The Creation of Mechateuthis' Arms Pt. 1

Two of the most common questions I get about my most popular creation, Mechateuthis, are how the arms work and how I made them. This post series should provide a good understanding of both. To make the arms, I started out by making cardboard templates of one half of each size of segment. I made 3 chalk lines on the cardboard corresponding to the top center seam, bottom center seam, and side bearing hole. By making all lines converge to a single point, the correct geometry for a uniform taper is achieved.

The bearing mount points (the circled points where the chalk lines and pen arcs meet) must be arranged to be at the same distance from the chalk line convergence point on each joint, even though the edge points are part of a different segment than the central point. This is so that the segments will have an even transition rather than a weird step down.

After using a compass and ruler to draw in the rest of the segments' outlines, I cut out each one, and used it to make the metal templates which I eventually used to cut out the segments.

Once I had all the templates built, I installed them one at a time in my self-built pantograph plasma cutter and cut 16 copies of each. Once the segments were cut, I had to remove the slag (something like 16 hours with a pair of wire cutters breaking it off)drill the bearing pilot holes, and bend the cutouts into the proper shape.

After that, I clamped them to the table, and welded the bottom seam using my TIG welder.

While leaving the bottom clamps in place I clamped the top seam in place and welded it.

After the welding, the segments usually needed a bit of adjustment.

After the welding was complete, I stacked the segments together and pounded on them to force them into a uniform
cross-section shape.

That's it for part one. If there is sufficient interest, I will make a post on the next part of the process.

Thanks for reading!