Ad Astra Observatory

This is the balance calculation spreadsheet that I used when designing Trixie.

It’s not the best-documented. I was transferring all the components from a paper napkin into the spreadsheet.

The calculation (weight * distance) is the same concept as laid out in The Book (_The_Dobsonian_Telescope_ by Kriege and Berry). So as I built my parts list (and had things to weigh), I got better and better approximations of the balance.

If I’d been building against the Royce plans, I’d have needed weights for the lower, middle, and upper assemblies, plus two sets of trusses. That would have allowed more balance adjustment than I currently have, since I would have been able to choose where to put the middle assembly, and, thus, the mounting plate. I have a large imbalance when I switch between camera and eyepiece, because my design restricts the placement of the mounting plate. No biggie; it works. Just something to keep in mind. And the spreadsheet let me know that it was going to be a problem before I even mounted up (note that “with photo rig” is ~0 and “OTA only” is nose-heavy by 200 inch-ounces).