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Urethane advice for hydraulic press?


#1

I just picked up a very inexpensive 6 ton hydraulic press. I know
it’s not as spiffy or as powerful as a 20 ton Bonny Doon, but at
about 1/18th the price I’m willing to give it a try to see if it
meets my needs!

I make jewelry and smallish metal items out of copper, brass, bronze
or silver. Typically working in 24g to 18g. Want to be able to press
things up to 1/2" deep, but more typically, 1/8" to 1/4".

I’ve used a hydraulic press exactly once and with minimal
instruction.

Urethane sheets are expensive and come in a variety of “durometers”.

So, I have a few questions:

  1. What “durometer” should I be aiming for?

  2. How thick a sheet do I need to go 1/4" deep? 1/2" deep?

  3. Can I just stack two of the sheets I need for 1/4" deep to go
    1/2" deep?

  4. Good sources for inexpensive sheets of the above?

  5. What material do you usually make your pattern (dies?) out of?
    Limited runs for me, so durability over 20 runs is not important at
    the moment.

  6. How thick does the die need to be get a 1/4" deep item out of it?

Other useful questions and their answers would also be much
appreciated.

I’ll report back on how well the press works out.

Thanks in advance!


#2

Hello David,

The words “Hydraulic Press” in your post title caught my attention
as I am a retired engineer with the majority of my career spent in
fluid power (hydraulics, pneumatics, vacuum and lubrication) -
jewelry has now become my hobby.

In review of your questions, I would suggest there are many
approaches to asolution you might follow. In all the approaches I
can imagine, I find myself in need of a fair amount of additional
For this writing, I can suggest an initial three, very
broad stroke of the brush paths for you to consider, as follows:

1 - Find someone in your locale who is familiar with hydraulic
pressing and seek advice from them - die materials, press pressures,
press speeds, press depths are usually somewhat specific to the part
or piece you are pressing;

2 - See if there are any press dies already made or in existence
that you could try out to see if they work to your satisfaction,
then make a purchaseof them;

3 - Experiment, first by implementing good safety practices then
using yourpress with manufacturer samples to see if you are able to
produce product to your satisfaction;

I feel certain my answers are not the ones you had hoped for but
please do not give up - nearly everyone who makes presswork pieces
has passed throughthis stage before producing the product they were
hoping for.

Best Regards,

Bob A. DeMarcki


#3

Get Susan Kingsley’s book Hydraulic die forming for jewelers and
metalsmiths it will answer most of your questions.


#4

Hi David, I’m ngoing to answer below each of your questions

I just picked up a very inexpensive 6 ton hydraulic press. I know
it's not as spiffy or as powerful as a 20 ton Bonny Doon, but at
about 1/18th the price I'm willing to give it a try to see if it
meets my needs! 

I think you’ll quickly want a 20 tonner, because 6 isn’t much when
you get into forming. You’ll be able to puff simple shapes in thinner
metals, and possibly the 18g you want, but I suspect you’ll run up
against the limitations of 6 tons very soon.

I make jewelry and smallish metal items out of copper, brass,
bronze or silver. Typically working in 24g to 18g. Want to be able
to press things up to 1/2" deep, but more typically, 1/8" to 1/4".
I've used a hydraulic press exactly once and with minimal
instruction. Urethane sheets are expensive and come in a variety of
"durometers". So, I have a few questions: 
1. What "durometer" should I be aiming for? 

In the Shore A scale, which is probably what Potter and Rio Grande
useautomatically without the distinction between Shore A and Shore D.
I just checked Rio’s catalog and sure (shore ?) enough, they list the
urethane as the number followed by a small d, with the d standing
for ‘durometer’, but the urethane IS (Shore A scale) 85d, or Shore A
90d. I’ve bought pads from MSC Industrial Supply in the past, and
they will list it in a slightly different way, where the letter
after the number indicates the shore scale, NOT 'durometer. In MSC’s
catalog, d will mean shore scale d, and a will mean scale a, so be
careful. Shore scale D is a harder range, so if you order ‘75d’ from
MSC, it will be HARDER than the ’ (shore A) 95d ’ from Rio. If you go
to Potter USA, check with Kevin about this.

