'Otter'. Build log.

[Voicecoil]

I would say that a decent long straight edge and a large square are pretty essential when building a machine - unless you happen to have access to a large surface table of course!

[Blazing Black Beard]

I would say that a decent long straight edge and a large square are pretty essential when building a machine - unless you happen to have access to a large surface table of course!

So is there any way I can check straightness? Is there any way I can rectify it if it's not straight?

Is there any way I can reference another known straight face without too much expense?

Is there a way I can still use the lower grade steel box section, cut the the mounting points and then tweak the linear rails with something known to be straight?

I see people using the known good face of aluminium extrusion to set their first rail but this build doesn't use that for the structure.