Options for installing linear guide rails ?

[blackburn mark]

1. use taught piano wire and shims ?

that doesnt sound like fun

if your using profile rails im guessing the easyest way is to use a DTI guage

for my X axis rails that were mounted to the sides of my machine (80x120 aluminium slotted extrusion and already pretty straight) i fitted one linear bearing and a DTI on a magnetic stand and concentraited on getting the rails parrallel to the surface my bed would be fitted to, mine is only a short machine though (700mm) if i was making a much bigger machine id consider mounting my rails on the horisontal plane if i could and use epoxy
i cant remember exactly what its called now but there is a special epoxy that is thin and slow to set so if you make two channels where your rails are going to be fitted and another channel to join the two together when you pore the epoxy in, it will level to perfection (in therory) you will have to do some research on this though, im not sure anyone on this fourm has used this method.
the problem with a large machine and fine precision is you only have to stub your toe on it and it will go out of true unless its very heavy or bolted to the floor or both :lol:

EDIT: oops... i didnt realise... you have asked a similar question elswhere and got similar answers

[flanagaj]

that doesnt sound like fun

if your using profile rails im guessing the easyest way is to use a DTI guage

for my X axis rails that were mounted to the sides of my machine (80x120 aluminium slotted extrusion and already pretty straight) i fitted one linear bearing and a DTI on a magnetic stand and concentraited on getting the rails parrallel to the surface my bed would be fitted to, mine is only a short machine though (700mm) if i was making a much bigger machine id consider mounting my rails on the horisontal plane if i could and use epoxy
i cant remember exactly what its called now but there is a special epoxy that is thin and slow to set so if you make two channels where your rails are going to be fitted and another channel to join the two together when you pore the epoxy in, it will level to perfection (in therory) you will have to do some research on this though, im not sure anyone on this fourm has used this method.
the problem with a large machine and fine precision is you only have to stub your toe on it and it will go out of true unless its very heavy or bolted to the floor or both :lol:

EDIT: oops... i didnt realise... you have asked a similar question elswhere and got similar answers

This post was to cover the detailed aspect of installing the linear guide rails on an 8' * 4' machine, where as the other was more to do with machine frame construction. I have thought about using aluminium, but I don't think the slot and the linear deviation of the profile is accurate enough.