Improvements in or appertaining to Pantographs.
Year: 1890

page_text: Date of Application, 27th May, 1890-Accepted, 7th Feb., 1891
GUBIT DIE DI MUITICATION.
Improvements in or appertaining to Pantographs.
A communication from abroad by JOHANN GERHARD DAMMANN, of Berlin, in the
Empire of Germany, Mechanic.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both
in the County of Lancaster, and 323, High Holborn, in the County of Middlesex,
Civil Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement :-
Guiding arrangements for pantographs and the like, as hitherto used, have the
disadvantage that the movement of the drawing pencil does not take place with
equal facility at all points, but in certain positions of the pantograph, friction occurs
in the guides which hinders their movement and thus prevents a piece of work being
exactly reproduced.
The new guiding apparatus forming the object of the present invention avoids
these disadvantages, as no pressure or drag, which acts against the lines of the guide,
takes place in it.
The new guiding arrangement, when used as a drawing apparatus, will naturally
be most advantageously employed in conjunction with such devices as are not
intended to reproduce an exact copy of the original on a larger or smaller scale,
but in which, besides an increase or reduction of the original, an alteration is
intended to be made in the proportions of the length or breadth.
Even this does not exhaust the applicability of the present invention, for it can
(when suitably duplicated) form in itself a drawing apparatus which can, for
example, be utilised for manifolding exact reproductions of the original.
The invention taken in conjunction with a pantograph is shown on the annexed
drawing (Figure 1) in which the guiding apparatus is here shown in a double form,
one group of links being for clearness sake shaded, the other group being left
unshaded. The shaded group consists of the fixed bar A, and the links B, C, D,
E, F, pivoted thereto and with one another. The parts of the second group which
correspond to those of the first group are designated by A¹, B, C, D, E and F¹,
and the bar A is rigidly connected with the bar A.
The pantograph P is then pivotally jointed at the points a 6 of the links C D
and CD. In order to prevent any sticking of the joints ab in any position of
the pantograph and also to render possible an easy working of the joints of the
guiding apparatus, the connecting links of each group, that is to say, the links B, C,
and links D, E, F, bear a certain proportion to one another. The link D is, in
this instance, the length of B, and the distance of the joint c from d (being the
fulcrums of E and F and of D and F respectively) is equal to one eighth of the
length of B.
The link C is equal to the length of the link B and the link E is th the length
of link B.
The second group of links A', B, C, D' has exactly the same proportions as the
first group.
If the pantograph P be now used, no stoppage can occur at any place, and it
works with equal ease in any movement.
In Figure 2, the present invention is represented in a four-fold form, combined in
such a way that (as stated at the commencement of this Specification) it can itself
serve as a manifold reproducing apparatus without the addition of the usual
pantograph.

page_text: In this figure, A is the fixed bar with which there is connected a group
of
links B, C, D, E, F, and a similar group B, C³, D³, E³, F³.
A pantograph is not, however, as in Figure 1, attached at the joint a of the
rods CD and at the joint b of the rods C³ D³, but these points are connected by a
bar A'. On both sides of this bar, two other groups of links B', C', D', F', E',
and B, C, D, E, F are coupled in which arrangements the joint a' of the
links CD', together with the joint 6 of the links C* D* guided by the slotted
bar A', can slide backwards and forwards by means of the latter.
Now, if the guide-pencil be fixed at a', it follows that every drawing pencil
rigidly fixed in the slotted bar A² follows the movements of the guide-pencil
exactly, and produces an exact copy of the drawing traced thereby, so that as many
exact copies can be made simultaneously as there are drawing pencils inserted in the
bar A². The slot in the bar A' enables the position of the joint of the links C
and A' to be adjusted.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is :-
A guiding arrangement of the kind described, taken either by itself, or in
combination with a pantograph, lazy tongs or the like, the said arrangement
consisting of a fixed bar A on which one arm of an articulated angle piece BC
having arms of equal length is pivoted, whilst the other arm of said angle piece is
also connected with the fixed bar A by means of an articulated angle piece D, F,
with arms of equal length, one arm F of which is connected by means of a pivoted
link E with the arm 13 of the first-named angle piece, the link D having the
length of B and the distance of joints c and d being equal to one eighth of the
length of B, whereby the guide-apparatus, when made in duplicate, may be used as
a manifold reproducer, substantially as described.
Dated this 04h 1... SM 1900
C
WM. P. THOMPSON & Co.,
Agents for the Applicant.