Re: Mark IV Mount

[Chris Albertson <chris@topdog.pas1.logicon.com>]

Tom,

I read your TN42 on the mount and housing.  First off, I liked
the model photography.  It must have taken some effort to do
but the result is better then a three view or isometric.

Just two ideas about the housing:

1) Why not use inverted "T" section for the rails?  Use a
   V-belt pulley for the wheels.  Avoids the problem of junk
   in the tracks.  Steel T is also _much_ stronger than
   Al. channel.  As a backup to the wheels a hardwood block
   with a slot in the bottom can ride the "T" to prevent
   a disaster in case of derailment.

   Alignment and level will need to be near perfect unless you 
   have a big motor to move to roof.  Al. channel may conform 
   to the wooden support and there is no way to adjust after 
   installation.  A steel T is strong enough that it does not
   need continuos support.  It could span 3 or 4 feet between
   adjustable support points.  Adjustment for parallel and level
   could be with shims, stacked washers or whatever. 

2) At the North end, rather then terminating the rails, let them
   extend for 12 inches or so but bend them downward at about 
   30 ~ 45 degrees.  Let the roof extend to the North about 12
   inches also.  This extension to the roof needs to be hinged,
   or maybe it is just a rubber flap.  In either case the inclined
   rails force the roof extension up as the roof moves south

   Other ideas would work too The idea just that as the roof
   slides north "something" falls off the north end of the track
   and pops up as the roof goes south.
-- 
--Chris Albertson

  chris@topdog.logicon.com                Voice:  626-351-0089  X127
  Logicon RDA, Pasadena California          Fax:  626-351-0699