[TheForge] treadle hammer design

Thu Jan 30 17:40:59 2003

George's observations here are, as usual, very pertinent.  Again, I'd like =
to thank him for contributing so materially to this discussion.

However, in deciding for yourself what sort of treadle hammer you might =
need, I suggest you consider whether your use of the tool will be similar =
enough to George's that his observations are pertinent to YOU.

Indeed, if you plan to do only repouse' or similar light-blow work, then a =
simple treadle hammer might very well be best for you.  \

One of the inspirations for the Grasshopper was Sheppard's Big Lick TH.  =
That one moves a 90-lb ram vertically on sliders.  Very simple, and =
Sheppard does wonderful repouse'-type work with it.  Plus it's vertical =
motion is very nice, and tidy.  I wanted something different because (1) I =
didn't care for the ~1:1 linkage, which meant I couldn't get a really hard =
blow, and (2) I wanted more than the 9" stroke (IIRC) that the Big Lick =
provides.  These weren't issues to Sheppard, and may not be issues to you. =
 I suspect George would be very comfortable with a Big Lick TH, had that =
happened to be the first hammer he'd ever acquired.

George's observations that many small springs are better than a few large =
ones is very interesting.  I don't have the experience to comment on it, =
but I admit is surprises me.  I HAVE  heard similar statements, less =
clearly stated, from other quarters, however.

But it should be pointed out that the Grasshopper takes a different =
approach than this large-spring/small spring controversy.  Rather it uses =
four very large springs over a fraction of their "normal" stretch to =
balance (and ONLY to balance) the weight of the ram.  The ram floats =
weightless, and stays anywhere it's put.  Then to provide a return =
(rising) force to the ram, at the bottom of the stroke, an adjustable =
"kickback" is provided that is equivalent to a small spring compressed by =
the ram mechanism only at the very bottom of the stroke.

Now, I have NOT compared the Grasshopper to George's TH, or any quite like =
it, nor have I specifically tried doing anything like respouse' work on =
it, but I submit that the behavior of this weightless (55+lb mass) ram =
bouncing on a "light spring" should be very comfortable to someone wishing =
to strike very light, repeated blows.

However, I want to emphasize that I DO consider the hardness of the blow =
to be of importance.  Power hammers are wonderful, and someday I may =
bother to equip my shop with an air hammer.  (I was very impressed by the =
KA-75 when Bob Bergman demo'ed a few years back at Gichner's hammer in.  =
Quiet, when mounted on a heavy base, effective, multi-use.  Very nice.  =
Might not rattle the nosy neighbor quite as much as I could with a 50-lb =
little giant, but there something to be said for staying on his good =
side.)  So when I designed the Grasshopper, I specifically designed it for =
hard-hitting:  Amplified ram motion (twice the pedal motion), very long =
(34") ram stroke, weightless hammer (for no spring resistance) and solid =
250-lb anvil.

As a result, I find that I can do SOME of the work of a power hammer using =
the Grasshopper.  Drawing out reins for tongs, for example.  Making simple =
twist-type tongs (See Tom Tucker's book) out of 1" x 3/16" stock, I found =
I could easily upset + draw out the reins down to 3/8" square.  No sweat.  =
I used 2" fullers (i.e., 1" radius) because smaller than that tended to =
cut rather than fuller.  Maybe some folks don't need this ability.  That's =
for you to decide for yourself.  (Don't think for a minute, however, that =
a Grasshopper will REPLACE a power hammer.  It merely extends the =
capabilities of a TH further into the range one formerly needed a power =
hammer for.)

So what I'm saying, and what I'm driving at generally, is that the =
Grasshopper may be as close to a striker as you're likely to get in a TH.  =
If lesser capabilities will fill your needs, then maybe the Grasshopper =
isn't worth the time and trouble for you to build.

Bruce Freeman

>>> [email protected] 01/28/03 10:28AM >>>
The one issue, Treadle-hammery, that I want to address is "hard hitting".
While there are exceptions to just about everything, I have found that=20
the hardest hit is rarely applied.
Control matters more than impact. Progressive development (the one =
place=20
I find "progressive" to be tolerable)
is key to achieving a desired outcome.  A drop-hammer hits hard, one=20
stroke and you have a wrench body or a horse shoe.  The tooling does =
the=20
skill-oriented work and BOOM....you're done.

A treadle hammer or a striker deliver impacts, the smith needs control=20
over the developing effect or process
and either guides the striker or actuates the treadle hammer as needed.=20
 A hard hit is usually less effective than a series of carefully applied=20=

moderate impacts.  Further, if a chisel or other tooling is slightly =
off=20
(asymmetric) then a hard blow simply exaggerates that asymmetry.
Most chisel cutting or chasing has to be stroked moderately and=20
repeatedly as the chisel is moved into positions opposite the last hit.=20
 Working hard along one side of a pattern will skew the piece. Both=20
sides of a pattern must be worked and developed together.

My own experience is that from a 3B Nazel down to a simple treadle=20
hammer, the hardness of the hit matters less than the control and=20
development of the work through a series of hits. =20
The latter means that the hardest hits are rarely employed.  An=20
apprentice once asked "when do we strike the decisive blow"?
There isn't one, there is a series of well delivered impacts.  And, as=20
with power hammer tooling, treadle hammer tooling will either get the=20
job done with ease or, if made wrong (for the power source, not the=20
project) make the operator work awful hard.

George Dixon
a never-provocative blacksmith........

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