Has anyone had experience with or considered a friction drive rather than toothed drive? I know it gets good reviews in high end systems but why wouldn't you be able to machine out two diameters and use stepper to work with the resultant ratio? . Some reasons might be problems:

1) The small contact area between metal rollers, while sufficient for low speed tracking performs differently at high speed slewing?
2) The risk of slipping can lead to loss of position and potential collisions
3) Exact specific ratios are easier to achieve by # of teeth rather than carefully machining two diameters to match
4) What is popular and working is tried more often by others hard to get suggestions for machining
5) Possible environmental effects on performance? I don’t know.
Seems a stepper/encoder/controller solution would work great with a friction drive at any size and be in the reach of DIY fabrication of the rollers.

found this link www.dfmengineering.com/news_telescope_gearing.html

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