Holder for eddy current probe with spring

thingiverse

Eddy current probes are widely used in non-destructive metal testing. A small pick-up coil is excited by an AC current, generating an alternating magnetic field as it oscillates. When the probe tip makes contact with a metal surface, the eddy currents triggered in the metal alter the pick-up coil's properties. These alterations enable users to detect defects like cracks within the metal or measure the thickness of paint layers on the surface. For example, see the Eddy Current Wikipedia page at https://en.wikipedia.org/wiki/Eddy_current for further information. The same effect is utilized in inductive proximity probes, a common feature found in 3D printers. To integrate eddy current probes into their setup, users can motorize a stage to scan the probe across the metal surface until it slightly touches the target. When the probe comes into contact with the metal, the holder reduces the force exerted on the surface by utilizing the plastic spring that holds the probe. Currently, the actual force exerted is not measured; however, this could be accomplished by adding a strain gauge to the spring in a future modification. Here are some setup instructions: The holder was printed as one piece without support with the thin spring portion pointing upwards using PLA material and a 0.2mm layer height on a simple Da Vinci Jr. 3D printer. The four holes on the top plate are used for attaching the holder to an old 3D printer's extruder head. The included FreeCAD script file can be used to customize the design as needed.