[TheForge] Treadle Hammer Springs; shock absorber?

[Dave Smucker]

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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