An Improved Portable Machine for Testing the Strength of Paper.
Year: 1889

page_text: Date of Application, 22nd Feb., 1889
Complete Specification Left, 22nd Nov., 1889-Accepted, 18th Jan., 1890
PROVISIONAL SPECIFICATION.
An Improved Portable Machine for Testing the Strength
of Paper.
WILLIAM SINCLAIR, 10 Rutland Crescent Kinning Park, Glasgow, County of
Lanark Scotland, Commercial Traveller do hereby declare the nature of this invention
to be as follows:-
An improved portable machine for testing the strengths of papers and of such size
that it may be conveniently carried by the user.
Referring to the accompanying drawing it will be seen that it consists of two metal
crosspieces B & E held rigidly a convenient distance apart by the two round parallel
guides A A. Between the guides and sliding freely upon them are two other cross-
pieces C & D.
Connected to C and passing through holes in D & E is a bolt N
terminating in the thumbscrew H. Also connected to the crosspiece C but on the
other side is a rack K passing up to the indicator L and moving by means of a
pinion a pointer round a dial graduated in "lbs." or other proportions. Between
crosspieces C & D and surrounding guides A A are two spiral springs F F and also
between D & E are two other spiral springs G G also surrounding guides A A. The
wire of the latter springs to be of smaller diameter than that of FF.
Upon B & D are two small presses M M to hold the ends of the ends of the paper
to be tested. When the paper is fixed in the presses M M, by turning the thumb-
screw H the crosspiece C will move towards D thereby compressing the springs F F
because of the paper fixed between D & B not allowing the crosspiece D to travel
down, but as soon as the paper breaks the crosspiece D will be pressed sharply
towards E by reason of the compression of the springs F F, the concussion which
would otherwise follow being checked by the springs G G which also serve to keep
the crosspiece D in its proper position. The amount of travel required by the cross-
piece C to break papers of various strengths being recorded on the dial L by means
of the rack K. By turning the thumbscrew H in the opposite direction the cross-
piece C will return to its former position ready to be used again.
Dated this 20th day of February 1889
COMPLETE SPECIFICATION.
An Improved Portable Machine for Testing the Strength
of Paper.
WILLIAM SINCLAIR Paper Agent 385 Dumbarton Road Glasgow does hereby
declare the nature of his invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
For explanation the following diagrams are appended-the indicating letters of
which are the same for like parts in all the figures. The machine consists essentially
of two parallel guides A A which are secured firmly at the ends to the ends of the
two crosspieces B & B 1. so that the whole forms a rigid rectangular frame B. A.
B 1. A. Between the crosspieces B & B 1. and sliding freely on the guides A. A. are
two other parts C & D. (they may also be called crosspieces). One of these cross-
pieces C. by means of a bolt E (passing through holes in the crosspieces D & B 1)
and the thumbscrew F can be made to approach the crosspiece B1 or recede from
it. The thumbscrew F is made in such a way as will be seen by the drawing Fig. 5.
that the flat face F 1. always keeps in contact with the face of the crosspiece B 1.
whichever way it may be moving the crosspiece C. The other crosspiece D is kept

