Thanks for the sympathy
It was, heck it will be again, a great scope. I designed it for looking at the moon and planets. It has a 10 F8 Primary mirror and a 1 inch secondary mounted on a very thin fishing wire spider.
The scope won first place at the Texas Star Party, a special award and 1st place in small optics at Stellafane in Vermont
. At Stellafane only 4 of the 10 Judges saw the scope during build judging. Those 4 talked the others into giving it an award even though they missed it
Took me so long to make the primary mirror that I ended making a machine to grind with
Probably show that later.
I was poor and a great gear for the scope mount was about 1600 while an OK gear was 800. A regular gear drive was out of the budget so I had to come up with something I could make.
The large hunk of aluminum on the side and bottom of the mount is a slip clutch. I built an arm with very tight tolerances that connected the slip clutch to the fine thread screw attached to the stepper motor.
The problem was how to turn a rotary motion of the telescope axis into a straight line motion the fine screw would take. I solved that by making a "U joint" at the end of the arm. The U joint held a brass cylinder in a block and was threaded for the screw. The other side of the brass cylinder had a precession rod attached that was inserted into a reamed bore at the end of the arm. As the stepper turned the screw the brass cylinder moved along its length and the arm followed.
Over the years people have tried this type of drive using a bent screw, was pretty southern engineered if you ask me and I never even tried it.
Problem was that the arm moved in an arc and the screw turned in a straight line. The arm would bind up and place force on the screw and bend. My solution was to place a u joint and bore on the end of the arm so that as the screw turned the arm would automatically lengthen and shorten depending on its position on the screw. On the end of the screw the arm would be long, get shorter as it neared the middle and lengthen as it traveled to the other end. The problem with using regular motors to turn the screw was the inability to control and vary it's speed.
By using a stepper motor and two contact switches we could program the screw to turn to a "start" position, then start moving the screw to the other end counting it's steps so that it knew where it was and how fast it needed to revolve to keep a star in the center of the eyepiece. The arm extended and contracted as needed on the shaft and life was good
I had a good friend design and program the small black box computer you see mounted to the arm of the mount.
When the screw reached the limit switch at the end of travel it would sound a garbage truck backup alarm and after a pause, for people to move out of the way, it would rapid slew back to its start position and resume tracking.... I loved that backup alarm
After trying to explain all that I remembered why I like videos better!