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Yoke bolts

Started by Hockeyman181, 10/16/2020 03:32AM
Posted 10/16/2020 03:32AM Opening Post
Anyone know the Torque setting on the four bolts holding the yoke to the base on a LX200 gps 12" ? 
See pic 
yoke bolts white arrows

Our back yard Pier .That's the cover on top.
Posted 10/25/2020 08:46PM #1
Yoke Bolts solution.
 I contacted, thru the Meade Instruments website, with my question on torque units and values for these bolts in my LX200 GPS. The answer I got was ambiguous at best. The value was '10 inch pounds". Being a experienced machinist I had to question this value. Meade was applying a high grade hardened cap screw to hold these heavy yokes to the base casting holding the major electronics. The size used was a 1/4-20 2.5 inches long. This bolt was also a shank bolt with a min one inch of thread. Using a bolt of this type in an Aluminum casting is somewhat dangerous. Most outdoor applications used by the U,S. Navy and others are known as mixed alloy application. This is due to changing atmospheric and environmental conditions that cause oxidation. 
Also the use of this bolt was not applied correctly, in my opinion. Using the photo I attached in my first posting. All the bolts were the same length! The casting threads on the upper two holes were open ended. The bolts were found to only engage one third of the tapped hole. I set to work to replace these upper bolts. The lower bolts appear to be a blind tapped hole. I did not disassemble the base. Meaning the length of bolt was limited to a certain length. I measured the approximate length needed and ordered four three inch long cap screw of the same value from www.boltdepot.com . Purpose being to engage all of the threads for maximum gripping power on the top two holes of each yoke. The original bolts on the bottom two holes only gripping a min of 1/4 inch into the casting. I increased these bolt length to 2.5 long but fully threaded. 
Assembling these into the scope I applied a hardened chromed six milometer washer along with a gripping washers. I also used a type of loctite fluid to help to prevent electrolytic oxidation between the steel and aluminum . I used a blue non hardening type available at any Home Depot. Torquing the top two bolts to a value I thought was sufficient. The bottom two were set at 15 inch pounds. Slightly more that recommended. I still am suspect of this value given to me of ten inch pounds. 

I hope my story and solution helps others with a yoke bolt issues. 

Our back yard Pier .That's the cover on top.