Page 18 - CITS - ED - Mechanical

ENGINEERING DRAWING - CITS

Fig 5

Exercise 1.6

Draw three circles tangential to each other if centres A,B & C are given. (Fig 6)
• Mark centres A,B & C.
• Join AB, BC & CA and form triangle ABC.
• Bisect any two angles of the triangle. Bisectors cut the opposite sides AB and BC at F and G.
• 'A' as centre and AF as radius draw a circle.
• 'B' as centre and BF or BG as radius draw another circle.
• 'C' as centre and CG as radius draw the third circle.

Fig 6

Exercise 1.7

Draw external tangents to circles of dia 40 and 30 and center distance 60 mm. (Fig 7)
• Draw a line and mark two points C and C at 60 mm.
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• Draw two circles of dia 40 and dia 30 with center marked as C and C .
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• On dia 40 circle (D ) draw a concentric circle of dia 10 (D ) (dia 40 - dia 30).
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• From center C draw a line 't' touching circle D at P.
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• Join C and P (angle P is right angle).
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• Extend line C , P upto the circle D meeting at P .
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• Draw C P parallel to C P .
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• Join P and P forming the (common) tangent T to circle D and D .
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• Similarly draw tangent T . Tangents T and T are called external tangents.
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CITS :Engineering Drawing (Mechanical) - Exercise 1