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Pancake dies


#1

Many years ago I read about stamping out parts in airplane aluminum
using hand saw cut dies in tools steel. I was wondering if anyone
has detailed about the process of cutting these type of
small dies, or know where I can find more

I believe the process was patented in the 1960s, perhaps in England?

Thanks in advance
chris


#2

Contact Dar Shelton of Sheltech. If you think you want to actually
make dies yourself, unless you seriously like to go bonkers, have
Dar do them for you. He can give you lots of background info too. His
prices are very reasonable and he knows what he’s doing. Usual
disclaimer, just a happy customer.


#3

Are you thinking of the RT Stamping system? Does that ring any bells?
You can do an Orchid archive search and it will bring up a few hits.

Laney


#4
Many years ago I read about stamping out parts in airplane aluminum
using hand saw cut dies in tools steel. I was wondering if anyone
has detailed about the process of cutting these type of
small dies, or know where I can find more I believe
the process was patented in the 1960s, perhaps in England? 

I could be wrong on this, but I think you’re blending two stories.
Pancake dies to cut sheet metal were, I’ve heard, first widely used
in cutting LARGE panels of aluminum for airplane manufacture in world
war 2. The cutting, too large for a normal stamping press of the
time, used steam rollers to drive over the dies to cut the metal. At
least that’s what I’ve heard.

Then for jewelers, the idea of small hand sawed pancake dies was a
project researched and published by Robert(?) Taylor (at least I
think that’s his name. been a while since I read his paper). That
was indeed in england, and the process was named “RT blanking dies”,
a name still often used. I thought it was in the 80s, though, not the
60s. Could be wrong on that too, but that’s my memory of the
things…

Peter Rowe


#5

it is called the RT process and there is-was a patent in the UK. The
process is older than that. It was practiced in the US during WW2 at
Douglas aircraft. for dies see:

http://www.sheltech.net/products.html

jesse


#6
Many years ago I read about stamping out parts in airplane
aluminum using hand saw cut dies in tools steel. I was wondering if
anyone has detailed about the process of cutting these
type of small dies, or know where I can find more I
believe the process was patented in the 1960s, perhaps in England? 

The process was used in the 40’s for cutting airplane parts. I don’t
know if the use pre dates that. Roger Taylor in the UK patented a saw
for cutting these dies in the 70’s or possibly the 60’s. He also
wrote about cutting of the dies for jewelry production and through
this writing they became known as RT dies or the RT blanking system.
The saw and instructions used to be sold by Rio Grande under that
name. Lee Marshall first with his company Bonny Doon and now Knew
Concepts has made a series of saws that are much easier to use than
the RT saw for cutting these dies. Susan Kingsley’s book, “Hydraulic
Die Forming for Jewelers and Metalsmiths” has good instructions for
cutting these dies. Dar Shelton who sometimes posts here is an expert
in cutting these dies hopefully he will chime in with some tips.

James Binnion
James Binnion Metal Arts


#7

It’s called the RT Blanking System. See
http://www.hswalsh.com/itemdetail.aspx?i=TB230&a=B

Regards, Gary Wooding


#8

Chris, This is a very effective way of producing accurate “short
run” parts I am very familiar with this type of tool making and can
help you. If you prefer I can make them for you please contact
offline to discuss.


#9
The saw and instructions used to be sold by Rio Grande under that
name. Lee Marshall first with his company Bonny Doon 

Just for the stray reader’s FYI - the RT system/concept is that you
saw out a blanking die in sheet metal, leaving the two parts
attached. If you make a leaf, you’d saw the whole leaf except for
the end of the stem (this is in steel sheet, BTW). The sawing is done
at a definite angle which must be equal all around. That angle leaves
a sharp edge, so when you’re done you put a piece of silver
(whatever) sheet between the parts, press it and bang! instant (so to
speak…) leaf pattern… They are short run dies


#10

There is a website “sheltech.net” You might get some info about your
dies there.

Good luck.


#11

The pancake die was invented by Leighton Wilkie with the
collaboration of his two companies, Continental Tool and DoAll
bandsaws, along with Douglas around 1930. It was the first DoAll
tilting table bandsaw (patented) that allowed the user to cut at an
angle thereby creating a kerf with zero clearance when opened. It was
part of the “Continental Process” of independent tooling for presses.
The prototype DC3’s had their wing struts cut by this method.

