1. Mechanical Drawing and Instrument Use
Chapter 3
Mechanical Drawing
and
Instrument Use

2. Mechanical Drawing
Drawing accurately with the aide of rulers, scales, compasses, etc.

3. Drafting Board with adjustable angle

4. Parallel Bar
Ends of the straight edge are controlled by a system of cords and pulleys. For this reason you can move it up and down the drafting board maintaining a horizontal position.

5. T-Square
It is composed of a head and the blade. When put against the side of a table that is straight it becomes your straight edge that is perpendicular to the table.

6. Triangles
All vertical and most inclined lines can be drawn with the 45 and 30x60 triangles. The various degrees that can be used can be found on page 29 in your book.

7. Compass and Dividers
Compass are used to draw circles from about 1” radius to about 6” radius.
Dividers are used for subdividing and transferring distances into equal parts

8. Lead Holder Holds different types of lead in order to draw.

9. Circle Template Instrument used to trace various sizes of circles.

10. Protractor Measures angles.

11. Erasing Shield
Protects lines on your drawings from being erased.

12. Scale Used to measure at different scales.

13. Drawing Paper Standard Paper Size ANSI Paper Size “A” Size: 8 ½” x 11”
“B” Size: 11” x 17”
“C” Size: 17” x 22”
“D” Size: 22” x 34”
“E” Size: 34” x 44”
Roll Stock
“A” Size: 9” x 12”
“B” Size: 12” x 18”
“C” Size: 18” x 24”
“D” Size: 24” x 36”
“E” Size: 36” x 48”
Roll Stock

15. Lead Types Hard Leads Medium Leads Soft Leads
Extreme accuracy and line work
9H, 8H, 7H, 6H, 5H, 4H
Medium Leads
General purpose in technical drawings, lettering, arrowheads, darkening
3H, 2H, H, F, HB, B
Soft Leads
Not used in mechanical drafting, used for smudging and sometimes in renderings
2B, 3B, 4B, 5B, 6B, 7B

17. Neatness Lift your equipment
Remove graphite from lead after sharpening
Never place articles on drawings
Wash hands frequently with soap
Do not rub eraser crumbs with hand, use the brush
Use eraser shield
Touch drawing with back of finger nail
Do not sweat on drawing
When lettering, place paper under hand.
When darkening, move left to right if right handed. Or move opposite if you are left handed.