High Carbon steel is bought in billet form from the mill. It is reheated and put through our rolling mill to reduce the dimension. It is like rolling pasta .. start with a larger piece of dough and keep rolling until it is the size / shape required. Once down to size, the steel is cut into “blanks” of 375mm long needed to make each tool. These blanks are heated to a minimum of 1250 degrees Celsius in a gas furnace.
“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 a 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 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
We use grade "A" kiln dried American Ash, arguably the best about, with straight tight grain. No greater than 12% moisture content. A cut plank goes into a 4-spindle copy lathe (same machine that makes rifle butts). The lathe slowly follows a mode and 4 handles are turned in a 24-minute cycle. Once lathed, we must router the inner D of the handle and fit the reinforcing rivet through the Hilt. All handles are hand sanded prior to approval for use. Fitting the handles
We taper the handle to fit within the socket of the strap. The straps are loosely arranged around the stem of the shaft and together they are placed in a set of reducing rolls. The straps are rolled over the stem of the handle, compressing the metal in the wood. Heat is added to align the straps correctly. Once the straps are firmly in place, the metal is clamped around the timber and rivet holes are drilled and rivets peened in place. Finally, straps and handle are polished to produce the smoothest handle possible.