page_text: in place on the guides A A by the spiral springs G G (which encircle the guides A A.)
on one side and by the stop H on the other side, which stop is fixed securely to
the screwbolt E and at such a place on the bolt E that there is no pressure
exerted on the springs G G. The bolt E is securely fixed into the crosspiece C so
that it is unable to turn when the thumbscrew F is turned. The two cross-
pieces B & D are made alike (except the attachment to the guides A A.) in every
respect and are really two small presses as shown in Figs. 3 & 4 they are to hold
the ends of the paper to be tested the position of the pressing surfaces of the
presses must be so arranged that when the paper is placed in position they will
hold it clear of crosspiece C as shown by dotted line O Fig. 2. When the paper is
securely fixed in the presses B & D then by turning the thumbscrew F (the thread of
which may be right or left) the crosspiece C will be brought towards the cross-
piece B 1. This of course will exert a pressure on the springs G G. because the paper
fastened between the crosspieces B & D does not allow the crosspiece D to travel
down (except a small distance caused by the stretching of the paper). This pressure
ultimately breaks the paper and the force stored up in the springs G G sends the
crosspiece D rapidly back to the stop H. It will be seen that the stop H does not
interfere with the pressure put upon the paper as the stop moves immediately
away from the crosspiece D as soon as the thumbscrew F is turned. It is necessary
before another piece of paper is put in the machine to allow the crosspieces C & D to
return to their original position. With regard to the indicating part of the
machine which is to show the pressure which is exerted to break the paper, it will be
seen that the nearer the two crosspieces C & D come to one another the more pressure
there is stored up in the springs & G. so that all that is required is an apparatus that
will show by means of a dial the distance between the crosspieces C & D and
record in pounds or other convenient indication the pressure that is required to break
the paper and which will be recorded on the dial. This device is illustrated in
Fig. 1. 2. 4 & 6. Referring to Figs. 1 & 2 it will be seen that there is a bar of
metal D1. firmly secured to the press or crosspiece D and also to a box I on
the remote side of the crosspiece B. To the front I is attached a dial I 1. and in
the centre of the box I there is a pinion C3. (Fig. 6) the spindle of which comes out
through the centre of the dial 1. and is attached to a short lever J formed as
shown in Figs. 1 & 2. This lever is securely fastened to the spindle of the pinion C3.
Between this lever and the face of the dial and turning freely round about the
dial is a pointer K which has a pin K 1. projecting from its surface which
engages with the lever J so that when the pinion in the box I turns, thereby turning
the lever J round about the dial it will also turn the pointer K. on the end of the
pointer K which overlaps the edge of the dial (there is pawl K 2 and all round the
edge of the dial) there are small ratchet teeth which the pawl engages with. These
teeth are so set that the pawl can only move over them in one direction, but in
Fig. 1. it will be seen that the pawl K2 is extended on the other side of the
pin K 3. upon which it works and that there is a spring K 4. to keep it down
upon the teeth of the dial-the finger of the operator can therefore disengage the
pawl from the teeth when required. Fastened to the crosspiece C and extending
through a hole in the crosspiece B is a rod C¹ which is fastened to a small rack C2.
in the interior of the box I (shown in Fig. 6). This rack engages with the
pinion C 3. also in the box I and by moving longitudinally can turn the pinion in
either direction. Suppose the paper is fixed in the presses B & D then when the
crosspiece C begins to travel towards B1. the rack will move in the same direction,
thereby turning the pinion C3. This causes the lever J. to move round the dial
which also pushes the pointer K round with it (the direction of the ratchet teeth
must be set so as to allow of this). When the pressure on the springs G G
overcomes the breaking strain of the paper, the crosspiece D will immediately fly back
to the stop H. carrying with it the indicator but as the rack (2. does not move it
being fastened to the crosspiece C and the motion of the thumbscrew F being arrested
the pinion C3. turns in the reverse direction as it passes over the rack C 2. until it
arrives at the starting place. This of course turns the lever J back and consequently

page_text: it leaves the pointer K at the place corresponding to the pressure for breaking
the paper-the pawl K 2. holding the pointer in position. The stretching of the
paper has no effect upon the indication as the pressure is always represented by the
distance between the crosspieces C & D. After each testing the crosspiece C should
be returned to the starting point, and by lifting the pawl K 2. out of the ratchet teeth
on the dial I 2. it may also be returned so that the projecting pin K. 1. engages with
the lever J ready to repeat the operation.
Having shown how the machine has to work the following details explain the
construction.
The guides A. A may be of any section but round ones are preferable as being
more easy to manufacture, the ends of them may be screw cut and one end screwed
firmly into a tapped hole in the crosspiece B while the other end may be secured by
a nut on either side of the holes, through which the guides go. One of the cross-
pieces B is formed into a small press and is identically the same as the crosspiece D
except in the method of attachment to the guides A A (the crosspiece B being firmly
attached while D can slide freely along them). The construction of the presser to
hold the ends of the paper will be seen by referring to Figs. 3 & 4 which are the end
views of the machine. In Fig. 4 it will be seen that M is the portion which presses
down on the paper and the pressure is applied by the thumbscrew N. The thumb-
screw N is turned down to a slightly less diameter nearer the end (as will be seen by
the dotted lines in the figure) and fitted into a corresponding recess in the projecting
piece P. Near the end of the thumbscrew aforementioned a semicircular groove is
turned and a small round pin is driven tightly into a hole so that the side of the pin
fits into the groove round the screw, and prevents it coming out of the recess while at
the same time it allows it to turn round, by this means the part M may be raised
from the other pressing surface of the press to allow the paper to be placed in
position. The pressing surfaces of the presses require to be accurately surfaced so
that they may take an even hold of the paper. As mentioned before the thumbscrew F
always keeps in contact with the crosspiece B 1. whichever way the bolt E may be
moving. This is effected by the thumbscrew F having a projection turned on the
face F1. which fits into a corresponding recess in the crosspiece B 1. and has a semi-
circular groove turned round the projection which fits the side of a pin F 2. driven
firmly into a hole through the crosspiece B 1. as shown in Fig. 5.
The whole machine is preferably made of brass, except the two spiral springs G G
and the small spring K. 4 on the pointer K which springs should be made of steel.
The thickness of the wire of the springs G G must be such that when compressed
they will store sufficient power to break the strongest paper required to be tested.
The spindle of the pinion C 3. may be either made of iron or steel, but preferably
of steel, also the small screws used for fastening parts together should preferably be
made of iron. The edges of all the heads of thumbscrews should be milled so that the
fingers may have a good hold upon them.
The drawings accompanying the specification are made to the size of a portable
machine, but sizes may be modified to suit various circumstances.
Having now particularily described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed I declare that what I
claim is
An apparatus made substantially as described and for the purpose specified.
WM. SINCLAIR.