When the 28BYJ stepper is first powered up, its position is unknown. In addition, the motor does not rotate a specific angle per step; rather a full turn is often an unequal number of step pulses (e.g. it might take 2037.5 pulses per 360 degrees). Plus the motor gearbox can have indeterminate backlash
This positioning sensor / encoder enables:
- The setting of an initial position when first powered up
- The control of the motor’s position during operation
- Greater accuracy of positioning
This sensor/encoder kit makes a switch connection every 1 turn or 4 times per turn. The sensor/encoder can be mounted either on the rear or on the front of the motor’s mounting bracket, for even more flexibility. This is a positioning sensor only.
The kit comprises these parts (you need to assemble this kit):
- Micro switch mounting plate
- Micro switch
- Mounting screws and nuts for the micro switch
- A single-nub actuator and a four-nub actuator (use one of these)
- A micro switch spacer used when the mounting plate is mounted on the rear of the motor’s mounting arms
The motor and the motor’s 3mm mounting screws are not included in this product. Full instructions are though.
Note that the actuator disk is 3mm thick, with 1.5mm on the round shaft closest to the motor, and 1.5mm on the flats section of the shaft. Before buying, please make sure that there is adequate space remaining on the shaft for your coupling. That coupling should also butt against the actuator, retaining the actuator disk.
Top Tip! Because there is backlash in the motor’s gearbox, and because the switch will activate in either site of the actuator disk nub, it is advised that you should always rotate the motor in the same direction to take a positional reading – in order to attain a consistent position each time.
This positioning encoder will indicate the position of the shaft but not to close tolerances or precise angular accuracy. i.e. you cannot use this encoder to control the motor shaft where its angles are to be precisely measured or positioned to close tolerances.