Re: [DIYbio] Re: ultracentrifuge

The original poster said "70,000 rpm or 200,000G". The distance from the axis of rotation at which 70,000 rpm generates ~200,000g is 3.5cm. Additionally, the speed of the round is somewhat pointless a car traveling at a paltry 20 mph will kill you. Even the energy can be a poor indicator of how quickly, efficiently, and destructively that energy will transfer into a body. Unless you fill a 1.5 mL eppendorf with lead, the .45 ACP round is 10X as heavy as the tube that's spinning. Also, at a 12.8 cm radius you only have to spin at 40,000 rpm to reach 200,000g. Only if you increase the rate of rotation 50% to 110,000 rpm and quadruple the size of the rotor to get a force of 1,700,000g (only 8X specification), yes, the projectile that is 1/10th the mass of a .45 ACP round acquires a speed 3X the muzzle velocity of an ACP round. Also, metal bullets are freaking heavy and easy to detect, why would anyone carry them around if plastic bullets were just as lethal?

This is an ANALYTICAL ultracentrifuge people, not a preparative one!

On Wednesday, March 7, 2012 12:42:05 PM UTC-6, Roninlaw wrote:

Assume spinning the end of the test tube makes a total diameter of 12.8 cm. = 5.04 inches /12 = .42 feet * 3.14 * 60 * 110,000rpm / 5280 =  1648.5 mph

A Colt .45  is just over 500 mph

Sent from my iPhone

On Mar 6, 2012, at 5:26 PM, mad_casual <ademlookes@gmail.com> wrote:

I assume since you say eppendorfs, you're making an analytical ultra (as opposed to preparative). As someone gives below, the 5.56 NATO round is 11.8 grams of copper jacketed lead rifled at ~950 m/s. Assuming your 3.5 cm radius (assumed from 200,000G <-> 70,000 rpm), your eppendorfs will be ~1.2 g of plastic jacketed water travelling (tumbling) at ~250 m/s. About 1/3 the mass and 3X the velocity of a paintball. I wouldn't want to take one in the mouth, neck, eye, or groin unprotected, but with goggles and a lab coat I wouldn't be too worried about projectiles.

As others point out, the question is more about how quickly is your rotor going to wear out. I think with plastic, you should make an effective system for collecting the rotor pieces and consider them and consider them single use/disposable.

On Wednesday, February 29, 2012 9:49:14 AM UTC-6, Richard Proctor wrote:

im going to be working on cathals dremelfuge. ive found a US company
called Portescap who manufacture very high RPM brushless motors that
can hit in excess of 70,000 RPM or 200,000 G .

My main concern is whether the material in 3D printing can really deal
with those kind of forces.

The balance must be that the thing is light enough to not cause the
motor to lower its RPM but be stable enough to not cause eppendorf
bullets :-s

thoughts anyone....i'll be running FEA analysis on selection of
polymers in the next week.

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