The blog has been spotted on Hackaday, so a TL;DR:
Why do this?
I'm positioning a probe with micron precision for a teeny micron-scale 3D printer called RepRapMicron. Float glass is a pretty darn flat work surface, but I need a Z touch probe and glass microscope slides do not conduct.
Why tin oxide?
I need a thin-film technique that is accessible to as many hackers as possible. Silvering is excellent, but tarnishes. Conductive tape is too thick, so are paint-on solutions, graphite etc. I do not need high conductivity so futzing around with vacuum chambers and wires is not necessary. I hope.
Why not just buy tin chloride?
Historically, New Zealand has had problems with people making illicit substances because it's so isolated. Shipping is a nightmare. So buying chemicals and lab equipment can be problematic. Plus, I don't imagine NZ is unique in that regard. But if you can get it, fine, buy it.
We do these things not because they are easy, but because we thought they would be easy.
My confusion as you've been describing your thin-film experiments is how the circuit will work for z-touch detection. Will the tin extend under the sample area? Then you detect z=0 via a current from probe to a clip on the slide?
ReplyDeleteIs the slide not flat enough to zero to one side and add an offset?
The original plan was to have no tin oxide under the work area, only off to the side. The tin oxide layer is just too uneven to build on at the micron level - I need the flat "float" glass surface of the slide to do that. Also the tin oxide may block the UV light that cures the resin.
ReplyDeleteThat said, I'll coat the whole slide so I can poke at it and see what it does. I might try electroplating it to see if I can generate circuitry. So many experiments, so little time.
My eye operation was successful, but I have to wait a few more days before I can continue work. Vision is good but it's still pretty sore and sensitive.