I am the owner of the blog and the creator of that 3D printed Curta. The tolerances are small -- too small for the printer actually, but I am printing them so t

I am the owner of the blog and the creator of that 3D printed Curta. The tolerances are small -- too small for the printer actually, but I am printing them so they will allow hand fitting the parts that require a specific mechanical fit. The forces aren't too bad unless parts are misaligned which has happened, but the easy solution is to stop turning it when it jams up. When parts are aligned well and lubricated, everything runs very well -- misalignment was my fault for overlooking a few things.