Retractable electrolysis probe holder

This is a model from an idea hatched a dma.space in October 2026. It is a retractable galvanic electrolysis probe needle holder that solves the problem of the delicate probe filament becoming easily bent and damaged.

Assembly: Screw the probe end of the core together loosely with like (todo:measure) 2x M8 or M10 cap head screws and nuts. Solder one dsub female crimp pin to a long wire and feed it through the middle of the pen core front to back, going tightly around the screws. then insert the core in the pen body for a test fit and work it around. Pull it out and tighten the screws some more. When it feels right, add another M3 on the slide mechanism for a thumb handle. It takes a while for it to work in and slide well ime printing in pla and will need to be adjusted several times, but should reach consistency in a few dozen/hundred retractions. 

v3 was the first working model. It needed to have a few screw pockets sunk in more with help from a soldering iron on the screwdriver tip, and help sinking the pin holder into the clamp end. With a small drill bit jammed into the pin holder and the soldering iron heating the drill bit I was able to squeeze the clamp down nicely. Might be a good starting point if you want to modify this. The slide fitment might be a little snappier than v9.

v9 addressed a lot of those little issues with fitment and shouldn't need any modifications to be used. It is designed to flex the tail up when the center is screwed together tightly in such a way that the tension can be adjusted finely after it is worn in.

slide action pictures are of v2. gif and keyboard glamour shot are of v3.