In article .com, RicodJour wrote:
On Jul 7, 9:41 pm, (Doug Miller) wrote:
RicodJour wrote:
On Jul 7, 7:24 pm, (Doug Miller) wrote:
RicodJour wrote:
I'll argue my point with a very simple test that you can do for
yourself. Drill a hole the exact size of a nail in a piece of wood,
drilling along the grain. Soak the wood overnight. You don't have to
boil it. Try to insert the nail the next morning. The wood will have
expanded, and the hole will have gotten smaller, not larger.
Nonsense.
Which part of my experience is nonsense?
First, in assuming that a sample size of 1 is sufficient for generalization;
second, in failing to understand all the factors involved -- see below.
Like I said, try it for yourself.
My experiment is already underway. I drilled a 5/8" hole in a small scrap
about two hours ago, and dunked it. I measured it with a dial caliper just
prior to immersion at 0.628" diameter.
I just fished it out -- the hole is visibly elliptical already, and measures
0.661" along the long axis, parallel to the growth rings. Note that this
absolutely contradicts your claim that the hole will shrink.
This morning, by the way, the dimensions of the hole are 0.674 along the major
axis of the ellipse, and 0.626 along the minor axis.
And the bit that drilled the hole slips easily through it -- falls through, in
fact, without being pushed or pulled.
Basing things on your sample size of one seems to be acceptable to
you. I wonder what I did wrong? 
I'll conduct further tests with additional samples, and post the results.
I'll check it again in the morning.
The hole
may not be perfectly round, but the net area of the hole will be
smaller. I've done this. Try it, you'll see.
Pardon me for being very skeptical of your claim to have actually done
that.
I'll perform my own test and report the results.
Please do. I wouldn't have it any other way.
BTW, the test was an accident. It was an offcut piece of red oak with
a drilled hole that I'd left outside - yes, I know I should clean up
more carefully. The piece was outside for about a week and there'd
been only a day and a night of rain I think. Out of curiosity I stuck
the same bit into the hole, or tried to, and it wouldn't fit. I could
spin the bit in a little, like I was drilling it, but from your
description it should have slid in easily as the hole could only get
bigger in all dimensions. It was only a partial test as I didn't try
the bit after the piece dried out - I just threw it away.
In other words -- no systematic testing conducted, just a conclusion drawn
from examining a sample size of one piece.
I never claimed it was a systematic test, Doug. I'm relating my
experience.
And I'm saying that you've drawn an incorrect conclusion from limited
experience, a conclusion that you mistakenly believe to be typical.
Did it occur to you that small holes can easily be obstructed by only a
handful of wood fibers that swell into the hole? The only *valid* test is by
measuring a hole that's considerably larger than the grain of the wood.
A couple of observations and a couple of questions about your
"systematic" approach.
We _are_ talking about a small hole. Please note the subject line in
this thread, view the picture of the puzzle, and take it from there.
The puzzle uses a 16d nail (0.165") - where did the 5/8" come from?
Please note the point I raised above: it's not possible to draw valid
conclusions about the behavior of the material, with samples at such small
scales.
The nail runs along the grain, as did my accident-sample - is that how
you drilled your hole?
To avoid any possibility of confusion, let's avoid using terms such as "along
the grain" or "across the grain", etc, and instead make specific reference to
the orientation of the tree:
The nail in the puzzle photograph, and of course the holes, is parallel to the
trunk of the tree; that is; axially with respect to the growth rings.
Is that how your sample hole was drilled?
My test hole was drilled radially with respect to the growth rings.
Subsequent tests will use holes drilled radially, tangentially, and axially,
to compare the effects.
My original point was that the wood will swell in all directions, and
will swell more where it is not restrained - i.e. the hole.
But that is not correct. As another poster pointed out, when a substance
expands, any two points in it get farther away, without regard to whether they
are separated by solid matter or air.
As Eigen pointed out, the smaller dimension in an elliptical hole is
the more critical clearance dimension.
Basically no change -- a difference of 0.002" (three-tenths of one percent)
could easily be a measurement error.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.