[TheForge] drop hammer

[mrscherm at aol.com]

The real old drop hammers were replaced by almost as old "board drop 
hammers", where there were maple boards attached to the upper die, and 
a pair steel wheels (electrically driven), drove and raised them to 
their high point and released when the operator stepped on the pedal. 
These were very popular with "closed die" forgers up until the 1970s, 
and replaced with air driven hammers (Bannings). At auction, you can 
have one pretty cheap, as in free, if you pay to have it hauled away, 
but most weigh in the area of 15 to 20,000# and are about 15 feet tall. 
The cost of moving them is much more than the scrap value (as it would 
have to be torch cut to smaller pieces for melting). Often they are 
buried rather than moved.
Michael

-----Original Message-----
From: Bruce Freeman <FREEMAB at pt.fdah.com>
To: theforge at mailman.qth.net
Sent: Mon, 03 Oct 2005 14:20:46 -0400
Subject: [TheForge] drop hammer

What with all the discussion about cheap power hammer, what about a 
drop hammer.
Okay, traditionally these were run from a water wheel, but the were 
later
motorized with steam engines, no doubt.

What I'm envisionaing is a classic drop hammer, heavy head on an oak 
beam,
pivoted on the far end - low tech. Then come up with an appropriate 
modern
"lifter". One problem with traditional cam-type lifters was the 
friction on
the cam. Maybe a modified cam using a steel wheel rolling on the bottom 
of the
beam would work.

Rough calculations suggest this is quite feasible. Assume a 3' beam 
with a 100#
head, and a double-wheeled cam (lifter) halfway along the shaft (none 
of which
details matter). Now assume a 4" cam "stroke" leading to an 8" hammer 
motion
(based upon foregoing proportions). Neglecting friction (!) I calculate 
this
hammer could be run at ~150 blows per minute with one-half horsepower. 
Now
electric motors of 1 HP are commonly available cheap, and gas motors of 
a few HP
are junked all the time. Electric motors run either ~1700 or ~3400 RPM, 
meaning
a 10:1 or 20:1 speed reduction would be needed, and this could be 
accomplished
with a gearbox, belts and pulleys or sprockets and chains with not too 
much
trouble.

So there you go. A "novel" concept in a junk-yard hammer.

Bruce
NJ

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