FreeCAD: How to make gear with Involute Gear tool

1. Switch workbench to Part Design workbench.

2. Select [Part Design]-[Involute gear...] menu.

   

3. Control panel for Involute gear will be displayed in Tasks tab. And a gear with the center (0, 0, 0) and the Z axis as the rotation axis is displayed on the 3D view.

   

   You can set following parameters in the control panel. After parameter settings, click OK to finish editing.

   Parameter	Meaning of the parameter
   Number of teeth	Number of gear's teeth
   Module	The value obtained by dividing the pitch circle diameter by the number of teeth. For example, if a gear has 30mm diameter and 20 teeth, you should set 1.5 (= 30/20) into this parameter. In general, the gears must have same module value to mesh each other.
   Pressure angle	Pressure angle. The angle between the radial line passing through the pitch point and the tangent line of the tooth profile.
   Heigh precision	If True, heigh precision. Other, low precision.
   External gear	If True, external gear. Other, internal gear.
   Addendum Coefficient	The height of the tooth from the pitch circle to the tip, normalized by the module.
   Dedendum Coefficient	The height of the tooth from the pitch circle to the root, normalized by the module.
   Root Fillet Coefficient	Radius of the fillet at the tooth root, normalized by the module.
   Profile Shift Coefficient	Outwards shift coefficient of the gear profile, normalized by module.

   

   

   Example of number of teeth

   

   

   Example of pressure angle

   

   

   

   Example of enable/disable heigh precision

   

   

   Example of enable/disable external gear

   

   

4. Gear angle and position can be changed on Data tab. Select the created gear on model tree and edit rotational angle, axis and position on Data tab at bottom of Combo view.

   

5. To make the gear 3D in Part Design workbench, the gear should be at inside of body. Create new body, then Drag the gear on the model tree and place it under the body.

   

6. Select the gear on model tree and extrude it. If you want to create internal gear, do boolean operation with the extruded gear and another cylinder.

   

   

References

• "歯車のピッチ点，ピッチ円，圧力角"、小西克享、埼玉工業大学、機械工学学習支援セミナー（PDF）
• PartDesign InvoluteGear - FreeCAD Documentation