“Blanks” are removed from the furnace, and the blades are forged first – passed through a series of rollers (like pasta again) to reduce the thickness. Once rolled, the now large plate of steel is put into a guillotine in the shape of the spade and cut. Next, we make the strapped sockets – using the same process as before, the socket is parted with drift and rolled and then cut to shape. Each strap has to be positioned out of the way in order to roll the other strap. No more reheating at this stage. The strapped sockets are then cut to shape and formed in a 2-stage socket forming press. The straps are left as rough formed, as they will require further heating and forming prior to handle fitting. The spade blade is moulded in a cast mould, and the forging process is complete.
Hardening and tempering
The metal has been allowed to cool down very slowly, so it is soft. To make it tough, the spade is processed through a large gas fired oven. Then the spade and the first 20% of the socket are very quickly transferred to an oil quenching bath which cools the steel down in a quick and controlled manner. After hardening, the spade is sent though a tempering oven, cooler than before, which relaxes the steel slightly to stop it from being brittle. Our target hardness is approx. 43HRC (Rockwell C scale). It is essential to not make the socket area too hard – this area needs to flex under load. The stress point of a spade is always the intersection of the blade and the socket or the intersection of the handle and the socket……by making a strapped spade the stress points are blended…..so under load the forces are evenly distributed and the opportunity for failure is greatly reduced. Hardening to tools