Hope this helps!
Phil


#12

Pancake/RT dies, continued

Below I’ve copied and pasted three consecutive posts I made to the
Bonny Doon forum a couple of months ago regarding the tool steel used
to make blanking dies. They cover my opinions and some factual basis
to support those opinions, the facts provided by the manufacturers of
the steel, so from my perspective there’s no debating the fact that
some steel comes harder than other steel. The issues of exactly why
are not so mething I’ve researched, but I have a mountain of
firsthand experience working with the steel, that can offer insight
into the whole process.

One of the first things I did when I started sawing dies back in
1986 was to try to make it as easy as I could. The two obvious ways
were to a) only use steel that was thick enough for the specific job
(while also considering that I’m selling tools that I intend to last
a long time, so I actually use thicker steel than is absolutely
required), and b) use as big of a sawblade as I can get away with.
Two main factors determine what blad e size that is : first and most
important is the degree of sharpness of the turns in a given design,
and second is the fineness of detail, such as in a hand with
articulated fingers. With such a hand, a smaller blade may be
desirable because

a) it will take less steel away from the fingers and the spaces
between them (leaving more mass behind for strenth), and

b) the cutting angle will be less acute (which will also functionally
achieve what “a” does.

So, bigger, simpler designs can be sawed with bigger blades, and I
usually use size 1 for all but the biggest, toughest jobs. It becomes
physically more difficult to propel bigger blades, so size 1 may be
too hard for some to use. Size 2 is hard for me, and approaches the
oint of diminishing returns as far as effort put in to speed of
sawing resulting.

Earlier I said “easy”, and I should have included “faster” , because
that’s really why I use bigger blades. I only use size 4/0 on
designs with the most detail/sharp turns, and go up in blade size
accordingly for different degrees of complexity.

Recently a client asked for a small design, only an inch across, but
very detailed, that she said took her four hours to saw herself. I
understand people’s frustration, because I can imagine sawing such a
design with a 4/0 blade in a harder-than-average piece of steel.
Well, it’s routine for me, and even though it is no picnic, I
actually can’t imagine taking that long sawing any die, so I do
sympathize. I did have to saw this die for her, but I used size 2/0
because all the critical turns were rounded, and it saved a lot of
time. Really, just the difference between 4/0 and 2/0 is very
significant, as is the jump from 2/0 to size 1.

Another thing I did recently, to try and deal with what seems to be
a trend of even more harder-than-average steel (maybe I’m just
getting older, but I am also stronger than when I started dies, so I
doubt that I’m the ‘problem’, yet), is to find the best possible
blades. The brand (Swisss) that I’d been mostly using for almost 20
years just wasn’t working as well as I was used to (was it the
blades or the steel ?.. see below for part of the answer) so I tried
some Scies and some Pikes (also Swiss) again. Only marginally better,
but there was a significant improvement when I got a hold of some
Pike Platinum blades. They made sawing the hard-hard steel tolerable
and went through the softer steel like… well, certainly not like
butter, but like softer steel, which can be a lot. By feel and
experience, I’d say that some steel is up to twice as hard to saw as
other steel, even though they may only be a few points apart on the
scale (see below).

posts to the BD forum, in sequence:

"I always knew it wasn't my imagination, and it wasn't just the
sawblades. It's right there in the stated variance range
provided by the manufacturers. Brief research this weekend turned
up numbers of Brinell 179-212 as the range from Sheffield, and a
max of 229 from one American company. I'm going to try and get
info from Starret and Precision Marshall this week. But let's
look at the Sheffield numbers, which corresponds to about RC
16-19. Four points on the Rockwell C scale, call it three,
conservatively. Looking at the tempering chart for Starrett
--just as a way of correlating the numbers to some sort of
meaningful,real-life situation -- 3 points corresponds to about
200 degrees F difference in temper. Three points is still the
real phenomenon, the real difference in hardness, the 200 deg is
just my way of giving it functional meaning. So what does 200 deg
difference in tempering make ?. In a nutshell, 'ALL' the
difference. Temper a die to 500 F and it will not respond to
peening blows for realignment, but at 700 F it will. 550F and the
steel will barely start to take marks and move a little bit, but
at 750 F it readily moves, and takes significant marks. 600F and
it becomes a bit more responsive, and 200F more, at 800F, the
steel seems downright soft under the ball peen. 

