[AZ-Observing] Re: Dove Tail sizes?

Bill VanOrden wrote:
> I am currently machining a new dovetail cap for the Atlas EQG I have and was
> trying to find out what the "standard" size of the most common dovetail
> mounting would be.
> 
> I can make anything I want but figured maybe I should pick a common size.  I
> can accommodate a dovetail up to about 2.5" wide at the widest part.

Bill,
   I've made a number of dovetail plates to mate with my newer Losmandy 
GM-8.  I can send you drawings if you'd like, but the essentials are:

   dovetail angle: 60 degrees
   distance across flats: 2.93"
   minimum dimension: 2.676
   depth: 0.25"

   Or in other words, I used a conventional end mill to cut the plate 
1/4" deep by 2.93" wide, then cut the dovetail using a 60 degree cutter 
to 2.676" across the inside dimension.  This dovetail matches the 
Celestron CGE, current Losmandy GM-8, G11 or Titan, or Astro Physics 
mounts.  Probably as "standard" as you can get.  (Older GM-8 mounts used 
a 50 mm dovetail, which is why I distinguish between those and models 
produced within the past four or five years.)

   A smaller "standard" is used on Celestron CG-5 and Vixen mounts. 
That one is somewhere around 50 mm, but I don't have details.

   Be careful about leaving stock for the final cut.  If you're not at 
your final depth, keep in mind that you need to allow about twice as 
much distance in the X/Y as the vertical.  I've gotten good results on a 
Bridgeport leaving about 0.003" for the final cut and climb milling at 
about 1200 RPM with cutting oil.

                                -- Mike --
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cal_donley@xxxxxxx
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