I have been finding a problem with a low-pressure probe switch for my deltabot. A few days ago I attended an AdaFruit hangout where Limor Fried mentioned using magnets as contacts. Then I recall somebody on Hackaday or Make doing a 3-contact probe that they used to probe a coin.
Then… I figured that combining the two ideas might make an excellent low-pressure contact probe.
Original drawing source is at http://birenboim.com/tmp/needleProbe.scad with render http://birenboim.com/tmp/needleProbe.stl.zip
Blue disks are magnets. Darker gray-blue are pins. Red are wires. Yellow are insulators. (acrylic? Machined nylon?)
All in a (smoky) case.
Upper plate, glued to probe pin is (somewhat) free floating.
The magnets should attract the pins and help keep the probe aligned and centered. When any one of the magnet/pin contacts is broken, the switch will open.
Could be an excellent high-sensitivity, low force probe.
I have, at least, two problems:
1) I need a very thin, flexible wire for the upper lead.
2) I need to find a way to connect leads to the magnets.
Soldering magnets could be problematic. Conductive glue?
Would such a probe be valuable to you?