Lecture 17 TA 101 A Engineering Graphics 2018

Lecture 17 TA 101 A Engineering Graphics 2018 -19 -I By Dr. Mukesh Sharma Professor DEPARTMENT OF CIVIL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY KANPUR-208016, INDIA

True Shape of Plane through EV and Auxiliary Plane A 1 F XH RH XA 1 , RA 1 PH H F RF S A 2 XA 2 P A 2 XF PF TS RA 2 P A 1 SF TL A 1 A 2 EV SA 1 SH

S SH A 1 S' A 1 F XH RH EV A 1 XA 1, RA 1 PH H P‘A 1 F P SF’ A 1 SF XF TS R P F Lines are parallel to hinge line PF’ F True Shape of Plane through EV and Method of Rotation

2 H TL 3 H 4 H 3 F H F IH 2 F 3 A 3 B 4 F H 2 B TS A IF IA IB

CH a. H d. H b. H H F b. F d. F a. F c. F Are the lines parallel?

a. H c. H b. H d. H H F F P c. F c. P b. F d. F a. F Are the lines parallel? d. P a. P

Conditions for lines to be parallel - Lines appear parallel in all views - If oblique lines appear parallel in two adjacent views; they are necessarily parallel (no need to see third view)

Test for Perpendicularity f. H c. H d. H a. Hb. H c. F TL a. F d. F e. F H F b. F i. H k. H g. F 900 f. F k. F i. F l. F 900 TL 900 l. H g. Hh. H e. H H F j. H TL A h. F B j. F C Are the lines perpendicular? condition: at least one of the lines should be in TL and make 900 angle with other line. If none of the lines is in TL and show 900 angle between them, they are not perpendicular

Test for intersection c. H b. H a. H d. H H F a. F c. H b. H a. H H F c. F d. H b. F a. F d. F b. F A B Conclusion – point of intersection of two lines must stay aligned in all views

a. H 2 H XH 3 H 1 H YH 4 H b. H 4 F b. F H F 1 F a. F YF XF 3 F 2 F A Line in a plane – if a line is in the plane, all points of intersection should stay aligned in all views

Construct a line parallel to a plane b. H 1 H c. H d. H a. F 2 H H F 2 F d. F c. F b. F 1 F Line 1 -2 in top view and Point 1 F is given See we forced the line 1 -2 to be parallel to line b-d in front view As a result, line 1 -2 is parallel to the given plane (abc)

A line perpendicular to a plane Very useful in finding shortest distance from a point to a plane 3 H 2 H p. H o. H 1 H o. F 4 H H F 4 F 3 F TL EV 900 p. F 1 F 2 F A line is perpendicular to plane when the line is in true length at a 900 angle to an edge view of the plane. Line OP is perpendicular to plane 1 -2 -3 -4 How to draw a perpendicular from a point with this concept?

Draw a perpendicular to a plane from point – Recall edge view of plane and perpendicular at 90 0 needed PARALLEL OH 2 H TL OA 3 H 3 A 2 A p. H 1 H PA H A 900 d EV 4 H 4 A 1 A H F 2 F TL d 3 F p. F 4 F 1 F OF 1. 2. 3. 4. 5. 6. 7. 8. Get the edge of plane See if any line in TL on the plane See through the line and project all points Line 2 -3 in top view in TL in In aux view take distance from Front and locate points Draw a perpendicular from OA on EV ~ OA PA (in TL? ) Project PA to Top view (see the arrows) Project PH to Front view see PF