New 20 ton hydraulic press

I have been trying to make a press that is more affordable yet still
retains all the qualities of my current line of presses. I have come
up with a design that fits in a flat rate box so that saves a lot of
money on shipping. I reduced the size to save on weight and space, I
eliminated the weldingso it can be disassembled for shipment all
over the world. The press can ship to Australia for about a 120
dollars. It will ship in the continental US for 15 dollars. The
press fits all of my standard tooling as well as other
manufacturer’s tooling. They take a standard low profile 20 ton
jack, available from many sources all over the world. It can be
assembled in about5 minutes using just a wrench. Here is a link to a
video I made describinghow to put it together. The presses are
unpainted since shipping flat ratewould be hard on paint. The press
costs 450 dollars.

Kevin Potter

I have been trying to make a press that is more affordable. . fits
in a flat rate box 

Kevin, that is amazing. It seems to be about the size of my 2-ton
arbor press. I’d gladly swap out 2 tons for 20. Soon.

Neil A.

Kevin, Looks like a clever design for the new20 ton press, and
there’s definitely a demand for something in that price range, but I
have a few questions about it. I’m curious what kind of testing that
frame design has undergone, and indeed, your old frames, for the
50,20, and 12 ton versions. For instance, did you test them to
failure, and if so, what tonnage did they fail at?. What about
repetitive stress testing ?. I know it’s impractical for a modest
shop to have sophisticated setups that automatically test the limits
and endurance of things 24,7,365, like big companies do, but I think
it’s fair to ask what you’ve done along these lines, because of the
potential hazards involved with so much force, and because I know
that the Bonny Doon frames have been tested quite a lot, both the
old models (which I have abused quite thoroughly for 20 years, the
20 ton frame with a 25 ton ram, mostly), andthe new ones (high-tech
analysis of stress and deformation, etc.). People are going to buy
presses that they can afford, and they should do so with as much
as possible. I can’t make people buy Bonny Doon, though
we all pretty much know they’re the best thing going, but they’re
not the only press in the world and not everyone who needs a press
actually needs a BD. You offer a product that’s more affordable, but
where does it fall on the scale of durability, of long term use at
or near full capacity?. Do you know where it falls, and do you know
how it is likely to fail ?.I think these are fair questions, and can
only help everyone in the long run. I want to better know what to
tell my die customers what their options are, as well, as there are
quite a few these days.


Hi Dar,

The standard 20 ton press has been tested to destruction. It fails
at 90 tons. The metal tears away. Presses do not fail in a
catastrophic explosion like people seem to believe. They fail with a
“tink” sound and it is the most undramatic thing you have ever seen.
You wouldn’t even know it failed. But since my press is only rated
for 20 tons, I am sure it is more than adequate. As far as
engineering goes the press is designed to have no welds ina tensel
situation - they are all in compression. The frame is cut from a
single sheet of US made steel. The Bonny Doon has dozens of joints,
all relying on welds. Any number of which could fail. But as you
have pointed out, they haven’t. Seeing that my press has no welds to
fail and is relyingon 1/2 inch thick steel plate with large radiused
corners. Cracks do not start along unwelded plates, they start at
weld seams. Welds cause heat affected zones and cause embrittlement
in the metal. If you look at all the large industrial presses in the
world, none of them are welded together. they are bolted and are cut
from plate or machined from plate. I don’t want to get into a
pissing contest about who makes a better press. We are only talking
20 tons here. My press is more than adequate for the job, as isBonny
Doon’s. I’m sure Lee would have designed his press differently had
they had the CNC laser equipment available to him when he designed
it. My platen is locked into the frame and will not tip over, at
least not front to back, which is where you would have a problem
with a piece shooting out.

I have several hundred 20 tons in use over the world right now. I
warranty them for life. Not one has failed in the five years since
I’ve been producing them. They are in schools, colleges,
universities, and private studios, as well as the Royal Canadian
Mint’s Research & Development section. General Motors also has a 50
ton for use in their R & D laboratories running 50 ton Enerpac
hydraulic system. I suppose they could have bought anything they
wanted, but they chose mine. We sold 165 presses last year. The
reason my presses cost so much less has nothing to do with quality
and everything to do with design. I don’t have to do as many welds,
I don’t have to cut as many pieces and I don’t have to drill any
holes. Therefore, my labor costs are significantly lower. And you
are buying it directly from methe person who made it. I’m just
passing my savings along to my customer.

