Z TOOL TOUCH PROBE
A Tool Touch Probe makes setting the Z height a breeze, it is fast, accurate and also the "in process" tool changes are easier as you will not have to touch of on the part again.
WHAT PROBE TO BUY
There are big differences between industrial and hobbyist versions:
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Price $10-3000
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Material, 3D Printed Plastic vs hardened steel and stainless steel.
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Accuracy, 0.1mm vs 0.001mm
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Custom software integration
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Industrial probes are always active probes so transmitting (often via wireless) a signal to the controller.
Plate Style Probes
​These are my least favorite. Once you forget to hook up the wire you know why ... the result is a crash and possibly the loss of an expensive tool. Also PCD and very sharp single flute endmills don't like these plates. Once the electrical contact is made the motor needs to come to a stop that distance will be the amount the tip of your tool will be pushed into the metal plate.
Check out the video I made, building a Z-Tool Touch Probe for my CNC-Router.
It has an optical sensor and excellent repeatability.
My Goal was to make an easy probe that you can possibly make yourself (detailed drawings available) and marry some of the industrial features with a hobby price tag.
The Components
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The base needs to be from steel as any ding or nick will tilt the entire probe.
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The body can be made from Aluminum or Stainless Steel.
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The touch surface and shaft are preferably hardened.
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The play between the guide surface and the shaft should be minimal something like 0.005mm is good.
My Pro Tipp
If possible use a "Normally Closed" circuit. This way the software can detect if there is an issue with the switch or the wire and you avoid an expensive crash. I use Eding CNC and it says: Probe not connected.
Avoid using a Relay or standard switch in your design. They are too slow and have a switching hysteresis all that will take away from the probes accuracy. Use an optical switch with a build in amplifier. It will work great and has no drift due to wear.
