Selective Electroplating

Duke Bletsch Lab

Motivation

Electroplating, the process of coating one metal with another using electricity, is usually used to make uniform protective layers—but I wanted to see if it could instead be used to 'print' images onto metal.

Background

Electroplating is the process of coating a conductive surface with a thin layer of metal by running an electric current through a solution of dissolved metal ions. This allows precise, micron-level control of coatings used for corrosion resistance, conductivity, or aesthetics, with common metals including nickel, copper, and zinc.

Electroplating

Setup

The system was built on a 3018 benchtop CNC router, with a plastic basin of electrolyte on the bed and the cathode workpiece fixed inside. A custom 3D-printed nozzle holding the anode replaced the spindle, both electrodes were wired to a constant-current power supply, and the CNC was controlled via Candle G-code software.

Calibration

A custom Python script was created to convert images into G-code, using grayscale pixel brightness to control nozzle dwell time and plating thickness. Because plating results vary by metal, electrolyte, and electrical parameters, a gamma correction function was implemented and calibrated through test gradients. Image-processing analysis was used to tune parameters.