The bolt together 20 ton has a 5 inch opening and once again, there
are no welds and no bolts in any tensel situation. The press was
able to withstand 50 tons without breaking. A larger cylinder would
not fit in the press so I could not test it further. In theory, it
should be stronger than my standard press because the opening is
narrower. What most people don’t realize is that a 20 ton jack can
barely reach 20 tons. It takes over 100 foot pounds of torque at the
handle to get a 20 ton bottle jack to 20 tons of pressure. I am 200
pounds and I have to mount the press to a 2,000 pound table and hang
off of it. The handle bends and the jack will actually bypass before
you can achieve the full 20 tons. This is with any 20 ton bottle
jack. The pump is a 10 to 1 ratio. Every 10 foot pounds of torque at
the handleequals 1,000psi at the cylinder.

I feel like I am bragging, and I don’t mean to be, but you are
obviously calling the quality of my products into question. The 50
and 100 ton presses I build are mostly sold to laboratories and
people who do coining. Your average jeweler is not buying these,
though some have. I am constantly innovating to improve my products.
The new bolt together press will enable people all over the world to
purchase this at an affordable price. It can beshipped to Europe in
flat rate boxes. Meaning it can be shipped to Australia, the UK,
France or anywhere around the world for a little over $100 instead of
$700 or more. I don’t include jacks with these presses because bottle
jacks are available all over the world and it makes absolutely no
sense to ship a bottle jack when they buy it locally. There is
nothing specialabout any bottle jack. If you want one with a gauge,
they are available through JackXChange and they are available through
KYB Norco. That jack canbe put in any press and you can buy it direct
without any markup. Or you can buy an inexpensive Harbor Freight jack
(with no gauge). How you go is upto you - they will both get the job

I am really glad you are busy with your dies. I refer every single
person who wants a custom die to you since I do not do custom dies,
and they really appreciate your fine work. I hope I answered all of
your questions. Feel free to refer people to my press, I will not be


Congratulations on an outstanding post and product. too small for me
but ideal for most folk. In case you didnt know, I use drop hammers,
circa 1889, with hammers up to 400 lbs and coining presses up to 250
tons. Blanking presses up to 25 tons. Same principles but a bugger to
move about.

Kevin, Thanks for the detailed explanation about your presses. My
apologies if it sounded like I was questioning their quality in a
negative way ; I wasn’t trying to discredit them, but I understand
howmy apparently undiplomatic approach could have come across that
way. I really only wanted to know what sort of background r&d and
destruction testing had been done on them, and how they might hold up
to extreme situations and long term use. You answered all my
questions and then some, to a greater satisfaction than I expected,
and Iam glad to know exactly how well they are designed, and how much
thought you’ve put into providing a good product at a great price. I
wasn’t actually sure what I should be telling people about them, so
this is a big chunk of important for me to have. I should
have been more inquisitive before this, and being more discreet about
it would have been more gentlemanly, but I do have a thing for typing
first and thinking later.


To Kevin and Dar - I read with great interest both Kevin’s post
about his new press, and Dar’s questions which followed. I
personally am planning to buy a press soon, and because I have a
tiny, mostly hobby-based business, I can’t help but wonder about the
advantage of buying a press like Kevin’s over picking up a cheaper,
harbor-freight model, which might do the job for me for now. So from
the point of view of an outsider, I would like to say I think it’s
fantastic that Dar was able to question the parameters of the Potter
press, and can now recommend it with confidence where he feels it’s
appropriate. I am very pleasedto know about the testing the new
20-tno has undergone, it gives me every reason to prefer Kevin’s
press over the cheapies. I think that having the courage to question
the work of colleagues is a wonderful characteristic, and while
feathers can occasionally be ruffled, it is in this case helping
tokeep us aware of the parameters of our tools, and helping us all
work toward a fine quality product. In short, kudos to both of you!
Lisa Weber


Congratulations on your new creation.

