The idea for this particular post started when I read the pancake
die on Kevin Potter’s site. A couple of sentences that
pointed out to me a very good reason to do a bit of elaborating
about the process that I’ve lived and breathed since some time in
1986. Kevin says, about the dies he’s offering :
"Pancake Die Information:
The pancake dies are designed to cut non-ferrous metal (copper,
silver, brass, gold, nickel) 20 gauge and thicker to about 16
gauge. They work best when the metal is hard. If the metal is too
soft, you will get a burr and it will be difficult to remove your
part from the die. DO NOT ANNEAL METAL FIRST.
If you use metal that is too thick or too thin, it is possible
to damage the die. As long as you stay within the recommended
gauges, the dies should last youmany years under normal use. "
What I immediately thought was that I ought to make more well-known
the fact that the RT/pancake blanking process is not limited to the
constraints of these dies of Kevin’s, mainly for the benefit of
people who may not be very familiar with the process and it’s
capabilities and/or limitations, over all. Necessarily, it followed
that I’d need to explain in detail the differences in approach and
manufacturing, and end product between the dies I sell and the ones
Kevin does, and also about these differences as they might apply to
people making their own dies. Then I knew I’d be best serving t= he
metalsmithing community by including the issues of why and how the
possible versions of pancake dies might be better suited to
different people and applications ; a few sentences had rather
quickly inspired what could turn out to be a rather large amount of
writing for an Orchid post, and probably best done in stages instead
of all at once.
The main distiction between varieties of pancake die I’ll go over is
about the die material itself, and I’ll divide that into three
categories : a) I make almost all my dies out of heat-treated tool
steel (HTTS from here on) ; b) non-heat-treated tool steel (NTTS );
and c) cold rolled steel, which Kevin uses (CRS from here on). HTTS
is what industrial cutting dies are made from, and gives the most
durable dies by far, and is the only good choice for certain
applications and designs. Very early on I found that, in the process
of learning to heat treat dies (by trail and error) after they were
sawed out, that this was critical in getting dies that would perform
well without failure. It also became obvious (trial and error, and
let’s just assume that ‘T & E’ is an integral part of everything I
talk about ; I learn by doing) that dies for certain design and metal
combinations had to be heat treated to different hardnesses, to
prevent failure from either deforming, because the steel isn’t hard
enough, or from breaking or cracking because it’s too hard. Pancake
dies are thin plates of steel and cannot be hardened to the degree of
industrial dies made of half-inch or inch-thick steel. The decision
of exactly what hardness to temper a die at is often a compromise :
hardness must be sacrificed for toughness so dies won’t break, and
flexibility (or the lack of risk of breaking) must be sacrificed so
that dies will not deform permanently.
Using tool steel, and especially hardening it after sawing the die,
allows you to cut harder metals and more intricate shapes, than using
cold rolled steel, and when dies are cut in the ‘normal’ way- at an
angle to create very-tight tolerance between the shearing edges- it
allows you to cut thinner and softer metals than with Kevin’s dies.
Kevin’s dies are cut with a laser, but the laser can’t cut at an
angle to the surface of the die, so this leaves a gap or kerf that
can be thought of as analagous to a pair of scissors that are
slightly loose at the joint. You would be able to cut cardboard or
thicker paper, but thinner, softer material would bend and stick
instead of getting sheared.
This is a critical issue when cutting pancake dies the normal way as
well ; the same factors apply, and the angle has to be precise for
the die to be tight so that it can cut cleanly, and work well on
thinner, softer materials. The difference being, obviously, that it
can be done cutting dies in the normal way, at a specific angle,
which is determined by thickness of die steel and width of sawblade,
and cannot be done with dies not thusly cut at an angle. When I make
people dies for very-thin metal, they sometimes have problems opening
the dies because the tolerance is so tight, and I have to stress that
they must be made that tight so that they will work well, and for as
long as possible, with the thin metal they are cutting. Any looseness
allows for the problems of sloppy cutting, metal sticking in dies,
and damage to the cutting edges, with the worst case scenario being
the need to remake the die. Kevin’s dies are made of thicker steel
than the tool steel I use, so some strength advantage lost by them
being CRS is regained by them being significantly thicker. Also, some
of the disadvantage caused by acute-angled cutting edges in dies cut
in thinner steel the normal way ( which is all, and then
some,regained by heat treating ) is avoided by the thick CRS dies
being cut with right-angled cutting edges. He also tells me that some
minor hardening of the surface of the laser cut area takes place, a
good thing, but very different from the full-thickness hardening
achieved by the heating / quenching / tempering process used with
HTTS dies.
It becomes apparent that these CRS dies are good for what
applications Kevin states that they are, and in the specific designs
he offers them in. Even though it goes directly against my careful
approach to specific cutting angles for dies, Kevin’s approach is
functional for a limited range of applications, and is a good choice
for certain people’s needs. Sharp points will be the first areas to
‘wear out’ on CRS and NTTS dies, and it will manifest first as
bending of the tips /points , which leaves parts with slightly
curled tips. Eventually the deforming will be so severe that the tip
areas will fail to cut all the way through the metal. Both Kevin’s
thick CRS dies, and thinner NTTS dies can be useful and productive
for many applications, and a good economical option instead of
paying me to make HTTS dies, which can be overkill in some
instances. My mentality has always been to provide the best, most
durable dies I can. This began with finding out right away (in 1986)
that the malleability of unhardened tool steel rendered it
unacceptable, in my mind at the time, as a die material I would sell
to people. I also figured that if I went to the expense and effort
of using tool steel, I ought to also heat treat it, and get the most
out of the material, so that my customers would get the most for
their money, and the most out the process. Since I also began as a
provider of custom dies, I quickly had to expand the capabilities of
the process, both in size and thicknes s, over what was afforded by
the equipment available at the time, and the suggested parameters at
the time. Many of these envelope-pushing projects simply would not
have worked using anything other than HTTS dies, and I almost never
make CRS dies, except for a few people who cut pewter, or watercolor
paper, or card stock-like paper.
Heat treated tool steel dies can make make runs in the tens or
hundreds of thousands of parts in most non-ferrous metals, and
really, I haven’t had any long-term orders large enough to find out
the true limits. for so mething like a 1" circle cutting 24ga.
sterling, a die would probably cut millions of parts. Some designs
and some metals can be very hard on HTTS dies -stainless steel, and
white gold, for example- but I’ve had dies cutting ornament -sized
pieces in.025" thick mild steel in a punch press (high-impact, not
nice to dies) for 30,000 parts with no significant wear, and I
recently made a die that had to cut unhardened tool steel, the same
steel the die was made from, and it works just fine.The simple fact
is that a die made of heat treated tool steel is orders of magnitude
more durable than one made of NTTS or CRS, and allows much more
intricate designs to be cut, and a much greater range of materials.
It is true that as long as the die material is stronger than the
mat= erial being cut, you can have a functional die, so the questions
become about whether a specific design,or metal will be more than
the die mate= rial can deal with. The original RT Blanking System
guide book suggested using brass dies to cut materials like paper or
plastic, and there is nothing wrong with that approach, assuming
that the dies are made following proper sawing angles, to create the
tight tolerance required for cutting thin, soft materials. When it
comes to tougher jewelry metals, intricate designs, and long
production runs, the obvious best solution is HTTS dies, though NTTS
and CRS dies will be useful for some projects.
I have recently uploaded photos of various projects to my
photobucket site, in the ‘dies and parts’ album :
Dar Shelton