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Non printed parts

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Richard Bowman edited this page Jan 19, 2018 · 10 revisions

There are a number of non-printed parts in the microscope design. The most basic version of the microscope requires:

  • 3x M3 screws, hexagon head, 25mm threaded length.
  • 3x M3 nut, preferably brass.
  • 4x M3 washer
  • 3x Viton O rings, 30mm inner diameter, 2mm thickness. Can be replaced with #32 elastic bands (used to tension the actuators, you may want a spare or two!)
  • Camera and lens. This could be the Raspberry Pi camera module, a webcam, or even an RMS-threaded microscope objective and a tube lens, depending on your requirements. See below.
  • LED for illumination.
  • 3x M3x8mm screw for attaching sample clips (2) and illumination arm (1)
  • 2x M2x6mm screw for securing Raspberry Pi camera module (optional, until v5.17 when they are required)

Camera and lens

This is the most significant choice (at the moment) for your microscope. It will set the price and the performance of the microscope, and there are quite a few options. For camera, you can use a Raspberry Pi camera module, a Logitech C270 webcam, or a USB webcam with M12 lens mount (WaterScope sources these from China, I'm afraid I don't have a part number for you). The different options are compared in the Camera Options page.

For the lens, you can either use the lens that came with the camera or an RMS objective lens, and tube length correction lens. The "tube length correction lens" sits inside the optics module, and shifts the image formed by the objective so it focuses properly on the small camera sensor. I use a Comar Optics 40 PQ 16 or 40 PC 16. For the objective, the LS65 version of the microscope has 25mm from the objective thread to the sample, so you need a 25mm parfocal objective (sometimes called 185mm on eBay/AliExpress). If you have a larger 35mm parfocal objective, you can use the same optics module with the LS75 version of the microscope, or use an LS65 frame with a 10mm spacer, and the LS75 illumination. Sunlight Optical is often a good place to try for inexpensive microscope objectives. Any suggestions of where to get inexpensive 50mm achromatic lenses from greatly appreciated!

Higher quality images can be obtained with an achromatic tube lens (if you are using an achromatic objective). There are some designs for using a 12.7mm diameter lens with a focal length of 50mm, this isn't perfectly documented yet, but the lens in question is a ThorLabs AC127-050-A.

Substitutions

If you can't get any of the above, there are usually work-arounds. If you find a good substitution, please edit this page and add it in.

  • Hex head screws
    • WaterScope's come from Anglian Fasteners, the page for hex head screws only lists down to M4 but they do stock M3.
    • If you can't get hex head screws, get another head shape and jam a nut up against the head. The nut then takes the place of the hex head, and keeps the screw attached to the gear. Ultimately, what you need is about 25mm of M3 thread, with a hexagon at one end - either the head of the screw, or a nut jammed up against it. The two outer actuators are slightly shorter than the central one, so two 25mm screws and one 30mm screw works well if you're using the extra-nut-trick (the extra nut uses up around 3mm of thread).
  • Brass nuts
    • These are embedded in the actuators, and used to move them up and down. Brass will have lower friction and smoother motion, but steel should also work fine. I've not tried Nylon, it may well work nicely, though you'd need to be careful to avoid damaging them.
  • Viton O rings
    • You can substitute Nitrile O rings, but these can perish over time if exposed to UV light. For most applications this isn't too much of a problem, particularly if you use coloured plastic (which will prevent most of the band from ever being exposed to light).
    • If you can't get O rings, you can use #32 rubber bands, which are 3x1x75mm in size. You'll need to wrap them around the base of the microscope feet in order to get them tight enough to work. There are slots in the feet to allow you to pass the band from the inside to the outside and then wrap them around. This is described in the last revision of the v5.15 instructions. In v5.17, those slots are printed with thin bits of plastic closing them off at the bottom (in order to help them stick to the bed better). You'll need to snap those thin bridges with a screwdriver or other tool in order to wrap the band around the outside of the foot to tension it. In quantity, O rings are not too expensive. Hopefully WaterScope will be able to sell non-printed part kits soon, so you can get bulk prices.
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