Gearmake is a small utility program to help an engineer quickly visualize a gear profile. Gearmake is being developed on a Pentium III-450 running slackware linux, and written in the C programming language. OpenGL and GLUT libraries are used to for graphical display. The program will regenerate the gear and rescale the viewing window whenever a gear parameter is changed. This program was written as a final project for MAE 152 at UCSD.

Gearmake generated the involute gear profile through joining piece-wise functions of angle (theta). Assuming the standard positive x-axis corresponds with theta=0, the program steps from theta=0 to theta=2*pi. Along the way, the proper radius is evaluated. The steps below describe the basic algorithm as of version 0.03:

1. Find the space occupied by each complete occurance of a gear tooth. This is evaluated as delta_theta = (2*pi) / (number of teeth).
2. Calculate inner, outer and pitch diameters. The pitch diameter is given by ( diametral pitch ) * ( number of teeth ). The outer and inner diameters are the pitch diameter add/subtract addendum. ( for simplicity, the program will consider addendum = dedendum). The addendum is given by 1 / ( diametral pitch)
3. Start a loop which will assign the beginning value of theta to the piecewise radial function. The values of theta assigned will be 0, 1*delta_theta, 2*delta_theta, ... , (number of teeth - 1) * delta_theta.
4. The piecewise function is:
   1. involute curve from given value of theta until r > r_outer. return theta at r = r_outer.
   2. outer radius from theta (from step 1) to base thickness (radians) - current value of theta. this is done because the involute tooth profile is symmetric, and the radial distance spanned by the outer radius is = radial thickness of tooth base - 2 * radial thickness of the involute.
   3. mirrored/reverse involute curve from theta ( same theta given to upper limit in previous step). proceed until r < r_inner. return theta.
   4. proceed from value of theta given in step 3 to the next beginning of the piecewise function, at index * delta_theta
5. The user is then allowed to modify the values. The radial thickness of the tooth base may be modified independently of the other parameters.
6. When the user is satisfied with the result, gearmake allows the user to adjust resolution prior to DXF export.