Re: New G11 Question Concerning Stiction
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Hi all, Good discussion on balancing.?? To recap: 1. Slew or position your counterweight rod to be horizontal. 2. At that position, there is zero weight on the DEC clutch pad, so carefully release the DEC clutch knob (watch for the scope to flip over!) and test for balance.? Reposition your scope or scope weights or dovetail until you are fairly in balance.? Perfect balance is not required as the motor, gearbox, and clutches have good strength.? 3. At this same position, if you have a amp-meter (ammeter) on your Gemini power input, you can slew the RA to East and to West and compare the Gemini (mostly RA) motor current.? If the slew current in both directions closely matches, your RA is in balance. If you use this, you do not need to release the RA clutch at all.? So this is the best general approach if you use high friction clutches. 4. If you don't have an electronic measurement of motor current, then still with counterweight horizontal, you can release the RA clutch and gently push the RA axis East then West.? Try to use the same force in both directions and try to judge the angle it takes to stop again.? These should be about the same.? You adjust your counterweights until it is about equal response. 5. If your RA axis clutch area has a machined groove for the "wavy washer" (an alternative form of the Belleville spring washer,) then adding one of these springs in will help push up your scope load, and it will reduce the outer area torque hold of your 4.25 inch OD clutch pad down to about 2.5 inch (the OD of the wavy spring).? All the scope load that was on the 4.25 inch clutch disk will now be on the 3 spokes of the same clutch pad at the diameter of the wavy spring.? It does not eliminate the clutching completely.? It just reduces the torque of the clutch disk.?? 6. If you lower your RA angle to zero using the back ELevation knob (putting the CWD shaft totally vertical) then rotate the counterweight shaft horizontal, then release the RA clutch, ( like the DEC at horizontal ) there will be zero weight on the RA clutch pad.? This adjustment of EL to zero means having to re-polar align your RA axis, and exhaust your wrist by manually turning the back Elevation knob.? Not fun, but it works of course.?? So...DEC is very easy to balance on all mounts, but the easiest and most accurate way to balance RA is to go electronic....use a power supply that shows the amps of the Gemini (mostly the motors).? This works with or without a wavy washer, for all mount versions new and old, and all Geminis new and old.?? Best regards, Michael On Sun, Jul 4, 2021, 5:17 PM Brian Valente <bvalente@...> wrote:
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Michael Herman