Part eight by Jason Ballamy

The piston started life as a length of 35mm dia 6082 aluminium round bar which had a chucking spigot turned onto one end. Then holding by this spigot it was turned to finished diameter, piston ring grooves cut and the bottom bored out to leave the skirt.

Next, using the rotary table on the mill, the internal cavity was machined out.

With the rotary table repositioned, the wrist pin hole was drilled and reamed.

Once the chucking spigot had been parted off the head needed shaping to match the profile of the cylinder head so some co-ordinates where worked out using Alibre. A holding collar bored out from some Corian to avoid damaging the piston and then the profile done in a series of cuts.

The cuts were then blended in with a file before polishing the top of the piston.

The wrist pin is just a length of silver steel (drill rod) hollowed out and fitted with a couple of bronze plugs to stop it scoring the cylinder bore.

And finally a family shot of con rod, piston and pin.

See Part one here  part two  part three  part foupart five  part six  part seven  part eighpart nine