Why can`t scopes have fixed collimation?

[binarymizar]

Well, the promised clear skies have yet to materialize this eve so it`s time for another stupid question from me!

Why, during the manufacture of scopes, can`t the correct collimation be "set"? Is it because changing temperatures affects the mirrors and tube (i.e. Do they expand and contract)? Or what?

[Kaptain Klevtsov]

hi BM. Usually the 'scopes are collimated at the factory and don't need a lot of playing with. The adjustment is there for tuning purposes only if my Skywatcher 200mm f/5 reflector is anything to go by.

I've checked mine loads of times now and adjusted it once and then back again. I got a badly collimated collimating laser off e-bay so I sent the 'scope wonky, scratched my head then collimated the collimater and the 'scope. Put it back where it had been.

Captain Chaos

[The Warthog]

I'm not sure you could do that, and get it right every time, as a manufacturer. If your mirror was built in to a non-adjustable holder, how would your Quality Control people set it right before shipping, if It was a lttle out of collimation?