[TheForge] Old Punch Press ... is it worth it?

[Don Robertson]

I happen to have 2 of these 1 is a 2 1/2" ton and the other a 5 ton.  These 
were primarily used in production line manufacturing.  There were die blocks 
with a set function IE punching holes or slots, notching or bending tabs. 
The 2 that I have came from a aluminum window frame manufacturer and were 
used to cut slots in the stiles.  They function when a trip lever is 
actuated.  The large flywheel is turned by either a line shaft or electric 
motor and when the lever is tripped it engages the shaft and throws the 
plunger down.  So in some ways the operation is much like a power hammer. 
If you were to make a frame with a set of springs and dies that were guided 
by a die block it could be a 1 hit power hammer.  There is an adjustment on 
the plunger that can be adjusted for the space in the down position.  The 
throw or travel will always be the same.  That would be the need for the 
springs to allow for the difference in the material thickness.  A power 
hammer works on the same basic principal but with springs in the head to 
compensate for the thickness.  Also a power hammer has the ability to adjust 
the stroke.  A punch press is fixed stroke.  What the crank shaft has is 
what you get.   I have a air hammer so I haven't explored to possibilities 
of utilizing one in that function.  I have considered using it as a punching 
tool with the punch being backed up by a die spring that would allow the 
crank to rotate through its cycle.  Most of these were equipped with safety 
features that would require both hands clear to activate.  I have used my 
units to punch holes in Stainless Steel tags and other things.  The biggest 
part is making the dies which in a lot of cases has become a lost art. 
Welcome to CNC lasers and Plasma cutters.  Enter the program load the 
material push a mouse button and presto its done.  I am sure there is a 
practical use for these still today.  If it rotates and you can turn it by 
hand trip the lever and pay attention to the function of how it operates. 
Remember it is a solid connection from the shaft to the plunger once the 
lever is engaged and if it hits the base plate without any thought given to 
allow for something compressible (spring)  It will make an abrupt stop.  By 
the way it has no eyes and cannot see your fingers, toes or limbs.  Be 
careful and be safe.

My 2 cents for today


Don Robertson
Diversified Repairs LLC
Chesapeake, Va.


-----Original Message----- 
From: Peter Fels & Phoebe Palmer
Sent: Wednesday, May 21, 2014 1:26 PM
To: mspencer at tallships.ca ; Blacksmithing List Sponsored by ABANA
Subject: Re: [TheForge] Old Punch Press ... is it worth it?

There may be a shear pin, but none is evident on mine.
It needs to be remembered that these machine frames were made from
brittle cast iron that does not fail gracefully.
They are designed to complete a stroke of fixed depth, every time.
If the dies are misaligned or the work too resistant.....BANG!
It's not a power hammer.
OTOH, they are fast production machines for stamping and the like.

On May 21, 2014, at 10:17 AM, Mike Spencer wrote:


PF wrote:

> Let's be clear...If you run the flywheel at speed, and stick a cold
> piece of steel under the die, and the machine can't finish it's
> stroke....  You have a fair chance of a catastrophe!

Which leads to the notion of the shear pin, soft flywheel key or
similar, engineered (possibly for shade-tree values of "engineered"
:-) to fail gracefully before major parts fail catastrophically.

I have no idea when this trick became popular nor where or how widely
it was adopted.  But if one were repurposing something that has the
capability of removeing major body parts on failure, one might try to
incorporate it into the modification plans.

A neighbor here has an old punch press, about 8' tall, non-working but
apparently in restorable condition.  I know he'd part with it for
scrap price or, to a loving home, even less.  Shipping could be a
problem beyond Lunenburg County, NS, though.  :-)


Idle thoughts,
- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~.
                                                          /V\
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

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