EM Workbench

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The FreeCAD ElectroMagnetic External Workbench Icon


The ElectroMagnetic (EM) Workbench provides the CAD front-end interface to some open source free solvers. At present it supports the 3D magnetoquasistatic impedance solver FastHenry (i.e. inductance and resistance extraction at "low" frequencies). Support for the 3D electrostatic capacitance solver FasterCap is ongoing.

Screenshot EM window.png


The EM Workbench is an external workbench, that can be installed from the FreeCAD AddonManager.svg Addon Manager. This can be done via the Tools → Addon Manager menu.

The electromagnetic solvers FastHenry2 and FasterCap must be installed separately. Their binary codes as well as the sources are freely available from FastFieldSolvers.



FastHenry is a software for computing the frequency-dependant self and mutual inductances and resistances of a generic tridimensional conductive structure, in the magnetoquasistatic approximation. It can also generate Spice-compatible, multiple-frequency equivalent-circuit models.

Knowledge of FastHenry is a pre-condition for the proficient usage of the ElectroMagnetic Workbench for FastHenry. We suggest you to read the original FastHenry User's manual and play a bit with the sample files that are provided with the installation.


FasterCap is a powerful three- and two-dimensional capacitance extraction program.

Knowledge of FasterCap is a pre-condition for the proficient usage of the ElectroMagnetic Workbench for FasterCap. We suggest you to read the original FasterCap help file and play a bit with the sample files that are provided with the installation.

FastHenry Tools

These are tools used to interface with FastHenry:

  • EM FHNode.svg FHNode: Creates a FastHenry Node object
  • EM FHSegment.svg FHSegment: Creates a FastHenry Segment object
  • EM FHPath.svg FHPath: Creates a FastHenry Path object
  • EM FHPlane.svg FHPlane: Creates a FastHenry uniform conductive Plane object
  • EM FHPlaneHole.svg FHPlaneHole: Creates a FastHenry uniform conductive plane Hole object
  • EM FHPlaneAddRemoveNodeHole.svg FHPlaneAddRemoveNodeHole: Add or Remove a Node or a Hole from/to a conductive plane
  • EM FHEquiv.svg FHEquiv: Creates a FastHenry node Equivalence object
  • EM FHPort.svg FHPort: Creates a FastHenry Port object
  • EM FHSolver.svg FHSolver: Creates a FastHenry Solver object
  • EM FHInputFile.svg FHInputFIle: Creates a FastHenry Input File

FasterCap Tools

At present, FasterCap is supported via some Macros in the Export_mesh.py file available in the ElectroMagnetic Workbench GitHub source code.


The EM tools can be used in macros and from the Python console by using the EM API.


Some video tutorials are available for the EM Workbench beta versions:

External workbenches

FreeCAD workbenches are easy to program in Python, there are therefore many people developing additional workbenches outside of the FreeCAD main developers.

The external workbenches page has some information and tutorials on some of them, and the FreeCAD Addons project aims at gathering them and making them easily installable from within FreeCAD.

New workbenches are in development, stay tuned!