Hi Ed,

I guess the costs depend on your situation. I use an off-cut that is
laying around anyway, and most of it remains when I'm done, so my
material cost is zero. I don't have an 18" precision square, however,
and that would be significant cash for a tool that I would only ever
use to square this sliding table fence.

I agree that the initial squaring can take more time than with a big
precision square, but we're talking the order of a few minutes. Once
the fence is squared, scribe a line on the sliding table so it's easy
to return it to the square position without recalibration.

As for periodic checking of squareness, you just need to grab a scrap
panel, make five cuts on it, break the resulting strip in half and
compare the width of the ends between your fingers. On the other hand,
getting out a square and dial indicator, doing the check and putting
them away takes time, too. If one process takes longer than the other,
I expect it wouldn't be by much. I'd never think to describe making
five cuts on a tablesaw as an "ordeal", but perhaps some woodworkers
do.

I do agree that using the precision square to align the fence every
time you change the fence will give you better squareness accuracy than
using the rotating stop or a scribed line. If I can resolve a scribed
line to 0.010" by eye, and that scribe mark is about 24" away from the
fence pivot point, my squareness would be within about 0.0075" in 18"
compared to your 0.001" in 18". There may be situations in woodworking
where this extra accuracy would be helpful, but I'm at a loss to think
of any at the moment.

As always, your milage may vary.

Cheers,

Tim


wrote:
Hi Tim,

Yep, this is the classic test cut method and it can produce very
accurate results. You've improved on it a bit by including precise
measurement of the final cutoff (via micrometer or calipers) and the
use of a dial indicator to monitor the fence adjustment. Personally, I
can't help but feel that it's actually a more costly and time consuming
method. Sure, you avoid buying a large square but you could still
obtain accuracy to within thousandths with a smaller square (+/-0.001"
at 6" is +/-0.003" at 18"). And, there is some cost in cutting up a
peice of sheet goods every time you want to square up your sliding
table (not to mention the investment in time). The ordeal would make
me reluctant to check my alignment (which I do frequently) and
reluctant to change the setting (cut angles). The indicator/square
method is quick, easy, accurate, and economical - which means it will
be done without hesitation whenever it is necessary.

Thanks,
Ed Bennett