FCGear InternalInvoluteGear

InvoluteGear

InvoluteRack

Gear

Description

The FCGear InternalInvoluteGear command creates an internal involute gear wheel with spur gearing by default that can also be transformed into a helical gearing or a double helical gearing.

Internal involute gears from left to right: Spur gearing, helical gearing, double helical gearing

Usage

1. Switch to the Gear Workbench.
2. There are several ways to invoke the command:
   • Press the Internal Involute Gear button in the toolbar.
   • Select the Gear → Internal Involute Gear option from the menu.
3. Change the gear parameter to the required conditions (see Properties).

Properties

See also: Property View.

An FCGear InternalInvoluteGear object is derived from a Part Feature object and inherits all its properties. It also has the following additional properties:

Data

accuracy

• Datanumpoints (Integer): Default is 6. Change of the involute profile. Changing the value can lead to unexpected results.

base

• Datagear (PythonObject): Python gear object.
• Dataheight (Length): Default is 5 mm. Value of the gear width.
• Datamodule (Length): Default is 1 mm. Module is the ratio of the reference diameter of the gear divided by the number of teeth (see Notes).
• Datanum_teeth (Integer): Default is 15. Number of teeth (see Notes).
• Datathickness (Length): Default is 5 mm. Thickness of the uncut outer part of the gear.

computed

• Dataaddendum_diameter (Length): Default is 17 mm. Inside diameter, measured at the addendum (the tip of the teeth).
• Dataangular_backlash (Angle): (read-only) The angle by which this gear can turn without moving the mating gear.
• Dataoutside_diameter (Length): (read-only) Outside diameter.
• Datapitch_diameter (Length): (read-only) Working pitch diameter.
• Dataroot_diaeter (Length): (read-only) Root diameter, measured at the foot of the teeth.
• Datatransverse_pitch (Length): (read-only) Pitch in the plane of rotation.

fillets

• Datahead_fillet (Float): Default is 0 mm.
• Dataroot_fillet (Float): Default is 0 mm.

helical

• Datadouble_helix (Bool): Default is false, true creates a double helix gear (see Notes).
• Datahelix_angle (Angle): Default is 0°. With the helix angle β a helical gear is created – positive value → rotation direction right, negative value → rotation direction left (see Notes).
• Dataproperties_from_tool (Bool): Default is false. If true and Databeta is not zero, gear parameters are recomputed internally for the rotated gear.

involute

• Datapressure_angle (Angle): Default is 20° (see Notes).
• Datashift (Float): Default is 0. Generates a positive and negative profile shift (see Notes).

precision

• Datasimple (Bool): Default is false, true generates a simplified display (without teeth and only a cylinder in pitch diameter).

tolerance

• Databacklash (Length): Default is 0 mm. Backlash, also called lash or play, is the distance between the teeth at a gear pair.
• Dataclearance (Float): Default is 0.25 (see Notes).
• Datahead (Float): Default is -0.4 mm. This value is used to change the tooth height.
• Datareversed_backlash (Bool): true backlash decrease or false (default) backlash increase (see Notes).

version

• Dataversion (String):

Notes

See FCGear InvoluteGear.

Useful formulas

See FCGear InvoluteGear.

Scripting

Use the power of Python to automate your gear modeling:

import FreeCAD as App
import FreeCADGui as Gui
import freecad.gears.commands
gear = freecad.gears.commands.CreateInternalInvoluteGear.create()
gear.num_teeth = 20
gear.helix_angle = 20
gear.height = 10
gear.double_helix = True
App.ActiveDocument.recompute()
Gui.SendMsgToActiveView("ViewFit")

InvoluteGear

InvoluteRack

Gear