I’ve read a number of postings recently regarding hydraulic forming.
Let’s talk about automotive presses, jacks, urethane, Bonny Doon
presses, and how to make the right choice when making any purchase.
My first press was the front end of my truck. I had a 5 ton jack
that I would stick under the front end axle, sandwich the gold in the
conforming die and place it on top of the jack. When the front end
started to lift I could figure on about 3000 lbs of pressure coming
to bear on the metal. This was right after "The Metalsmith Papers"
was published in 1981 and I was hooked by Mark Paisins article about
hydraulic forming. It was almost ten years later that Lee Marshall
engineered the first hydraulic press for metalsmiths. That press has
gone through several improvements over the years always improving to
become the best press for the metalsmith.
I’ve learned a lot since then, one important lesson was “Don’t try
to re-invent the wheel”. If the right tool for the job is available
it is far better economics to purchase it than to try to build it. If
the right tool for the job is not readily available then you must
determine if it is economically feasible to research, design, and
engineer a new tool.
You should know that I do own an automotive press and Yes, an
automotive press (which is designed to press bearings) can be used
for metalsmithing applications, but it is certainly not as effective
or efficient as a press designed for the sole purpose of
metalsmithing and it’s processes. I use my automotive press for
pressing bearings only, which it does quite well. I came close to a
serious injury once when I tried deep-drawing in the automotive
Ask yourself these questions: “What is my time worth”, “What is my
safety worth”, and “What does my jewelry deserve”? Are you a
professional jeweler, a retiree, a hobbyist? Each will have their
own needs, but whether or not you are a professional jeweler, one
that makes a good living by creating jewelry, or a retiree with
limited time, or a hobbyist with a limited budget, an automotive
press is going to prove itself expensive over time due to it’s
limitations, the extra time involved to setup dies, the lack of
safety, the lack of expected results, and the lack of support.
Also Yes, the ram or jack that Bonny Doon uses is the same one you
can buy from Harbor Freight for less than $40 (without gauge). If you
want to put a gauge on it you’ll need a mill ($) and specialized
tooling to install the gauge, and then you’ll need to learn how to
port the pressure through to the gauge. You might convince a local
machine shop to port the gauge for you. When you are finished you’ll
not only have spent lots of money, but lots of time too, this I can
guarantee! There are many ways to build your own press but none
of them will save you time or money over the long term. I know this
intimately as I have built and used many “homemade” presses. Again,
ask yourself, how valuable is your time? How important is it for you
to obtain the right results when making your jewelry?
Understand that the new press frame from Bonny Doon is designed for
the sole purpose of metalsmithing, and is built to a much higher
standard than what is required of an automotive unit. All presses
flex and stretch under pressure, some more than others. The
automotive press frame will flex quite a lot when used. Here’s a
test: take a 3" circular blanking die and blank some 18 ga or thicker
metal. The automotive press will usually go off with a very loud bang
as the die shears the metal. This is due to the instant release of
stored energy/force of the stretched frame springing back to rest.
The new MKIII Bonny Doon is designed and built to minimize flexing
thereby minimizing the instant release of stored energy so you can
blank without the annoying “shotgun blast” each time you pop a piece
of metal. The lack of flex also allows for repeated results with more
accuracy when using silhouette dies, conforming dies, non-conforming
dies and coining dies.
At todays silver, gold and platinum prices can you afford to get
less than perfect results each time you form your metal?
Now, let’s talk about urethane! There are numerous formulations of
urethane probably numbering in the thousands. You can purchase
urethane and/or make your own, at quite an expense to you, your
health, your time, and your wallet. The urethane from Bonny Doon is a
formula designed for forming metal under less-than ideal
circumstances, the metalsmiths shop, where small runs in various dies
demand more from the urethane. I’ve seen lots of low quality urethane
fall apart or crumble with little use due to it’s inferior make.
Rubber can also be used in place of urethane, but you will have
troubles trying to repeat your results, you’ll end up with lots of
torn metal and unusable parts. As always, you will get what you pay
for, especially when it comes to urethane.
“Buy once and buy well” is a saying from my mother who grew up
during the depression when people could not afford to waste money. It
was smarter economics then to spend $5 on a pair of long lasting
leather shoes than it was to spend $2 on a pair of short-lived
I sincerely hope this guides the prospective press buyer into making
the right choice for their needs. I truly wish for all of you the
time and inspiration to create beautiful and unique jewelry. Avoid
the pitfalls of re-inventing the wheel and wasting your time and
money on inferior tools.
G. Phil Poirier