The Conservative. (M'connelsville, Ohio) 1866-1871, 1870-06-10
Stearn's Patent Eccentric Head Blocks
for Circular SaW.MiIls.


We hope every person who sees this no
tice will read it carefully, and if not per-
sonally interested himself, will call atten-
ton to it. To the casual observer it would
seem of little importance, but it is a mat
ter OF vital importance to nearly everyone
in this country. We use the language of the
inventor himself in describing this
great improvement in the manufacture of
lumber. His invention was first patented
in 1856, and has been before the public for
fourteen years, and ON the 18th OF April,
1870, the patent was extended for seven
years longer. The construction of the
Head Blocks for a circular saw-mill is of
much more importance than many are apt
to suppose. The saw must run well 10
make good lumber; but if, from any cause,
it inclines one-siIth or One-eighth of an inch
sideways, it matters not so much as to
have blocks which do not set the logs accu-
rately, for fthe boards are set 3-16 or Of an
inch or more in thickness than others,
nothing will correct the error. The boards
will be sawed as badly as they are set. But
on the other hand, if the saw is so filed or
set that it draws sideways, it does not show
it so much in the lumber, as it ordinarily in
cines the same way every time. This can be
corrected in the filing and setting.
To get perfect head block, many difficult
ties are TO be overcome, apparent only to
those experienced in building and running
mills, and who have also devoted much atten-
tiOn to learn the causes of and the remedy
for imperfect saving. The accuracy of thick
ness desirable, can never be secured by me-
chanicsl principles heretofore employed.
Neither the rack and pinion, screw, in
cline plane, or ANYTHING OF the kind,
will give it. A quick motion will give thicker
board than a slow one. A light log will be
4, Mrrrrak
/ ing of connecting shaft, used in connection
with rack and pinion, or screw, increases the
variation; one part of the gearing gets
clOgged with saw dust, while the other parts
are free, another cause Of IrregUlarlty. The
screw blocks are slow, labOrious things.
There is no self-adjusting principle connected
with them. The handle must be stopped
with precision, or there will be great variations
/ of thickness. Much time is lost IN adjusting
the thickness, and anything like accuracy Is
out of the question. The cOgs IN the rack
and piniOn blocks soon wear loose, and leave
/ the knees free to be thrown too far
lby quick movements of the lever, or to be
| AIRED and drawn forward under the motion
of the saw with light cant. COgs also wear
very iTregular-One cog more than another
| The force of logs turned against the knees
often break off the corners of the cOgs, caus-
ing great irregularity in the lumber. The
| screws in screw blocks, with 90 much turn
ing under pressure to move the logs, wear
| loose very fast, in two places, viz: The
| threads in the nuts on the knees, and between
| the collars where they are attached to the
| frames. They soon get very loose, and per-
NIT the jarring of the mill and the drawing of
| the saw to move the cants, as they become
thin and light, so as to make the lumber un-
even IN thickness. The crOwning excellency
claimed for the Stearns Blocks, lies in the
| delicate and nearly absolute mathematical
precision and uniformity in the adjustment
| Of the thickness.
| This point of so much importance is sevur-
| ed by the use of eccentrics, so applied in Civ
| ing lateral motions to the log, As TO be reach
/ ing or passing their centers when completing
! the motion, and adjusting the thickness. Its
motion will be fastest when first started and
will continually decrease until it ceases on
reaching a dead centre. This gives slow
movement when nearing the required thick
ness, and leaves no mOmentums for cOntinu-
ing the motion beyond. The advantage over
all resistance is complete. The heaviest logs
| are adjusted with the same precision as the
Highest. The setting arms work in pairs-One
/ advancing while the other is receding, so
that the log is set forward by the back
ward as well as the forward motion OF
the handle. This prevents retrOgade
motion of the log. It also doubles the pur-
chase, making the movements light and easy.
This application of the eccentric secures 4
most perfect self adjustment Of thickness
without any trouble and delay on the part of
the sawyer. So perfect is the eccentric move
ment as to accuracy, that we do not gain or
lose the thickness of paper in saving up a
large log. In the first place, we have the self
adjusting principle, giving such a slab as
vii, leave a board at last neither too thick
nor too thin; and then "a we neither gain or
lose as much as the thickness of paper In
cutting up log, the last board is sure to
come out right every time. Though the
movement of the handle be continued, the
knees cannot be thrown forward nearer
the saw than the thickness of board.
Thus the cants for boards are sawed,
leaving either a perfect board, or an
Inch and half or two inch plank, as the
SAWYER chooses, without stopping even to
look at the blocks, and the last board as
quickly as any. The wear of the eccentrics,
or their journals, or the yokes, never causes
the least inaccuracy. The eccentrics have
plenty of surplus rise, and if they should
wear a sixteenth of an inch less, it could
make no variation in the setting-not the
thickness of greenback in saving up a
whole log-so perfect is the adjustment
made by an eccentric on reaching dead
center. TaperiDg lumber may be sawed, as
one block may be thrown out Of gear while
the other is moving the difference. The
beauty an. excellence of this
arrangement cannot be fully un-
derstood without seeing the blocks,
and watching their operation on the
mill. The simplicity, directness and power
of the movement, the evident durability OF
the blocks, and the ease, dispatch and per-
feet accuracy in setting the various thick
nesses in the dark pleases all who witness