ENGINEERING DRAWING TUTORIALS

  CONSTRUCTION OF AN OCTAGON IN A GIVEN CIRCLE GUIDELINES : 1.     Draw a circle of given radius     2.     Draw a horizontal line “AB” across the circle through the mid-point “O”.     3.     Construct a perpendicular line “CD” cutting across “AB”, dividing the circle into four equal parts.     4.     Bisect “AC, CB, BD and DA”.     5.     Now join points “EF and GH”     6.     Now the circle has been divided into another four (4) equal parts, making eight (8) parts. 7.     Join points on the circle where a line touches the circumference (circle) (AE, EC, CG, GB, BF, FD, DH, HA) to form an OCTAGON

  TO BISECT AN ANGLE   1.     Draw the given angle “ABC”.     2.     With center “B”, take a radius not greater than “BC/BA”, draw an arc to cut through “BA and BC” at “D and E”.     3.     With center “D” at any radius, draw an arc(opposite to the ‘ABC’ angle), Repeat for center “E” so that its intersect the previous arc at “F”     4.     Now join point “F” to point “B”   The given angle has been divided into equal halves.