Re: ... and daytime polar alignment


Mike Dodd
 

On 4/21/2019 12:52 PM, 'Joseph Zeglinski' J.Zeglinski@rogers.com [ap-gto] wrote:


Hi Mike,
One thing that always concerns me is whether I can rely on a bubble
level – of any precision – to be correct when placed on the
counterweight shaft. I have about 60 lbs at the END of mine, and surely
there must be “some flex” of the shaft, or even a slight dip in the
threads at the end of my AP900/1200 mount axis, or its end cap.
Yes, that's a definite possibility. Placing the level as close as possible to the threaded end of the shaft is best. But there absolutely could be some mechanical inaccuracy in the shaft.

So, I
prefer to place the bubble level right on the mount body itself. There
should have been one in the design, possibly where the AP nameplate was
fastened.
That sure would have been nice. Too late now.

On the DEC balance, I hold the level right on the doveplate edge –
where the Starrett groove fits nicely along the D-Plate edge - since
the OTA can flex, especially a truss, according to some.
That's a very good idea.

--- Mike

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