Some time ago I did some experiments and some mathematical curve
fitting to derive a formula for doing this. The formula is quite
messy so I designed a program for it, that my son created and placed
Its not 100% accurate, but sufficiently close for all my
requirements in silver, gold, platinum and palladium.
In your example, it states that you should start with square wire of
side 3.684, or round wire of diam 4.157.
You can also specify the required length, and it will tell you the
length of stock to start with.
Because its very unlikely that you will have stock of this size, it
allows you to specify the size of the round or square stock you do
have, which you can then roll down to the size you actually need.
In your example, if you wanted a length of 45, and had some round
stock with diameter 5. It tells you start with a length of 22.9,
which, after rolling to 3.68 square will have a length of 33.2. If
this is then rolled to a thickness of 2, it will have a width of 5
and a length of 45.
After getting the stock to the required starting size, anneal it and
roll to the required thickness in as few passes as possible.
Let me know how you get on, or if you have suggestions for
Regards, Gary Wooding