Alpena weekly argus. [volume] (Alpena, Mich.) 1871-1893, 1885-04-08
Timber and Tools.


IL is a fact we'll known to mill men
hat it is not always the harder woods,
IN the ordinary acceptation of the term,
hat are the most wearing to the saws.
Many practical persons marvel at this
end wonder to themselves why piece
Of timber showing small crushing ten
sion and other strengths, requires
more power to work into lumber, and
at the same time wears out the saws
and cutting tools faster than other va
rieties OF timber. the strength of which,
In most respects, is greater.
log OF black walnut and one of
burr oak OF the same sized worked into
the same sized stuff will show widely
different results on both saws and ma.
chinery. If we attempt TO rive or split
these logs the walnut will work much
easier than the oak, and so far as tho
various strengths are concerned the
oak is superior by far, but when cut
into by tools of any description the
walnut will present much greater re-
sistance than the oak, and the same is
true as regards many other varieties of
hard and soft timber.
IL we take q longitudinal section of
these comparatively soft timbers which
are so hard on the cutting edges, we
will find the minute pores or interstices
filled with minute glistening particles
or crystals, ard subject to chemical
analysis we win find them composed of
silica, one of the very hardest minerals
known, while with the hard. easy-work-
ing woods they will be found nearly or
quite absent by both the microscope
and analysis. These lutte particles, so
finely divided as to be lnsusceptible of
ordinary touch, are really better grit
than ordinary sand, and are the means
of cutting off the fine edge of cutting
tools, as saw teeth, plane irons, and
the like.
Two plane irons, made of a fine
quality of steel, as near alike as il was
possible for skilled mechanic to
make them, were each hardened in
our laboratory by means of mercury,
then finely sharpened, so that the edges
of each presented precisely the same
appearance beneath the magnifier.
These were each inserted in an ordinary
plane and one placed on the oak, the
other on piece of walnut, both pieces
OF wood having been previously
pressure, each iron was crowded for
ward four inches. On the oak stick, the
pressure from the rear indicated 800
pounds, while with the walnut the in
dicator showed pressure of over l.
600 pounds. The irons were both now
Withdrawn, and the first placed be-
meath the microscope; the one used on
the oak presented a general upset ap-
pearance. the edge OF the iron showing
a slight tendency to turn downward,
there being sufficient heat generated
10y the friction to partially draw the
temper along the minute edge, which,
however. would not extend back suli-
cent to materially affect the wearing
and cutting properties of the iron if in
constant use.
The iron used on the piece of walnut
showed scratch, notched appearance
all along the minute edge, and by the
ald of the most accurate means of
measurement ut hand, these notchcs
were all of the same depth, but differ
ent distances apart, proving conclu-
sively that the particles of grit or crys-
tails which caused them, by being hard
er than the best mercury-hardened
steel, were all of the same size, and
evenly distributed Us far as regards
depth of deposit in the grain OF the
wood. The small spaces of the iron
edge between these notches or scratches
we're found nearly as the entire edge
appeared originally, showing again
hat the cellular tissue of walnut, out
Tide its mineral deposits, was really
otter than that of oak; hence, were it
g., hoe he, l,n, 81. "A
ut much easier. OF course, If the iron
iad been drawn back and again showed
trough, the notches would have been
more apparent and general, increasing
zach time, and distance showed until
he entire cutting edge had been OF it.
elf cut off.
Consulting the laws governing plant
II vegetable growth, we are told that
I'll food before becoming fit for assimil-
ltion must be reduced to its gaseous
tate. If this be so, tho question
lrises, how, or by what methods of
olant-growth and assimilation, is it
possible for silica to appear in its orig
nal crystalline state among the tissues
ii the growing or mature tree? while II
universally known that this variety
Of wood grows only where this mineral
| $ abundant in some of its modified
'orms. This, however, is not of great
interest to manufacturers just how il
gets there, but that it is present is
shown conclusivcly. To get rid of 1t,
even were it possible, would destroy
the beauty and general characteristics
If walnut, and to overcome its action
On tools, rapid motion and softer iron
IS the best, safest and most eflicacious
method. Lander Trade Journal