5 tube balancing argument

[Ken Howe]

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
wrote:

> 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
               http://www-biology.ucsc.edu/people/areslab/ken.html