So, 3 points is, to me, a significant difference, and even if
the raw steel only has 1/2 of this variance, it is still going
to be noticeable, all other factors being equal. I have no doubt
that the makers of the tool steel adhere to their stated
standards strictly. My point is that, within that stated range,
I can tell the difference when sawing dies with a jewelers saw,
between "harder" and "softer" plates. Case closed. I've sawed a
few miles in that material over about 20 years, so I know what
I'm talking about. " 

"I got the Starrett numbers today, which are Rockwell B 88-95,
or Brinnell 175-212, which translates to (depending where I look)
to Rockwell C 7-15 or 9-19, even more of a range on that scale
than I had estimated. I can't say that I can consistently tell
the difference when I'm cutting the large pieces up into die
plates on the bandsaw, but with a jewelers saw in hand, it's a
whole other story. Yes, there can be a lot of variation in
sawblades, between brands, and grosses, dozens, and single
blades of the same brand, but it's generally less, because
manufacturers ARE aiming for a specific hardness. What has never
been a question (not really) is that there is some difference in
saw-ability between batches of steel, and I have heard from a
person, who heard from a person who is a metallurgist that there
can even be variation in areas of one plate. That isn't
something I can say I've noticed for sure, but I have seen some
funky steel. Every once in a while I'll get one where, when I
harden the dies, they won't stay flat no matter how I do it, and
all it usually takes for 'normal' steel is to quench vertically.
The worst piece of steel I've seen was so defective that I could
break of corners with a pair of pliers and see an abnormally
large grain structure. 

The normal difference in saw-ability I've encountered has made
life frustrating now and then, but this looking at the numbers
is something of a relief, and I've found that buying the most
expensive blades helps a little. So, again, the steel is
consistent within it's stated range of specs, except for a rare,
rogue plate, like the 'crumbly' one I got 20 years ago, but not
so perfectly consistent that an experienced hand, with a
delicate feel, and a precision tool (small sawblade) can't
notice variations.Truthfully, I doubt that it takes experience
to tell the diffference, just one bunch of blades and two pieces
of steel that are of different hardness. " 

"I just talked to Precision Marshall, and the guy there said that
when the steel is annealed in large batches, they are simply
following a prescribed cycle, not aiming for a specific pinpoint
end-hardness that the entire batch must adhere to. Obviously,
this leaves the door open for slight variations in the condition
of the end product. All they want is to provide the steel in an
annealed, machinable state, and they do that. The guy also agreed
that the range of composition specs (tiny differences in the %'s
of other metals alloyed in ) might also affect resulting
hardness." 

Dar Shelton
www.sheltech.net


#13

I’m writing this for two reasons, in whatever mixture of motivations
it seems like; one is to present accurate about pancake
dies and the other is to promote myself, because I make pancake dies
and that’s been my profession for 24 years, so it’s safe to say I
have accurate Apparently not everyone who needs to does
though, and this bothers me, because it’s about people out there not
fully understanding the capabilities of the process, not knowing the
extent and effectiveness of it’s applications. I’m not into an
adversarial, me-versus-him approach, so I will just call the other
pancake dies (that I know of) that people can buy “laser-cut dies”,
and for the purposes of this particular post I’ll call the dies I
make “angled dies”,“hardened dies”, “angled, hardened dies”, or
maybe "sawn dies ". These terms describe the difference in how the
types of dies are made, and that has everything to do with how they
perform.

I will have to start at the beginning because the most basic thing
about properly made pancake dies is that the cut that creates the
cutting parts of the die are made at an angle that is NOT
perpendicular to the surface of the die plate. Since lasers are not
able to cut cleanly or accurately enough unless they ARE
perpendicular to the steel die surface, these dies (obviously) have
cutting parts that are not made at an angle.This difference is
critical, and the easy analogy of a pair of scissors will
demonstrate why.

Effectively, cutting a die at a specific angle, depending on steel
thickness and sawblade size, creates a zero tolerance fit between
the cutting components of the die, very much like a pair of scissors
that’s snugly fitted , where the blades slide along in contact with
each other, no gap between them for any material to pull in and get
stuck, or cut sloppy, or not cut at all. Laser-cut dies do have a
significant gap between the cutting edges, and from the analogy, and
everyone’s experience with scissors, it’s easy to understand why this
gap has the potential for causing lots of problems.

Having a gap isn’t always a problem, and using hard steel isn’t
always necessary, so the laser-cut dies are useful to some extent,
and work on thicker material as advertized, but there’s something
about cutting pancake dies without the angle that is contrary to the
fundamental concept of pancake dies, in my way of thinking. This
isn’t an abstract idea either, because it’s deeply rooted in
experience : the problems caused by loose t= olerance (the gap
between the cutting edges) far outnumber problems caused by any other
issue, and when you’re in the business of making tools that work and
cutting parts that people are happy with, you’d better figure out
how to make dies that you don’t have problems with. Which is the
first thing I started working on back in 1986 when I got the “RT
Blanking System”. Instructional material available at the time was
vague and rudimentary but I became obsessed, and one of the first
problems that jumped out was that the table of angles given resulted
in loose dies that either left burrs on the backs of parts, and at
worst, allowed metal to bend, get pulled into the die, and jam itself
in there. It doesn’t take much of a gap in some situations to begin
to cause these problems, so the way I approachit, there is very
little room for deviation when setting the angle of cutting. When
working with metals thinner than 22 ga. (generally speaking) the dies
simply need to be tight, sometimes so tight that they need to be
opened with some force.

