Re: Mount Clutch Tensions
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Hi Rodney, Bob, and gang, Bob raised the question about how some folks have to really wrench down the clutch knobs to get the gear to stay put...other don't seem to. It does not make sense to new users of the system... so here goes a quick explanation of the design, what goes wrong, and a simple solution... The mount was originally designed (G11, GM8) to be a push-to, with its very nicely accurate RA and DEC markings.?? Only later when the astrophotography field really developed, did everyone find these mounts to be superior due to their high stability and low PE. The Gemini system provided complete GoTo, and its easy computer interface makes it a delight to find deep sky targets for imaging.?? But... the clutches... are the same as originally designed for push/slip operation.? The clutches lead to trouble for AP work with heavy mass systems.? ?There are reports all over the web about how these slip.. a subtle bump in the dark and ... much wasted time re-synching or re-aligning while the precious imaging target slides across the sky.? ? ? The 3-handled clutch knobs are a benefit, and extra cost, but the system still slips for high scope weights.?? ? Losmandy supplies a plastic disk, which they now say they have a higher friction plastic, but they did not have them in stock for my GM8 or my older CG11. The biggest problem is not really the friction, it is inevitable oily contamination. ? ? I found was diffusion of oils from the lubricated needle bearings, and the tight surfaces allow that to move into the clutch surface by capillary action.?? ? ? Over time, the clutch disk will get an entire surface coated in oil and that of course can never by held firmly by the clutch mechanism. The nice website has written that cardboard is a better clutch material... but of course cardboard can get moist...and does not resist oils. I have found a much better material for this purpose - oil and water proof and higher friction.?? ? ? I use mine on the GM8 and CG11, and have a heavy Meade LX200R 12 inch SCT on the CG11.? It does not budge during imaging.?? ? ? You don't need much clutch knob force to hold the scope system quite firmly.?? ? ? ? ?This saves possibly distorting the flat metal surfaces.?? ? ? The RA and DEC will still budge if strongly pushed, but not with a casual bump in the night.?? ? ? If one sets mount limits, particularly for unattended astrophotography, there is no issue, but even if the system RA were to run into the mount, these clutch disks will slip to prevent serious damage.?? Let me know in an email to mherman346@... if you want a set of these improved clutch disks for astrophotography work.? ? ? ?I have? G11 (2 of 4.25 inch OD), GM8 (2 of 3.0 inch OD), and also for my own CG11 (one each 4.25 and 3.5 inch OD).? Let me know if you need a different OD for Titan etc.? They mail in a flat envelope that should ship at low cost.? Very best, Michael On Wed, Oct 11, 2017 at 11:33 AM, tom loeblt@... [Losmandy_users] <Losmandy_users@...> wrote:
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Michael Herman