Ring blanks and inside diameter
Dear Karen,
Let's say I have a strip of metal that is 1mm thick and
precisely 1" long. If I form that into a circle, which
circumference is precisely 1" - the outside, the inside, or the
mid-point between the two? In other terms, does the outside
surface "stretch" or does the inside surface "compress" when
forming the circle?
The solution to that question is in the book PROFESSIONAL
GOLDSMITHING by Alan Revere . ISBN 0-442-23898-3 TO ORDER - call -
800-844-9442
On pages 208 - 209 in the appendices there is a very comprehensive
table which shows the relationship between the ring size needed and
the flat length of the ring stock as determined by the thickness of
the ring stock. The appendices alone are worth the price of the
book.
The outside stretches and the inside compresses so the thicker the
ring stock, the longer the flat length the ring stock needs to be
cut.
The Book is well written, well illustrated, and well bound . It is a
very good value . I most highly recommend it. A standard disclaimer.
ROBB
Hi Karen,
Let's say I have a strip of metal that is 1mm thick and precisely
1" long. If I form that into a circle, which circumference is
precisely 1" - the outside, the inside, or the mid-point between
the two? In other terms, does the outside surface "stretch" or
does the inside surface "compress" when forming the circle?
I think you will find that the correct technical answer is that the
1" circumference is approximately 1/3 of the way out from the inside
surface. This is because metal tends to stretch more easily than it
compresses. This is, of course, all pretty theoretical as, in the
real world, the actual dimensions are affected by a number of
variables - the accuracy and angle of the cut ends, the evenness of
the temper of the material etc., etc. For this reason it is usual,
except in a very few cases, to make and ring under size and then
expand it to size.
Best Wishes,
Ian
Ian W. Wright
Sheffield UK
ROBB wrote re Alan Revere’s book: On pages 208 - 209 in the
appendices there is a very comprehensive table which shows the
relationship between the ring size needed and the flat length of the
ring stock as determined by the thickness of the ring stock. The
appendices alone are worth the price of the book.
That is very true, after 15 years of collecting jewelry books, that
is the book I still grab most often to the point that the appendices
are literally falling out from use.
Marta