You have pointed out your impression that a cut frame is inherently
stronger and safer than a welded one, and that Lee might have
designed his differently, had the technology been available to him.
I’d like to correct these assumptions, and point out a few other
areas of safety concerns that our frames have been engineered to

You stated “I’m sure Lee would have designed his press differently
had they had the CNC laser equipment available to him when he
designed it.”

Actually we had laser cutters here in New Mexico back in the mid
80’s. I believe the first laser cutters were developed in the late
60’s. Lee did in fact have laser cutters available to him. He chose
not to go this route for several other design and engineering

The Bonny Doon Presses are designed with several criteria including
cost and value. One very important factor in its design is Safety.

The Bonny Doon press has been fully destruction tested with a 100
ton ram. No welds broke and none of the welds showed signs of stress.
All the welds were designed by a certified welder and mechanical
engineer to be shear welds. Shear welds are inherently much stronger
than tensile welds. With a 5X safety factor (20 ton rating/100 ton
safe) I can easily claim a very safe press. All certified welders
understand heat affected zones or HAZ, and know how to minimize its
affects. Welding is used extensively in buildings, bridges, aircraft,
and our cars. You should also know that laser cutting induces the
very same HAZ in the metal. My point is that any technique of
construction will have its pros and cons. The job of good design and
engineering is to take into account all of the material constraints
and all of the desired criteria and blend them into the ideal piece.
Welding is a great method of producing a quality press with
tremendous strength. We at Bonny Doon know that we have created the
very best design using the very best techniques and materials for our
stated design criteria. And after 20+ years it’s still only $995
which includes the very best obtainable hydraulic jack which is
forged rather than cast.

An important and serious safety concern was the return springs. We
are able to use large return springs in the BD press because they are
fully contained inside the upright columns.

Exposed springs are a very real safety concern. A good example of
this can be seen with the garage door manufacturing industry. Over
the last 40 years there has been a steady migration away from the old
pivot type garage door which relied on large exposed springs. After
several injuries and many liability claims most door manufacturers
are now making the roll-up type door. Several nationwide hardware
stores no longer sell the old style garage door springs due to
liability issues because the users are fully exposed to harm when a
spring fails. Most manufacturers of exposed springs now include an
internal safety cable or a cover to help catch flying debris when a
spring does fail. An additional benefit of using larger springs is
that the ram returns faster which translates into faster cycle times,
allowing the user to do more in a given amount of time.

For safety reasons the ram in the BD press is oriented with its
handle to the side. This places a steel column between the operator
and the parts being pressed.

Gauges are always provided with the Bonny Doon press, another safety
design criteria. Gauges allow the operator to do most operations
inside a container such as a formbox without the need for visual
exposure. Without gauges one must rely on visual clues, or attempt to
“count the strokes”.

The tip-over platen is another safety design. We did test several
methods such as the one you use to keep the platen from tipping
over. Unfortunately this can create a group of events to cause a
catastrophic failure. Anytime the workpiece is off center in any type
of press there is a danger. With the lower platen locked into the
uprights any failures will take place at much higher pressures. With
the tip-over platen the ram and/or workpiece simply tilts out of the
press frame at much lower pressure. Centering the workpiece is a
safety issue professionals are trained to fully understand when
qualifying to use any industrial press. In its simplest form you can
observe what happens when using a hammer off center. How many people
have struck their stamp with a hammer off axis only to have it fly
across the room.

Lee Marshall now has almost 60 years of engineering experience in
machine design including time working with National Can and Coors.
Lee holds several patents for press tooling and assemblies. All his
years of experience were brought into the first Boony Doon press in
1990. We have made slight updates over the last few years, but it is
still the best design that includes all of the design criteria of
Safety, speed, rigidity, accuracy, low cost, longevity, and 22 years
of time proven production and support.

There are lots of hydraulic presses on the market, one can go to
Harbor Freight and buy a shop press for under $200. You could also
buy a 20 ton industrial press for well over $10,000.

