IMPROVE- MENTS IN MACHINERY OR APPARATUS FOR CUTTING FRETS IN METAL OR OTHER SUBSTANCES
Year: 1866

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in
the County of Middlesex, Gentleman, for the Invention of "IMPROVE-
MENTS IN MACHINERY OR APPARATUS FOR CUTTING FRETS IN METAL OR OTHER
SUBSTANCES." -A communication from abroad by Madame Henriette
Delong, of Paris, in the Empire of France, Fret Cutter.
Sealed the 12th March 1867, and dated the 14th September 1866.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at
the Office of the Commissioners of Patents, with his Petition, on the
14th September 1866.
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 MACHINERY OR APPARATUS FOR CUTTING FRETS IN METAL OR
OTHER SUBSTANCES," a communication to me from abroad by Madame Henriette
Delong, of Paris, in the Empire of France, Fret Cutter, to be as follows:-
This Invention relates to certain peculiar constructions and arrangements
of machinery or apparatus for cutting frets in metal plates and other sub-
stances, and consists according to one arrangement, which is intended for those
metals which do not come under the denomination of "precious metals," of a
wooden or other table supported on suitable standards, and having a perforated
metal plate sunk therein through which the fret saw operates. Immediately
beneath this plate there is fitted a guide through which the saw reciprocates,

page_text: and which serves to prevent undue vibration or "chattering" of the blade
when in operation. The saw, which consists of a thin steel blade with finely
cut teeth thereon, is passed through the table, and is secured at its upper and
lower extremities by means of pinching screws to a vertical rod or spindle,
each of which slide in metal guides situate above and below the table re-
spectively. These guides consist of cast-iron arms or brackets which are
secured to the back of the table, and which project sufficiently over the table
to allow clearance for large sheets or plates to be manoeuvred with facility.
The upper spindle is provided with a loose collar, which is connected to the
front end of a vibrating lever, the fulcrum of which is carried by the upper
bracket; a screw thread is formed upon the spindle above the collar, and an
adjusting nut screwed thereon having its bearing against the top of the collar,
whereby facility is afforded for straining the saw. The lower spindle may be
coupled direct to a lower lever corresponding in every way with the upper one,
and working on a centre in the lower bracket. The opposite ends of both
these levers are rigidly connected by a rod, which is again coupled to the upper
end of a connecting rod worked by a revolving crank on a crank shaft below.
This crank shaft is thrown in or out of gear with a driving pulley by a friction
cone which is operated by a foot lever. A belical spring tends always to keep
the friction cone in gear, and the depression of the foot lever throws the cone
out of gear, when the machine immediately stops. When it is desired to
leave the machine at rest it is kept permanently out of gear by forcing a
vertical sliding rod down upon the foot lever by means of a cam hand lever
acting upon the rod, and situate convenient to the hand of the operator. On
releasing this cam a helical spring elevates the rod, and by allowing the foot
lever to rise again the machine will be set in motion. The sawdust or other
cuttings are removed by means of a pair of bellows operated by the upper
saw lever, a curved pipe from the nozzle of the bellows being brought close to
the part on which the saw is acting.
.
In the second modification, which is intended for fine work in the precious
metals, the cuttings of which it is important to collect and save, the metal to
be operated upon is laid on a small metal table or plate supported on a fence
or guard through which the saw operates, and beneath this metal table is
situate a larger circular plate provided with a raised rim for the purpose of
catching the metal cuttings or dust, which may be collected in a leather
pocket attached to the lower plate for that purpose. In this machine the saw
is fitted up in the same manner as in the first-described arrangement, but in
lieu of being worked from a driving pulley by steam power it is worked by a
treadle, the crank shaft being driven by a belt and pullies from a first motion

page_text: shaft provided with a fly wheel, and actuated by a treadle in the well-known
manner.
The same frictional arrangement as that herein-before described is
shaft provided with a fly wheel, and actuated by a treadle in the well-known
manner. The same frictional arrangement as that herein-before described is
employed for throwing the saw inechanism in or out of gear at will.
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 14th March 1867.
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 Fourteenth day of September, in the year of our
Lord One thousand eight hundred and sixty-six, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Henry Johnson, Her special license that I, the said John
Henry Johnson, my executors, administrators, 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 at 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 "IM-
PROVEMENTS IN MACHINERY OR APPARATUS FOR CUTTING FRETS IN METAL OR OTHER
SUBSTANCES," a communication to me from abroad by Madame Henriette
Delong, of Paris, in the Empire of France, Fret Cutter, 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 scal, 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 accompanying Drawings, and
to the letters and figures marked thereon, that is to say :-
The said Invention relate to certain peculiar constructions and arrange-
ments of machinery or apparatus for cutting frets in metal plates and other

