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I wouldn't say that a fork is necessarily more complicated than a GEM , I just like to over engineer and get it right the first time with out compromises.
I did consider a GEM for a while but soon realised that when you start talking larger scopes a friction drive is by far cheaper than a worm wheel drive to make.
I also don't like the meridian flip that is required with a GEM.
You can use a friction a drive for a GEM but general rule of thumb is to try to make the friction disc 1.5 - 2x the size of the objective so you can imagine how big and cumbersome disc like that would be on a large GEM scope.
There are ways around it by using a smaller disc but then things get more complicated in getting traction.
A fork lends itself very well to a friction drive with large discs.
You use largish discs for getting a good primary reduction and to allow for more traction torque to be used on the bigger rim.
With a worm wheel set it is common on well constructed mounts to use a gear the size of the objective or a bit smaller depending on scope design , and of coarse a GEM is more suited to some scope designs than others.
So don't discount a fork , you just don't have to go quite as big as mine.
My next scope will more than likely be a 16" f6 as I like the Royce Conical Cross Section mirrors and they only come in 16" size at the moment but am hoping for larger in the future.
Are you listening Rob
Mark
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