Z-probe for my CNC mill

Hi everyone,

I am determined to make more time for my hacking projects. A good (and simple) start to what I envisage will be a long line of projects is a z-probe for my eShapeoko CNC mill.

GRBL now supports such devices, and the first thing I will want to use it for is to mill out the PCB for the CNC control box. Currently it is a mess of wires, and I want to implement a few things on the PCB that will make it nicer for me to use. Mainly externalising some more control switches, and providing lots of blinkenlights mounted on my yet-to-be-milled control panel - for example all the relevant control switches (feed hold, abort, cycle start/resume), LEDs for the homing switches to help me figure things out (and to look cool), and externalising the Arduino’s Tx/Rx LEDs to the panel - something I’ve found very useful for figuring out what’s going on. Also for looking cool.

I have all of these set up currently, but it’s time to get it to the next level.

So! First step is the z-probe. I’ve seen a few designs for the RepRap (e.g. http://hydraraptor.blogspot.com/2011/04/auto-z-probe.html), but I would like to:

  • Design my own mount to fit on the CNC mill. I have a rather different mounting solution for the toolhead than most, and would like to make something that allows various ‘accessories’ to be mounted (e.g. dust skirt, dial indicator mount, microscope webcam, laser etc.)
  • Have some method of ‘fine tuning’ the probe, being able to dial in tiny increments might be helpful but perhaps not necessary if I do it right.
  • Perhaps make the probe tip myself on a lathe. (Bonus over-engineered step, gold plate it because why not)
  • I really like the HydraRaptor magnet design, because then it could be semi-permanently mounted and kept out of the way when necessary.

So - if anyone has any experience in z-probes I’d love to hear from them. Also, who was it who brought the mini lathe in to the space that time? Or if anyone else would be willing to lend me access to theirs, I can repay them in beer/high fives/custom coasters…



The little metalwork lathe lives at the Hackspace at the moment. Plans are afoot to convert it to CNC, but it should remain usable for a while yet :smile:

That’s good news :smile:

I’m travelling with work at the moment, but hopefully will get some free time to start designing something.

I found another interesting link however, not so much just a Z-probe, but something with a little more functionality:

The digitised quarter is pretty impressive.

Hopefully you’ve seen this link?


It all depends on whether you want a Z-probe or a touch probe for your CNC Router. Z-probe makes more sense for CNC routers.

Mind you, touch probe works nicely for z-probing. You could also do a variant of my force sensing effector design?

I hadn’t seen that one - what a wonderfully simple design. The pins vs. ball bearings is an interesting issue I hadn’t thought of.

I do like the idea of a touch probe rather than a z-probe, having thought about it. A touch probe functions almost identically in a z-probe role, plus it would be useful for non-conductive materials (I saw someone who wanted to probe a piece of slate with a conductive probe, and opted to coat the slate in conductive paint - clever, but a workaround not required with a touch probe).

The one-penny probe is nice, but if I was going for it I’d at least make an enclosure around those electronics.

I haven’t seen your force sensing effector design in great detail Macaba, is there somewhere I can look for it? :smile: