US2439291A - Set shift parallel rule - Google Patents

Description

April 6, 1948.

D. T. E. FlELDlNG 2,439,291

SET SHIFT PARALLEL RULE Filed July 10, 1945 INVENTOR- DA V/O THOMAS EDWARD F/EL DING BY WLW ATTORNEYS.

Patented Apr. 6, 1948 This invention relates to a device for use by draughtsmen in drawing cross hatching or similcr parallel lines on mechanical drawings.

The object or the invention is a device which can be used without a T square or a set square and which will enable a series of parallel lines to be drawn at any desired angle to the normal horizontal or vertical lines of the drawing.

The device according to the invention consists of a relatively long base strip with a flat face and two longitudinal upturned edges to form a slide, a cursor capable of being moved from end to end of the slide, a rack being formed on one of the upturned edges, a pinion on the underside of the cursor to engage the rack, a rotatable wheel or knob above the cursor by which the pinion can be rotated to cause the cursor to travel along the strip and a straight edge carried by the cursor and angularly adjustable in relation to the base strip along which edge the ruling tool can be drawn, the said straight edges being pivotally mounted on the cursor so that it can be moved to cause its edge to make any desired angle with the basestrip and the ends of the base strip being formed with notches or apertures through which pins or the like can be inserted to secure the strip to the drawing paper.

The invention is illustrated in and will be described with reference to the accompanying drawings in which:

Fig. 1 is a plan of the device,

Fig. 2 is a section on line 2-2, Fig. l.

The device comprises a relatively long base strip A with a fiat face a and two turned up edges o d to form a slide. A cursor B is slidabh mounted on the base strip A, the edges of the cursor extending over the edges d a of the slide. A rack 01 is formed on the inner face of the edge a of the base strip A and a pinion 12 carried on a short spindle b passing through the cursor engages the rack :1 A wheel or knob 13 is secured on the outer end of the pinion b so that rotating the wheel or knob the pinion can be rotated to transverse the cursor 13 along the base strip A. A spring 22 carried by the cursor B bears against the outer face of the edge a of the strip A to prevent tilting or angular movement of the cursor relative to the base strip.

The wheel knob 22 is preferably toothed, the teeth bei g engaged by a spring pawl b to retard the rotation of the wheel or knob at each tooth and so allow of the cursor being moved along the base strip a given distance at a time. Each end of the base strip A is formed with a notch (1 preferably of V shape or with an aperture through each of which a pin or the like such as the pins 0 can be passed to hold the base strip A onto the paper.

A flat lug or projection B is secured to or formed integrally with the cursor B projecting at right angles therefrom. The lug" or projection B carries a pivot 02 on which a straight edge D is mounted on the underside of the lug,. the under-face of the straight edge being in the same plane as the undersurface of the slide, formed by the edges a d of the base strip A. A'lock nut d is provided on the upper end of the pivot d whereby the straight edge D can be locked in any desired angular position relative to the base strip A.

Projections e shown in dotted lines in Fig. 1 may be formed on the edge or of the base strip A so that the device may be used with a T square if desired.

The pivot end of the straight edge D may in the form of a circular disc d graduated in degrees and a datum line or pointer b may be inserted on the projection B to facilitate the setting of the straight edge to any desired angle.

To use the device a line is drawn parallel to the bottom edge of the drawing to be cross hatched or to have parallel lines drawn through and at asuitable distance therefrom to give the drawing pen a clear stroke along the straight edge D. The cursor B is then moved to one end preferably the left hand end of the base strip A and the two notches a at the ends of the base strip are then located with their apices on the line and the large headed pins c inserted in the notches and pressed into the paper to hold the slide in position. The straight edge D is then moved to the desired angular position (or it may be set before the slide is secured by the pins) and the device is then ready for use. After each line has been drawn the notched or toothed wheel or knob b is rotated by the left hand of the draughtsman one or more notches or both according to the distance desired between the lines to be drawn, the spring I) which engages the notches ensuring that the wheel or knob is rotated exactly the same angular distance at each movement. The movement of the wheel or knob b is communicated to the pinion b which engages the rack a on the base strip A and thereby causes the latter to move along the strip by equal steps and since the straight edge D is affixed to the cursor B it will move along the drawing with the same number of equal steps so that if a line is drawn at each step all the lines will be equidistant from adjacent lines and at angle according 3 to the setting of the straight edge D relative to the base strip A.

I claim:

A drafting instrument comprising an elongated base strip having upper and lower lateral flanges along its longitudinal edges extending in the same general direction, the lower flange having rack teeth at its free edge, a cursor disposed against said flanges and slidablelongitudinally of said base strip, said cursor having an upper flange hooked over the first-mentioned flange,

said cursor having a flange at its lower edge extending under and in spaced relation to the lower flange of the base strip, a spring means carried by the lower flange of the cursor and interposed between the latter and the adjacent flange of the base strip urging the upper flanges of the base strip and cursor into contact, a straight edge extending from the cursor, a spindle journalled transversely in the cursor, a pinion on the spindle and disposed between the base strip and the DAVID THOMAS EDWARD FIELDING.

REFERENCES CITED The .following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,213,664 McCuaig Jan. 23, 1917 1,632,267 Beem June 14, 1927 1,980,884 Sidney Nov. 13, 1934

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