It serves the functions of a Tee square, set square, protractor and scale. They come in different sizes and a pattern called ‘Pantagraph’ type. It is fitted on the top left side, edge of the drafting board, mounted on an adjustable frame or table. It requires large area of working place. The angle of the drafting board can be adjusted by pedal operating system. There are two counter weights to balance the angular position of the board and the drafting head. It is more suitable for production drawing office.
On the other end, a protractor head H with switvelling and locking arrangment is fitted with two scales at right angles.
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.
The scales are bevelled on both sides, graduates to 1:1 & 1:2., 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 900 between them.
mini drafter is an important device used for making drawing quickly& accurately. This instrument gives faster drawing as it like the purpose of T Square, Set Square, Protractor and scales
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