Tool length probe?

Is there a tool length probe available for CNC work? I find it hard to believe that a machine with such a degree of accuracy relies on pushing a bit into a plastic card to check the length. And what about multi-pass programs? Having to re-calibrate every time I do a tool change is a pain.

For end mills and ball mills, it’s not that big of a deal, I guess, disregarding consistency and accuracy. But what about v-bits? Pushing a 0.1mm v-bit into the table to check its length is completely counter-intuitive.

I could even build a probe easy enough, but if the software doesn’t support it, what’s the sense?

If there’s a tool length probe available, can someone point me to it?
If there’s not, can someone make one?
If nobody’s going to make one, can someone at least code the feature into the firmware and provide the spec so that people can make their own?
Watching a line and waiting for a that line to change states can’t be all that involved…

it’s a step further than a tool length probe, but the way I’m setting it up would be completely compatible. I recently started working on a 3d touch probe:

for a tool length probe, nothing would change to the code, just an alligator clip on the drill bit and a touch plate instead of the 3d probe. it’s the same type of signal (maybe just inverted), but that’s an easy enough addition if needed.

Unfortunately, it’s not just something you add to the code on a lazy Sunday afternoon. I’ll need a few of those before this project is complete

In the meantime, you can just use a multi-meter and measure the resistance. When it starts beeping, you know the reference point for determining the new Z-height. (measure with the old one and the new bit and calculate the difference)

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How interesting - I saw that video once while I was searching around. Nice work!

I thought about doing like you recommend. Maybe some .1mm shim stock and a multimeter. Setting work origin on some copper-clad could be done similarly.

Seems like that’s my best lead for now. I just wanted to ask the community and/or official support what the deal was.


Use a tool setter. Here’s an example (non-affiliate link).