Drafting Machine / Mini-Drafter

Mini-Drafter is a device used to draw parallel or inclined lines very effectively with ease. It is mounted on the top left corner of the drawing board by means of a clamping mechanism which is an integral part of the device. Mini-drafter is an instrument which combines together all the features of a T-square, set squares, scales and protractor and hence is a unified instrument capable of performing the functions of all these instruments put together. One end of the mini-drafter is clamped by means of a screw, to the distant longer edge of the drawing board. At its other end, an adjustable head having protractor markings is fitted. Two blades of transparent celluloid accurately set at right angles to each other are attached to the head.

The machine has a mechanism which keeps the two blades always parallel to their original position, irrespective of their position on the board. The blades have scales marked on them and are used as straight edges. The blades may be set at any desired angle with the help of the protractor markings. The L-shaped scale which is graduated in millimeters acts as the working edge of the mini-drafter. The L-Shaped scale also has a degree scale for angle measurement. The working edge can be moved to any desired location on the drawing board. In some machines, the blades are removable and hence a variety of scales can be used. Thus, by means of this machine, horizontal, vertical or inclined parallel lines of desired lengths can be drawn anywhere on the sheet with considerable ease and saving of time. Drafting machines are common among the college students and draughtsman.

Fig.1 Mini-Drafter

The drafting in the machine come in different sizes and a pattern called ‘Pantagraph’ type. The protractor head has a spring loaded clutch relieving handle, which rotates and locks at 150 intervals automatically. For setting any angle other than multiples of 150, the clutch spring is released and by rotating the centre knob, the zero line is set to the required angle and the friction clutch knob is tightened. It is capable of rotating 1800, thereby any angle can be set. They can be reversed with the help of dovetail slide fitting. There is a fine adjusting mechanism on the drafting head to set the scale parallel to the edge of the board. The scales also can be adjusted if there is any error in measuring between them. The angle of the drafting board can be adjusted by pedal operating system.

Procedure for Clamping Mini-Drafter

Set the protractor head with reference mark indexing zero degree, then fix the clamp of the mini-drafter at the top left corner either along the top horizontal edge of the board or along the left vertical edge of the board. With the drawing sheet placed underneath the scales of the mini-drafter, fix the drawing sheet to the drawing board with the scales of the mini drafter aligned either with the vertical or the horizontal borderlines of the drawing sheet.