As always, I recommend to the serious jeweler or metalsmith when
pondering the purchase of a hydraulic press, or any tool, do the
research, define exactly what you need, plan for the future, and buy
once, buy well. Or if you chose to make your own press have a
certified welder do the work.

And when using a press, no matter what type or style, remember the 5
C’s, Consult, Cover, Center, Contain, Column. That is, Consult your
notes and your colleagues, Cover your face with protective gear,
Center the work in the press, Contain the work if possible, and
utilize the Column for safety.


New 20 ton hydraulic press, drop hammer

Hey Ted, I saw an interesting bit on the tv show ‘How It’s Made’ the
other day (for the 2nd or 3rd time). They were making teapots,
forming decorative spout halves in solid metal, male & female
conforming die sets. The voice said “a 1/4 ton drophammer “, about a
guillotine-looking contraption with the weighted male punch at the
end of a rope that was used to hoist it up and then release it to
drop and do the work. I was very surprised how much depth and detail
this setup achieved ; we’re taling about maybe 18 ga brass getting
formed with ridges and complex curves, at least an inch deep, and
maybe 4-5” long by 3” wide, all in one drop. That same kind of
forming /drawing is not a simple thing to do with the kind of
hydraulic setups we’ve been exposed to in the normal,
jewelry-oriented workshops, with the equipment made available to us
by places like Potter USA and Rio Grande. I’ve tried enough of this
kind of stuff to know that making solid metal conforming sets is no
mean feat, and even with themore readily created plastic steel
molds, you still have the problem of doing the pressing/drawing.
There is a fairly wide gap between industrial, commercial tool & die
operation s and individuals in the jewelry and art worlds, though
Phil and Lee (new and old Bonny Doon) have doneas much as is
practical along these lines (and Kevin, with his pressesand
tooling).I haven’t seen Phil’s deep draw cd/book, but i’ve been
exposed to the basics of it, and like I said, I’ve played around and
done some things. Maybe there isn’t really that much of agap, but
what got my attention about the tv segment was how fast and how
completely the drop hammer setup did a very nice bit of forming with
very little actual ‘tonnage’. It’s the impact and quickness of
theforce that does the trick, as I’m sure you know, and that’s the
big difference between hydraulics and a drop hammer. I don’t have
experience withpneumatic setups, but I imagine they would have to
have the same kind of fast-moving, high-mass object to back up the
quick acting motionof the pressurized-air punch/die. The times I’ve
tried bigger and /or more complex drawing/forming with hydraulics,
it’s taken lots andlots of tonnage, and/or taken lots of time,
because the urethane takes time to move, or it takes multiple
pressings. It was really a bit of ashock to see just how much they
were getting out of that 1/4 ton drop hammer.


Hi Dar,

I first saw drop hammers working in Sheffield back in 1968, making
all kinds of formed metalwork like you describe. I was hand making
back then tho doing a lot of hand hammer forging both hot as well as
cold. I didnt know that I would find a complete drop stampers/minters
workshop from 1851 in 1987 some 40 miles from here that no one
wanted, as it was outside of its usual working district, this being
Birmingham Sheffield and London.

I knew I had to have it, tho initially didnt know what I was going
to make with it all!!. The old silversmith even taught me how to set
it up. I bought some 10 tons of stuff from him at just over scrap
price BUT with the promise I would never scrap it but use it.

Google for Ted Frater, bronzesmith and minter, there youll see how
it all came together and allthe work that developed from this
equipment. Afterall a drop ammer is just a very accurate way of
moving metal. Its fast, efficient and profitable. The real cost is in
the tool steel dies both male for one sided work and female for
double shaped designs. So if like me you choose to comission a die,
it has to be correct technically, artistically and the product
saleable!. The jewellry industry in the UK and most probably in the
USA as well, was mechanised with drop hammers at least from the
1860’s. There still used today in Birmingham as theres nothing
simpler nor accurate or as cheap to run as a drop hammer. As for
speed, drop stamping single sided buttons, with all the blanks
prepared and ready, 200 an hour is doable. Then theres the brazing on
of the omega shaped loop on the back of the button, then all the
usual finishing, packaging marketing etc. Way to go!!


