Tool Length Sensor

ER collets are not indexable. For a machine equipped with an ER collet, one therefore needs a fixture to measure tool length after each tool change. Mach3 provides an option to automatically determine tool length with a sensor. The software stores the measured value in its tool table.
The sensor switch should be easy to activate and should respond precisely and reproducibly, even if the key is pressed off-center. I put a simple hinge roller lever switch into an enclosure. A pushrod supported by a recirculating ball bushing activates the switch.




Initial tests showed that this setup can reach an accuracy of 0.01 mm. Unfortunately, Mach 3's tool length feature is unreliable: Now and then the software will make the Z axis hit the endswitch in rapid motion after the sensor is activated. 

 

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