Convert PDP-11 RK05 disk pack to PDP8 - test-drb@ccmp.vtda.org

6 Mar 2014

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  Date: Wed, 5 Mar 2014 18:41:30 -0600
 From: Kyle Owen <kylevowen at gmail.com> 
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  On Wed, Mar 5, 2014 at 3:42 PM, Paul Koning
<paulkoning at comcast.net> wrote:

 On Mar 5, 2014, at 3:08 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
  ...
 You don't ahve to mechanically balance it as well. Of course just
 centring the disk accurately is non-trivial... 
 What's the required accuracy?  With some patience and an inexpensive dial
 indicator, centering to .001 inch (25 micrometers) is doable; lathe
 operators do it all the time with their 4 jaw chucks. 

 What about using an inspection microscope over the disk surface to visually
 align it? I imagine you could get a bit more precision this way, perhaps.

 Kyle 
For ~$50+ (U.S.) you could get a 0.0001-inch capable test indicator
off of eBay.  Or spend ~$300 for a Starrett (or equal).  (Plus the
cost of an indicator holder.)

Bob