USB Microscope Station

I’ve been getting into SMD soldering for my larger projects, however it’s not something I work with daily so naturally I went the cheapest route to get a microscope for the task. The common USB microscope can be had for less than $20, the caveat being that you need a robust mounting station in order to actually make any use of it. I got fed up with trying to use the thing without one, and all the CAD I found online led to underwhelming 3D printed results so I spent last Sunday making my own using 3D printing, some scraps of wood and some parts from an old 3D printer that were burning a hole in one of my bins.

The wood frame makes it simple to attach accessories.

This will be a quick and dirty build log, as I’m still working on getting things properly set up on the back end. Since I received many requests for build details I figured I’d just seize this as an opportunity to begin filling in some proper content! If you need clarification on anything feel free to comment below and I’ll do my best to articulate…this was quite literally a 1 day build from design to completion, so this will be an extremely rough guide.

CLICK TO DOWNLOAD ALL THE REQUIRED FILES (Thingiverse)

Bill of Materials:

Note: The specific 3D Printer threaded lead screw, rails and linear bearings are a bit tricky to provide a clear source since these were in a junk bin, so you may need to adapt by editing the provided CAD files, or just simply using it as a basic outline to build your own from. This was a bit of an up-cycling project, specific part numbers weren’t a part of most of this build. Additionally, any wood parts can probably be substituted with any 2×4″ or 2×6″ scraps. This is intended to be a fairly loose guide, and not a full blown tutorial.

Item Where to find (if applicable)
USB Microscope (Generic) (1x) Amazon https://www.amazon.com/Jiusion-Magnification-Endoscope-Microscope-Compatible/dp/B06WD843ZM/
Threaded Lead Screw Rod + Nut 8mm (1x) Harvested from a Maker Select v2
Steel Linear Rod, 10mm x 300mm (2x) Harvested from a Maker Select v2
Linear Bearings with Flange (10mm ID) (2x) Harvested from a Maker Select v2
M3 Hex Socket Head Screws 5-10mm length (14x) (Any assortment kit of your choice should be more than enough, there’s a lot of wiggle room for sizing here)
Pan Head Phillips screws (9x) (length depends on chosen wood depth) (Can be substituted for any self-tapping screw that doesn’t exceed the thickness of the wood frame parts)
“Chicago Screw” / Screw Post 8mm ID, 18mm L (1x) Amazon https://www.amazon.com/gp/product/B07QC5Z4QT/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
M6 Hex Socket Head Screw, 10-14mm L (1x) (Anything that fits the description will work fine)
688ZZ Ball Bearings (3x) (Find from your preferred source, can be substituted for any radial ball bearings of the same dimension)
M3 x 5mm Brass Knurled Threaded Heat-set Inserts (14x) (Find from your preferred source)
Scrap Wood 9cm x 2 cm x 40cm (1x) (From your scrap pile or preferred hardware store)
Scrap Wood 9cm x 2 cm x 13cm (1x) (From your scrap pile or preferred hardware store)
Scrap Wood 9cm x 2 cm x 16cm (1x) (From your scrap pile or preferred hardware store)
White Lithium Grease
(From any hardware store, or online vendor)

 

Optional Materials (Electronics):

Raspberry Pi 3 B+ (1x) Raspberry Pi Foundation
5 inch Raspberry Pi Touch Screen (aka 800×480 HDMI TFT LCD Display Module) Discontinued, but there are plenty of clones floating around
LEDs + Perfboard
I simply soldered three LEDs to some perfboard and printed the Loc-Line clones and soldered a USB cable to the LED’s which plugs directly into the Pi.
These are basically optional if you are planning on displaying the USB microscope elsewhere, below the basic method of making an auto-boot display from a Raspberry Pi 3-4 in case you want to replicate this.

 

Assembling the Station

This article is written with the assumption you’re able to discern from the CAD model a proper order of assembly. There really isn’t a lot to it, but these are the steps I took. You are welcome to refine these steps.

  1. 3D Print all of the printable parts. Items are all categorized within the .STEP and Fusion 360 files included.
  2. Using a soldering iron, insert brass threaded inserts into their respective cavities (anywhere you see an M3 x 8mm screw in the CAD)
  3. Press-fit 688ZZ bearings into their respective holes (Bevel Gear Handle, Cap & Base)
  4. Cut the wood scraps to length using your preferred method of cutting (You may use the CAD files as a reference, but as long as the frame is as tall as the Lead Screw you will be fine)
  5. Assemble wooden frame using drywall screws
  6. Attach the 3d printed base to the bottom of the frame
  7. Insert the guide rails into the base
  8. Press-fit Bevel Gear #1 into the Lead Screw, leaving approx 5mm of extra screw sticking out of the bottom
  9. Place the Lead Screw & Bevel Gear assembly into the base, with the Bevel Gear side at the bottom (it should fit snugly into the bearing)
  10. Assemble the carriage by screwing in the two Linear Bearings into their respective places, and then do the same for the Lead Screw Nut
  11. Press-fit the aluminum Y-rail into the carriage
  12. While holding the assembled Carriage above the Lead Screw & Linear Rails, turn the Lead Screw by hand to feed the carriage into the threads, and then keep turning the Lead Screw by hand until the Carriage is about halfway down the rails.
  13. Attach the Cap to the upper portion of the Lead Screw & Linear Rail assembly, leaving about 10mm of railing at the top
  14. Attach the Z-Brace to the top portion of the Lead Screw & Linear Rail assembly by pressing down
  15. Using sheet metal screws, attach the Z-Brace to the wooden frame
  16. Insert the Chicago Screw into Bevel Gear #2 (See CAD for direction)
  17. Insert the Bevel Gear #2 assembly into the bearing that is attached to the Base, so that it meshes with Bevel Gear #1
  18. Press-fit the M6 Screw into the Handle
  19. Screw the Handle/screw assembly into the Chicago Screw that now resides in Bevel Gear #2
  20. Apply white lithium grease to both bevel gears
  21. This is optional, but I added another piece of scrap wood at the base of the wooden frame with just a simple drywall screw so that it can rotate, but you may have a better idea for your base.
  22. Also optional, add your Raspberry Pi + LCD Screen to the top of the wooden frame
  23. Lastly, I added an optional LED arm that I reused from another project to the end of the Y-rail, I included a part in the CAD files in case you wish to attach something there.

Setting up the Raspberry Pi

I won’t go into too much detail here because you may already have your own Raspberry Pi + screen, or even choose to use with a smart phone or PC, but here’s how I set up the software to autoboot to a live view of the microscope. This isn’t the most ideal way to go about this but it works great for me, and is quick and easy.

  • Install “mplayer

sudo apt install mplayer

  • Add mplayer to autostart:

sudo nano ~/.config/lxsession/LXDE-pi/autostart

  • Add the following at the end of autostart:

@mplayer -fs tv:///dev/video0

That’s it for the Raspberry Pi configuration.  Simple, right? It’s not the best solution but this is how I got this done. When you turn the Pi on, it will load the OS and then immediately display what the microscope is seeing. I’ve experienced very little latency. This will still be improved on eventually. Note: if you have other devices connected via USB, you may need to use an alternative to “video0”.

Final Thoughts

This seriously was not intended to be the most elegant solution, but it sure works for my purposes. I will come back to refine this when I find the extra time, or make improvements. The CAD files are open source, so feel free to remix and change it, and please be kind enough to give Graybotics some credit. I’d love to see what people do with this rough guide! Feel free to reach out if you need clarification on any of the steps, I tried to make the CAD files as clear as I could in a short amount of time.

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