Overview

The double-acting rams, driving the stick and the bucket, are made from 10mm outside, 8mm inside, copper plumbery tubes, cut to length. Each end is fitted with plastic "furniture nuts", found in DIY stores (they are M4-tapped inside, and the outside is designed to be hammered in 8mm holes – usually in wood). One of them is drilled at 4.2mm, to allow an axle rod to slide freely.

The inside end of the rod is sloted (with a hacksaw) on about 10mm, then M4 threaded. A 1mm nylon wire is fitted in the slot, then locked by an M4 hexagonal nut, which also gives guidance of the rod inside the tube.

Each wire goes through a 1,2 mm hole drilled in the plastic nuts, then a length of elastic cord, up to an axially drilled Meccano allen bolt. Since the wire is too rigid to be wound around a small drum, each extremity is finally linked to a standard Meccano cord. With a good lubrification (Teflon type) applied to the sliding parts, such an arrangement can transmit a significant amount of power.