Technical Drawing.

Details:-

• Importance & relevance for Accessory designers 
• Technical drawing inputs (Orthographic & Sectional views, exploded views Assembly Drawing, Isometric views and exploded views)

• Drawing of accessory products with precision and scale. 
• Articulation of Bill of Material (BOM) and communicating the technical specifications (use standard formats)

DRAWING INSTRUMENTS

        Drawing instruments are used to prepare drawings easily and accurately. The accuracy of the drawings depends largely on the quality of instruments. With instruments of good quality, desirable accuracy can be attained with ease. It is, therefore, essential to procure instruments of as superior quality as possible.

      Below is the list of minimum drawing instruments and other drawing materials which every student must possess:

1. Drawing board

2. T-square

3. Set-squares - 45 and 30'-60' 

4. Drawing instrument box, containing:

(i) Large-size compass with inter-changeable pencil and pen legs.

(ii) Lengthening bar

(iii) Small bow compass 

(iv) Large-size divider

(v) Small bow divider

(vi) Small bow ink-pen

(vii) Inking pen

5. Scales

6. Protractor

7. French curves

8. Drawing papers

9. Drawing pencils 

10. Sand-paper block

11. Eraser (Rubber)

12. Drawing pins, clips or adhesive tapes

13. Duster

14. Drafting machine

15. Roll-n-draw.

Lines

Various types of line used in general engineering drawing.

(A) _______________________

Continuous thick or Continuous wide

     Visible outlines, visible edges; crests of screw threads; limits of length of full deph thread, lines of cuts and section arrows; parting lines of moulds in views; main representations in diagrams, maps, flow charts; system lines (structural metal engg.)

(B) __________________________

Continuous thin (narrow) (straight or curved)

      Imaginary lines of intersection; grid, dimension, extension, projection, short centre, leader, reference lines; hatching; outlines of revolved sections; root of screw threads; interpretation lines of tapered features; framing of details; indication of repetitiv details;

Continuous thin (narrow) freehand

     Limits of partial or interrupted views and sections, if the limit is not a chain thin line.

Continuous thin (narrow) with zigzags (straight)

Long-break line

(E) _  _  _  _  _  _  _  _  _

Dashed thick (wide)

   Line showing permissible of surface treatment.

(F) _  _  _  _  _  _  _  _  _  _  _

Dashed thick (narrow)

Hidden outlines, hidden edges

(G) __ . __ .  __ .  __ .  __ . __ . __

Chain thin Long-dashed dotted  (narrow)

Centre line; lines of symmetry; trajectories; pitch circle of pitch circle of gears, pitch circle of holes,

Chain thin (narrow) with thick (wide) at the ends and at changing of position

Cutting planes

(J) _______ . ________ . _________

Chain thick or long-dashed dotted (wide)

     Indication of lines or surfaces to which a special requirement applies.

(k) _______ .. ________ .. _________

Chain thin double - dashed or Long-dashed double dotted (narrow)

     Outlines of adjacent parts Alternative and extreme positions of movable parts Centroidal lines Initial outlines prior to forming Parts situated in front of the cutting plane.