Inductive Sensors, Z-axis sensor does not align with steel gantry

Just installed the Inductive Sensors on my Longmill V4 and I have it all perfectly working now but needed to use a hack and was wondering if this is a known issue and if there is a more elegant solution:

The Z axis sensor does not sense the gantry in its current position. It seems like the 3D printed part holding the sensor holds it too far out and therefore it does not sense the gantry. Taping a piece of steel onto the gantry right under the sensor (to extend the gantry) makes it all work fine.

The left photo on attached screenshot shows the initial 3D print from the sienci blog when these sensors where launched and the other photo shows my installation (with the newer 3D printed holder that I have seen in videos where it seems to be working fine too) where the sensor is not aligned centric with the gantry. You can see the driver bit taped to the gantry there too.

Thanks in advance for any comments, cheers, Michael

@mschwanzer I have an earlier machine, but it still lines up like yours - not centered. It does seem to work fine though. One thing I noticed is that the Z axis gets much closer to the sensor before it triggers than the X and Y.


Hi I adjusted the sensor by moving the nuts to increase or decrease the clearance between the end of the sensor and the plates. Alignment does not seem to matter.

so I had the same problem on my build and my simple solutions was a small electrical conduit half bracket that I flattened out on one side and glue a magnet onto to and stuck it to the side of the gantry i can remove it easily and put it back. here are a couple of picture. hope that helps =)


Thanks for the comments. I really like the simple solution @thunderingdragon created and it inspired me to find an even simpler solution: widening the hole backwards just a little bit with the CNC router itself. I was aware the 3D printed (ABS?) plastic would be brittle and I might ruin the part and would need to replace it completely. Anyway it worked, just clamped it down, manually jogged an 1/4 bit around a little bit and the sensor now sees the gantry. Can’t go to far because the nut still needs to clear the rail. Thanks again, happy routing!