In article , Trent© wrote:
On Wed, 20 Aug 2003 16:02:02 GMT, (Doug Miller)
wrote:

If you have an accurate square, you already have all the equipment you need.

NOTE: if your square also came from Sears, you do not have an accurate
square.

Hogwash!

If you think this is "hogwash" then you've never had your hands on an accurate

square -- or else your definition of "accurate" differs considerably from
mine.

I do NOT consider 89.95 or 90.05 degrees to be accurate. Maybe you do. But
that is about the best you're going to get from Sears.

I consider it accurate if I get an accurate cut across the entire
length of the work area...usually 8 to 12 ft. for most of my work.

What device are you using?...to discover that a square is off .05
degrees? lol

Feeler gauges to determine deviation. Quick mental calculation to determine
deviation per unit length. Calculator to convert deviation per unit length to
deviation in fractional degrees. It's simple trigonometry.

And are you drawing that 'square' line with an 8' for
12' square? Or are you putting another fallible scribing tool on the
work to finish the line?

As I mentioned in another post, I'm using the square to align my table saw,
jointer, and radial arm saw. I never mentioned using it to scribe lines, and
in fact I don't do that.


I've got several different kinds of squares...none that I paid more
than $20 for...and they're all dead-on. They can easily be checked
for accuracy before you purchase them.

"Dead on" means no measurable deviation.

Correct...by a 'measuring' device'.

Unless you're using precision
measuring instuments (e.g. a dial indicator, or a set of feeler gauges), you
have no basis for making that claim. Making a pencil mark, flipping the square

over, and making another pencil mark is sufficient to demonstrate approximate
squareness (+/- 0.05 to 0.1 degrees), but is insufficient to support the claim
of "dead-on" accuracy.

I meant 'dead-on' for my purposes, of course. Why would you think I
meant differently?

Then you're using terminology incorrectly. Dead-on is an absolute term, not a
relative one. There is no such thing as "dead-on for your purposes". It's
either dead-on, or it's not.

What you meant was it's close enough for your purposes. And I have no quarrel
with it, stated that way.

How far off do you think the bubble on a LEVEL is? lol

Irrelevant.

Its all relative. If you think a line drawn with a square should be
dead-on...meaning NO deviation whatsoever...then I have never had a
proper square.

And I don't think you have, either.

Quite so. I *do* have one that's accurate to +/- 0.001", though. You don't.

And one is from Sears.

Either your definition of "accurate" is *very* different from mine, or you
don't know how to measure it.

Obviously, its very different.

I have two 12" combination squares, a Starrett that I use for woodworking, and
a Sears that I use for rough carpentry. The Starrett is square +/- 0.001" over
its entire length (90 degrees +/- 17 arc-seconds). The Sears deviates from the
Starret by 0.011" along its length (90 degrees +/- 3 minutes 9 seconds).

Hardly accurate across 100 ft. But just as accurate as any of
mine...for woodworking.

No, it's not. Align your table saw with your square. Then use that square to
set your miter gauge at 45 degrees. Now cut a mitered frame, say 30 by 38
inches (which happens to be the size of my living room coffee table). Assemble
the frame. Then measure the gaps at the joints. Maybe you're happy with what
you see.

When I do this, the joints have no visible gaps, and a 0.002" feeler gauge
(the thinnest I have) cannot be inserted.


By *my* definition, the Sears tool is not accurate. Perhaps by your definition
it is.

Yes...it is.

If it's good enough for you, fine. But don't claim that it's "dead-on" when
you understand neither what the term means, nor how to measure it.


Even most of the $2.95 framing squares are dead-on accurate nowadays.

Speaking of hogwash...!!

You say three-dollar framing squares are "dead-on accurate". I say, prove it.
Compare one against a square of known accuracy (e.g. a 24" Starrett), and
measure the deviation with feeler gauges. Then post your results.

I've got several 'squares' that I've
built...2'x4'...2'x8'...etc...that are 'dead-on'...for what I want to
do.

"Good enough" is *not* the same as "dead on".


--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)