IOptron CEM25p periodic bump
Today was "take apart the CEM25" day again. The mount had developed a serious periodic bump. We're talking about at least a dozen arc seconds rms. Needless to say, when taking 240 second exposures, this can seriously reduce capture time as the worm gear rotates about every 10 minutes.
Near as I can make out, the worm gear had some burrs, probably caused by clumsiness on our part. Probably dragged the worm gear over the disc gear while trying to adjust something on the scope.
I sanded down the burrs and it moves smoothly again. Ultimate test requires clear skies.
That sucks, how did it turn out. If still no good, maybe replace the gear - best way to make a problem go away!
I had worked on the worm gear and the performance improved quite a bit. Then I clumsily dragged the gears again. It happens when we are trying to balance the mount in dec. If we don't loosen the rings enough and force too much the RA slips and the gear drags across the worm. I'll have to work on the worm gear again. I think that maybe the telescope is a bit too much for the mount.