Saturday, January 23, 2010


Ola learning to dance

I made a little progress this morning. It took a while to convince the RepRap stepper control that it should listen to my Mega Arduino, but eventually, it gave in. Turns out I had the pin numbers reversed. Oopsie.

Anyway, I took a short video clip showing the somewhat boring radial motion of the build platform. The motion appears very smooth. It is not exceedingly strong, I can stop and cause the stepper to begin stepping skips by grabbing the platform, but I don't think that will create any issues for RepRap printing.

My next step will be to get radial motion on the radial arm platform too, and then create some tests to see if I can calibrate and draw 2D shapes accurately with a mounted pencil.

I apologize for the audio quality; it's my first attempt to upload video/audio.

Update: I got the second motor mounted and working, sort of; Ran into a few issues: 1) The radial circle was quite a bit off, more than 1/2 cm; so I had my son spin it while I held a pencil steady to get a new better circle, and cut it out on the scroll saw (My friend says I should use a router and a jig; probably if I need to make another repolarepstrap, I may try that out), 2) so, now the belt for the radial arm platform is too long; ideally, it would be 2 inches (5 cm) shorter; as it is, I sanded out part of the side support to prevent the pulley from rubbing. That brings up 3) the pulleys are slipping around the stepper axle. I either need to add a flat so the screw pins can hold onto the axle better, or use epoxy or something and just permenantly fasten the pulleys -- which I want to wait on because 4) I may need to get another pulley as I sort of stripped one of them trying to drill it out to fit the axle; it is very rough and skips belt teeth.

I'm eagerly watching your project! I've been waiting for folks to try alternate axis schemes (like using an arm, or your polar scheme), and love to see the results! I can imagine a polar scheme particularly useful for creating good smooth prints of certain kinds of parts, like gears or generally cylindrical things. best of luck :)
Nice to see it working so well !

Wel done
It would be interesting to use this with an arm mechanism.

The arm could be implmented without the ability to rotate as the turntable would do it instead.

It would also be a belt free machine.

I have nearly been thrown out of the local ikea for playing with the angle poise lamps and taking pictures of them.
The part about the project I like is that the whole contraption is mind numbingly simple compared to mendle. I am still waiting to see the how the program compensates with Polar vs Cartesian coordinates.
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