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Restoring an Old Star-Liner Equatorial Mount
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Restoring an Old Star-Liner Equatorial Mount
(the restoration process can
be viewed at: https://youtu.be/CusD8MXkoSc
I have owned a large Star-Liner Equatorial Mount with 2 inch axes for over 50 years and in that time it has held a homemade 8 inch f/7 Newtonian, a homemade12.5 inch f/8 Newtonian, a 14 inch SC, a 6 inch refractor, an ATM 10 inch true Cassegrain. Here a few examples of scopes on my Star-Liner mount used for viewing the night sky from our property in SE Pennsylvania:
Currently my Star-Liner holds a massive12 ½ inch true Cassegrain made by Parallax. Despite its weight, the Cassegrain does not stress the weight capability of the Star-Liner mount. Even with a reasonable wind, the hefty Star-Liner offers comfortable and steady visual tracking views of celestial objects. Between the scope’s rings and the counter weights on the DEC axis, balance is incredibility easy and accurate and the sliding weight on the upper end of the Cassegrain makes balancing with 2 inch diagonal and heavy two inch eyepieces a cinch.
I have a deep fondness for the reliability, simplicity and ridged stability characteristics of my 50 year old Star-Liner mount. So, when another Star-Liner mount became available, I jumped at it and basically I rescued it from becoming Dumpster Food. My “new” Star-Liner is smaller than my original one and has only 1 ¾ axes instead of 2 inches. On arrival, it had no pier, or counter weights, or setting circles or a Hurst motor for the clock drive. So the task ahead included restoring the Star-Liner and building a pier, new setting circles, counter weights, adding a Hurst motor to the clock drive, etc.
My “new” Star-Liner was shipped from Arizona and so it has acquired the name of my “Arizona Star-Liner”. It was shipped in a wooden chip box shown here.
The mount arrive in February 2021 in a sturdy shipping container and was removed for inspection and plans were developed for restoring the mount. The axes were badly corroded and would need a thorough cleaning followed by polishing and smoothing out rough spots on each axis.
The first step involved taking the Arizona Star-Liner apart as shown here with both axes now polished. One of the ball bearings on the RA axis was corroded and unusable and had to be replaced. Pressing out the old bearing and pressing in the new bearing produced considerable anxiety as I had some fear the bearings aluminum housing might crack. All components were cleaned and parts requiring lubrication were lubricated with silicone grease.
Since the mount came with one unusable setting circle, I made setting circles out of an Aluminum 10 inch OD disk ½ inches thick which I bored with a centered 1 ¾ inch hole in both the RA and DEC setting circles so each would fit onto each corresponding axis. The boring of the 1 ¾ hole is shown next.
I also wrote a computer program to generate the numbering pattern for the setting circles, and pasted the patterns onto the 10 inch disk. For smooth rotation of the setting circles during coordinate selection, the region centered around the 1 ¾ inch bore is covered with a Teflon surface. For pointing to the coordinate on the setting circle, the possible use of a laser diode pointer is being developed instead of the traditional mechanical sharp edge pointer. The details of the setting circle computer program is available here.
Next, I made counter weights to slip onto the DEC axis. The counter weights were made from an automobile’s brake rotor. It seemed natural to use rotors used on a Saturn car since the purpose of the system under construction is for astronomy. Each Saturn brake rotor weighs 9 pounds and they can be stacked on one another and bolted together to make nearly any desirable total weight in 9 pound increments. The center of the master counter weight is welded to a 1 ¾ inch ID cylinder to fit on the DEC axis.
Using a 5 foot long cylinder with a 6 inch OD and a 5 ¾ ID and a 12 inch long base cylinder with a 6 inch ID, I assembled a pier with sturdy 2 inch wide angle iron legs ¼ inch thick to hold the Arizona Star-Liner mount. The base legs were welded to the 12 inch long cylinder
The base legs of the pier were equipped with pneumatic tires for portability on our property. Each leg weighs 22.8 pounds and the 5 foot long steel cylinder pier weighs about 40 pounds. The outer span of fixed wheels, i.e., non-steering wheels, is 56 in., and the outer span of the steering wheels is 24 inches. My pier’s total weight with wheels is about 125 pounds. The legs are removable for transportation. As a last step, the legs and 5 foot pier were painted a flat black.
The Arizona Star-Liner Equatorial Mount soon proved to be another excellent mount in the Star-Liner series. Of course, it does not have a GoTo capability, which didn’t exist 50 years ago in amateur telescope mount. But for someone like me, who grew up finding deep sky objects through star-hopping and setting circles and pure memory of star patterns seen in the eyepiece, a GoTo capability, which I have enjoyed on smaller but less reliable mounts, although admirable, is not a necessity for me. The incredibly long flawless operation of my first Stat-Liner, purchase around 1970, may be the result of the absence of GoTo slewing. In the final product, the 5 foot pier places the eyepiece in a comfortable position. And with Jupiter and Saturn now at a negative declination, I can view those planets very comfortable without a diagonal and without bending my neck. Making such observations is a joy to experience. As a reminder, details of the restoration and rebuilding process can be seen at: https://youtu.be/CusD8MXkoSc.
Epilog: Arizona Star-Liner Mount Gallery
Pictures are worth a thousand words as perhaps the following selection shows:
- BillinBallard, RogerRZ, Jim Curry and 22 others like this