Re: [ATM] Upgrading a battered 10" Newt focuser

[Martyn Cole <mgc@dsl.pipex.com>]

In message <42E08A37.4040004@yahoo.com.au>, Bob
<astropabob@yahoo.com.au> writes
>Hello Martyn,
>
>
>A fine "half-round" file and a fine flat file.
>Also a compass (for drawing circles).
>
>My method:
>Push the compass point into a piece of stiff card and draw a circle the
>same size as the original hole in the scope tube. Tape the card inside
>the tube aligning the circle with the hole in the tube.
>This gives an accurite centre for the original hole.
>Draw a 60mm circle on the tube with your compass and remove the
>card as it's no longer needed. (I used a fine line felt tipped pen in the
>compass to draw on the steel tube.) Use the corner of the flat file to
>make "shark's teeth" like cuts _almost_ down to the line all the way
>around the circle. This operation took me 10 mins or so. Then use the
>"half round" to file the shark's teeth off and down to the line and tidy
>up the circle. Also took about 10 minutes.
>Cheap tools, half an hour, and a nice finish.
>
>Good luck.
>
>Bob
>

Bob,

in the end I chose your method for resizing the hole.  I bought a
cheapish set of files and set about it.

It proved remarkably easy and took me just over half an hour to cut and
fit the focuser.

I used a black marker to paint the nuts on the inside of the tube, I
presume this will suffice to keep reflections to a minimum.

Next job is to fit the dovetail for the finder and get everything put
back together again and collimate with my newly acquired Tectron tools.

I'm sure I'll find plenty of uses for the nibbler tool that I also
bought but decided was too "dangerous" for me to use for this project.

Many thanks to all for giving me the confidence to get started.


I'll be back soon I expect for suggestions for spiders to mount the
diagonal, currently it's just a 6.5mm (0.26") bar passing across the
diameter of the tube.


Regards,

-- 
Martyn.
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