'Otter'. Build log.

[Blazing Black Beard]

There's a really useful motor/ballscrew calculator spreadsheet somewhere on this forum which I found really useful, though I can't seem to find it at the mo. - worth digging out and putting in your predicted mass/lengths/desired speed to see what motor/power supply suits.
On the subject of steel tubes I stumbled across this last week whilst looking for something else:
https://www.barrettsteel.com/product...recision-tube/
other vendors seem to do similar products, it appears that the straightness spec. is better than normal stuff.

Voicecoil thanks for that. I'll try to dig out the spreadsheet.

Good point about the straightness spec. I may just use the 100x50x3 section as strengtheners in the lower part of the frame if it's not as straight as required. Is there any way I can check the straightness and rectify the rails should I need to? I can see lining up the rails might be an issue if I just use a gauge and the face of this box section should it not be adequately straight.

[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.