The Universal joint is a clever mechanism that lets you add bends into a rotating shaft. Using a UJ you can transmit power around a corner! Make this simple joint from blocks of wood and laser cut parts. Everyone can download the laser cutting file for free at the link.
Download the file UJ.pdf and use your laser cutter to cut out the four parts from 3mm plywood. If you don’t have a laser cutter you can often get access to one at a local Maker Space or Fab Lab, search the web for one near you.
You will also need.
2 x lengths of 12mm dowel approx 100mm long.
3 x 20mm wooden cubes – I sourced these from eBay.
4 x 12mm no8 round head screws + suitable washers.
You need to drill two pilot holes right through one of the blocks, 2.5mm diameter holes as shown.
In the two remaining blocks, drill a 12mm hole roughly half way into the block. Glue the dowel into place in the block then glue the laser cut pieces into place as shown. Wait for the glue to dry completely.
Using some 120 grit sandpaper sand off approx 1/2mm from the inside surface of the each of the four circles so that the centre block is a loose fit between the circles.
Screw each of the four circles into place as shown. Screw the washers down then back them off slightly so that the joint is free to move.
Use your universal joint as part of a model or as an experiment in pure mechanism.