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RT Blanking system?


#1

Does anyone know about the RT Blanking Syatem? I am trying to
produce some pieces of jewelry which need many shapes the same
and it looked like the answer. So after buying some stainless
steel blanks I re-read the instructions in the book, “The
Encyclopedia of Jewellery Making Techniques” and found that they
show some sort of special saw and blades to cut the steel. So
now I am back to square one unless someone can tell me if its
possible to use a regular jewellery saw and blades to cut the
stainless steel. Any help will be appreciated. Sharron in sunny Saigon


#2

Sharron, Although stainless steel may work for a few copies - it
will not hold a sharp edge. You need to use tool steel for more
than a dozen copies, and, if you want a really durable cutting
die - you must learn to harden the dies after you cut your
design into them. Instructions on hardening the steel should be
available from your supplier.

Yes, you must cut the dies at an angle. This can be as simple as
arranging a bench pin at an angle - or you can build a "jig"
that incorporates both a saw frame and an angled surface plate
to support your work. I beleive that these are available “ready
made” from Rio Grande, and perhaps Frei-Borel. I have purchased
the tool steel from Rio in the past, as well as from MSC Supply.
Rio may still have the book and/or video on this technique.

Depending upon what material and thickness you are cutting with
the die, and also depending on the thickness of the tool steel
plate you will be using… I would recommend that you start with
an angle of about 20 degrees to the saw blade. Experiment a bit
either way on your first half dozen dies, but this is good
starting point. You will need to use heavier saw blades - 2/0 or
thicker - again depending on the tool steel thickness and the
guage of material that the die must shear.

What are you using for a press? I do not recommend the little
screw presses - but perhaps you have access to one of the bigger
ones. We use a foot press/“kick press” for the small dies, and a
hydraulic press for the dies over about an inch and a half…
This method has saved us a lot of money for small production
runs. An average blanking die made by our die maker runs about
$280. I can make one, by the RT method - start to finish, and
harden it in about a half hour!

To date, the most pieces I have punched on one of our dies
(hardened) was 500, but I have some silversmith friends who
claim to have gotten over a thousand pieces out of a die before
having to make a new one.

Brian P. Marshall
Stockton Jewelry Arts School
Workshop 209-477-6535
Classrooms 209-477-6731


#3

Look at : http://www.bonnydoonengineering.com/ You will find all
sorts of stuff here including about what is called
the “RT” system . This "system was aparently invented originaly
at Douglas Aircraft in the 1930’s. There is a video tape
available on “RT” in the US . A book on this was supposed to be
available last year but is apparently unavailable. The book on
Hydralyic die forming by Susan Kingsley includes on
this technique including cutting dies… Dar Shelton in New
Mexico cuts dies for this on a custom basis… All the info on
what and where is pretty well on the Bonny Doone site. Jesse


#4

Sharron: you may have bit off more than you want to chew. I have
used steel tool dies a lot, and I would never want to cut one.
Yes, you need special blades and you need to do about a zillion
strokes per minute, at the right angle for the thickness and
type of metal you are cutting. After they are cut, then you have
to harden (cook) them, etc, etc. I suggest you contact Dave
Shelton, Sheltec, 4207 Lead, SE, Albuquerque, NM 87108 USA,
(505) 256-7073. He is the best tool steel man I have ever found.
He made all of mine and I highly recommend him. Good Luck, ‘Red’


#5

Hi Sharron, I used the RT Blanking system some years ago to cut
shapes and found it rather difficult to use. It does not take
regular saw blades as I recall. I actually still have the
system tucked away somewhere. I think though that I did not
have much patience with it, as a friend of mi9ne at the tiome
swore by it. You cannot cut complex shapes; you have to stay
with very simple ones without a lot of back curves. Good luck. Alexis


#6

If you search the first year or two of Orchid archives you will
find an extensive discussion of how people are doing this,
including John Burgess’ excellent discriptions of the processes.

Chunk Kiesling


#7

I have the “system” from Rio Grande. The sawframe is mounted on
a pole, the sawing platform can be set at any angle. The angle
math is done for you based on the kerf from regular 4/0
jeweler’s blades. The exact angle is the key. Your particular
application (if there are long, thin parts or sharp corners in
your die or if you need several hundred of a pattern) might
require that that you harden your steel, I don’t bother. I use
1/16th" steel. Takes perhaps an hour for me to cut a die. I
chop 20g. sterling and can get at least 200 chops from a die. I
have no problems with the larger screw press sold by Rio, though
something fancier would probably be a lot
quicker. -Dana Carlson


#8

Alexis I must disagree with you about being able to cut complex
shapes with RT blanking dies or pancake dies . It is possible
to do very complex shapes with it if you use the right tools to
cut the dies and practice your sawing skills. The old saw sold
by Roger Taylor (RT) is not a very good tool in my opinion. He
is selling a newer version that I have not tried so I do not
know if it is any better. Both of them use standard jewelers saw
blades. There is a good tool for cutting these kind of dies
sold by Lee Marshall at Bonny Doon engineering which guides a
standard jewelers saw frame . You can also just use a regular
jewelers saw without any guide mechanism as long as you are good
with your technique.

Jim


@jbin
James Binnion Metal Arts
4701 San Leandro St #18
Oakland, CA 94601
510-533-5108


#9

The “correct” angle off of the vertical to cut the dies can be
calculated with high school trigonometry.

Sin (angle) = thickness of blade cut divided by the thickness of
the tool stock.

If the angle is more than this the die will not open and it will
not work. If the angle is less than this there will be a slight
gap when the die is opened . This provides a slight clearance
between the cutting edges. A very little bit of clearance is ok ,
too much and the die won’t cut but will simply deform the blank.
Jesse