I just recieved two relatively new dies back in the mail that
malfunctioned. I can feel the cutting edges click as they contact
each other as I open and close the empty die, which I can do freely;
this means that the die is relatively tight. Extra-tight dies are
harder to open, and loose dies don’t contact at all, so this die is
medium tight, but it (both did) jammed while cutting 24 ga.
patterned brass. These are dies that are made with every effort to
perfom well, not performing well because of this one main issue,
cutting angle and tightness. In reality, another thing is often
involved, which is that if metal is loaded too close to the egde of
the design on a die that’s just a hair loose, that invites the metal
to pull into the die and jam it, while loading with more excess
material bordering the design can prevent that from happening. That,
as opposed to a die that’s very tight, where you can literally load
on the very edge of the design and have sharp, feathery pieces of
scrap leftover, and a part that’s still clean as a whistle. I’m
talking about very slight differences in cutting angle, maybe 1/2 to
1-1/2 degrees, which result in tolerance differences of fractions of
thousandths of an inch, up to maybe a couple thou… Another very bad
thing that can happen when a die jams is that it usually jams on one
side (left or right, not front or back) and forces the whole punch
part of the die over to the other side. This can cause the cutting
edges to overlap on that side, and when the die closes in this
position, the cutting edges have nowhere to go but to crash through
each other and damage that area of the die. This is almost always
catastrophic in that the die will never cut cleanly again, and often
never cut again without jamming. The problem with trying to sharpen
cutting edges in this situation is that you’d be removing metal from
exactly where you need to have more metal, and this (adding metal)
is of course impossible to do. Not quite entirely impossible, as dies
can sometimes be peened to stretch the steel and force a little bit
into the gap, effectively tightening the die up. Sharpening is
counterproductive and is not advisable at all.

Again, I’m talking about small amounts of looseness in dies
potentially causing big problems, so a gap of maybe .005" or .008" or
whatever, left by a laser cutting perpendicular to the steel, is
completely unacceptable to my approach to making pancake dies.
People using the dies and having any of these problems ought to know
exactly why they are occuring, and know that the process itself is
not to blame, that clean parts in thick or thin material are not
hard to make when the dies are made a certain way. Also, that
designs are not limited to basic, simple shapes. Using tool steel,
and hardening it after the dies are sawn, opens the door wide for
cutting more intricate shapes. It’s not that much of a stretch to
say that anything you can saw, you can saw as a pancake die if it’s
sawn and heat treated properly. The other huge advantage to heat
treated, tool steel dies is longevity, but that’s a whole other
barrel of monkeys. I really wanted this post to beabout angle and
tightness, so, class dismissed.

Dar Shelton


#14

This is Kevin Potter. I make laser cut dies. My dies have no angle,
yet they cut very well. As long as you work within their
capabilities. If you are going to cut metal below 22 gauge, they
don’t work. If you want intricate designs, they don’t work. But,
that is where Dar comes in. He’s very skilled and makes an excellent
product. My dies cost $18 and I have a couple hundred different
designs for you to choose from. I have sold thousands of them and
have had two people complain and it was always a result of the metal
being too thin or annealed. Once I explain to them how they work,
everything was fine. My dies are un-heat treated, but that is what
keeps them very affordable. I have many customers doing production
with them and selling the shapes on Etsy to other artists. If the
die should wear out, you can buy another, they are $18. You can
usually get a couple hundred strikes out of the die, so it will more
than pay for itself.

A customer of ours, Melissa Muir, has made a great video
demonstrating = the use of dies in our hydraulic press.

She mentions a few of the items that Dar describes. She even has a
blog,

http://www.ganoksin.com/gnkurl/105

I don’t do custom dies. I have been referring those wanting custom
dies to Dar. He offers a very valuable service and has made some
very amazing dies. If you’ve never been to his website, you should
check it out.

http://www.ganoksin.com/gnkurl/lw

Kevin
www.potterusa.com


#15

Kevin,

You’re such a gentleman, because I doubt that everyone in your place
would be as gracious about how I posted about laser-cut dies. The
most important thing here (ultimately, here in this environment of
discussion and interactive learning) is to get it all out there, to
have all the options and possibilities presented, to inform
interested people about all their choices in the matter.

