IMPROVEMENTS IN SAW TEETH, AND IN MACHINERY OR APPARATUS FOR FORMING THE SAME
Year: 1869

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN SAW TEETH, AND IN MACHINERY OR APPARATUS FOR
FORMING THE SAME."-A communication from abroad by Robert
James Lusk, John Lough, Thomas Ritchie, James Ross, and
William Lough, the younger, all of Buckingham, in the County of
Ottawa, Canada, Timber Manufacturers.
Sealed the 13th July 1869, and dated the 12th May 1869.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 12th May 1869.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN SAW TEETH, AND IN MACHINERY OR APPA-
BATUS FOR FORMING THE SAME," a communication to me from abroad by
Robert James Lusk, John Lough, Thomas Ritchie, James Ross, and
William Lough, the younger, all of Buckingham, in the County of
Ottawa, Canada, Timber Manufacturers, to be as follows:-
This Invention has reference to an improvement in the shape or form

page_text: of saw teeth, applicable cither to straight or circular saws, and also to the
apparatus for forming the improved teeth. First, with reference to the
form of the teeth. In the ordinary plan adopted for constructing and
shaping saw teeth the teeth are first cut out by dies. A taper steel bar
is then held on the under side of each tooth, and hammered on the
opposite or under side of the tooth, the effect of this is to widen the
point of the tooth on the upper side, the point of the tooth is then filed
to the required degree of sharpness and "set." The defect of this mode
of "swaging" or of widening the tooth as described is that the under or
cutting side of the tooth remains narrow, whereas by this improvement
this portion of the tooth is widened at a point where such is actually
required in order to cut efficiently when employed in sawing timber,
thus reversing the ordinary condition or shape of the saw tooth at this
important point. Another defect in the ordinary form of setting the
saw is also obviated by this Invention. Thus in place of treating each
tooth separately by a hammer and file a dressing machine extending
over a considerable number of teeth, or indeed over the entire
number if required, at one and the same time, and containing an
adjustable reciprocating plane carrying a file is employed, and the same
treatment is extended to each one of a number of teeth simultaneously,
thereby avoiding any difference and creating complete uniformity in the
teeth. The peculiar form given to the lower or cutting side of each
tooth is accomplished by passing the saw, whether straight or circular,
through an apparatus provided with a nipping surface or compression
bar and a suitably shaped fixed steel die. The unformed point of each
tooth passes into the said fixed steel dic, and pressure is applied by a power-
ful lever to the nipping surface which has the effect of making the tooth
assume the shape of the die, or, in other words, the widened under
cutting surface before mentioned, each tooth of the saw being subjected
in turn to this treatment. The saw is retained or held firmly and
released again for fresh adjustment as each tooth is shaped by a cam
lever and grooved sliding block working in suitable slotted arms or
projections formed on two holding plates, between which the teeth are
passed and guided by a guiding strip, the grooved sliding block
pressing against the back of the saw. When after much use the teeth
"
of the saw become impaired or worn out the saw is straightened and
gummed" and put through the same process for widening the teeth
by the employment of this apparatus.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 12th November 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of May, in the year of
our Lord One thousand eight hundred and sixty-nine, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
licence that I, the said John Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said John Henry
Johnson, my executors, administrators, or assigns, should at any
time agree with, and no others, from time to time and all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN SAW TEETH, AND IN MACHINERY OR APPARATUS FOR
FORMING THE SAME," a communication from abroad by Robert James Lusk,
John Lough, Thomas Ritchie, James Ross, and William Lough, the
younger, all of Buckingham, in the County of Ottawa, Canada, Timber
Manufacturers, upon the condition (amongst others) that I, the said
John Henry Johnson, my executors or administrators, by an instrument
in writing under my hand and seal, should particularly describe and
ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in
the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying Drawings, and to the letters and figures marked thereon, that
is to say:
The said Invention has reference to an improvement in the shape or

page_text: 'form of saw teeth, applicable either to straight or circular saws, and
relates also to certain peculiar apparatus for forming the improved
teeth.
And in order that the said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the annexed Sheet of Drawings, the
same letters of reference indicating corresponding parts in all the
corresponding Figures.
Figure 1 is a back elevation of the saw tooth press; Figure 2 is a
transverse section of the same taken along the line 1-2, in Figure 1;
Figure 3 is a plan of the said apparatus; Figure 4 is a similar view with
the side removed and arranged for treating circular saws.
Figure 5 represents two detached views of a die for shaping saw
teeth.
Figure 6 represents a plan of a saw dressing machine, constructed
according to this Invention; Figure 7 is a section of the same.
Figure 8 is a side view of an ordinary saw tooth; Figure 9 is a front
view of the same.
Figure 10 is a side view of the improved saw tooth, and Figure 11 is
a front view thereof.
In the ordinary plan adopted for constructing and shaping saw teeth,
the teeth are first cut out by dies, a taper sheet bar is then held on the
under side of each tooth and hammered on the opposite or under side
of the tooth; the effect of this is to widen the point of the tooth on the
upper side. The point of the tooth is then filed to the required degree
of sharpness and "set." The defect of this mode of "swaging" or of
widening the tooth as described, is that the under or cutting side of the
tooth remains narrow, whereas by this Invention this portion of the
tooth is "widened" at a point where such is actually required, in order
to cut efficiently when employed in sawing timber, thus reversing the
ordinary condition or shape of the saw at this important point. Another
defect in the ordinary form of setting the saw is also obviated by this
Invention. In place of treating each tooth separately by a hammer and
file, a dressing machine extending over a considerable number of teeth,
or indeed, over the entire number if required, at one and the same time
is employed, and the same treatment is extended to each tooth simul-

