Quote:
Originally Posted by AndrewJ
Gday Mark
Just a few comments
Just for info, many people still use the original plastic gears quite happily
and they are quite fit for purpose when correctly installed.
When you look at the toothcounts and gear reduction involved, it takes around a 1% "relative" error in the transfer gears teeth to give 1arcsec error at the OTA. The rest of the geartrain swamps this.
The biggest problem generally identified with the Meades are they use straight cut wormwheels, vs fully enveloped worms, and this can result in more point contact and hence tooth to tooth variability on how the worms interact.
The transfer gear mesh IS adjustable within a set range, and most peoples drives do fall within this range.
You may have been unlucky, but most do fit reasonably well.
The original factory fitting sometimes leaves a lot to be desired,
but most of it is easily tweaked.
That said, the gears in the Meades are not good enough in most cases to allow long duration unguided tracking with long focal lengths.
Andrew
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G,day Andrew
When you mentioned ajustment, are you referring to method 1 in the Peterson kit i.e. loosen one mount bolt whilst tightning the other to engage the gears at a slight angle? If there was another means provided I certainly could not find it and pitching the cogs on an angle is not a viable method as far as I am concerned. I may yet machine up a fully adjustable tray for mine as I am not totally happy with the peterson solution either. The plastic gears may be OK but accurately machined brass or bronze will always be better and when we consider the effect backlash has on autoguiding even if it is only a 1% will improve things (remember I only had about 30% engagement in my RA transfer wheels at best). When setup properly my meade tracks well (certainly good enough to correct with an auto guide camera) but the wobble in the forks kills it. A light breeze puts an end to imaging for the night. I don't know of many mounts that can be used unguided for long focal length AP, and certainly not at the prices meade charges for their mounts in any case.
Mark