IMPROVEMENTS IN "MANUFACTURE OF METALLIC LASTS
Year: 1885

page_text: COMPLETE SPECIFICATION.
I ALFRED JULIUS BOULT of 323, High Holborn, London in the County of
Middlesex, England, Civil Engineer do hereby declare the nature of the invention
for IMPROVEMENTS IN "MANUFACTURE OF METALLIC LASTS and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement:-
--
This invention has relation to the manufacture of metallic lasts and its object is
to facilitate the manufacture of metallic lasts of the graduated sizes required so
that such lasts being easily and cheaply made will be generally used in the trade.
The invention is a new method of making patterns of graduated sizes from which
the iron lasts are cast and it will be herein after fully described.
Iron lasts have commonly been cast in graduated sizes and of proper form similar
to those which I make by this process but the mode of manufacturing being slow
and expensive iron lasts although much more desirable than wooden lasts have been
but little used, and wooden ones have had the preference.
Heretofore in making iron lasts, it has been necessary first, to turn a full set of
wooden lasts including all the sizes from the smallest to the largest. These wooden
forms were then taken by pattern makers and carvers and hollowed out and fitted
up to serve as patterns.
Each one of these wooden patterns was used to obtain, by casting a metal
pattern. In this manner a full set of metal patterns including each size and
half-size was obtained and the wooden patterns being of no further use were
thrown away This slow and expensive way of making these wooden patterns
has discouraged the manufacturer of iron lasts.
The object of this invention is to facilitate the manufacture of iron lasts by
dispensing for the most part with wooden patterns.
In carrying out this invention I first make a pair of wooden patterns of proper
shape and of the largest size which is likely to be required and from this single
pair of wooden patterns I obtain by this process all the sizes in metallic patterns
required. Having made and fitted up the first and largest pair of patterns of wood,
in the style required I then cast a pair of patterns from them in what is known as
non-shrinking pattern-metal, which is a composition of lead, tin, zinc and antimony.
CD 0.71

page_text: This pair of metallic patterns are similar in size and form to the wooden patterns
and having obtained them I have no further recourse to wooden patterns By the
aid of this first pair of patterns, I now proceed to get patterns of all the other sizes
required, in the following manner. A composition of copper and tin, is made and
when melting, the same, a hardening consisting of tin and zinc is added. This
metal is commonly known as bronze and it shrinks in cooling Other shrinking
metallic compositions may be used The metal should like the bronze shrink in
cooling sufficiently to reduce a pattern' cast in such metal in cooling, a degree
known as half size in last making.
Having prepared this metal I cast a pair of patterns of this metal from the pair
already cast of the non-shrinking metal already referred to and the result is that
a pair of patterns is obtained which is a half size smaller than the first pair. In a
similar manner a third pair of patterns is obtained from the second pair which is
just half size smaller than the pair they were cast from. By similar proceedings
I obtain in the shrinking metal all the sizes of last patterns required down to the
smallest and from these patterns the iron lasts are cast in the usual manner.
In making the shrinking metallic composition the proportions of the ingredients
preferred are as follows:-
For the middle sizes a compound of copper and tin, in the proportions of about
six parts by weight of the former to one part of the latter, to which one part of
zinc and a half part of tin are added as a hardening answers an excellent purpose.
For the smaller sizes what is known in the art as yellow brass will serve and
for the larger sizes iron will be found to be capable of a reduction by shrinkage
and finishing off which will suffice for the half-size required.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The method or process of first making a pair of last patterns of the largest
size and secondly casting in metallic composition which will shrink half a size in
cooling from this first pair and from each successive pair as made, smaller pairs of
last patterns thereby producing a graduating series of last patterns from the largest
to the smallest size substantially as specified.
2. As a new article of manufacture, last patterns cast in bronze, or metallic
composition which will shrink half a size in cooling substantially as specified.
Dated this 12th day of May 1885.
ALFRED J. BOULT.