An interesting you tube video by "Tom's 3D". He talks about 3D printers but much of the technology applies to machine tools. After all they both run G-code.
In this video he measures the accuracy of end-stop or "home" sensors and compare microswitches, with and without levers and also varies kinds of non-contact sensors. He runs each kind into a stop at both high and low speed and after 100 tries has data for standard deviations. Result is that removing the lever from the microswitch reduces standard deviation by about 3X. I assume because the per has about a 3X mechanical advantage. But it's surprising is that a $2 inductive sensor beats even the non-lever switch. It might be moot as all the measurements are in microns (micro meters) But on the other hand if these dirt-cheap inductive sensors are this good and importantly they are water and oil tight with no moving parts we should be using them. Here is the winner at 0.27 microns standard deviation ebay.com/itm/LJ12A3-4-Z-BX-Inductive-Proximity-Sensor.... <https://www.ebay.com/itm/LJ12A3-4-Z-BX-Inductive-Proximity-Sensor-Switch-NPN-DC6-36V-Great/272907213327?hash=item3f8a899a0f:g:6fwAAOSw~gRVyHZ-> The blue end looks like a button switch but it isn't. This is a non-contact sensor. It triggers when it senses a metal part at 4mm distance (with a surprising 0.27 micron standard deviation) Here is the video, The application is different but look at his test setup. It pretty much mimics what you would do on a milling machine. https://youtu.be/il9bNWn66BY How to use them: There are three wires two are power, you apply between 6 and 36 volts, typically 12 volts. The third wire is either normally 12V or zero and then switches state when the sensor is tripped. Of course 12 volts would fry your computer so people use a voltage divider of optical isolator or even a switching diode. The typical use for these is industrial automation, food processing, manufacturing or whatever. I have ordered a few and will experiment. -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
