FCGear CycloidRack

CycloidGear

BevelGear

Gear

Description

The FCGear CycloidRack command creates a cycloid gear rack with spur gearing by default that can also be transformed into a helical gearing or a double helical gearing.

Cycloid racks 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 Cycloid Rack button in the toolbar.
   • Select the Gear → Cycloid Rack option from the menu.
3. Change the gear parameter to the required conditions (see Properties).

Properties

See also: Property View.

An FCGear CycloidRack 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 15. Number of points for spline.

base

• Dataadd_endings (bool): If true (default), then the total length of the rack is teeth * pitch. If false, then the rack starts with a tooth-flank.
• Dataheight (Length): Default is 5 mm. Value of the gear width.
• Datateeth (Integer): Default is 15. Number of teeth.
• Datathickness (Length): Default is 5 mm. Thickness of the uncut part of the rack.

computed

• Datatransverse_pitch (Length): (read-only) Pitch in the transverse plane.

cycloid

• Datainner_diameter (Float): Default is 7.5. Diameter of the rolling circle of hypocycloid, normalized by the Datamodule (see Notes).
• Dataouter_diameter (Float): Default is 7.5. Diameter of the rolling circle of epicycloid, normalized by the Datamodule (see Notes).

fillets

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

helical

• Databeta (Angle): Default is 0°. With the helix angle β a helical gear is created (positive value → rotation direction right, negative value → rotation direction left).
• Datadouble_helix (Bool): Default is false, true creates a double helix gear (see Notes).

involute

• Datamodule (Length): Default is 1 mm. For racks the module equals the pitch and so is the distance between corresponding points on adjacent teeth (see Notes).

precision

• Datasimplified (Bool): Default is false. If true the rack is drawn with a constant number of teeth to avoid topological renaming.

tolerance

• Dataclearance (Float): Default is 0.25 (see Notes).
• Datahead (Float): Default is 0. Additional length of the tip of the teeth, normalized by the Datamodule.

version

• Dataversion (String):

Notes

See FCGear CycloidGear.

Useful formulas

See FCGear CycloidGear.

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.CreateCycloidRack.create()
gear.num_teeth = 20
gear.helix_angle = 20
gear.height = 10
gear.double_helix = True
App.ActiveDocument.recompute()
Gui.SendMsgToActiveView("ViewFit")

CycloidGear

BevelGear

Gear