The springs that they are referring to that are causing problems with
garage doors are not coil springs, they are torsion springs. The
springs I usein my press are coil springs. They are the same springs
that are used in trampolines and children’s bouncy swings. I get the
springs from a company out of Rockford, IL. They are one of the only
spring manufacturers in the US. They make the springs that go on
trampolines that are in the Olympics as well as for gymnastic
apparatuses. The springs are only moving a couple of inches and are
used for returning the ram to the lowered position. They are not
torsion springs that shatter like glass.

Since we are discussing engineering, my standard 20 ton press has 6
inches of 1/2 inch plate in a tensile situation. The yield strength
on 1045 plate is 95,000 psi. The numbers can speak for themselves.

I don’t know what to say about the plate tipping off. I figured it
would bebetter to prevent it from tipping off in the first place.
That way the parts didn’t fall out of the press.

You guys obviously are doing something right because you have never
had a press fail, have been in business for over 20 years and are
backed by the largest jewelery tool distributor in the world. I’m
sure my little businesscan’t possibly be affecting your sales. I’m
just one guy working to make aquality product and give people some
options. Competition is a good thing and makes us all strive to build
a better product. That is why I built the press that fits in a box.
It’s funny that a small press that fits in a flatrate box could cause
such a ruckus. I’m sure there is plenty of room in this industry for
both of us. No need to turn this into a blood sport. We arejust
making jewelry. Let’s face it, we are not saving lives or changing
the world.



I will be purchasing your “flat rate” press (hopefully) early January
2013. I have read each email in this thread with great interest and
completely enjoyed your video that showcases your new easy to ship
press. I think it will be a perfect fit in my studio. Even more
exciting because in January I will begin my journey into teaching and
the press will be a great addition to create even more class


Thanks to Phil Poirier for giving some of the technical details
behind the Bonny Doon press frames. Getting these details out about
both the BD and Potter units is a good thing, and necessary, since a
press is an important piece of equipment for anyone thinking about
getting one. I’ve been around these things since the late 1980’s and
this is really the first time I’ve read this much about them all at
once. I tend to only learn the basics of the equipment and
technology I use, except for the tools I make and use, of course,
which I know more than a little about. The important thing -not that
it’s wise or necessary to reduce things down to one thing- is that
both press designs havebeen tested to failure at tonnages far
exceeding their rated and intended usage capacity. Then it goes to
safety, longevity, and cost. I don’t know enough about the actual
likelihood of things shooting out of hydraulic presses to say much
about it. It has never happened to me, but I’ve seen the results of
people doing stupid things, and heard of stupid things done, and
done a few stupid things, and everybody still has their eyes and
fingers. Many things need to be weighed in order to make the ‘right’
decision, and that can be a different decision for different people.
I used a couple of funky press setups before I found BD in 1992, and
I still used a cheap, H-frame, 50-ton press for several years after
that until it gave out. I did not do any serious forming work until
I had a Bonny Doon, because I was advised not to, and this made a lot
of sense, the way the 50 -ton frame twisted slightly at high
pressure. There are several other presses available that are similar
to the BD design, and at least one that’s based on the design in
Susan Kingsley’s book. I’m not going tosay anything about others
that I don’t have experience with. There’s always the old idea that
‘you get what you pay for’, which is somewhat modulated by how much
markup there is ;another area where I’m not going. Then the old idea
is just an idea, and not a universal rule ; not a law of nature,
just a generalization. Obviously, the other essential and important
thing is to research before you buy. You don’t need a top-shelf
20-ton press for blanking small parts with pancake dies, but with
forming at high pressure, you better not mess around without
equipment designed for the work. DS


I’m sorry you misunderstood my rebuttal. I read your post and felt
the need to clarify some of your references to Bonny Doon, our
processes and designs, and Lee Marshall.

