I wasn't gonna post this to this group, since it had only metal content,
but I got a neat reply that does have wood content, so here it is. If I
get flames, I won't do it again:
Some years ago I needed a good way to support steel bars that were to be
welded, collared, etc.. to make gates and railings.
Things needed to be really flat for several reasons, which, I'm sure
are obvious to most of you.
I used some saw horses that I have had in my shop for years, but it
was hard to keep them from moving since the floor was not perfectly
flat. Also, as I moved around the area with my helmet on, I'd
occassionally kick a leg and knock the whole thing out of alignment. To
get things perfectly level, I had to constantly be shimming the
components, by as little as 25 thou here and there to make up for all
I chose to make some adjustable 3-Legged saw horses which solved the
uneven floor problem and eliminated the need for shims. By uneven, I
mean uneven by only a sixteenth of an inch or so in 4 feet.
My mentor Bob Walsh, from Pepin Wisconsin also showed me how to make
and use "winding sticks" to make certain that both beams of the saw
horses were parallel (in the same plane).
Here's where you can learn more about it:
I used planks held in B&D Workmates to weld scaffold frames on a
rutted and sloping driveway. With the tops of both planks level and
parallel the frames built on them were flat even though one plank was
half a foot lower than the other.