Prototype Manufacture

With the mechanism functional the proportions of each component was reconsidered and slimmed down,  this also resulted in the clearance holes for the fixings being reduced to 4mm in diameter. Once the modifications were complete a final cutting pattern was drawn up and the required components for the final working prototype laser cut.

Although each component was accurately cut and fitted well together there was little strength in the original design which saw the two leg mechanisms (as seen on the test rig) joined together by acrylic rod. It was clear that the chassis would be under a large amount of torque once the motors were switched on so a stronger frame needed to be constructed. 

To solve the problem an inner frame structure was made using 3.2mm steel rod which was brazed together and had an m3 thread cut onto each end to connect it to the other components. The brazed steel components are pictured below.

Once the linkages were built up onto the frame it became apparent that some fine adjustment had to made to ensure an accurate alignment between the motor and the drive point of the linkage. Using the original test rig this was re-visited and the necessary changes made.

As the picture on the right details, different pivot points were drilled and tested again on the original test rig to help ensure the mechanism worked as it should.

To help find the correct location of the cam in relation to the linkage a series of holes were drilled in a line from the centre of the cam face out towards the edge.

 Cams!

A total of eleven cams were laser cut to ensure that a near perfect interface between the cam and the motor drive shaft was achieved. Each cam was cut, tried for size and then adjusted until the best possible fit was realised.