CNC Simulator Pro

user guide

7.2. Gear Maker

The Gear Maker tool is a SimCam utility that helps you create gears.
Enter the data you want to base your gears upon and click the Update button when done. The input data is:
Shaft spacing: The distance between the center of the two gears.
To the right of the Shaft spacing value is a checkbox named Lock. Use this when you want to lock the spacing to a certain value that you do not want to be negotiated. When this value is locked and the Module/ Diametral Pitch conflict in such a way that a calculation cannot be made, the program will adjust the Module/ Diametral Pitch value instead. This can cause non-standard Module/ D.pitch values. If you leave this box unchecked, the program will recalculate (suggest) the Shaft spacing and preserve the Module/ D.pitch value.
After you click the Update button, you can see the resulting calculated values in the top left corner of the graphics window.
Also, if an input value has been recalculated, its textbox will have a light red background to draw attention to the change.
Pressure Angle: Pressure angle in relation to gear teeth, also known as the angle of obliquity, is the angle between the tooth face and the gear wheel tangent. It is more precisely the angle at a pitch point between the line of pressure (which is normal to the tooth surface) and the plane tangent to the pitch surface. (Source Wikipedia article Pressure angle.)
Module (metric): When gear dimensions are in the metric system, the pitch specification is generally in terms of module or modulus, which is effectively a length measurement across the pitch diameter. The term module is understood to mean the pitch diameter in millimeters divided by the number of teeth. (Source Wikipedia article Gear.)
Diametral Pitch (imperial system): When CNC Simulator Pro is set to work in inches, the Module value is replaced by Diametral Pitch. For an explanation of this value, see the Wikipedia article about Gears.
Gear Ratio/ Teeth: You can either select to enter the Ratio between the gears, or tell the program how many teeth you want on each gear. If the number of teeth is entered, the program will calculate the ratio and vice versa.
Clearance: Please read about clearance in the following Wikipedia article: Backlash (engineering).
You can animate the gears by clicking in the Animate checkbox. 
When you are done and happy with the gears, click the Create button to create a layer with the gear contours in SimCam. This layer can then be used to create a milling CNC program.
You can select whether you want to create contours for the first gear (to the left), the second gear, or both. Also, select the resolution you want the gears created in. Higher resolution means more line segments and longer programs.
Note that each gear contour will end up on its own layer, making it convenient to handle them separately.