So (shore A assumed) I suggest getting 60 and 80 duro pads for your
setup. 95 is harder, and better for picking up surface detail (and
75d d-shore is even better but it takes more than 6 tons), but for
simple puffing 80 and 60 are going to work

2. How thick a sheet do I need to go 1/4" deep? 1/2" deep? 

minimum would be 1/2" and 1", respectively, but the official line is
to use thicker, I believe.

3. Can I just stack two of the sheets I need for 1/4" deep to go
1/2" deep? 

yes

4. Good sources for inexpensive sheets of the above? 

MSC, Potter, then Rio, lower to higher. Lee Marshall (original Bonny
Dooner) had ‘the best’

5. What material do you usually make your pattern (dies?) out of?
Limited runs for me, so durability over 20 runs is not important
at the moment. 

pattern dies… pattern dies… short runs… brass, aluminum,
nylon, Lexan (not acrylic/plexiglas)e?

6. How thick does the die need to be get a 1/4" deep item out of
it? 

1/4" plus a hair


#5

You can also try common ruber, I think that you can buy it in
hardware store /in my country, Poland, I buy it in store for
shoemaker./. Rubber work faster then urethane. If I want deeper form
I stack piece of rubber. If you have any question feel free to
contact me.

Pawel


#6
1. What "durometer" should I be aiming for? 

You’ll want the Susan Kingsley book on Hydraulic Die Forming for
metalsmithing, it will answer all these questions and more.

Also check Rio Grande, Bonny Doon and Potter USA for how-to videos.

What durometer you’ll want depends on what you want to do. When
you’re aiming to go 1/2" deep, as you mentioned, this may be a two
step process, first the softer durometer, for my set, I think that’s
an 85 and yellow. Next, anneal, pickle, dry well and press again,
this time with the harder, or red urathane. Perhaps it’s a 95?
Apologies, I took a class back in 97 and now go by the color of what
I have.

As to inexpensive, I once got very lucky and got some super cheap at
a surplus warehouse of sorts but in general, this is one of those
items where you just have to pay full retail. (Unless someone else
posts.)

I suppose check McMaster Carr and compare prices.

Best of luck!

Elaine


#7
6. How thick does the die need to be get a 1/4" deep item out of
it? 

1/4" deep or more. More, I guess, or the piece will bottom out, and
have a flat spot.

Elaine


#8

This will be no help as far as stating what durometer to use, but you
might get a chuckle out of how I got mine. There used to be a place
in the neighboring town that manufactured Urethane in big sheets.
Several friends and I had just had our brand new hydraulic presses
made according to the specifications in the Kingsley book and were
eager to put them to use. So we ambled over to the Urethane
manufacturer and asked about purchasing some. To our disappointment
they only sold wholesale, and in huge sheets. Seeing the
disappointment on our faces, and learning that we were going to used
it to make jewelry, the man took us aside, and said.

“We close at 5 PM, and dump our scrap in the dumpster out in back.
Just be careful not to fall in when you go to get some.”

Later that evening, we came back, and were able to fish a nice
quantity out of the dumpster. It is yellow in color but we haven’t a
clue as to the durometer, but it works just fine. That was more than
15 years ago, and the stuff is still pliable.

The factory has since closed, but every time I use my hydraulic
press I remember the kind man who let us do dumpster diving. Alma


#9

I found out from Phil Poirier that Rio Grande carries the same
original formulation of urethane (aka polyurethane) that Lee
Marshall figured out a long time ago and had made specifically for
press forming. Not all urethane is created equal ; some of the 'cheap
stuff 'I got from MSC gave out (torn apart, ripped, fell apart,
depending on the severity of the operation) much sooner than the
stuff from Bonny Doon. Another case of ‘you get what you pay for’.

DS


#10

Hi David. Mr. Owen’s advice is spot on. Susan Kingsley’s book is a
fabulousresource and something you should consider getting a copy
of. It looks small but it’s packed with great info and will really
help. To help avoid confusion. The urethane we carry is the Shore A
scale. But it’s also worth noting that not all Shore A scales are
the same from one manufacturer to another. Bonny Doon uses a
urethane that has been well tested and lasts.

