Sadly, the prototype universal joint shown previously came off the printer very fragile and was not suitable for this device.

Another, thicker joint was designed and printed, however, due to the size restraint and requirement for two degrees of freedom the part just wasn’t strong enough to take a load and broke quite quickly.

There seems to be just two options available:

1. Buy or manufacture a metal universal joint. While commercial universal joints are available close to the size needed, interfacing them with the current design may lead to problems, either with the strength of the joint or with the size of the joint. Most universal joints are designed to transfer torque around an angle, and so are designed to fit on a drive shaft.
2. Do not use a true two degree of freedom joint. By replacing the joint with two hinges, close and at 90 degrees of one another, a similar effect can be gained, and the increased space may allow for a stronger design. The key holdback is the move away from the human form and how that may affect control down the line.

Currently, a two hinge design is underway. If this is deemed unreliable, the omercial option will be reconsidered.