page_text: substances, and consists according to one arrangement, which is intended for
those metals which do not come under the denomination of "precious metals,"
of a wooden or other table supported on suitable standards, and having a
perforated metal plate sunk therein through which the fret saw operates.
Immediately beneath this plate there is fitted a guide through which the saw
reciprocates, and which serves to prevent undue vibration or "chattering" of the
blade when in operation. The saw, which consists of a thin steel blade with finely
cut teeth thereon, is passed through the table, and is secured at its upper and
lower extremities by means of pinching screws to a vertical rod or spindle, each
of which slide in metal guides situate above and below the table respectively.
These guides consist of cast-iron arms or brackets which are secured to the
back of the table, and which project sufficiently over the table to allow clear-
ance for large sheets or plates to be manoeuvered with facility. The upper
spindle is provided with a loose collar, which is connected to the front end of a
vibrating lever, the fulcrum of which is carried by the upper bracket; a screw
thread is formed upon the spindle above the collar, and an adjusting nut
screwed thereon having its bearing against the top of the collar, whereby
facility is afforded for straining the saw. The lower spindle may be coupled
direct to a lower lever corresponding in every way with the upper one, and
working on a centre in the lower bracket. The opposite ends of both these
levers are rigidly connected by a rod, which is again coupled to the upper end
of a connecting rod worked by a revolving crank on a crank shaft below.
This crank shaft is thrown in or out of gear with a driving pulley by a friction
cone which is operated by a foot lever. A helical spring tends always to keep
the friction cone in gear, and the depression of the foot lever throws the cone
out of gear, when the machine immediately stops. When it is desired to
leave the machine at rest it is kept permanently out of gear by forcing a
vertical sliding rod down upon the foot lever by means of a cam hand lever
acting upon the rod, and situate convenient to the hand of the operator. On
releasing this cam a helical spring elevates the rod, and by allowing the foot
lever to rise again the machine will be set in motion. The sawdust or cuttings
are removed by means of a pair of bellows operated by the upper saw lever, a
curved pipe from the nozzle of the bellows being brought close to the part on
which the saw is acting.
In the second modification, which is intended for fine work in the precious
metal, the cutting of which it is important to collect and save, the metal to
be operated upon is laid on a small metal table or plate supported on a fence
or guard through which the saw operates, and beneath this metal table is
situate a larger circular plate provided with a raised rim for the purpose of

page_text: catching the metal cuttings or dust, which may be collected in a leather
pocket attached to the lower plate for that purpose. In this machine the saw
is fitted up in the same manner as in the first-described arrangement, but in
lieu of being worked from a driving pulley by steam power it is worked by a
treadle, the crank shaft being driven by a belt and pullies from a first-motion
shaft provided with a fly wheel and actuated by a treadle in the well-known
The same frictional arrangement as that herein-before described is
employed for throwing the saw mechanism in or out of gear at will.
manner.
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 I 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 represents a longitudinal vertical section of an improved fret
machine, and Figure 2 is a front view of the same.
A wooden or other frame A supports the cast-iron arms B, which are cast
in one piece and carry the saw mechanism. This mechanism consists of two
levers C, C, working on fixed centres at cat or near the middle of their
length, and connected together at one of their extremities by the rod D, whilst
their opposite ends are connected to the rods E, E', which carry the saw
blade s. This saw is secured to one end of each of the rods E, E', by a
collar e provided with a pinching screw. The upper lever C is connected to a
collar d, within which slide freely the rod or spindle E, which is provided with
a screw thread upon which is screwed the nut a, which serves to strain or
tighten the saw blade. The rods E, E', are guided in the arms b, which form
slides for them to work in. The mechanism receives an alternating or reci-
procating movement from a connecting rod F coupled to a crank G on the
sbaft H; this shaft carries a pulley I and a friction cone J, which serves to
throw the machine in or out of action, according as it is brought in contact or
removed from the pulley I. The throwing out of action is effected by pressing
upon the treadle P carried by the levers K keyed on to the rocking shaft L.
A vertical lever M is fixed to one end of this shaft and engages with the
groovej of the friction cone J, so as to impart to this cone the movement of
the treadle. A helical spring N throws the cone into gear when the pressure
on the treadle is removed, and the latter is elevated by a small helical
spring n.
If it be desired to keep the machine out of action for any length of time,
another arrangement of mechanism is employed. A rod o is fitted against
one of the standards of the maiu framing A, and is guided vertically in slides o ;