I talked about how my approach and perspective evolved and why I
feel so strongly about pancake dies needing to be tight, and in
countless situations it’s an unavoidable fact and not a view that’s
ever going to have a reason to change. The idea of pancake dies
without the angle is alien to me, but it’s also an absolute fact
that on thicker metals, the need for tightness is not absolute. The
dies you make work for many applications, they are certainly less
expensive than mine, and they ought to make a lot of people happy
about not having to saw or cut parts by hand with tin snips or
scissors.

The bottom line is that people have more than one choice ; not every
one needs custom dies, or to make thousands of parts of a design
that would destroy an unhardened die, or to cut 36 ga. aluminum soda
cans or cookie tins. But everyone fabricating sheet metal parts
ought to know the capabilities of the pancake/RT die process, and
the original post was formulated because someone who was cutting 24
ga. with one of your laser-cut dies called me and was surprised to
find out about how I make them and what they can do.

She was getting a few dozen or a few hundred (I forget which) before
they got to have too much of a burr, then getting another die and
repeating the cycle, and she was frustrated.

Obviously, she shouldn’t have expected to have them work well on 24
ga. so the dies were being asked to operate outside their comfort
zone.

I thought to myself how I must be living too much under a rock, out
here in Hooterville , not doing enough advertising, because doesn’t
everybody already know about me and know all the cool things I do.
Such is the plight of the self-centered narcissist, and such a blow
to find out that not everyone does know, and the big wide world is
racing by with new people in it, replacing the old ones. Such is the
jewelry industry, demonstrated by the thousands of abandoned dies I
have in my storage room. Years ago, Iused to look at them and think
"if even half of these people sold decent amounts of jewelry, I’d
have a crew of chimpanzees working double shifts and be raking in
the cash". But they don’t, so most people don’t need dies that cut
thousands of parts, don’t know or care about how dies are made. Most
won’t be making jewelry in five years ; it was shocking to find out
what a revolving door the industry is. I don’t= know how accurate
that assessment is, but judging from the number of one- time die
customers, it’s true to some degree.

Back to the point, assuming I have one, is that there definitely is a
range of needs that people have as far as part-cutting options. I
recently got some parts for a quote ; they were BIG parts, the small
one was 8" by 3" and the biggest one was over 12" long. The material
was very thin aluminum, and sure I could have made a die for the
’small’ one, and had the bigger ones cut on a wire edm (a machine
that will cut at an angle) but the edm ones would have cost $400 or
more. Also, the thinness of the aluminum was a problem because huge
dies like that tend to have more problems with extra-thin metal than
small dies do. So I felt the best option for this person was steel
rule dies, which are widely used in industry for cutting everything
from leather shoe blanks to cardboard boxes to… thin sheet metal
parts. They are exactly like cookie cutters and will be much better
suited to those big parts than pancake dies, and probably less
expensive, since huge pancake dies are way above the price range of
normal, jewelry-sized ones.

Well, so much for having a point and sticking to it. Over the years
I’ve also done work for many people who have tried cutting their own
dies, and for whatever reason, end up using me. It just isn’t
something everyone does well right away, and there are a lot of
things that need to be done just-so to get dies that will perform
well. Casting is a good analogy, or actually just about any jewelry
skill. You can get all the equipment and read all the instructions
and still end up with bad castings until you learn how to do it. I
was amazing with a jeweler’s saw since I was 14 years old, but give
me a piece of steel and a stationary saw and I had to start over,
and it was a couple years before I got really good at it. Even
something as seemingly simple as sawing tabs off of parts cut from
dies can be foreign. I just did some dies for people who do amazing
work coloring copper jewelry with a mini torch, but the jeweler’s
saw was alien to them. It’s second nature to me, so I made one die
where the only way to remove the tab is with a saw (or a chisel,
maybe), and I had to encourage them to get a saw and learn a new
(immensely valuable) skill.

Anyway, if I wasn’t busy making dies and parts for people, I’d have
more time to write about it. I appreciate everyone and anyone, and
you Kevin, for telling people about my service; it’s how I get most
of my work. I tell new people looking for a press about your site ;
there are always new people coming through that door, and the
hydraulic press really has opened up the possibilities, and having
one in your price range is a good thing for people who can’t really
afford the more expensive ones. A Caddy is nice but it doesn’t need
to be everyone’s first ride…

Dar Shelton
sheltech.net