Tom's Telescope Project
with a
wood Yoke Mock-Up
Statistics:
The Pier is 4-inch OD x 36" high (ie base plate-to-collar) .. larger is better, however.
Base Plate is 12 x 12-inch
Polar Axis-Mounting Plate is 8-inch by 12-inch
All metal plates are 1/2-inch steel
Yoke is designed for 4-inch diameter Telescope (and can be (re)used for 8-10-inch diameter Telescope)
The weight is approximately 90 lbs (metal only, no scope, no yoke man!)
Design Characteristics:
Notice that the extended polar axis-mounting bracket (8" x 12") moves the center of gravity toward the "right" (in photos #2 and #3) and, yet, a vertical hanging telescope will clear the pier assembly. Most of the weight of the polar bearing lies above the pier, itself.
Any future drive gear assembly and motor (not shown) will be bolted and placed under the polar axis-mounting bracket . The weight of the drive gear asembly will also help balance the opposing weight of the telescope hanging off the end of the yoke.
Quite by accident I was able to pick up the polar bearing (shown below) for $10.00 (!!!) However, I was planning on using a large diameter pillow block bearing. This bearing is critical as it is the only moving component once the scope has been locked in ... it must be tight. The ID should be as large diameter as possible.
The weight of all this far exceeds the weight of anything I'll load onto it (including my 13" dia. scope). So far it seems extremely stable--even open like this and under a moderateto-heavy wind load.
Design Changes (for next time ?):
The screw type azimuth locking nut which holds everything to the pier is not satisfactory. Better to make a smoothly rotating collar .. and then lock it to the pier with a set screw.
| #1) General View w/Yoke Mock-up | #2) Side View-Polar Axis | #3) Side View w/out Yoke | ||
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| #4) General View w/Yoke Pointing East | #5) Yoke and Polar Axis-Bearing | #6) Polar Axis-Bearing on Mounting Plate | ||
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| #7) Close up of Alt-azimuth Assembly | #8) Looking through Polar Axis | #9) Looking from Below | ||
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| #10) Base Plate | ||||
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