Arch Rebar Helical

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Arch Rebar Helical.svg Arch Rebar Helical

Menu location
Arch → Rebar tools
Arch, BIM
Default shortcut
Introduced in version
See also
Stirrup Rebar, Column Reinforcement


The Helical Rebar tool allows the user to create a continuous helical reinforcing bar inside an Arch Structure object.

This command is part of the Reinforcement Addon, that you can install with the Addon Manager, via the menu Tools → Addon manager → Reinforcement.

Arch Rebar Helical example.png

One continuous helical reinforcement bar inside an Arch Structure

How to use

  1. Select any face of a previously created Arch Structure.svg Arch Structure object.
  2. Then select Arch Rebar Helical.svg Helical Rebar from the rebar tools.
  3. A task panel will pop-out on the left side of the screen as shown below.
  4. Select the desired orientation.
  5. Give the inputs like front cover, right side cover, left side cover, bottom cover and diameter of the rebar.
  6. Select the mode of distribution either amount or spacing.
  7. If spacing is selected, a user can also opt for custom spacing.
  8. Pick selected face is used to verify or change the face for rebar distribution.
  9. Click OK or Apply to generate the rebars.
  10. Click Cancel to exit the task panel.


Taskview panel for the Arch Rebar Helical tool


  • DataSide Cover: The distance between rebar to the curved face.
  • DataTop Cover: The distance between rebar from the top face of the structure.
  • DataBottom Cover: The distance between rebar from the bottom face of the structure.
  • DataPitch: The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix.
  • DataDiameter: Diameter of the rebar.


See also: Arch API, Reinforcement API and FreeCAD Scripting Basics.

The Helical Rebar tool can be used in macros and from the Python console by using the following function:

Rebar = makeHelicalRebar(s_cover, b_cover, diameter, t_cover, pitch, structure=None, facename=None)
  • Creates a Rebar object from the given structure, which is an Arch Structure, and facename, which is a face of that structure.
    • If no structure nor facename are given, it will take the user selected face as input.
  • s_cover, b_cover, and t_cover are inner offset distances for the rebar with respect to the faces of the structure. They are respectively the side, bottom, and top offsets.
  • diameter is the diameter of the reinforcement spiral inside the structure.
  • pitch is the parameter that determines how close or far apart each spiral loop is to each other.


import FreeCAD, Draft, Arch, HelicalRebar

Circle = Draft.makeCircle(radius=250)
Structure = Arch.makeStructure(Circle)
Structure.ViewObject.Transparency = 80

Rebar = HelicalRebar.makeHelicalRebar(10, 50, 8, 50, 50, structure, "Face2")

Edition of the rebar

You can change the properties of the rebar with the following function

editHelicalRebar(Rebar, s_cover, b_cover, diameter, t_cover, pitch, structure=None, facename=None)
  • Rebar is a previously created HelicalRebar object.
  • The other parameters are the same as required by the makeHelicalRebar() function.
  • structure and facename may be omitted so that the rebar stays in the original structure.
import HelicalRebar

HelicalRebar.editHelicalRebar(Rebar, 20, 100, 20, 20, 100)