You are shimming the saddle “for the mount” orthogonality error
Generally the mount won't have an orthogonal problem. The orthogonal problem usually occurs in the telescope tube assembly when the optical and mechanical axes don't coincide. This normally occurs in Cassegrains, and in the tube rings of refractors.
From: 'Joseph Zeglinski' J.Zeglinski@... [ap-gto]
Sent: Wed, May 15, 2019 10:31 am
Subject: Re: [ap-gto] APCC feature request
I don’t understand your concern, about needing a different saddle adjustment for every scope.
You are shimming the saddle “for the mount” orthogonality error, not for each of the scopes. Once you have the saddle orthogonally corrected, ALL other scopes will then be automatically now aligned to the new correct offset position.