Due to high working speed requirement in industry of rotating components, gear
design development become quite noticeable and rapid in the vicinity of engineering
parameters which become to have a large effect on its performance. In this work the spur
gear of straight tooth is chosen because of its wide usage in industry, also an equation
for joining the involute profile and fillet curve is generated. Variation effect on the shape
of tooth profile forming is studied. A suggested method for generating tooth profile is
obtained and a computer program is written for drawing the involutes and trochoid
curves. The results obtained from the new method are the true continuous involute and
trochoid curves in comparison with those obtained from Mechanical Desk software
which are approximated curves fitted results.