Wednesday, June 03, 2026
RepRapMicron Making Too Tiny Dots
I took the pointy contact probe from the previous blog entry and smacked it into the glass slide a few times to Z-10μm and it seemed consistent, though the Z axis seemed to pick up unwanted vibration. Will have to look into that. Anyway, it didn't seem to be flattening so I put some resin on the slide and picked some up with the probe point.
Now this point is a scrap one I over-etched, and it looked a bit too pointy. I figured a finer point would be more likely to exhibit damage, and I didn't have a use for it, so it got sacrificed. I got confused because the contact indicator was showing contact with the slide, and as far as I could tell the Z axis wasn't going down any further, but I could not see any resin deposited through the USB microscope.
So I took the slide to the Konus trinocular and looked at it under 90x. Couldn't see any dots. But I had a feeling, and so I brought out the not-so-brilliant Biolux microscope and had a good look at 160x (10x objective, 16x eyepiece) with some lighting and focus plane tweaks that I can't do on the Konus:
This was taken through the eyepiece with my phone (5x optical zoom), and the Biolux optics are gritty with age*, but I think you can see a horizontal trail of dots across the middle. So I was depositing resin, and deposited in excess of 20 dots on one dip of the probe.
The dots are spaced 20μm apart, and measuring the image pixel by pixel in the enlarged section suggests a diameter of approximately 3 microns. That's smaller than half a human red blood cell.
That's pretty impractical for me to work with at this point, and that line is not as horizontal as I would like it to be. Not that the wavyness matters so much if I'm drawing lines 20μm wide. But it's nice to know that in theory I can make features that small.
Anyone want to chip in for a 2x Barlow lens for enhancing the Konus?
* That image was so horrible it actually drove me to take the Biolux eyepiece apart and clean each lens individually with IPA. Not a huge improvement, but a bit better. Do I dare fiddle with the objective lens and risk ducking it all up?
