Maybe not “all”. When you first start out, there is such an overload of information… I think I read it in Practical 3D printing. Actually doing a search now brings me to the very good page on http://reprap.org. But now Google now that I’m very interested in 3D printing, so the results are much better 
@Whosa_whatsis I believe it was the illustrated guide or the wiki.
@Vik_Olliver , I’m pretty sure that it isn’t the problem, I used to have problems with the y belt skipping or coming off due to a botched pulley. But that is a thing of the past, if my belts were any tighter I would be able to strum a nice baseline on it.
Just checking the basics were covered. Stranger things have happened
Thanks for that though.
@Whosa_whatsis the use of a plumb line or spirit level is listed several times in the Wiki build manual under “Assembling the Z-axis” as well as on page 35 of @Gary_Hodgson 's visual instructions.
I’ll edit the wiki over the weekend unless someone wants to do that right now.
For the record, my favorite tool for this kind of work is a machinist’s square (though most smaller carpenter’s squares will work too). Of course, it’s easier with a design made with lots of right angles, rather than equilateral triangles that need to have things mounted to them at right angles.
If I still had access to machining tools I would be using that, unfortunately all I have is a nice set of calipers, which does the job well enough, but not as easily as it could be done with a square.
I must admit I’m quite fond of using an old-school plumb line.