its simple enough to cobble up a pair of NO momentary switches and use
them to fire off a solenoid to trip the dog clutch.
And far far safer.
Though to be fair...I work on these a couple times a month and only
see a few women (usual operators) with missing fingers or divits. But
then..they often quit right after an accident.
An interesting side note about presses. Lots of the old mechanical
dog clutch ones still in operation and being bought and sold.
However..and this may give you something to consider...most are bought
and sold for cash, with no receipts/bills of sale tendered. And often
the buyer has to give the seller a signed statement that the press is
being bought as Scrap and will not be operated, only destroyed.
In our litigious society...this is about the only way one can protect
himself when selling a mechanical press. And Ive brokered 15-20 in
the last 5 yrs. ALL..ALL...ALL being cash sales between good sized
Ive been told that 60% of the price of any new press, is insurance.
Few machine tool dealers will admit to being able to supply a punch
press. However they nearly all know someone who has one.....
======Until it doubles because of a stuck/sticky clutch.
The only truly safe setup is pull-backs or a sliding door or
sweep. These just sprain or break the arm/hand rather than cut
Unka' George [George McDuffee]
===========Merchants have no country.
The mere spot they stand on
does not constitute so strong an attachment
as that from which they draw their gains.
Thomas Jefferson (1743-1826),
U.S. president. Letter, 17 March 1814.
On Mon, 24 Sep 2007 23:34:46 -0500, F. George McDuffee
Even the pull backs are not perfect.
Back in the 60's I was working as a tool & die maker for a large maker
of automotive gauges (S-W) in Chicago. An operator lost both hands
due to mis-applied pull backs. The die he was running was in a long
stroke press, and the bushings in the punch holder completely left the
leader pins in the die shoe, when the press was at the top of it's
stroke. Well the cables on the pull backs somehow got wrapped around
the bushings. And when the press was tripped, the operators hands
were pulled into the die.
The die came to the tool room for clean up. No volunteers, the
foreman did the clean up.
Oh, absolutely. And you want to put guards around anything that
moves just so someone doesn't get 'brain fade' and put their hand in
where it shouldn't go - only takes a fraction of a second of
inattention to make a batch of hamburger out of a hand.
The term you want is a "Two hand no tie-down" safety circuit, where
you have to push two buttons roughly at the same time. And the press
won't reset if one or both buttons is held down, as would happen if
someone deliberately jammed one of the buttons to get out of pressing
it each time.
Clippard makes one that's 100% pneumatic (logic control valves, like
air relays) if the machine is all air powered and air operated, and
you don't want to run electricity to it just for the controls.
--<< Bruce >>--
A good start is to *NEVER* put your hands in the point of operation while it
is running. Use tongs or whatever. Make sure when you are not running it
or setting it up that the power is locked out. Turned off only is not good
enough, you have a child that might get inquisitive.
I'm not trying to scare you off this thing but I would like you to keep
writing perl stuff with all your fingers.
Oh, read part 24 osha regs. Here is a link to document on Michigan's osha
website since it was easier to navigate than osha.gov
On Mon, 24 Sep 2007 06:44:24 -0700, pyotr filipivich
But you STILL shut off the motor and/or block the punch with a big
chunk of timber or steel when putting your hands in there. And use
tongs or a stick to change the blanks with the power on. Old control
systems often have failure modes that can cause it to cycle.
You have to treat it as if it's out to get you.
Even with a proper two-hand-no-block safety system on the cycle
trigger switch you still don't let ANYONE operate it who does not
respect the safety concerns. Or you'll get your ass sued off when an
employee loses a body part.
And the best idiots get help in breaking all the rules - they'll
stick a hand in to hold the die in position (with a stick that in
retrospect was about an inch too short) and have someone else two-hand
cycle the punch...
This is why you don't see many antique machines in modern production
shops - safety issues that can't easily be retrofitted away.
This is why I was so piss poor slow doing old fashioned Letterpress
Printing (where you change the paper by hand) - I wouldn't try feeding
the press fast enough to let it go into continuous feed unless I had
the speed turned way down. And having the speed fast, tripping it by
pedal once the paper was in position, and waiting after the cycle to
make sure it didn't double-trip was no better.
But I can still count to ten without blank spots. This is good. ;-)
--<< Bruce >>--
Yeah......."sudden" is an even better discription of little presses.
That speed makes them far more dangerous then larger presses with
longer cycle times.....which are still plenty dangerous if you don't
follow safety protocols at ALL TIMES.
As long as the frame, crankshaft, bearing caps, etc. are in good
operating condition this is a great deal.
I and some friends once had access to a small machine like this
and we thought we might make our fortunes by knocking out
spoons (fishing lures), until we started to price dies. :(
Follow the strictist safety rules, as others have mentioned.
If it helps to hear another voice say the same thing..
Find a certified, experienced and trustworthy tool and die maker to
SHOW you how to operate your press correctly. After four thousand
hours working on mechanical and hydraulic presses up to 2500 tons
capacity, I was still very careful EVERY time.
With mechanical presses (yours), you get to jam it precisely ONCE.
When you do, something WILL break. People have been crushed by massive
flywheels and gears coming off the presses due to a smash. Don't be
fooled by the size of your machine. Find the formulas and calculate
the amount of energy that flywheel has stored. Your mushy body doesn't
stand a chance. That press will be *the* most dangerous tool in your
Thanks to all. I brought the press home (rather, it is in my
- It was VERY painful to maneuver my trailer in almost total darkness
(no streetlights on that street), into a narrow driveway at the dead
end of a street.
The flashing light that I made for it, saved my ass:
- The press was made by BLISS (no idea if it is good or bad).
- I want to clean it up and get into nice shape, maybe even change a
motor since I have a few spare motors.
- I want to try it out carefully (ie, keep hands in my pocket while
operating the foot pedal).
- I have not yet decided whether the press is worth the space that it
would take. My guess is that the answer is no.
- To my uneducated mind, it seems that most proper uses of this press
revolve around leather, not metal.
The good old american iron is an excellent candidate to build DIY iron
I did a conversion of an old bliss to operate with a hydraylic cylinder for
that manufactured wroth iron fences. He was able to punch 1" square holes in
1/4" plate and channel iron in 5 seconds. If you need a short throat iron
you can build one at reasonable cost using a scrap yard punch press and some
I fully agree. these presses are like any moving machinery, they will
catch you out if you dont respect them.
I guess im probably the only self emplyed drop stamp owner operator on
this newsgroup, and I made very sure the previous owner of of my 1880
drop hammer /mint showed me how to use it properly.
After I had rebuilt it asa fully working machine, the first thing I did
was to put some 4 by 2 in where the die went and drop it to splinters
till I had the hang of the lift/ drop/ rebound/park, control.
If you use them as they are meant to be , you should be allright.
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.