Most Hirth teeth get cut one at a time with milling cutters and an indexer, so seeing the maker engrave the full radial tooth pattern with a 100W fiber laser is a refreshing change of pace. The joint is destined for a tablet holder, where it serves both looks and function, and the laser route turns a slow machining job into a repeatable engraving job.
The stock was a rectangular aluminum block of roughly 50 by 40 mm, cut on a horizontal bandsaw. It went into a four-jaw chuck with an alignment guide, and a cylindrical boss was turned down to about 35 mm. Three pilot locations were engraved with the laser, then drilled as M3 clearance holes. The back was faced and an internal relief bore cut in a three-jaw chuck, and two circular blanks were parted off.
Several choices stand out to me. A dedicated fixture plate aligns the blanks under the laser, and the tooth pattern comes from a 200-layer 3D slice program run through LightBurn. A light skim cut on the lathe trued the perimeter, counterbores were machined with a piloted bit in a drill press vise, and an arbor press seated an alignment pin. The finished discs mount on blue printed arm segments with M3 socket head screws, a threaded center bolt runs through the stack, a flat black rubber washer sits between the mating faces, and a printed thumb knob closes it up.
Nothing here is perfect yet. A slight off-center alignment during engraving left minor uncut areas, and cutting friction caused thermal expansion that shifted the final measured diameter. Even so, the joint held its angle under hand torque and gave adequate clamping force. The complete holder build is still to come, which leaves the arm design itself an open question for now.
Project by This Designed That. Watch it on their YouTube channel: