Re: Likely causes of DEC stall?
¿ªÔÆÌåÓýI have also seen binding caused by a marred ring gear ¨C how it happened I don¡¯t know and the owner claimed not to know either. ? I didn¡¯t have any files fine enough to fettle that damage ¨C a 0.5mmt thick dremel disc was also too coarse. ? D. ? From: [email protected] [mailto:[email protected]] On Behalf Of Michael Herman ? Hi Taylor, ? I find my DEC Stalled messages from one of 2 causes: ? a. The DEC axis is not balanced.? This means the load is not in the dovetail saddle at the right position. Especially if it was balanced and I added a few shield (weights the front too much) or my deep sky camera (weights the back too much) To check this best: ? ?Always first install a 1/4-20 bolt in the front of the dovetail (should be a threaded hole there) so the scope can't slip out into the ground. ? ?Next, rotate your RA til the scope and counterweights are horizontal. This removes all weight from the clutch disk and the axis will freely spin. ? ?Then loosen the DEC clutch and this will cause the scope to flip up or down if not balanced (be ready to catch it!!!!).? ? ?Then carefully adjust the scope in the dovetail or else move other weights around (there are sliding weight systems for SCTs anyway).? Before I move my scope I put it back at CWD... because if horizontal there can be a lot of friction with the dovetail edges.?? ? b. The DEC worm is getting stuck. The Belleville washer you put in cannot make the worm get stuck. It's only a spring that keeps the worm from side to side motion.? So worm binding is most likely the worm pushed into the ring gear too tightly, or a speck of something (dust/sand) is jamming it.? So first try spraying in some lube (lithium grease, perhaps, or WD40?) and use a spark plug feeler gauge to slightly increase the worm to ring gear gap.? Always carry a set of US sized Allen wrenches if you go out to the field (or back yard!), because this adjustment is so common.?? ? Chip thinks the binding between the ring and worm is temperature related...as it surely can be. But the major parts that expand and contract radially from the DEC center are all aluminum.? I was hoping the expansion and contraction would scale so the gap would remain constant.? But as Chip also pointed out, if the ring gear is not perfectly centered, or one of the cylindrical needle bearings slightly higher, it will push the ring gear toward the worm gear at a certain high spot in the 360 degree rotation if the ring gear. So as Chip says, run your axis around 180 degrees clockwise, the back and 180 degrees Counterclockwise to be sure there are no high binding spots. ? All the best, Michael ? On Fri, Mar 6, 2020, 12:32 PM Brian Valente <bvalente@...> wrote:
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David C. Partridge