Spectronic-20 Sample Chamber Lid

thingiverse

The Spectronic 20 is a classic single-beam spectrophotometer originally manufactured by Bauch & Lomb. In its 58 year production run, an estimated 600,000 of these babies were made. The reason that the Spec-20 remains so popular is due to the instrument's simplicity, durability, reproducibility, and ease of use. All of the fundamental components that can fail in the device are off-the-shelf parts and easy to replace, especially in the older, fully analog versions. The source is just a GE 1630 bulb, the monochromator is a diffusion mesh, and the detector is a simple phototube. The display is simply a calibrated analog voltmeter. In the newer electronic versions, the detector is replaced with an off-the-shelf photovoltaic cell and the display is a very simple board using off-the-shelf electronic components and ICs. Both of these devices are easily repairable by anyone with a little electronics knowledge, a multimeter, and a soldering iron. This design is meant to replace the only thing I've found on the instrument that actually breaks - the sample chamber lid. While you can just use the broken lid, or set a painted styrofoam cup over the chamber to block light out, those solutions really don't always work well. You'll eventually lose the lid, or paint will flake down into the chamber and mess up your measurements. My solution was to design a cover for the original sample chamber that is fully 3D printable that can screw into or be glued onto the case or body of the device. For more information on the Spec-20, see the relevant <a href="https://en.wikipedia.org/wiki/Spectronic_20">Wikipedia article</a>. The design for the hinge is shamelessly ripped off from NCHippy's way-too-tough Large Hinge.