Hi guys, I was wondering if you could shed some light on the steps you take while checking the frame's alignment on a table. The past few frames I have done have been loosely checked by sight and string. While everything has been ok, I'd really like to get things much closer. I don't have the money for a legitimate surface plate, but from what I've been reading, a lot of hobbyist use a piece of thick counter top granite and the tolerances are pretty decent. I often see pictures like this:
I guess I'm trying to understand what the different steps in checking alignment are and what all the different tools are used for. I would appreciate any insight as to your process.