What I want to do
This is a substantial revision to an earlier design, which integrated a bunch of other earlier design concepts.
The earlier version came back from the Barnraising a little crunched. While the idea of being able to print the whole thing out on 8.5"x11" pieces of paper is something I really like, the three-piece design was a little fragile.
I figured that a stiffer material was needed, with fewer exposed tabs. I also wanted to introduce more flexibility and modularity into the design.
My attempt and results
Finishing what I started
I started out by finishing up and revising the files for the printable version and integrating everyone's comments. Now the fold lines are dashed, the tabs are more protected, and the grating is at a 65 degree angle. @fastie was right that the 65 degree angle gets a slightly clearer spectra. See my earlier note for assembly instructions.
A New Case
Then I designed a new box, with a little trial and error and a a good bit of patience. I started with cardboard, but that was too thick.
So I went to paperboard, essentially a black card stock about the thickness of a cereal box, and reworked the cardboard into to this pattern:
you will also need a board 5mm x 40mm x 235mm, some velcro, and this mounting angle for the grating:
I couldn't fit the box design all on one sheet all at once, and had to cut it up a bit.
I crimped the folds into the material by running over the fold lines with a ball point pen really firmly. This makes great creases and destroys ball points.
Then I started putting the parts together. The mounting board is masonite, 5mm x 40mm x 235mm, and covered in velcro. The block is a 45 degree angle block that ships with the existing desktop spectrometer. It is attached with velcro, as is the angle for the diffraction grating.
The collimation slit mounts on a 4cm x 6cm card and slides into a pocket in the front, locked into place by the top of the boxes' tabs. The idea of a little pocket for collimation slit cards was @amysoyka's.
The double-folded walls of the spectrometer make it really stiff and durable, and quite crunch-resistant, the velcro means that the distances can be changed, and the grating can be changed or re-mounted on a new angle, and the slit can be easily interchanged. The front tabs will also allow it to click into an oil testing kit sample station (more to come).
I haven't had a chance to really play around with this one as a spectrometer, but the initial spectra I captured (there was some weirdness on spectralworkbench today owing to a server switch) looked very clear.
Questions and next steps
Tell me what you think!
The mount for the grating needs to be a little narrower, as opening and closing the lid can sometimes tork it a bit.
also: Me and @warren brainstormed some ideas as to how to give credit to all the contributors to the oil testing kit in the design, and I asked if we could print the names of people's notes directly on the kit. Jeff said that there are shortened URLs that are just numbers for research notes. I'm going to put some printing on the outside of the different parts.