page_text: taneously, thereby avoiding any difference and creating complete
uniformity.
The peculiar form given to the lower or cutting side of each tooth
is accomplished by passing the saw either straight or circular through
a peculiar apparatus, the unformed point of each tooth passing into a
peculiarly shaped steel die and pressure applied by a powerful lever,
which has the effect of making the tooth assume the shape of the die,
or, in other words, the widened under cutting surface before mentioned,
each tooth of the saw being subjected in turn to this treatment.
When after much use the teeth of the saw becomes impaired or worn
out, the saw is straightened "and gummed" and put through the
same process for widening the teeth by the aid of this apparatus.
a (Figures 8 and 9) is the ordinary form of saw teeth widened on the
upper side, as shewn in the Drawings, while 6 (Figures 10 and 11).
represents the improved tooth widened on the opposite or under
side.
This part of the improvement will be readily understood from the
Drawings above, and although of great importance it is of so simple a
character as to require no further description. I will, therefore, proceed
to describe that part of the apparatus used for giving the tooth the
shape required.
It consists of two steel plates c, c, of the general form shewn in
Figures 1, 3, and 4, bolted firmly together by screw bolts d, d, the pro-
jection e forming part of the plates referred to is provided with slotted
spaces and f¹ for the reception of the saw g and slide block g' for
holding the saw firmly in place against the die when being operated on.
This slide block is provided on its front side with a groove g³, for the
reception of the back of the saw, and on its rear side with an inclined
surface on which the periphery of the cam lever g³ works; g³ is the
actuating cam lever referred to, and is of the general form shewn in
Figures 1 and 3. It is placed between the two projecting plates e, e,
and attached to them by means of the strong pivot 9'. This pivot or
bolt is shewn more clearly in Figure 2, and passes entirely through the
plates e, e, being provided at one end with a solid head g³, which is notched
at g to fit the sides of the plates e, e, to prevent the revolution of the
pivot. At the point of contact of the pivot with the plates the pivot is
flattened as shewn at 9", forming the sliding surfaces between the bars
e, e, while the centre portion in the slots provided in the plates is allowed

page_text: to remain round, as shewn as 98. On this round portion is fitted the
flange bush g of the form shewn in Figures 2 and 3. The cam lever g
is fitted accurately to the periphery of this bush, and revolves freely on it.
go is a moveable washer of the same general form as the head g³, provided
with a notch g fitting on to the plate e; g" is the nut placed on the end
of the pivot g, and clamps the whole together when required for work.
This pivot can be moved to any part of the bars e, e, to adapt itself to
the required size of saw to be treated by simply slackening the nut g
and sliding the pivot to the required position, when the whole is again
clamped up by the nut to prevent the pivot moving back when the
pressure is brought against the saw by the cam lever g³. h is a second
lever attached to the plates c, c, by a pivot arrangement h¹ with the
projections from the plates. This lever h is slightly bent near its
inner end, as shewn in Figure 3, and passes at that point between two
guide collars or coupling links h³, and attached to them by the pivot h*.
These circular connecting links are again attached by a pivot h³ to
the outer end of a compression bar i, shewn in Figures 1, 3, and 4.
This compression bar is of steel and of great strength and is used for
pressing the point and under side of the tooth into the die to be
presently described. This compression bar has the form shewn in the
Drawings, and works freely between the two steel plates c, c, in a suit-
able recess provided for that purpose. The inner end of this slot is
circular and deepened for the reception of the circular flanged end
of the compression bar, which fits and works accurately into it, both
above and below. A portion of the circular end of this compression bar
is removed, as shewn at i, Figure 4; a square shoulder is thereby
formed in the end of the bar adjacent to the saw tooth, and which comes
in contact with it and presses it squarely into the die. A small groove
is provided on the inner end of the compressing bar possessing a width
about equal to the thickness of a saw. The object of this groove is to
permit the passage of the teeth of saws with a small pitch. k is a
strong steel die passing entirely through both plates c, c, in the position
indicated in Figures 1, 3, and 4. The peculiar form of this die is shewn
in Figure 5. At or near its centre it is provided with a bevelled cheek
or recess k³, as shewn in the Drawings, for receiving the tooth and giving
it the required shape. is a grooved guide strip inserted between the
two plates and serving to steady, the straight saw when that description
of saw is being operated upon, and further guided by two set screws
passing through each of the plates c, c. When a circular saw is to be

