Mar 142021

The watermeal stuff made me want to zoom in so I got a $15 USB ‘microscope’ off eBay. It says it’s 50x-1600x but I don’t really know or care enough to check them on optics but it zooms pretty hard so I was pleased with the purchase.

Before long the frustrations of focusing and moving at tiny scales made me wonder how hard it would be to motorize it. Seen a lot of DIY builds with the DVD drive steppers and I had a couple and drivers so I started soldering wires onto those annoyingly tiny flexible pcb leads. Naturally the frustration of that process made me question my whole existence and I stopped long enough to remember I have a perfectly functional motorized XYZ in the form of a MP Select Mini v1 that I got tired of replacing the heater block and fan on. It’s always amusing and infuriating to me how long it takes me to get to the most painfully obvious solution even when it’s sitting in my closet.

I had a couple of bad ideas on how to fix the scope to the heatsink but eventually I settled on a 1/2″ square dowel drilled to hold zip ties. Then zip tie the dowel to the scope and to a machine screw held in the sink with washers and nuts. It’s rigid enough to manually adjust the zoom on the scope without bumping the frame so that works for me. I forgot to home the Z axis before I strapped on the scope so I’m not 100% sure I won’t crash it into the bed, but this is for moving around in spaces of a couple of centimeters so this works. A less lazy person would have used their perfectly functional MP v2 to make a neat little fitting, but I am lazy so when a drill and zip ties can get me there the printer stays off.

The scope has a built in LED but I added a 12LED RGB ring for more control of the light. The separate RGB channels does make some weird effects at this scale, but I think it makes everything look kind of like a nebula with space monsters and this isn’t about real science so I’m good with it. I should have wired the LED for gpio control but I’m lazy and I already made a bunch of ESP-LED things so I just velcrowed one on.

I actually haven’t done much to justify motorizing the scope yet. It lets me get some super sharp focus by adjusting the Z though. Also for what I’m doing I probably can only use the X and Z since Y would jiggle the water. I’m just doing stationary timelapses for now because I’m pretty far from coding anything that could help the camera follow a pod, but it’s a start.

The motors and camera are easy to control with python, fswebcam and gcode. I could probably send packets to control the LED from the same script but not sure I need that. And the original MP select box with a door cut in the front made a perfect housing for the whole thing.

 Leave a Reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>



This site uses Akismet to reduce spam. Learn how your comment data is processed.