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.
[Illustration: 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.