page_text: treated by this apparatus the plates e, e, must be of sufficient length to
permit of the saw being introduced between them, and with the slide
block g' and pivot g*
on the outside of the saw, as shewn in Figure 4,
for the purpose of keeping the saw closely pressed up against the die.
I will now proceed to describe the apparatus employed for the next
step in the operation of treating the teeth and bringing them to a
uniform set. At Figures 6 and 7 are represented respectively a plan and
section of this apparatus, g representing the saw as before resting on a
straight bed plate o with a checked surface at o' for the purpose of
giving room for the widened teeth of the saw, thus allowing the body of
the saw a firm bearing on the bed plate o. A second or top clamp
plate p is placed on the upper side of the saw, and firmly secured to it
by the screw cramp q; r is a plane or file holder of any convenient
length required. In a recess provided on its lower side is placed an iron
plates attached to the plane and moved by set screws t. To this move-
able plate s is attached by suitable cramps a file u; v is a guide or guage
strip screwed to the side of the plane by screws o' working in slots provided
in the strip. By this means the plane may be adjusted to any required
thickness of saw, and by the use of the set screws 6 the plane may be
adapted to any size of set.
With the foregoing brief description of the said Invention I will now
proceed to describe its mode of operation:―
Firstly. With reference to the improved form of saw teeth. By the
use of this improvement it is ascertained that the form of the tooth gives
greater freedom to the saw plate from the fact that each tooth cleans the
cut entirely through on each side, whereas the ordinary tooth does it
only on one side. The improved saw can be used in the gate from two
to three times that of the ordinary saw without being changed, and at
the same time do from ten to fifteen per cent. more work in an equal
length of time. Considerable saving in time and consequent expense is
also effected in "dressing up" the improved saw.
Secondly. With reference to the operation of forming the teeth by the
improved apparatus. The apparatus being arranged substantially as
described the straight saw to be operated on is screwed into two cramps,
one at each end, the cramps being attached to a suitable bench. The
connection between the apparatus and the saw is effected by removing
the sliding pivot g* and the block g¹ and placing the saw g between the
two plates c, c, by introducing it through the slot f between the

page_text: extensions e, e, of the plates c, c, and guided in position by the strip
and set screws P, P; this done, the block g' and pivot with the cam
lever g³ are again put in place, pressing the saw closely against the
die ; the clamp nut g" is then tightened and the apparatus ready for
work. One of the teeth of the saw being in the groove k¹ of the die k
and held firmly in position by the action or pressure of the cam lever g³
pressing against the bevelled surface of the moveable block g', which in
turn presses against the saw, pressure is now brought to bear on the
tooth by means of the lever h, coupling links h³, and compression bar i
to a sufficient extent to force the material composing the saw tooth into
the cavity of the bevelled recess k¹, and thus give the required shape or
form to the tooth. This being done the saw is relieved by turning the
cam lever g³ which allows the moveable block g' and saw to slide back a
sufficient distance to permit the tooth just operated on to be removed
from the recess; the succeeding tooth is then brought opposite the
recess and forced into it by the forward action or movement of the
block g' acted on by the cam lever g³, when by means of the lever h
the same process is repeated, and so on; all the teeth treated in the same
die will therefore possess uniformity of size and shape.
The rest and finishing operation consists in placing the saw just
treated on the bed plate o (Figures 6 and 7), and attaching it firmly to
the same by the top plate p and cramp q. The file u and guage strip v
are then properly adjusted on the plane to suit the thickness and set of
the saw.
This done the plane is passed to and fro over the teeth of the
saw until their points are brought to a true line, which by this process
can be accomplished with great exactness on account of the plane or its
file resting on a considerable number of teeth at one and the same time
and being also governed by the adjustable guides. The operation being
accomplished on one side of the saw the saw is reversed and the opposite
side treated in like manner.
When a circular saw is to be operated upon it may rest on its axis and
have the apparatus applied to each tooth in succession. The guide.
piece 7, as shewn in Figures 3 and 4, is removed to allow the teeth to
pass.
By a slight modification of the dressing machine, Figures 6 and 7, the
circular saw teeth may be brought to a true line or set by causing the
saw to revolve on its axis, which in this case will pass through the plates
above and below.

page_text: "
As before stated the apparatus heretofore employed for forming saw
teeth consists in so far as our knowledge extends of a simple "swage
taper steel bar and hammer, the swage being used for widening the very
point of the tooth, while the bar and hammer are used for widening the
upper side of the tooth. From this it is evident that uniformity of finish
cannot be obtained.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe in conclusion that what I
consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,―
First. The peculiar saw tooth b widened on the under or cutting side,
substantially in the manner and for the purpose herein-before described.
Second. The peculiar construction of pressing or saw tooth shaping
apparatus as herein-before described and illustrated by Figures 1, 2, 3, 4,
and 5 of the Drawings.
Third. The peculiar saw dressing apparatus, as herein-before described
and illustrated by Figures 6 and 7 of the Drawings.
In witness whereof, I, the said John Henry Johnson, have to this
my Specification set my hand and seal, this Twelfth day of
November One thousand eight hundred and sixty-nine.