page_text: it is further provided with a shoulder o¹, which serves as a bearing for a helical
spring R, such spring tending to keep the rod always elevated. A cam
lever Q, having a notch formed in its boss at 9, permits of the rod O rising
when brought into the position shewn in red lines, in which case the cone J
will be in gear; but when turned down to the position shewn in black lines
the treadle P and levers K which actuate the cone will be depressed, and the
cone will be drawn out of gear, the macbine in that case remaining out of
action. The moment the cone is drawn out of contact with the pulley I the
machine stops instantly, which is a most important feature in all fret cutting
machines. The saw s traverses a plate of copper m provided with a guide n
to receive the thrust of the saw on the side opposite the teeth and to prevent
vibration. A bellows S, actuated by the rod T connected to the lever C, blows
off the dust produced by the saw, which would obstruct the outline of the
design traced upon the surface of the work. This machine is constructed
and arranged with a view to operation upon large pieces of ordinary metal,
horn, or any other material capable of being so operated upon. It is not
suitable for the cutting of precious metals as it is not constructed so as to
collect the cuttings or dust; the precious metals, moreover, are generally in
too small pieces to be easily guided or manoeuvered in this machine.
I have represented at Figure 3 a second fret machine, which is more par-
ticularly adapted for the execution of fine and delicate work and for operating
upon the precious metals. This machine is arranged so as to be driven by
hand through the intervention of the wheel V, or by the aid of a treadle P¹,
which transmits motion to the main shaft H'; this shaft drives by means of a
strap the shaft H, provided with a crank G coupled to a connecting rod F;
this rod actuates the saw mechanism, which is precisely similar to that of the
first-described machine, the same letters of reference indicating the cor-
responding parts therein, as also those of the friction coupling arrangement.
The pieces to be operated upon are placed upon the small circular plate or
table f, through the centre of which the saw s works; this plate is fixed to an
arm G provided with a shield h surrounding the saw at the part where the
hand is placed to prevent it from being injured; a lower plate i receives the
metal sawdust or cuttings, and a leather pocket may be fitted thereto similar to
those employed in hand fret cutting. Figure 4 represents in vertical section
the application of moveable plates made adjustable in a vertical or horizontal
direction in a fret cutting machine of the improved construction before described,
and Figure 5 is a side elevation of the same mechanism. Upon the cast-iron
frame A, which carries the driving mechanism of the saw, there is fixed by
means of lugs a circular plate B,. having a circular groove a formed therein,
b

page_text: which serves as a guide for the circular horizontal adjustment of the plate C
round its centre, this plate carrying a projection which enters the groove a;
a support D is fixed upon the plate C, it carries at its upper end a second
plate E hinged or pivotted at d, so as to be capable of adjustment at different
angles, as shewn by the red lines in Figures 1 and 2; this plate. E carries
a quadrant guide e, the centre of which is the centre of oscillation d. In a
slot in this quadrant enters a set screw v, which is screwed into the support D,
and serves to fix the plate in any desired angle, which may be accurately
determined by division lines cut in the edge of the quadrant. The plate C
turns upon itself horizontally, and may be fixed in any desired position by the
two bolts V provided with thumb-nuts, the heads of such bolts engaging
against the projecting or overhanging sides of the circular groove a; in this
way the plate C is at the same time fixed and prevented from becoming dis-
engaged from the groove. A number of notches c are formed underneath the
said plate at equal distances apart, and a fixed spring R is provided with a
triangular tongue or projection r, which engages with one or other of these
notches when they pass over it. It will thus be seen that the amount of
horizontal movement of the plate C may be determined exactly the same as
that of the upper plate E. It will now be readily understood that by com-
bining the movements of the two plates C and E any inclination or angle with
the saw s may be obtained, and bevelled or angled cuts produced as required.
The lower plate is of larger diameter than the upper one in order to catch
the metal dust or cuttings, and for that purpose, as well as for the movements
of the plates, the saw is caused to pass through their centres, as shewn at S,
Figure 3. Figures 6, 7, and 8 represent a portion of the saw drawn full
size and shewing the pyramdal cut of the teeth, the summits of which are
caused to overlap. It has been found that this form of tooth is specially
adapted to the cutting of hard and thick substances.
I may observe that
although I have described reciprocating saws, it is obvious that endless or
ribbon saws may be employed, cut in the manner described, for the purpose of
producing fret work.
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 general construction and arrangement of machinery or apparatus
for cutting frets and irregular figures or curves in metal or other substances,

page_text: substantially as herein-before described and illustrated by the Drawings
annexed.
Second, the application and use to and in the cutting of metal frets of a
reciprocating or endless saw actuated by a crank, driving pulley, or other
'equivalent mechanical contrivance, substantially as herein-before described.
In witness whereof, I, the said John Henry Johnson, have to this my
Specification set my hand and seal, the Fourteenth day of March,
One thousand eight hundred and sixty-seven.
J. HENRY JOHNSON. (L.S.)