Long Overdue Update: I'm very proud to say that, some time back, I updated the Dremelfuge design with better tolerances and a better shape to handle tubes. When I tested it (only once so far) at full speed on a dremel with two tubes full of fruit smoothie, it didn't eject or break the tubes at all.
So there you go, Dremelfuge can now be considered the world's cheapest midi-ultra-centrifuge, capable of putting about 52,000g on up to six 1.5ml eppendorf tubes. Warning; Lots of risk, don't use this thing unless you have taken some serious precautions. Try to stay outside the plane of rotation.
Back to the original post:
Since my last post, I've been a very busy person.
Dremelfuge is now available for purchase on Shapeways from my shop there. There are two versions, one with an axle for chuck-fitting machines, and another with a bore into which the cutting-disc-holder from a standard dremel can be fitted. Price varies by location, but even at the $65 price which includes shipping to Ireland plus VAT, you could buy a Dremel to match it and still come in under €100 for a functioning centrifuge. I gather the price falls to $55 for American buyers.
Here's a video of me demonstrating Dremelfuge. I tested it with standard microcentrifuge tubes, and found that it stably spins them anywhere from 5000g to somewhere above 20000g. I say “somewhere above” because the tubes shatterd somewhere between the third speed setting and the fifth on the dremel. The math shows that the average force on a microcentrifuge tube quickly exceeds that of the commercial centrifuges I use in the lab. They go as high as 14,000g. Dremelfuge plus a Dremel 300 can put over 50,000g on a sample. Except that's too much for the tubes so they shatter.
One nice bonus is that it seems to be very stable on a Dremel 300; there's little to no vibration or rattling, even with highly unbalanced loads.
So here I have it: A centrifuge attachment for drills or rotary tools which spins them with even more power than the official thing, and costs a tiny fraction of the price to make and operate. I call that a success by every metric!
Thanks to Makerbot for making this possible in the first place, and my fiancee and family for their patience.
As always, I don't endorse use of Dremelfuge as anything but an ornament, for reasons of liability.
Update: I've tested Dremelfuge in my lab with E.coli cells and HL60 human suspension cells. It pellets both excellently! I've already shown it to spin down Miniprep columns, and the math shows it hugely exceeds the power of a standard lab centrifuge when used with a Dremel 300 (€89 in Argos and useful for just about everything else, too).
So that's it as far as I'm concerned: Dremelfuge is a fully functioning centrifuge. Can't wait to see it in use on some cool projects!