[RedGiant (David)]

Hi All,
Great forum, and very interesting to read. Not that I get a lot of time to loiter!
Whilst I've yet to purchase my first scope (looking at getting a Dob - but finances dictating the size). My question relates to trying to get some form of tracking facility attached to any future dobsonian. I had a friend many years back who had a 10 or 12 inch Dob, who had a worm drive attached to its basic Alt/Az mount. It wasn't a go-to nor any form of tracking device. It simply was a worm drive that as soon as you finished moving to any new position it would start tracking that object and keep it centred.
I've seen the Argo-Navis thingamajig and wished I could afford it. But to be honest I don't need anything that expensive.
Does anyone know of any web links to sites that can tell us how to build a simple worm drive of the type described above? or even purchase one that is relatively cheap?

For me I would just 'love' to by a Go-to but in Oz thats prohibitively expensive. I want the largest aperture I can afford so $'s to spend on the rest will be seriously depleted (I'll add what I can in later years), but having to continuously move the scope to keep up with a constantly moving object (from looking through other scopes) would be quite frustrating long term.

Thanks,

David