Multi-purpose drawing instrument

#This invention relates to a multi-purpose drawing instrument and has as one of its objects to provide a drawing instrument which can be employed in a simple manner to draw parallel and equidistant lines, increasing and decreasing shade lines, vanishing lines and vanishing lines in perspective.

#Another object is to provide a drawing instrument which is accurate and fast to work with.

#Accordingly, this invention provides a multi-purpose drawing instrument comprising a guide rod supported horizontally on upright end supports; a slide disc provided with roller support means which slidingly engages said guide rod so that the disc slides along said guide rod; a carriage slidingly supported on said guide rod above said slide disc and carrying a conical member with the side wall thereof in pressure contact with the guide rod so that when said conical member is turned the carriage moves along the guide rod, tightening means on said carriage for varying the contact pressure of the conical member on the guide rod; adjustment means for adjusting the position of the carriage transversely of said guide rod and for engaging the carriage with the slide disc when said carrage or slide disc is moved along the guide rod; a horizontally-disposed radial arm one end of which is rotatably connected to the center of the slide disc so that it can be rotated thereat and the free end of which is connectable to a foot ruler, means for clamping and clamping/said horizontally disposed radial arm to said slide disc at any desired angle relative to the guide rod or said carriage.

#An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which

#FIG. 1 shows a perspective view of the multi-purpose drawing instrument from one side thereof;

#FIG. 2 shows a perspective view of the drawing instrument shown in FIG. 1 from another side thereof;

#Referring to FIG. 1, the multi-purpose drawing instrument consists of a guide rod 2 supported horizontally on a pair of upright end supports 4 and 6, of which end support 4 has a fixed non-rotating base and a rotatable top part. The end support 6 has a pin 6a which when screwed down fixedly locates the end support 6 or when unscrewed allows the end support 6 to freely roll on rollers 6b and the guide rod to turn about fixed end support 4.

#The guide rod 2 carries a slide disc 8, which slide disc in the embodiment shown, is a circular protractor; this slide disc can slide along the guide rod on roller supports 10 (reference numeral 10a indicates the rollers provided for this purpose). Above the slide disc 8 is provided a carriage, generally denoted by reference numeral 12, which carriage is also slidingly mounted on said guide rod 2. The carriage 12 consists of a base plate 14 disposed over said slide disc 8, a pair of oppositely-disposed upright shoulders 16 mounted on the base plate 14 and connected together by a pair of roller rods 18; the roller rods 18 extend substantially transversely of and below said guide rod 2. The carriage supports an enclosure 20 and a conical member 22 which is maintained in pressure contact on said guide rod 2 from above by means of tightening members such as screws 24 which clamp the enclosure 20 to the carriage 12 with the guide rod in pressure-egagement between said conical member 22 and the roller rods 18. The conical member 22 is connected to a toothed wheel 26, at one end thereof; this toothed wheel is supported on said enclosure 20 for rotating the conical member 22 through a distance corresponding to the gap between two adjacent teeth. An exploded view of the toothed wheel and conical member is shown in FIG. 4. A release mechanism comprising a spring-loaded lever 28 is provided in the vicinity of the teeth of the toothed wheel 26. The lever is operated by a screw 32 for moving the roller 34 (abutment means) close to the toothed wheel or away from it, in known manner, so as to abut the teeth or release the teeth. In the former case, the toothed wheel 26 will turn against the pressure of the roller 34 and it will thus be possible to know that the toothed wheel has turned through a distance equal to the gap between two adjacent teeth from a feel of the step-like movement generated by the travel of the roller over a tooth from one gap to the next under the tension of the spring 35. A knurled head 36 is provided for turning the toothed wheel 26.

#The base plate 14 carries a slot 38 running transversely of said guide rod 2; this slot engages an upright pin 40 (FIG. 1) in the longitudinal direction so that the carriage 12 can be moved transversely of said guide rod 2 and relative to said slide disc 8. The upright pin 40 is provided axially on the slide disc 8 and serves also to carry the carriage 12 along with the slide disc 8 when either the carriage or the slide disc is moved along the guide rod 2.