence the cage design.

So far, I have been using an ideal Graham escapement with a ratchet wheel. They are simple to tune and to draw, and still in use in grandfather clocks today.

The issue is that with those sharp teeth, they are not that easy to print, and since proper function depends on the radius including tooth length... they are not the best choice for a printable clock.

The club-tooth escapement does not have this problem, and while it is harder to tune, it also offers more flexibility because the escapement and the wheel interact at multiple points, not just at the sharp end of a ratchet tooth.

Example of tuning difficulties: this escapement as drawn is not quite symmetric in its operation, and the impulse provided to the pendulum on one swing is a little larger than on the other. I need to tweak the pallet face sizes to adjust for that. :-)

Winner of the Pattywac Makerbot United Challenge for collaborative design: makerbot.com/blog/2011/05/16/pattywac-makerbot-united-challenge-winner/

Thank you team! :-)

Video of the first ticking powered escapement mechanism:
prototribe.net/vidplay/testjig2.html

___________WARNING_________

Several bugs have been fixed since this release, and the current tip-of-the-spear for development is a simplified 2-gear clock with only minutes and seconds.

Current development version to be found on git hub here:
github.com/syvwlch/Printable-Clock-Project

Current version of the 8-Gear Clock (revision D):
thingiverse.com/thing:8284

Current bleeding edge development version of the test jig:
thingiverse.com/thing:8275

Current repository for the latest version of the clockwork library:
thingiverse.com/thing:8155

Thanks to RustedRobot for his continued assistance debugging the clock!
___________WARNING_________

This is both a derivative of the printable clock PoC, and of my escapement library: thingiverse.com/thing:7822 . The involute gear profiles are from the MCAD library.

(EDIT: The clock got a mention by Cory Doctorow on boing boing!
boingboing.net/2011/04/23/model-files-for-a-wo.html )

I cleaned up the code so it would render faster, moved all the gear work into the library, and created a laidOutToPrint() module to facilitate creating the STLs of the individual parts. I included an optional print volume visualizer, so you can check every part doesn't exceed the printer's capabilities.

The assembled() module is still fully animate-able, and I've added colors to help see if everything meshes properly.

The clock itself now has clip-on hands, front & back frames, and most importantly, I switched to a different set of gear ratios (3.2, 3, 2.5 & 2.5) which allows for bigger shafts by keeping the ratios small.

Assuming an 80x80x80mm printing volume, you now have a bit more than 12mm (almost half an inch!) available for the overall diameter of the shaft, the two sleeves that slide over it and the necessary clearances.

I think this configuration is close to final, except for the escapement, which will need fine-tuning... but without re-printing the rest of the clock.

Using the MCAD library, I put together a little parametric script that creates a gear train to take the wheel of an escapement and gear down its rotation by 60:1 via three pinion wheels.

This is a proof of concept for the printable clock. If the escapement wheel rotated once per minute (i.e. could run the seconds hand), the other end of the gear train would rotate once per hour (i.e. could run the minutes hand).

I used three pinion wheels rather than the usual two because the smaller gear ratios make for easier printing (larger teeth without using gears that don't fit in the build platform).

(EDIT: Just realized that if you use an odd number of gears between two hands, they will rotate in opposite directions! Oops...)

Lastly, the whole gear train can be animated via the rotation_angle parameter. All the gears will rotate at the correct speeds and mesh.

(EDIT: posted a little animated GIF of the gear train moving in the comments below)

Green eggs and SCAD!

In observance of the upcoming holiday and Dr Seuss' just-passed 107th birthday (2011-03-02), here are a couple virtual colored eggs (no more PAAS stained fingers!):

vimeo.com/21636073

This is yet another example of coloring and animating with OpenSCAD. You can also tweak the file to print out the various parts in different colored plastic and assemble.

It's an ACME-standard peg bar!

These things are fragile, and really expensive in Europe for some reason, so here's a chance to print your own!
I've never made something printable before, so let me know if it can be tweaked in any way.

In the 1870's, in order to win a bet, Stanford hired Muybridge to take photos of horses as they run to see if their feet left the ground while galloping.