Experiment 56: Homemade Lab Centrifuge

I had an old (possibly from the 1960s) Hoover vacuum cleaner motor lying around, so I decided to turn it onto a lab centrifuge for chemistry experiments.  The motor was enormous and spun with such ferocity that I thought it would might go airborne and kill me, which scared me thoroughly.  For that reason, I used large bolts to attach it to a thick plastic/wood board, which I clamp to a table when I use the centrifuge.

The vacuum cleaner creates suction by spinning a cast aluminum turbine.  The aluminum turbine blades were relatively flat on top, so I decided to make this the centrifuge top.  I cut some plywood into a disc with a hole it in to go around the motor output shaft.  If the disc ever flew off in operation, someone could get seriously hurt, so I cut some scrap sheet steel into a large washer to go between the end nut of the motor output shaft and the plywood.  Once everything was assembled, I tightened the nut until everything was snugly in place.
Previously, I had requested and received free samples of 2mL plastic centrifuge tubes from a laboratory supply company, so I designed my tube holders around those.  I cut and drilled six wood cubes with holes sized for my centrifuge tubes and then glued these around the plywood disc.  Centrifuges can self-destruct if they are off-balance, so I carefully measured 60° increments around the circle so that the disc would be balanced.  To finish off the centrifuge, I added a cord and on/off switch salvaged from the old vacuum cleaner.

For being made from a vacuum cleaner, this centrifuge works surprisingly well.  I have successfully separated oil from mayonnaise, although mustard does not separate.  This centrifuge is extremely useful for settling precipitates out of solutions.  If I mix copper sulfate and sodium carbonate solutions, I get clear sodium sulfate in solution and blue copper carbonate precipitate.  By placing a sample of solution in the centrifuge, I can settle all the blue precipitate out and see the true color of the solution--it should be clear if I have used enough sodium carbonate.  One thing this centrifuge can't do is enrich uranium, but if that's the only complaint, I would say it works pretty well!