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Hello Douglas,
Good that you asked. I meant it the opposite way,
giving external diameter plus wall thickness of the
tubes:

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
rule.

As of now, I cannot measure the diameter to any
precision.
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
walls...

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
Wolfgang





> 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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