Curta Type I Case

thingiverse

I recently acquired a Curta Type 1 mechanical calculator. As an engineering collector's item, I decided to design a case for my Type 1. Using Fusion 360, this is my design, and although it is not intended to be an exact replica of the original Curta Type 1 Case, I believe this design works well with current 3D printer technology. The top has a spacer designed so that the Curta will not slide up and down in the case. I intentionally left a small space between this spacer and the top handle of the Curta calculator. You could experiment with a round rubber spacer, or rubber washer, or felt pad (this is what I used) with backing adhesive and just cut it to size and stick it on the 3D printed spacer part that is built into the top. You will be able to achieve a soft, snug fit for your Curta, so it won't slide up and down inside the case. The original Curta case used a round rubber spacer. I recently saw one for sale on eBay for $39. Ridiculous. Just make your own from something you already have a bunch of in a kitchen drawer or the garage. I printed this case using PETG with just a few minor tweaks here and there that I use on my particular Prusa i3 to get my prints just the way I like them. There are no tricks to printing either the top or the bottom. All angles and threads are designed with 45-degree angles, and no support material is needed for printing. For those who are new to 3D printing, print the bottom as normal, standing straight up on your print bed. The top needs to be printed upside down. In your slicer software, just rotate it 180 degrees, then print. In my slicer software, I programmed a filament change, so I could change the filament to a white color and printed the last several layers of the top. The bottom "lip" of the top will now have a white ring. I only did this for aesthetic purposes. This step is purely optional. Printing on my Prusa i3 at 0.2mm layer height, the top takes approximately 3 hours and 50 minutes to print. And if you do a filament color change like I did in the photos, the white layers took approximately the last 4 minutes or so of the print. As I recall, the bottom at 0.2mm layer height took not much more than 2 hours to print. These print times are only mentioned as guidelines; your print times could vary depending on your printer and filament settings.