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Curved-Bolt "Barn Door" Mount

astrophotography DIY eq equipment mount


Alen Koebel

Curved-Bolt "Barn Door" Mount

This is a curved-bolt (AKA curved-rod) variation of a barn-door mount (tracker) that I made in 2002 and used with my 35mm film cameras. It uses a 10-32 threaded rod bent into a curve to increase the separation between the two boards at a constant rate (a straight rod wouldn't keep a constant rate). A gear driven by a 1 rpm 12VDC electric motor through an identical gear turns on the bolt threads, increasing the separation at the required sidereal rate. It performed decently with lenses up to 135mm, allowing tracked exposures up to 10 minutes (the longest I tried).

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