5 tube balancing argument

Ken Howe howe at DARWIN.UCSC.EDU
Wed Oct 9 20:23:35 EST 1996

The first assumption is correct; that is, balance three first, then the
other two.  Along this line of argument, in a 24 hole rotor, 7 tubes can 
be balanced by balancing the first three then the next four.  13 tubes
by 3x3 then 2x2, etc.  In the 5 tube in 12 hole rotor case where the
tubes are balanced 3 then 2, the rotor can indeed be divided into two
equal halves- it's just not easily visualized.

Hope this helps.

Ken Howe
On 9 Oct 1996, John Dixon

> Date: 9 Oct 1996 15:38:58 GMT
> From: John Dixon <jpcd0 at mole.bio.cam.ac.uk>
> To: methods at net.bio.net
> Subject: 5 tube balancing argument
> At the risk of starting a bandwidth hungry inconsequential argument
> (judging by the amount of time spent in our lab jibbering about this), I
> would like to ask a simple question:-
> Some one here was doing 5 minipreps (equal volume) and was loading a 12
> hole microcentrifuge, when he found that the balance tubes had been
> cleared away. He was about to fill another sixth tube to balance 3
> opposite 3, when I said that you can balance five anyway. This started a
> massive debate, which has now come down to three positions. 
> I reckoned that if you put three tubes in, in a triangle ie in holes 1,5,9
> these are balanced. Then you can balance the two others opposite each
> other in holes 2 and 8.
> One guy maintains that this is not balanced at all, on the grounds that
> you can split the fuge into two halves where one half has two tubes and
> the other has three, therefore it must be unbalanced. I am not convinced. 
> Then another guy said that he balances five by putting them in as near a
> pentagonal position as he can ie 1, 3, 5, 8, 10. I dont think this is OK
> because you cannot remove a balanced pair to leave a balanced three,
> although I doubt it does much harm.
> Are there any centrifuge balancing experts out there?
> Apologies for innapropriate use of the newsgroup, but maybe some of us are
> trashing our fuges and more importantly several pints are resting on this!
> -- 
> John Dixon                                        Lab 44 (1223) 334131
> Wellcome/CRC Institute                            Fax 44 (1223) 334134
> Department of Genetics
> Cambridge University    
> United Kingdom                           e-m: jpcd0 at mole.bio.cam.ac.uk

               "You know, it sure would be amino world without RNA"

                                  Kenneth Howe
                     Center for the Molecular Biology of RNA
                             Department of MCD Biology
                             University of California
                              Santa Cruz, CA  95064

                          e-mail: howe at darwin.ucsc.edu

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