New Machine Build- first attempt sandtable

[vger]

cyclestart,

I was intending to suggest that only the mechanism under the sand table rotate. The table top itself would remain stationairy. Just rotate the single motor, screw, and magnet assembly attached to the turntable.

A thought occured to me about how to clear the "drawing".... suppose you mounted motor with an offset weight to the sand table as a vibratory eraser. Probably have to shock mount the table to allow a bit of movement, maybe with springs. Orient the motor shaft verticaly so the vibratory movement of the table would be circular in motion to erase the image.

Have a great day

Steve

[cyclestart]

Originally Posted by vger I was intending to suggest that only the mechanism under the sand table rotate. The table top itself would remain stationairy. Just rotate the single motor, screw, and magnet assembly attached to the turntable.

Ah, I went back and reread you're previous post. It adds some complication but solving design problems is half the fun The drives I'm using are very sensitive to any current disruption between drive and motor, making me a nervous regarding making any indirect. connections. Avoiding slip rings would be ideal.

I'll hold off on bothering you for parts for the time being

thanks
jeff.

[low_48]

I've looked at these machines as well, but not inspired yet to build one. I had the idea that maybe glass beads would be a preferred material instead of sand. Or maybe a sized grit abrasive. Did you use something like that, or play sand?
And for the analog version;
http://www.thinkgeek.com/geektoys/cu...d/?cpg=froogle

[cyclestart]

The sand is very fine grit from an art supply store. I don't know what others are using or what type of size of grit is ideal.

That pendulum is so cool
I'm going to buy that as a Christmas gift. Of course I get to play with it first !

[garagefela]

Hi there Cyclestart and everyone watching this great thread,


Cycle, just having look at the pictures of the patterns you have done and one thing seems to stick out, it appears that the edges of the patterns are not very well defined.

It looks like the sand is very fluid and sort of slumps back down after the ball has passed through and is not giving clean edges, sort of smudgy.

I once saw this great little doco on those uber talented guys and girls that do those massive beach sandcastles, animals, buildings just about anything that you can think of and a question was asked of them and it was along the lines of "how does it stay up"?

The answer was in the shape of the grains of sand, round grains of sand wont stick to each other very well but a cubic shaped grains will or whatever other shapes there are. ( experts please jump in) Not exactly sure of what shapes there are but you get the drift.

Having grains that won't easily slide past one another should help with the definition a bit.

Top job on the table and am eagerly waiting to see some cool designs done on it.

Cheers M

[vger]

Jeff,

When I get the chance I'll do some testing on the rotary coupling. It has multiple sliding contacts on each circuit and may not have much if any loss of contact while turning. I'll run current through it and observe it with my oscilloscope for any noise. It may be a couple of days before I can get to it.

Steve