On May 9, 12:12*pm, " wrote:
What acuracy is needed in terms of building a trailer

The biggest need is for the distance from the hitch coupler to the
tire to be the same on each side (means the axle is on straight
relative to the hitch, and the hitch is centered correctly).

Square is nice (matching diagonals).

For the rest, you can probably get away with +/- an 1/8th or more.
For individual joints, this variation can be filled when welding. *If
the main frame is accurate the rest of the structure is much less
critical. *At that point accuracy becomes more a measure of how hard
do you want to work: *The more accurate the cuts, the less work you
have to do to adjust or shim everything when clamping and lining
things up.

I would think that one of the handheld units would be more than
sufficient for what you want to do. *Take your time measuring and
calculating (take notes as you go if you find you have to change
things so you can remember why if you have to set it down and come
back to it), mark your lines across the whole piece with a square
rather than just a dot where your measurement is, it will give you
something to follow with the saw. *If a cut is starting to stray,
consider starting the cut over again from another side of the piece.
Get extra blades.
* --Glenn Lyford

Is the key the axle spring seat centers are equal distance from the
hitch on both sides or the tires are on both sides as you said?