Improvements in or relating to apparatus for tracing designs at regularly spaced intervals

摘要

616,441. Drawing equally spaced lines and curves. DIVAR SOC. ANON. Sept. 2, 1946, Nos. 26354 and 26355. Convention dates, Sept. 7, 1945, and May 6, 1946. [Class 97 (iii)] Apparatus for producing a step-by-step motion in repeating drawings of lines, curves or other designs comprises a guide 1 attached by pins 2 to the drawing surface 3 and a carriage 4 to which is detachably secured the ruler or templet for guiding the drawing instrument, and which slidably engages the guide 1. Pivoted in the carriage 4, about a spindle 10, is an oscillating lever 12 having a pin 24 engaging in a slot 25 of a roller 15 also pivotally mounted in the carriage 4. The travel of the lever 12 is limited by a fixed stop 26 or by a fixed stop 28 co-operating with an adjustable arm 27 which may be locked in the desired portion by knob 29. A slide member 17, of trapezoidal crosssection, slides in a similarly shaped groove 16 of the guide 1 and carries a pillar 19 to which are attached a metallic ribbon 18, whose other end is secured at 20 to the roller 15, and a spring 21 secured at its other end to a stem 22 on the carriage 4. Depression of the lever 12 causes the pin 24 to move in the slot 25, thus rotating the roller 15 in the direction of the arrow 31 at the same time binding the slide member 17 in the groove 16, thereby causing the ribbon 18 to be wound on the roller 15 so that the carriage 4 moves in the direction of the arrow 32. On release of the lever 12, when the pin 24 has reached the bottom of the slot 25, the slide member 17 is released from frictional engagement with the groove 16 and the extended spring 21 pulls this member also in the direction of the arrow 32 until the metal ribbon 18 is again unwound. Pressure may be applied to the end 33 of lever 13 to release the roller to enable the apparatus to be moved in the reverse direction. Adjustment of the distance moved in each step is made by adjusting the position of arm 27. In a modification the slide member 17 is dispensed with, the roller 15 being adapted to engage the groove 16 direct and a metallic wire is used in place of the ribbon 18.