In order to properly burn in and assemble the new lead parts, it is necessary that they be fused and new lead added, and this requires that a supply of lead sticks be available. These are usually made by melting the smaller particles of scrap and junk lead which is cast in convenient size.
The Ambu Mould, Figure [14], is especially designed for this purpose. It is made of heavy sheet iron, die stamped into grooves and mounted on a wooden base with a strong wooden handle at one end. A heavy pad of asbestos is placed under the iron to protect the wood.
Figure 14[[1]]
This construction allows the lead to completely fill the grooves before cooling, but prevents the mould from becoming exceedingly hot with constant pouring. A pair of these moulds will keep one workman busy, as he pours one, the other is cooling. This eliminates all waiting and waste of time.
The sticks made are 15 inches long, 5⁄16 inch thick, ⅜ inch wide at the top and ¼ inch at the bottom. In pouring in an open mould of this type, pour the lead in each groove at one end, so that the dross will all gather in one spot. Never move the ladle along the groove when pouring, as this will scatter the dross and make the entire stick dirty.
When poured at one end only, a short length of the stick may be broken off, thus removing all the dross.
Dusting the mould occasionally with Ambu mould compound will produce better castings and permit greater speed in the work.
AMBU PLATE BURNING RACK
The building of groups, even after the plates and post straps are secured is a job that requires quite a lot of skill. Before the plates can be burned to the strap, they must be absolutely parallel, must be the correct distance apart, and the top surface of the strap must be at right angles to the surface of the plates.