Hand Held Centrifuge Build

I have been yeast culturing or "ranching" for some time now. I find it brings me that much closer to making the beer completely from scratch. Everything was great at first and ok still. But Ive noticed smaller growths when making a starter compared to when I first started. So after talking to a few microbiologists, doing lots of research on a site called Homebrewtalk.com (the best site ever ), And listening to a few pod casts. I see no other choice but to move my master stocks into the freezer and re-culture from that to a working plate every 4-6 months. For a better vitality of the yeast master stocks I will remove as much water as I possibly can, move to the fridge for 24 hours then to the freezer. In order to do this I feel centrifugation is the only way to go. But not being able to drop a couple hundred on one I had to break out the old D.I.Y. toolbox and here's what I did.
I attached a sting to the red capped tube by drilling two holes near the top. I tried not to get too close because I didn't want to loose to much structural integrity.

The tube of yeast slurry I got from the bottom of a starter slides right into the red capped tube. Put the cap back on for support and just in case the tube breaks. Grab the end of the string and get to spinin that thing like it was one of those airplanes attached to a string. (Note: Watch out for children, pets, and SOWMBO <----her)

I spin for about 30 seconds to a minute. How long you spin really depends on how many you have to do, and how long you can last with out passing out.

After a quick spin I will pipette off the liquid part top up with more slurry and spin again until I get about 3-4 ml of compacted yeast. Add about the same amount of mineral oil and begin the freezing process.

+1 - Very nice! I like the simple aproach. Now, if I could only do that with my carboy...

HuMmmm I have an old router, 20 dollar speed control from hrbor freight....

I need to find a reason to build a centrifuge now

Great Idea! One tip, the longer the string, the greater the G-forces generated and the less time you need to spin. Of course this may mean swinging outside, and stopping it smoothly to maintain the pellet will be trickier.

So if you strung two of them using one of those collapsible mash stirrers you could do this by drill.

Interesting...

Using a string is something I would have never thought of (because I like to make everything as complicated as possible). Frankly, I'm surprised it worked. That is some great thinking. Good job.

I was thinking about making one of my DIY stirplates into a centrifuge. I just need a round to-it.

You are going to want to add some glycerol (20% or so final concentration) to the yeast before freezing. If you freeze the slurry alone, you are going to end up with mostly non-viable yeast.

What does the glycerol do?

Favorite HBT post of the week! Awesome idea.

Glycerol protects the yeast cell walls as the water freezes. Without it, when the water freezes, ice crystals literally stab and destroy some amount of the yeast cells. It is used by biologists who freeze cells in much lower temps than we do.

Glycerol also will lower the freezing temperature of the mix. I believe some have a problem getting the yeast to freeze at all with glycerol. My freezer goes down to about 0F, and I do get frozen tubes. Just barely, though.

I do about 70% yeast slurry, 15% water, 15% glycerol into the tube, shake really good, freeze as fast as possible. FlyGuy on this forum has an excellent write-up.

My local walmart has glycerol in the bandaid / hand sanitizer area. $3-ish.