DIY Z axis 0 sensor - Roland MDX 40

[maxlivesey]

Hi Folks,

First post here. I've recently acquired a used Roland MDX40 desktop mill which, as an amateur, I'm gradually getting to know and use. Some models are supplied with a Z axis sensor like this: https://www.lamtekno.fi/p6229-for-md...sensor-fi.html which allows the machine to detect the z axis. (picture attached)

At 115.00 euro it seems a little steep for me for what looks like a grounding sensor. - But I don't know, perhaps it's more advanced. I suspect it would be fairly straightforward to make a sensor easily enough - but I wondered if anyone knew the methods that this sensor uses.

It connects to the back of the machine with a 3.5mm mini jack. This has two wires connected to the control board pcb. I've tried just running the sensor software and attaching a wire from the jack to the tool head to make a circuit, but it doesn't trigger the sensor - the tool head just keeps moving. So there seems to be a bit more going on. It's made out of brass - I assume just to provide a material of the right hardness and conductivity? Is there another reason brass is used?

Does anyone have any experience using this z0 sensor and advise how they work?

TIA

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[awerby]

I don't think there's anything smart in there; as far as I can tell it's a simple conductivity device. The jack that plugs into it completes the circuit when the tool touches it during the zeroing routine, What you do need is the right height. Measuring mine, it looks like 12mm. It's apparently solid brass, and has got an insulating base plate that seems to be made of phenolic resin.