Homemade galvos make for a $100 3D printer

[Meatball]

A kickstarter project I found.

He's using homebrewed galvos, the audio out as a 16 bit output, the mic in for feedback, and a lot of coding.

Should work pretty well since his data rate is still < 20k. What do you guys think? I think I'm jumping in on it.

Lithography was always cooler than extrusion.

http://www.kickstarter.com/projects/...c?ref=category

[mixedgas]

Dripping saltwater as the Z stage? YGBSM. Too hard to calibrate the Z step size.


Steve

[james]

Hmmmm. Using a sound card to drive galvos? That's crazy!

It is kinda' weird that he made no attempt to bypass the DC decoupling caps. He's just using the headphone output jacks as-is.

That will limit the kinds of shapes he can make. They all have to be more-or-less centered around the origin all the way up the Z axis.

James.

[dnar]

His ideas are actually very smart. Watching with interest.

[Meatball]

Dripping saltwater as the Z stage? YGBSM. Too hard to calibrate the Z step size.


Steve

Aren't there cheap water level sensing solutions? I resistance measurement between two electrodes along the length of the liquid level axis?

[james]

That's not the point. The point is counting drops and the fact that all drops are going to be remarkably similar in volume; especially when averaged out over the number of drops it takes to change the water level an appreciable amount.

His drop of water is also his Z axis quantum of time; a computational cycle to advance the rendering script to go to the next layer; the smallest division of displacement on the Z axis.

Pretty smart!

There is some really cool stuff going on here. I'd like to get a better look at the galvos ad see just how well they perform.

James.

[chad]

Really cleaver hack! But I predict there are going to be a lot disappointed customers. The little cube thing is only 1/2", who knows how big the dave print is and it looks terrible. Home made open loop galvos are going to be a positioning reliability nightmare. The entire thing with saltwater and resin is going to be a wet gooey mess. It is going to be nearly impossible to get anything with accurate dimensions out of it. Like I said I think it really a cleaver hack, but as far as something that is actually usable from a end user standpoint, it is going to be a disaster. Hope I am wrong.

chad

[Galvonaut]

It is cheap but using an old DLP projector has far higher resolution by the looks of it. Far less gloop too!

http://makezine.com/2010/10/15/homem...on-dlp-3d-pri/

[mixedgas]

It is cheap but using an old DLP projector has far higher resolution by the looks of it. Far less gloop too!

http://makezine.com/2010/10/15/homem...on-dlp-3d-pri/

With a F-Theta lens, feedback equipped galvos can beat the DLP by a long ways. What nobody does on these laser driven 3D systems is pick a proper lens, not even a achromat.
I worked on a early 3D Systems He-CAD based system, which used a pair of G138 closed loop galvos. Step size was .0005" over a 14x14" field with a .004" thickness step, and that was in the late 90s. The galvos were mounted in a heated block to stabilize the position sensors. Four pinholes in the corners of the field allowed for registration using photodiodes.

The positioning accuracy of his home made open loop deflectors is going to be horrid, compared to a 75$ pair of 12K feedback galvos. The repeatability will be far worse. The virtue of those small test shapes is they look fine with a fat, poorly focused beam from the diode.

Steve