ETX TECHNICAL TIPS Last updated: 31 December 2004

ETX90 Fork extensions

Sent:	Wednesday, December 29, 2004 00:46:57
From:	Pete Stoves (pete@stovesy.freeserve.co.uk)
I have recently started along the astrophotography road, and felt that
the use of the flip mirror system and a rear diagonal prism and eyepiece
would help when my camera is attached to the main eyepiece. I was
struggling however with the alt movement of the 'scope. with the
diagonal fitted, the 'scope could not reach anywhere near the zenith, so
I came up with the following solution.

Spacers which fit between the etx base and the existing fork arms,
machined from 25mm thick hard Grey PVC. These are easily as strong as
the standard etx parts (I was quite surprised how plastic y things are
in the etx). I hope the photos show how things fit together. This
project does require complete disassembly of the etx mount, so take care
if you decide to do something similar.





This is Layer 1, The screws shown fix into layer 2. There are 2 posts
which emulate the existing posts on the fork arms.





This shows both layers. the top layer shows blind holes which receive
the posts on the etx fork arms. Layer 2 has to be attached to the fork
arms first by screws, when these are in place, layer 1 can be affixed to
layer 2.





This shows, layer 2 fitted to the fork arm. The control cables are fed
through both layers (the connector block has to be temporarily removed).





We have now attached layer 1 to layer 2 with the screws shown. the head
of the screws are recessed so both flat surfaces mate.
 




The finished article, Layer 1 is now fixed to the base, by using the
existing Meade screws. Reconnected everything and test.

I have thought that the declination stops in the fork arm could be
removed. This would allow for observations nearer the horizon for users
with equatorial mounts.

Any questions please don't hesitate to ask.

Pete Stoves
pete@stovesy.freeserve.co.uk

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