WIP: homing sensor for CNC 4th axis

WORK IN PROGRESS: Mount for an inductive sensor as a homing switch on the 4th axis of my CNC mill.


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It's a mount for an inductive NPN sensor with an M8 threaded shaft like the "Finglei Electric LJ8A3-2-Z/BX-5V" I'm planning to use
to a chinese 4th axis containing a 50:1 harmonic drive.

There are 2 versions of this gear box. With 6 and with 4 mounting slots.
The sensor holder was designed to fit both.
(Technical drawing will follow, after I have tested the sensor.)

Update: In MK2 I forgot to leave clearance for the heads of the M6x30 machine bolts. So I had to change the design slightly for MK3.

Blog posting:

Materials and methods

Cut an M8 thread into the hole in the 3d printed mounting plate.
Just attach the sensor holder to the existing mounting bolts that fasten the 4th axis to the work bed.
Add a modified steel spacer to one of the bolts that fasten the chuck to the face plate.
Adjust the position of the sensor to leave a gap of no more then 2mm.
Connect the NPN sensor to
VCC (brown),
GND(blue) and
to the signal input (black) with a 10KOhm resistor to VCC.



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B750e259b78e757adeb53e0da9b59ea1?default=blank&size=40BuchnerB added this to the Mechanical and Engineering collection ago
730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon published this design ago