RepRap: Blog

Probe #19 was manually etched. I put it in the etchant to a depth of 20mm for 60 seconds. Then, oh so tediously, tapped the tip on the meniscus 80 times. There's dedication. I'll put the picture later because people are bored with pictures of the tips in thumbnails.

So here's a picture of actual test squares.  The one on the right is 640μm square, the thing on the left is kind of freehanded. Dot spacing is 40μm.

The interesting illumination in that micrograph comes from me shining a light down the other eyepiece of the binocular microscope. I just happened to notice a lighting change, experimented, and this photo came out pretty good.

Drawing the dotty square shows that Probe #19is having wee issues with flow control. I suspect it was contaminated with superglue during fixing, and the slight unevenness probably isn't helping: 

 

It' slightly asymmetric at the tip. This probe is not etched to a perfect tip and then blunted, it's etched to a vaguely round end and then gradually sharpened. It may be that the sharpening process does not result in a perfect point.

Anyhoo, when I do get a dot, it's about 20μm diameter, which is pretty much what I'm aiming for. The first dot is always larger than all the others which is why, for instance, the top left corner is joined up.

The left square is just me noodling with the probe in direct contact with the slide while being moved around. As you can see, this does not result in a terribly even line width when flow control is poor. 

One other "failed" experiment: I tried drawing on a glass slide with thin conductive silver ink CircuitScribe Electon Inks electroninks.com), the idea being to etch a circuit into it in the same way as one mills PCBs. Sadly, the ink did not cover well, and I think that particular ink needs to permeate paper in order to achieve proper drying and a good thickness of conductive medium. Doesn't work well on glass or shiny cardboard anyway. Dries too fast to be deposited by probe.