Re: ATM A cage as secondary holder

[cshaw@ghg.net (Chuck Shaw)]

>From: Mel Bartels <mbartels@efn.org>
>I too have been doing some thinking on this subject - how to build a dob
>mount that is adjustable optically (for collimation) and mechanically
>(to align the mechical axis to the optical axis for more accurate
>pointing and tracking).  I see no way around it: we must be able to move
>one side of the altitude bearing up and down, and forward and
>backwards.

I agree with Mel (as usual!! :-)

Look on my website (in the 14.5" Lessons Learned Article) for a technique
Andy Saulietis showed me for easily and VERY accurately measuring the axis
alignments of an alt/az (aka dob) mount. Accuracies in the 10's of arc
seconds (or less) can be measured and adjusted out....

I also use an adjustment system to very accurately move one altitude trunion
fore and aft along the OTA for getting things aligned.  Actually pretty
simple to add to the OTA.....  I also use an adjustable hardstop inside the
Rockerbox for a positive locator for aiming the OTA parallel to the azimuth
axis during the initialization process.  Simple, accurate, and
quick...(again, kudo's to Andy!)

Chuck Shaw

cshaw@ghg.net (home e-mail)
cshaw@ems.jsc.nasa.gov (work e-mail)
http://www.ghg.net/cshaw  (Homepage: S4 - Stars, Sailing, Spaceflight & Stuff)

("Confetti" Catalina 25 #1)