Subject: checking for square?

From: Mark Raynes <[email-masked]>
Date: Mon, 31 Mar 1997 08:44:33 -0500

I have been having fun at woodworking for about 5 years now. One thing
that has always given me trouble is getting an assembly good and square.
I follow the standard method of measuring the diagonals to make sure
they are equal, but I get mixed results. Sometime the clamps are too
close to the corners, or too close to the frame that I can't slip the
tape measure underneath the clamps. All the tape measures have some play
in the ends,  and I wonder if that influences the results. Can the
actual width of the tape give inaccurate result? And when it is not
square, loosening one clamp and tightening the other makes little
difference.
Any information about techniques that you use would be greatly
appreciated.

I realize from your responses that  many of you are highly skilled so
these might seem like silly questions.  But I am beginning to build a
set of kitchen cabinets, and I realize that must get better at this real
quick!
I assembled my first case and actually got that square, but just cut
apart the first face frame because it wasn't. I've tuned saw as good as
I can get it, and I even bought a set of bessey clamps to help. However,
I don't think tools are the answer. Craftsmanship must be the solution.

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From: "John Hofstad-Parkhill" <[email-masked]>
Date: 1 Apr 1997 03:04:34 GMT

Mark:

Lot's of thoughts, but here are a few:

1). Try an inside measurement. I use my lufkin folding rule, but just about
anything will do. Lee Vally sells fancy brass knobs to make one - if you're
a tool junkie like me. Which brings me to...

2). The play on an end of a tape measure is supposed to allow you to make
accurate inside & outside measurements. How well this works in actual
practice is subject to debate. Which brings me to...

3). The actual measurement in say inches is irrelavant, what matters is
that whatever it is - it's the same. So slop or no slop as long as it's the
_same_.

4). Use a third (or fifth) clamp diagonally across the carcase to bring it
to square.

5). Use a known square part (like the back) to bring the carcase into
square.

6). Use a flat (really flat) and level surface during assembly.

7). Remember that when you're checking square on one end of the case that
it doesn't mean that the opposite end is sitting square.

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From: [email-masked] (Garrett Lambert)
Date: Tue, 01 Apr 1997 11:21:43 GMT

Try using a couple of "story sticks" instead of a tape measure. Just
cut two pieces of hardwood to less than the shortest diagonal length
you'll want to measure. Using a rasp or a sander, "vee" one end of
each stick - for assistance see the earlier thread on making a point
on the down-pointing end of a stick.  Take a very small C clamp or
spring clamp and  lightly clamp the two sticks against each other with
a vee end pointing out. Set them inside the carcass and extend to the
distance of one of your diagonals. Try the other one. etc., etc. and
use a bar clamp as per suggestion 4) below.

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From: [email-masked] (John Paquay)
Date: 1 Apr 1997 15:34:17 GMT

In article <[email-masked]>, [email-masked] says...
>I don't think tools are the answer. Craftsmanship must be the solution.

Carcases, IMO, are much easier to make square than are
face frames, because face frame pieces are so much narrower --
a face frame of, say, 2" wide pieces doesn't give you a lot of bearing
surface to help the butt-jointed assembly to self-register, and it's
easy to throw the frame out of square during clamping.

First off, use clamping cauls to both spread and focus the clamp
pressure at the same time.  You want the pressure to run along
an imaginary line through the centers of the pieces being joined,
both laterally and vertically.

Theoretically that's possible, but in the real world anything more
than a close approximation is pure luck -- so be careful not to
overclamp.  Too much clamp pressure exacerbates the problem
of your clamps not running directly along that imaginary line, and
the more pressure you apply, the worse it gets.  You can, by
overclamping, actually distort the pieces enough so that even if
everything was cut perfectly, the frame may not be square -- or it
may be square at one corner and not at another (which *should*
be impossible...)  Clamp only at the joints, and never rely on
clamping pressure to close joints that don't fit perfectly.

Just enough pressure to close the joint snugly is what you're after.

As you gain experience, you'll learn to move the clamping points
away from the imaginary center line to force the assembly into (or
out of) square during glue up.  One of my major Norm nits is that
he always talks about checking for square, but I've never seen him
have to do much of anything about it.  Geez, maybe he really IS
better than me...

-- 
John Paquay
Dept. of Physics, Purdue University
[email-masked],  [email-masked]
http://www.physics.purdue.edu/~jep/cshop.html
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From: [email-masked] (LEE WARD)
Date: Tue, 01 Apr 97 10:43:00 -0600

Yes cuts are critical,All cuts must be made EXACTLY same way and on same
part of scribe line,Many books will show ya how to Scribe n cut for max
effect. Books like "Measure Twice cut once" in most libraries.What ya
use to Scribe is as critical as cut itself,,When ya figger the
phenomenon known as "Stacked Tolerances" youll realize a product can
have 10 parts all off just a hair but that can add up to bein way off on
assembly so its critical to use the best technique possible..BTW the
book Measure Twice and cut once is not the same title as one by
NORM,,Norms Book of same title is about carpentry...There are many WW
books with good sections on measuring/cuttin and if you read a few youll
get the idea soon enuff..
                               Lee Ward

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