This nema17 stepper motor housing is designed for Fischertechnik blocks. It also includes connectors for the motor wires and an additional 3pin connector for a hall reference point detection. This makes the connection of this Nema17 motor easier. The extra hall detector can be used to set a zero point of the motor. This can be very useful after a powerup. The hall detector is built into the housing and the necessary signal is given by a Neodymagnet D2x3mm which is located in the shaft adaptor. The adaptor also has an output to the standard 4mm Fischertechnik shaft. The Nema17 Motor has a shaft of 5mm. After 3D printing, this 5mm bore still needs to be finished with a drill, 18mm deep. Then it goes smoothly on the motor shaft.
The adaptor is also used to mount FT gears. Either you choose the 3 holes of 4mm or the 3xM4 tapped holes for the mounting. The 3 holes tapped with M4 I do it with a small electric hand drill machine at low speed. That goes very smoothly with a nice pure M4 tapped wire as result. The adaptor is fixed to the 5mm shaft with an M4 screw. This thread you also have to make.
In the adaptor is a small bore provided for a Neodym magnet D2x3mm. Because the Neodym magnet is being pressed in I drill it with D1.9mm and then D2.0mm, 1.5mm deep. If you press the magnet in you must pay attention to the magnet polarity. The hall detector AH3144 is unipolar. If polarized incorrectly, it would not work! If necessary, you can press out the magnet and turn it over. I adjust the connection to the 3pin connector so that the connection of the wires matches the order of a servo motor, GND,VCC,OUT. Of course you are free to do this differently, as long as you make the connection correctly with your hardware. The hall AH3144 itself is internally protected against incorrect polarization. Nothing can go wrong but it won't always work.
On the adaptor I screw the gears 30T, 40T or the FT wheel FI-31019. In the 3 holes of 4mm you can also place pins. If you use the hall detector, no screw should stick out at the bottom. For this the M4 holes are provided so that the screws heads are on the other side. The photos give a clear picture of this.
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