I used to work in a wire & cable plant and on the wire extrusion lines we had these devices which would measure the offset of the conductor inside the insulation. It did this (I think, 95% certain) by inducing a current via a hollow-core transformer directly followed by a laser micrometer. The laser mic had some circuit to precisely locate the center of the wire by detecting the induced current, and would compare that to its dimensional measurement to present a calculated cross-sectional picture of the wire showing the location of the conductor inside the insulation and how off-center it was.
I am curious about the circuit used to find the center of the wire. I'm not interested in duplicating the entire unit, I don't care about any of that. I'm brainstorming a method of measuring linear accuracy in a CNC machine. I could send a current through the wire with a simple supply, no hollow-core transformer needed. Just need an idea what would be involved in finding the center of the wire. Any ideas? I'm thing maybe hall sensors [4] arranged in an array around the wire? Or maybe a pair of split coils with the wire passing through the center to function sorta like a LVDT? (That last one isn't very well thought out). How would you do it?
EDIT: I said "measuring linear accuracy" when what I meant was "permanent compensating for linear inaccuracy." This is a hair brained idea for making a CNC out of junkyard parts. Instead of paying hundreds or thousands of dollars for quality linear motion components with certified straightness/flatness, make it out of bent crap and force it electronically to move in a straight line.
I am curious about the circuit used to find the center of the wire. I'm not interested in duplicating the entire unit, I don't care about any of that. I'm brainstorming a method of measuring linear accuracy in a CNC machine. I could send a current through the wire with a simple supply, no hollow-core transformer needed. Just need an idea what would be involved in finding the center of the wire. Any ideas? I'm thing maybe hall sensors [4] arranged in an array around the wire? Or maybe a pair of split coils with the wire passing through the center to function sorta like a LVDT? (That last one isn't very well thought out). How would you do it?
EDIT: I said "measuring linear accuracy" when what I meant was "permanent compensating for linear inaccuracy." This is a hair brained idea for making a CNC out of junkyard parts. Instead of paying hundreds or thousands of dollars for quality linear motion components with certified straightness/flatness, make it out of bent crap and force it electronically to move in a straight line.
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