PartDesign InvoluteGear

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PartDesign InvoluteGear

Menu location
Part Design → Involute gear...
Workbenches
PartDesign
Default shortcut
None
Introduced in version
-
See also
FCGear Workbench

Description

This tool allows you to create a 2D profile of an involute gear. This 2D profile is fully parametric, and can be padded with the PartDesign Pad or PartDesign AdditiveHelix feature.

For more detailed information see Wikipedia's entries for: Gear and Involute Gear

Usage

Create the profile

  1. Go to the menu Part Design → Involute gear....
  2. Set the Involute parameters.
  3. Click OK
  4. The involute gear is created outside of the active body. Drag and drop it into a body for the application of further features like padding.

Create a spur gear

  1. Select the gear profile in the tree.
  2. Press the Pad button.
  3. Set the pad's DataLength to the desired face width of the gear.
  4. Click OK

Create a helical gear

introduced in version 0.19

  1. Select the gear profile in the tree.
  2. Press the PartDesign AdditiveHelix button.
  3. Choose as Axis the normal of the gear profile, that is Normal sketch axis introduced in version 0.20. (In earlier versions the Base Z axis can be used as long as the profile's plane has not been altered.)
  4. Choose a Height-Turns mode.
  5. Set the DataHeight to the desired face width of the gear.
  6. To set the desired helical angle an Expressions for the DataTurns is required.
    1. Click the blue File:Sketcher Expressions.png icon at reh right of the turns' input filed
    2. Enter the following formula: Height * tan(25°) / (InvoluteGear.NumberOfTeeth * InvoluteGear.Modules * pi), where 25° is an example for the desired helical angle (aka beta-value) and InvoluteGear is the Name of the profile.
    3. Click OK to close the formula editor.
  7. Click OK to close the AdditiveHelix' task panel.

Hint: To make the helical angle an accessible parameter, use a dynamic property:

  1. In the profile's property editor, activate the Show all option in the context menu.
  2. Again in the contest menu, select Add Property. Note: this entry is only available when Show all is active!
  3. In the "Add Property" dialog
    1. Choose App::PropertyAngle as Type.
    2. Set "Gear" as Group.
    3. Set "HelicalAngle" as Name (without space).
    4. Click OK
  4. Now a new property "Helical Angle" (space added automatically), with an initial value of 0.0°, becomes available.
  5. Assign the desired helical angle to the new property.
  6. In the formula of the AdditiveHelix' DataTurns property, you can now reference InvoluteGear.HelicalAngle instead of the hard coded value of e.g. 25°; again assuming InvoluteGear as the Name of the profile.

Properties

  • DataExternal Gear: True or false
  • DataHigh Precision: True or false
  • DataModules: Pitch diameter divided by the number of teeth.
  • DataNumber Of Teeth: Sets the number of teeth.
  • DataPressure Angle: Acute angle between the line of action and a normal to the line connecting the gear centers. Default is 20 degrees. (More info)

Tutorials

How to make gears in FreeCAD

Related