what is consider low backlash for gear box?

[eloid]

what is consider low backlash for gear box?
5 arc-minutes backlash or less
my other question is if you made a diy belt gearbox 5:1 or 10:1
what kind of backlash would be typical for this design...assumming
it was made with milling machine.. an tolenace where kept tight.

[HuFlungDung]

Some of my books say 6 arc minutes for ratios from 3:1 to 10:1 and 10 arc minutes for 16:1 to 100:1 (more gears involved).

A belt drive with timing belt may be comparable, depending on the static friction of the load being moved, and how much it stretches the belt upon reversing. I've used belt drives on knee mills without significant problems traceable to the belt stretch versus nut lash, etc.

[eloid]

any other spec i should consider when looking for planetary gearbox
for 5x10 machine using 900 0z-in motor or higher?