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    Re: Cylindrical Slide Rule tube poll
    From: Wolfgang Hasper
    Date: 2010 Jan 23, 22:14 +0100

    Hello Douglas,
    Good that you asked. I meant it the opposite way,
    giving external diameter plus wall thickness of the
    D = external diameter
    d = internal diameter
    inner tube    	D=54, 	d=52  	x1            235 long
    interm. tube  	D=58 	d=56 	x1            225 long
    outer tube    	D=62 	d=60 	x1            222 long
    These are the HR dimensions as given by R.v. Riets
    paper.  The theoretical clearance of 1mm will be
    reduced by the scale itself and maybe a transparent
    protective layer. The rest being compensated by felt
    lining.  A locking mechanism is assumed.
    My idea is to more or less make an actual reproduction
    of a HR which to me seems to be the best useable
    implementation of a cylindrical position line slide
    As of now, I cannot measure the diameter to any
    No tubes exist so far. My idea is to check the
    continental/german possibilities to have some
    manufactured (from Al)
    As a basis for all our joint efforts I am trying to
    determine the potential quantity, making that list.
    As of now, there are 10 persons interested in 14 sets
    of tubes, totalling 4.5 metres of each size of tubes.
    Should you be successful in finding a UK source
    earlier, I am sure all of us will be happy to use that
    and I will stop any activity at once.
    As far as I could find out according to a  standard
    tolerances for extruded aluminium tubes should be
    around 0.2mm (in diameter I suppose) which will force
    us to adjust the scales.
    I also thought about slightly larger dimensions and
    turning to exact size. But I am pessimistic, it is not
    only expensive but quite challanging to get the tube
    on the lathe without distortion given the thin
    I received some information on perspex / plexiglas
    No thin walled tubes available:
    format D,d,t
    40	36	2
    	34	3
    	32	4
    	30	5
    50	46	2
    	44	3
    	42	4
    	40	5
    60	56	2
    	54	3
    	52	4
    	50	5
    70	64	3
    	62	3
    	60	5
    Standard length is 2 metres. tolerance on ext. dia. is
    +/-  0.5 mm for the 40mm tubes and +/- 0.8 mm for the
    larger ones. Prices in the range of 10 EUR/metre
    It is possible to combine those to a slide rule with
    some weight...not ideal but affordable.
    So far for now
    > Hello Wolfgang,
    > Just to be  clear could you please confirm these
    > figures are meaning what I think they mean?
    > You say:
    > > The HR1 uses Aluminium tubes
    > > (all dimensions [mm])
    > >
    > > inner tube    54x1            235 long
    > > interm. tube  58x1            225 long
    > > outer tube    62x1            222 long
    > ------------------
    > Can I make sure you mean:
    > 54mm inside diam of the inner tube,  56mm outer diam
    > of the inner tube. 58mm inner diam of the
    > intermediate tube, 60mm outer diam. 62mm inner diam
    > of outer tube,  64mm outer diam.

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