Digital Setting Circle Installation

On Celestron C8 Fork Mount

by Grant W. Robertson - Jan 2006

This page and associated pictures shows the installation of Dave Ek's DSC electronics and mounting of the shaft encoders to both axis of theC-8 fork mount telescope.

The altitude encoder was an easy mount to the side of the fork. The swing of the tube through the fork base precluded the addition of any encoder mounting in this area.

The solution I used was to mount a gear directly to the fork hub inside the base along with a mating gear mounted from 3 existing modified pillars within the base.

Installation Photographs a set of photographs showing various stages of installation.

Construction Drawings a set of drawings showing how it all fitted together and the parts to be made.

Clear Sky Clock for the Coatesville PA area.

Dave Ek's DSC Project Home Page.

My C8

eMail me

List of Installation Photographs:

click on image to open in its own page

Telescope Base showing 3 bosses to be reduced in height by 1/4".
The 3 pillars where cut down with a dremmel and then levelled by passing under a 
large drill bit in a drill press.

Azimuth Encoder on mounting plate with gear attached to encoder spindle.

Azimuth encoder mounted into base. The slots provide adjustment to set gear 
backlash to a minimum.

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Gear mounted to fork hub.
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Gear aligned square to hub using spacer ring. Gear must also be set concentric to
 hub.

Completed circuit board. Go to David Ek's link for details.

New fabricated cover to house encoder electronics and connectors.

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Inside of cover with connectors,
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Board mounted into cover.
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Alt encoder  mounted onto fork axle.
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New cover mounted to base.
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Minimal available clearance from swing of fork to new encoder housing after 
allowing for connectors to fit above cover plate.

All cables connected. L to R - One 12v power cord, serial cable to computer, 
RJ11 to Alt encoder. (Azimith encoder is connected inside base).

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