Support Material – Sand?

12 05 2010

I just came up with an idea for having support material on a Makerbot or RepRap. The idea is quite simple, but I think it could work.

The idea is that you would have the whole platform essentially be a box that would be filled up with a bit of super-fine sand each time a new layer is deposited. The entire build area would be surrounded by a barrier to keep the sand in. Each time a new layer is deposited, a new layer of sand is added so that the sand level is just below the last layer of plastic. This would mean that the plastic couldn’t sag more than one layer thickness.

The sand could be deposited in a number of different ways. One idea would be a whole bunch of sand in a bucket above the machine and a valve just releases the sand while the platform moves below to evenly disperse it. The platform would shake to get a flat layer after the sand is deposited. Another way would be the same idea, but with a worm drive to push the sand at an even rate down. The first idea would rely on gravity, but the second one would be motor driven. Or you could have the bucket at the side of the platform (so it’s not in the way) and deposit the sand, then just have the platform shake violently for more time to get the sand flat.

The only problems I foresee with this are that it’s inaccurate and messy. The sand would have to be really really fine and controlled extremely carefully to get high precision. The sand would also make this less likely to be on a desktop. I’m sure it would create a big mess if there was an accident. This is the main reason I’m hesitant to try this. Another problem this might cause is inadequate layer adhesion. The sand could get in between the layers and make them not stick well. This would be especially bad with really fine sand.

I might try it at some point, but just add the sand by hand. I could add a manual stop after each layer then press yes to continue after I’m done. This would take forever, but it would be a great proof of concept.

Another thing I might try is cornstarch instead of sand. It would be smoother. I could wipe each layer of cornstarch with a brush to make sure its flat. This is another idea I like. If you had a brush that was the width of the surface and it wiped the cornstarch or sand after each new support layer.

Thats the basic idea of things. Sorry if my ideas are a bit scattered…

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