I hope this is of some help. Should you have any further questions
please feel free to contact our Tech Support team any time.

Mark Nelson
Rio Grande


#11

There are many plastic and rubber substances that can be used to
form in the hydraulic press. Urethane is a special plastic that
deforms, but does not compress/become smaller, and then goes back to
its original form. If you understand how the different thicknesses
and hardnesses work, urethane is fantastic. As others have pointed
out, not all urethane is alike. Not only are there different
"shores" and hardnesses, but there are also different formulations.
Be careful about buying a “bargain”. When I was first starting to
work with the hydraulic press, a friend organized a group to buy
urethane directly from a manufacturer, so that we could save money.
That urethane does not work as it should, so I wound up investing in
the urethanes that Lee Marshall developed for Bonny Doon that are
carried by Rio Grande. I am still using those urethanes, ~15 years
later.

I have uploaded two of my handouts to the FAQs section on my website
cynthiaeid.com Feel free to download my handouts for Hydraulic Press
Safety and for Urethanes.

Cynthia Eid
Cynthiaeid.com


#12

So. Cynthia Eid has been using the urethane for 15 years that I
developed for the Bonny Doon Press. my how time flies, and quality
still shines through. I know that she has given innumerable press
workshops through the intervening years, and if anything can damage
tools, it is the beginning student.

Now, would you care to do a cost estimate on how much those pads cost
when spread over their lifetime (taking into account that they are
still functioning?).

Yes, the urethane that Rio Grande sells is the same quality that I
developed all those years ago. I have always designed productsthat
last, and last, and last. Any time a product is cheaper, there is
usually a reason for it. If quality is left out of the equation, you
can certainly buy a cheaper product. Repetitive results are the
result of a quality tool. “Buy once, buy well” is the driving force
behind Knew Concepts, as well as the Bonny Doon line that I sold to
Phil Poirier some time ago. I am so proud of what he has done with
the press and its accessories. It is stillthe apex of hydraulic
presses and is still being copied by others trying to say “me too”.

You always pay for what you get, but you don’t always get what you
pay for. caveat emptor

Lee (the saw guy)


#13

I appreciate this an old thread about Urethane, I live in the Uk and have spent countless hours trying to find it to purchase in reasonable size sheet form 1"-2" inch thickness, please anyone in the Uk can steer me in the right direction. Save me from using lead or aluminium/tin, I have even resorted to ‘Siligum’ moulding compound.
Desperate Jackie


#14

Hi Jackie, Ted here ,the s/smith in Dorset,
If you havnt tried them, I found Ensinger the most experienced plastics people in the UK.
google for them, and give them a call . They will im sure be able to help you.
You may nor know but I do proper as in 250 ton coining with hyd presses. tho dont use urethane, all my work is with tool steel dies. Much more fun!.


#15

Hello Ted,
thank you for your reply, although I could not find Urethane at Ensinger. I am intrigued by your description of your work, do you have a website?.
Jackie


#16

Hi Jackie,
I did ,but he hosting co died and I havnrt had time to replace them.
Too busy on my current projects . Working up for a major show in june/july next year.
Youd be welcome to visit tho. Nr. C/Castle in Dorset.
Ted.


#17

Jackie, some 30 years ago when I started doing hydraulic forming with a friend we used some automotive rubber pad. I think it was a gasket material, perhaps for a truck, about an inch thick and black. It looks almost like rubber tire material but flat and no treads. We cut it into rectangles about 8 cm x 12 cm. It gets scarred up but still works. When the urethane pads were available, I changed to them. Donna in FL


#18

Hi Ted, I would love to visit, but it is rare I get down to Dorset now a days. Good luck with your show for next year.
Jackie


#19

Thank you Donna, I will pop along to a scrap yard over the weekend or a motor shop, it is so darn hard to source here in the UK and when I do find it in the US the shipping is nearly as much as the product then we have customs and vat :frowning:
Jackie