Chapter 10 Conventional Practice in Section View

Chapter 10 Conventional Practice in Section View

TOPICS Section view representation of rib, web, spoke and lug. Aligned section Conventional break

Section view representation of rib, web, spoke and lug

CONVENTIONAL PRACTICE There are some exceptions to the general rules of sectioning: v Webs, ribs, lugs, spokes, v Shafts, rods, spindles, v Bolts, nuts and thin washers. v Rivets, dowels, pins and cotters.

CONVENTIONAL PRACTICE The cross-section is technically correct. NOT RECOMMENDED The convention in a drawing is to show the preferred method for sectioning this type of object. CORRECT Convention Rotation

TERMINOLOGY Rib and Web are thin, flat feature of an object that acts as a structural support. Rib

TERMINOLOGY A web or rib is a strengthining or supporting part of a component. Web

TERMINOLOGY Spoke is the rod radiating from the hub to the rim of a wheel. Hub Spoke Rim Spoke

TERMINOLOGY Lug is an ear which is built as portion of an object for attachment.

TERMINOLOGY Lug is an ear which is built as portion of an object for attachment.

CONVENTIONAL PRACTICE Omit the section lines on the section view of v Rib, Web and Lug, if the cutting plane is passed flatwise through. v Spoke, if the cutting plane is passed longwise through.

CONVENTIONAL PRACTICE v When the cutting plane passes through a rib longtudinally it is not sectioned

CONVENTIONAL PRACTICE v When the cutting plane passes through the rib transversely it should be sectioned

EXAMPLE : RIB Normal multiview drawing Normal section view Section view drawing with convention

EXAMPLE : WEB : flatwise cut Normal multiview drawing Normal section view Section view drawing with convention

EXAMPLE : WEB : crosswise cut

EXAMPLE : WEB : multiple section view

EXAMPLE : SPOKE Misleading impression

EXAMPLE : LUG

Aligned Section

DEFINITION Aligned section is used when features are located on radial lines Aligned section is a section view that is drawn by imaginary rotating the object’s features appeared in a principal view about symmetry axis

Example : Hole Gives the impression that this holes are at unsymmetrical position.

Example : Hole

Example : Rib

Example : Ribs & Holes

Example : Aligned section& Keyway Example : Spoke of keyway

Example : Lug

Conventional Break

CONVENTIONAL PRACTICE For long objects that have to draw in a small scale to fit them on the paper, it is recommended to remove its long portion (which contains no important information) and draw the break lines at the broken ends.

Example SCALE 1: 1

Example SCALE 2: 1

STANDARD BREAK LINES Wood Rectangular cross section Cylindrical cross section Tubular cross section Metal

TO DRAW CYLINDRICAL BREAK 30 o R/3 R/3

TO DIMENSION A BROKEN PART f 16 Typical dimensioning method 800 f 16 800 not to scale dimensions