The next thing to be done was the beam that ties everything together. I started with some 2" x 1/2" aluminium flat bar and drilled and counterbored some mounting holes so that it could be held to a machining plate. I also drilled in from the sides for some of the pivot pins while it was a nice easy shape to hold. With it then bolted down to the CNC's table I removed the majority of the waste from one side with an adaptive tool path, this leaves quite noticeable steps much like the contour lines on a map except these were ar 1mm height increments.

Changing to a 4mm diameter ball nose 4-flute cutter a ‘scallop’ tool path was used to refine the shape. The tool stepping over 0.2mm per pass leaves very little handwork to complete.

The material was then turned over and two similar paths used to machine the opposite side.

Back to the manual mill and with a 6mm cutter the material that had been used to hold the part was separated leaving just 0.25mm thickness at the bottom of the cuts which could be cut through and the surface cleaned up with a file.

A bit of rounding over of the right hand end and that was another part crossed off the list.

The last shapely link required was the one from the end of the beam to the top of the pump rod. I milled a piece of brass to size, reamed two holes and slotted the ends manually before using a similar process to the beam to shape the ends and fish bellied central section.