I was in fact referring to exposed coil springs or more specifically
extension springs. I use these in our 55 ton Volume and Form Press.
Nowadays these springs all come with safety cables and inner
containment rods due to the possibility of shattering and personal

I reread my post several times and do not find any “blood sport”, I
think you may be misinterpreting my words. What I wrote was very
carefully written with respect and included nothing more than facts
about our press to clarify points that you had made. We all should
understand that whenever anyone writes in a public forum they should
expect a response, especially if what they write is debatable. When
writing to a public forum it is our responsibility to write
respectfully, accurately, and without any assumptions to avoid

I’d like to think that we “are” changing the world. Did you know
that Bonny Doon uses 100% wind power, and Rio Grande makes their own
solar power, in fact, they make more than they use. Creating quality
products that are built to last a lifetime, these are subtle ways
that USA built products "can" change the world.

Let’s change the world!
I wish you the best.

1 Like


I just finished reading this thread on Ganoksin.

It just amazes me that you struggle to try to make a good product
and offer it at a good price and the big companies come out of the
woodwork and try to crush you with vague speculation. They phase
statements that make the product seem unsafe, so nobody is willing to
try it. I understand that people need to know that some thought and
effort has gone into making it safe with some type of due diligence.

It just irritates me. It is hard enough to make a living in this
business to have other U. S. companies try to beat you down. They
should be ecstatic that you are building something in the U. S.A.

A little encouragement in our industry would be nice once in a

James Carpenter

I missed part of this thread but taking the jest of it from what I
read here, I had to speak about this great little press. Being in
the machining and CNC business, I just a week or so ago, finished
several dies & press plates for a good customer. I delivered these
and there was one of Kevin’s 20 ton presses in the shop. While I set
up a new CNC mill for the customer, they played with the new dies
and plates. They used the press all day while I was in their shop
and made some really nice pieces in the delivered plates. The press
worked very well and since part of what they were making was in 18
Ga. Nickel Silver and brass, the press was taking a beating… It
performed flawlessly.

I think the press is as safe as anything I have seen on the market
and MUCH safer than some I have used and seen.

Dan DeArmond

You are a good man Kevin.

This is really cool that we can talk about presses and design on this
forum. It is kind of like Motor Trend magazine for jewelery
equipment. We are both US makers of of tools which in it self is
pretty rare most things are imported. Both of our presses do the job
well, I guess it comes down to chevy or ford or Potter or Dooney, and
I guess there might be a dodge outthere as well. I love designing
tools, but first I was a goldsmith for 20 years, probably because I
like the symbolism attached to a piece of jewelery and the meaning
and care that went into the making of it. I still make jewelery and
love doing it even more than I ever did when I got paid to do it.
Making tools is something I always did but only for myself, I hada
machine shop in my jewelry shop and people would ask do you need all
that stuff to make jewelry? I would always answer I need the tools to
make the tools to make the jewelry. I have been to your site Phil and
I think we are both lovers of tools, I love your rose engine I get
rose engine envy everytime I see your dies they are beautiful. I
guess my comments about us not changing the world were misguided I
think we are helping jewelers and craftsmen to make better pieces and
do things that were not possible. Any wayit has been good talking to
you guys and hope all goes well in the new year. Sincerely Kevin

A man after my own heart, Someone that has the tools to make the
tools to make things. Im just the same, having a machine shop too to
make almost everything I need to support the metalworking I chose to
do. how many others are there on this forum that do the same? There
has to more than 2? mind you, the minting dies, there made by someone
who does it all day and has the machines and skill to interpret my


Thanks for the post. It’s interesting that you mention the rose
engines. I just completed a geometric chuck for the oldest of my
rose engines. For those unfamiliar with the geometric chuck, it was
the precursor to the Spirograph toy, but made for an ornamental
turning lathe and designed to cut wood or metal. I believe there is a
finally a resurgence of interest of the old tools and techniques used
by the 17th-19th century craftsmen. In the 1970’s I could buy a rose
engine for scrap prices, most were scrapped for their brass content,
especially during the two world wars. Now we have an organization,
Ornamental Turners International, that specializes in continuing the
craft forward into the 21st century.

For more on Geometric chucks see Wikipedia “Epicycloid”.