Thursday, 10 February 2011

Foam Inserts cutting and test.

Well the foam cutting for the foot inserts went very well today! The foam cut much better than expected on the CNC machine, although I did have to keep an eye on the process as occasionally a loose piece of foam would wind itself round the cutter which could cause issues.

I cut the foam in two parts, the lower part is more complicated, requiring several pockets to fit the complex shape of the rubber foot. The upper part was initially just a 280mm diameter circle, however I then decided to add the patter seen in the image. This is to allow air to escape through the breather hole in the aluminium top part of the foot, otherwise the foam blocks the hole when in compression.

I ran foot contact tests on the leg with and without foam inserts with a load of 300kg, the results were very good. The addition of the foam inserts naturally reduces the compression of the foot as desired. However, there is a little more bounce on initial contact. This may be aided with the air channels that were later added but have not been tested, alternatively a softer foam for the lower portion of the foot may give less bounce yet retain rigidity under load.