Re: ... and daytime polar alignment


Wayne Hixson
 

One thing about the Starrett glass levels. If you leave it on the scope or counterweight shaft and slew to the next position, it WILL fall off and it WILL break and it WILL be expensive to replace! I know!

Wayne


On Apr 21, 2019, at 10:09 AM, Mike Dodd mike@... [ap-gto] <ap-gto@...> wrote:

 

On 4/21/2019 12:52 PM, 'Joseph Zeglinski' J.Zeglinski@...
[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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