The present invention relates to fastening and adjusting device,
particularly for draughtsman compasses.
The draughtsman compasses of the known art are generally constituted
by two hinged rods each having a point at its lower end; usually one of the two
points can be substituted by a lead holder or a drawing pen, according to the case
(see e.g. GB-A-145216 and GB-A-1 279 195.
Usually, in these types of compasses one of the two rods is shorter
and a fastening member is hinged at its lower end for the lead holder or drawing
The fastening member is substantially constituted by a pair of jaws
that can be tightened by a screw and by a knurled ring; furthermore, the fastening
member is hinged with some friction in order to keep the selected angle during
The fastening member has to be pivoted to the rod in order to vary
its angle with respect to the rod because otherwise, when the compass aperture
increases, the lead holder or the drawing pen would work at an excessive angle
to operate correctly.
This very common type of mechanism has a rather satisfactory operation
but it is susceptible to improvements.
In the known compasses in fact, the pivoting point of the fastening
member is rather high, therefore the working aperture of the compass is greatly
reduced relatively to the length of the fixed point rod.
Moreover, the rotation of the fastening member is not easy because
of the friction, thus rendering difficult those jobs where it is required a particularly
precise aperture adjusting.
Also the locking of the lead holder or of the drawing pen can be
improved, mainly regarding the speed of execution.
Main aim of the present invention is that of providing a fastening
device for the lead holder or the drawing pen in a compass, having a rapid and
easy operation and furthermore with an improved aperture with respect to the known
Within this aim, an object of the invention is that of providing
a device easily manufactured from a productive point of view and hence economically
This aim as well as these and other objects which will be more apparent
later, are achieved by a fastening and adjusting device, particularly for draughtsman
compasses comprising a pair of upwardly hinged rods, characterized in that it
comprises a U-shaped element hinged at the lower end of at least one of said rods,
said lower end having a substantially curved surface, said U-shaped element defining
a cavity between its legs and said surface, a support member being inserted in
said cavity and locked against said surface by means of an adjustable abutment
member, said support member being adapted to support a lead holder,a drawing pen,
a point or similar.
Further characteristics and advantages of the invention will be more
apparent by the following description of an embodiment of the invention, illustrated,by
way of example, in the enclosed drawings wherein:
- Figure 1 is an elevated side view of the compass according to the invention;
- Figure 2 is a view similar to the preceding one but wherein the compass is
- Figure 3 is an isometric enlarged view of the locking device.
With reference to the cited figures, a compass 1, according to the
invention, comprises two rods 2 and 3, upwardly hinged to a block 4 having a hand
grip 5, in a per se known manner.
A U-shaped element 6 has two legs 7 hinged to the lower end of each
of the rods 2, 3 in order to define a cavity 15 between its legs 7 and the surface
10 of the rod end.
A threading 8 is provided on the element 6, partially covering also
the legs 7, for a locking ring 9.
A support element can be inserted in the cavity 15 for such elements
as a lead holder, a drawing pen a point or similar.
In the figures, a support element 14 for a point, applied to the
lower end of rod 3, is schematically illustrated by dashed lines.
At the lower end of the other rod 2 is instead applied a support
element 11, advantageously constituted by a single body comprising a drawing pen
12 juxtaposed to a lead holder 13.
The operation of the device is the following: as the desired aperture
of the compass is set, the rings 9 are loosened to allow the U-shaped elements
to rotate and to set them at the most suitable angle with respect to the working
At this point it is sufficient to again tighten the rings 9 to lock
the U-shaped elements at the selected angle, and at the same time, to lock the
support elements of the point and of the lead holder and drawing pen.
The abutment surface 10 of the lower ends of the rods 2 and 3 is
a curved surface for easing the continuous locking of the support elements.
If it is desired to use the drawing pen instead of the lead holder,
it will suffice to loosen the ring 9, in order to extract the support 11, and to
again insert it into the cavity 15 from its opposite end.
It has been practically observed how the invention achieves the intended
aim and objects by providing a device that allows the points' and lead holder's
or drawing pen's inclination to be adapted to the various apertures, through a
rapid and easy operation and also increasing the maximum working aperture of the
An advantage of the invention is that of allowing to incline and
lock the end organs by the one easy operation of tightening a ring.
A further advantage of the device according to the invention is that
of always ensuring a safe locking that depends on the tightening strength of the
ring, which is adjustable at will and therefore does not suffer after some time
from the wearing out of hinges or similar, as in the known compasses.
The device according to the invention may have numerous modifications
and variations, all within the inventive concept; furthermore, all the details
may be substituted with technically equivalent elements.
The materials employed, as well as the dimensions, may be any according
to the specific needs and the state of the art.
Where technical features mentioned in any claim are followed by reference
signs, those reference signs have been included for the sole purpose of increasing
the intelligibility of the claims and accordingly, such reference signs do not
have any limiting effect on the scope of each element identified by way of example
by such reference signs.