[TheForge] Treadle Hammer Springs; shock absorber?

[Bruce Freeman]

I think my earlier response to Ron got lost in hyperspace.

To say "the treadle stops at floor level" is NOT the same as saying "the treadle hits the floor."  No one suggested the treadle should HIT the floor.  

On the Grasshopper, the treadle is quickly adjustable.  If it hits the floor this stroke, it needn't the next.  You don't even have to break rhythm to adjust it.

Bruce
NJ


>>> davesmucker at hotmail.com 3/21/2007 2:23 PM >>>
The whole purpose of the use of  leaf springs for the linkage arms on Clay 
Spencer's (and the original ABANA design) is to provide a shock absorber at 
the bottom of the stroke.  I also agree that Clay says NOT to let the 
treadle hit the floor, too much shock to the leg.  Clay should know -- he 
has only used his a few million times.

Dave Smucker

>From: "Ron Childers" <munlaw2 at hcsmail.com>
>Reply-To: munlaw2 at hcsmail.com,Sponsored by ABANA <theforge at mailman.qth.net>
>To: "'Sponsored by ABANA'" <theforge at mailman.qth.net>
>Subject: RE: Re: [TheForge] Treadle Hammer Springs; shock absorber?
>Date: Wed, 21 Mar 2007 12:52:17 -0400
>
>I think Clay said to not let the treadle hit the floor; would a cushion of
>some kind at the end of the treadle travel lessen the shock to the
>extremities?
>
>Ron C
>
>-----Original Message-----
>From: theforge-bounces at mailman.qth.net 
>[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Bruce Freeman
>Sent: Wednesday, March 21, 2007 12:41 PM
>To: theforge at mailman.qth.net 
>Subject: Re: Re: [TheForge] Treadle Hammer Springs
>
>I suppose you could.  It would have to be heavy enough not to stretch too
>much when you first step on it, yet light enough that it will stretch a bit
>to absorb the shock.
>
>But if the treadle stops at the floor level, I don't think it's all that
>much shock on the leg.  If it stops significantly above the floor, maybe
>that's the problem.
>
>Another issue is the linkage ratio.  The Grasshopper uses a 2:1 ratio - 1"
>of treadle motion gives 2" of hammer motion - a mechanical DISadvantage.
>That may mitigate the shock somewhat.  It may not be possible to use such a
>ratio on other hammers due to the fact that it would increase the force
>against the leg.
>
>Bruce
>NJ
>
> >>> wmullett at bright.net 3/21/2007 12:20 PM >>>
>Bruce,
>
>Your the wiz-bang at the mechanics of these.  Since most of the real force
>of hammering comes from the inertia of the hammer, why couldn't you use a
>heavy spring on the treadle connection to the head that will reduce the
>impact to your leg.
>
>The Chinese use split bamboo sledge hammers for that reason.  They kind of
>act like a wet noodle when they swing them.
>---------------
>From: Bruce Freeman <freemab222 at yahoo.com>
>Date: Tue Mar 20, 8:58 PM
>To: Sponsored by ABANA <theforge at mailman.qth.net>
>Subject: Re: [TheForge] Treadle Hammer Springs
>
>Do you have any way of adjusting WHERE this stop
>occurs?  It would probably be less jarring if it
>stopped at the floor - where the leg is fully
>extended.  (Another feature of the Grasshopper.)
><Grins and polishes nails on lapel.>
>
>Bruce
>
>--- Marc <marc at ironringforge.com> wrote:
>
> > Actually, Bruce, the part of the treadle hammer that
> > bothers my knees
> > the most is the sudden stop when the blow hits the
> > work. My leaf spring
> > cushions that blow very nicely.
> >
> > The spring tension affects my own energy level much
> > more than my knees.
> > I find I can draw out some good size stock pretty
> > quickly, but I'm
> > pretty winded after a while. I think using your
> > half-spring idea would
> > help quite a bit there, and I;m anxious to try it
> > out.
> >
> > --Marc
> >
> >
> > On Sun, 2007-03-18 at 19:12 -0700, Bruce Freeman
> > wrote:
> > > Middle aged knees... I know about those.  I
> > sometimes
> > > wonder whether it's worse to exercise or not to
> > > exercise!
> > >
> > > Build a Grasshopper and you'll have NO spring
> > tension
> > > working against your leg!
> > >
> > > Bruce
> > > NJ
> >
> >
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