Z-axis opto probe

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DICKEYBIRD

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Here’s a CNC widget I built that works well for my retro’d ORAC lathe so I thought I’d post it here. It’s been finished for several weeks and has been a real time saver.

It’s a Z-axis opto sensor probe that’s semi permanently mounted to the back side of the carriage of my lathe. Since most of my CNC lathe work is modifying or repairing existing parts that don’t get faced off, I’m constantly touching-off tools on the face or a feature of the part which sometimes leaves a mark. I’ve used most all the usual methods to set Z-zero, plus I even rigged up a USB microscope but it’s a real pain to accurately do this on multiple parts.


So, I decided to build this device. It has a little opto sensor/board I got off ebay from Holland, a spring loaded plunger with a flat-faced dial indicator tip on it mounted in a box made from aluminum scraps with a pressed-in acetal bushing. It’s dead-nuts repeatable & as accurate as I can measure with a tenths D.T.I. The sensor requires 5vdc and a ground to send an input signal to Mach when it’s triggered by the shaft. I use the “Set Home Z” button on Tool 0 in the standard Mach3 Turn screenset. I have set up all of my tools’ Z-axis offsets in the Mach tooltable so I can now home the Z axis to a feature of the part, slap on which ever tool is needed and cut away with confidence that it’ll come out on the money.







Here’s a pic of a typical setup

 

kuhncw

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Very nicely done, Milton. Thanks for posting it.

Is the sensor board you used still available on Ebay?

Chuck
 

DICKEYBIRD

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Thanks Chuck, I got a few of them several years ago but don't see them listed now. It looks like the 3D printing movement has generated a lot of the demand for the things though. Just search for "opto end stop" on ebay and a bunch of choices pop up.
 

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