Hi Bojan,
You helped me a lot with ideas how to proceed, many thanks!
Now I have ordered timing pulleys, I choosed a 60 teeth pulley with no flange and a 16 teeth pulley, it gives a non standard 3.75:1 ratio. Small pitch, wider belt and bigger pulleys should give a bit less elastic and smoother run compare to the normal kits, at least according to my ideas and help from forums. But I can not use the handterminal with this non standard gear ratio, but I never do that anyway.
I bought them at
https://www.active-robots.com/ in Great Britian because I live in Europe Union and then I don't have to pay custom fees and taxes. They was one of few that could offer the 60 teeth pulley with a 12 mm diameter bore.
I have done some updates and put in more links with information:
http://www.astrofriend.eu/astronomy/...ebuilding.html
At page three there is a link to a belt length calculator.
/Lars