[TheForge] sesaw treadle hammer

Thu Feb 13 08:02:00 2003

Jerry,

Not really.  Both are dynamic mechanisms and the dynamics are completely =
different.  In a compound bow, the force delivered by the string to the =
arrow increases in a large step as the arrow is released and the fletched-e=
nd approaches the bow.

The Grasshopper by contrast balances the hammer completely at all points =
in the stroke.  This would be equivalent to a bow that delivered NO force =
to the arrow.  (Not real useful, that!)

Bruce
NJ

>>> [email protected] 02/13/03 01:19AM >>>
Hmmm. Let me see.

A compound bow uses eccentric pullies to balance pull (arms) and force
(bow).

The Grasshopper hammer uses an eccentric pully to balance weight (pull) =
and
force (leg)

Same mechanism slightly different purpose.

They're not the same eccentric of course but you wouldn't use the same cam
in a Chevy as you would in your outboard motor either.

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

----- Original Message -----
From: "Mike Sweany" <[email protected]>
To: <[email protected]>
Sent: Wednesday, February 12, 2003 8:26 AM
Subject: Re: [TheForge] sesaw treadle hammer

>
> Not sure how it's applicaple but just running it through my mind, and =
well
I'm using my mind so...
>  Bruce Freeman <[email protected]> wrote:Not sure how the compound bow
mechanism would help. A compound bow delivers a strong pull through most =
of
its stroke, but only a weak one at full extension   where you have to hold
the arrow to aim. How is that applicable to a treadle hammer?
>
> The Grasshopper uses an eccentric pulley - effectively a continuously
changing lever arm - to balance the continuously changing force of the
spring with the (surprise!) continuously changing torque of the ram. Yes,
the torque of the ram changes as the arm changes angle.
>
> (If instead, you put the ram on rollers or sliders and hang it from a
cable above, then there is no torque per se, and the weight of the ram is
unchanging. Get a strong equal-force spring and you're home free.
Unfortunately equal-force springs are typically quite weak.)
>
> Good luck,
>
> Bruce
> NJ
>
> >>> [email protected] 02/11/03 02:08PM >>>
>
> Bruce, hmm maybe a self contained weightless ram.
> Been thinking, and darn I know it is dangerous, but that never stopped =
me
before.
> Wondering about the compound bow mechanism anybody played with that =
one??
> too nice a day to be inside (BIG LONGING SIGH)
>
> Bruce Freeman wrote:Mike,
>
> Between the speed and the pine test, it sounds like you've pretty much
confirmed my observations from 1998.
>
> You could skip the see-saw mechanism, and simply balance the ram by a
means similar to that used in the Weightless Eammer. I suspect the =
mechanism
used in the Grasshopper Treadle Hammer might also work, but that was
calculated for a slightly different mechanism than a swing-arm hammer, so
I'm not sure.
>
> Bruce
> NJ
>
> >>> [email protected] 02/10/03 01:51PM >>>
>
> Well it belongs to a friend of mine I'm guessing a at a 10,15lb head and
maybe twice that or a bit more on the back side.
> he kinda just stuck it together, had to beef up the arm, 1-1/2" pipe, =
(it
kept bending)
> We stuck a piece of pine in it and stepped on the pedal. it would =
compress
the pine about what you'd expect from swinging a ten lb without a lot of
oomph behind it.
> DragonsWatch wrote:Hi Mike,
> What is the total weight of your ram/counter weight? Do you figure you =
are
getting a comparable blow to another TH with the same weight?
> Inquiring minds want to know :-)
>
> Thanks,
> Larry
>
> Mike Sweany wrote:
>
> > I did see a sesaw/counterweight style treadle hammer last weekend .
> >
> > Upright, hammer arm was mounted at and angle to the upright, bush down
on treadle, whack. Counterbalance returns the hammer head for the next =
blow.
> >
> > Not fast not elegant but it will sure deliver a good whack. the anvil
was adjustable in height to maintain a square blow .
> >
> >
> >
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