Coil Winder

The coil winder project is an original design that I made for use in my research at the Morphable Biorobotics Lab. The device uses two stepper motors to precisely wind copper wire into air-core electromagnets. This device was designed to reduce production time as well as reduce human error in producing electromagnets. One motor guides the wire feed by advancing the carriage by one wire-thickness per revolution of the second motor. This process ensures that the coil is wound neatly without overlapping wire turns. 

The device is controlled by a Teensy 4.0 and is programmed via Arduino IDE, where user input allows for the following parameters to be customized:

• wire thickness; reported gauge on stock spool

• desired coil length

• desired number of layered windings

• winding motor speed

Upon completion, the device holds the motors at rest to prevent the coil from turning and undoing its windings. The user then applies adhesive to the coil before sliding it off the winding shaft.  For best results, heat shrink tubing is applied to the shaft before the device is turned on, allowing the tubing to be slid off the device and then out from inside of the coil when the adhesive dries. 

The wire is first fed through the linearly-restricted carriage, then threaded through a 3D printed eyelet on the rotating shaft. This secures one of the coil's terminals, whereas the other terminal is made by cutting the wire free from the spool when the winding process is complete. 

Some important design considerations during this project were:

• keeping the rotating shaft level and preventing vibration --> connect shaft to bearing and clamping the bearing housing to fix its position

• maintaining constant tension in the wire --> hold motors at rest rather than cutting power when coil is complete; turning the spool to tension the wire prior to starting the device

• preventing tension in the wire from snapping it if the spool does not turn quickly enough --> reduce friction by adding bearing to spool-holding shaft, allowing the winding motor to easily turn the large spool

• ensuring windings remained organized as layers were added --> program winding motor to halt and linear motor to pull wire on top of the previous layer upon reaching the end of the coil length, then reposition the wire at exactly the end of the coil before resuming winding

The coils I manufactured for my research were required to be 10 mm in length and 1 mm in diameter. The depicted coil (wallet, for scale) has 4 layers of windings to maximize magnetic field strength for testing purposes.