[AZ-Observing] Re: Dove Tail sizes?
- From: Michael Collins <cal_donley@xxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Mon, 16 Jul 2007 00:08:47 -0700
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 --
--
cal_donley@xxxxxxx
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