[TheForge] Re: Hammers

[Peter Fels And Phoebe Palmer]

Mike;
Wonder if a hammer  and it's handle arent like a pendulum on it's wire, 
in that, if the weight  isn't right  for the length...then it requires 
more energy input to keep it swinging?
Regardless of how skinny the neck is, some hammers just stay on the rack 
or in the pile on the floor. Everything looks right and feels wrong. 
Having rehung a favorite hammer and inexplicably blown it,,,I think the 
difference has to do with the handle. Notice that one instinctively ends 
up gripping each handle at the most comfortable place. The counterweight 
 effect of the butt sticking out past one's hand seems to have  some 
influence too.
The flexing slot thing, as I  understood it, was promoted by Beau 
Hickory  ( no wall flower him) who reportedly saw it on one of St 
Francis'  hammer handles and went home and copied it. Saint F said that 
the lengthwise crack Beau saw was an accident caused by an over long 
wedge in the head of the hammer.
There seem to be 2 basic styles of  hammer swinging. One is ballistic, 
where the handle is loosely held at the moment of impact and this style 
benefits greatly by having a narrow handle neck. The other uses lots of 
body english, pushing and smearing the metal  to one side  at the moment 
of contact; keep this type of smith away from those pencil necked geek 
hammer handles...........Pete

Mike Spencer wrote:

>Andrew Vida <osan@netlabs.net> quoth:
>
>	As for that, weight is one factor, but another it the diameter
>	of the handle.  I have watched many smiths, particularly the
>	less experienced ones, wielding hammers with these thick
>	handles.  It took a while for me to figure that one out, too.
>	I had a favorite hammer but I always got fatigued, but there
>	was this large Stanley ball pein that I could work all day
>	long without tiring.  I finally figured out that the Stanley
>	had a very narrow handle.  When I whittled the other handle
>	way down, I was in heaven with that hammer.
>
>I would say just the same.  Bill Gichner once gave me a 2.5# cross
>peen with a warped handle.  Didn't seem too wonderful and I blamed it
>at first on the warp.  But after I slimmed the handle at the grip and
>necked it down a bit near the head, it immediately became my favorite
>hammer and still is, even after replacing the handle with a straight
>one (and repeating the mods.)
>
>There's another theoretical factor that I haven't explored but it's
>one that may make a difference.  The "center of percussion" isn't
>necessarily the same as the center of gravity.  It's similar to the
>"sweet spot" on a baseball bat. [1] With a steel head and
>a wooden handle, both centers fall somewhere within the head but a heavy
>handle moves both back toward your hand.  If your hammer doesn't hit
>the iron on (or on a line through) the center of percussion,
>vibrations are set up that probably can fatigue your hand and arm even
>if you don't notice them as you would the painful crack of a badly
>hit baseball.
>
>Ideally, the handle would have zero mass and the center of gravity and
>center of percussion would (effectively) be in the center of the face.
>I just googled this and the only mention wrt hand hammers seems to be a
>post by (otherwise unidentified) Ron G on Keenjunk:
>
>    I have made a lot of bad handles and a few good ones. I agree that a
>    thin neck (light weight neck) is a very good thing, but not because of
>    flex or shock absorbtion. The key IMO is to get the 'center of
>    percussion' (AKA sweet spot) as close as possible to the point of
>    impact, and thereby creating less shock. This means a minimum weight
>    handle - especially in the neck. [2]
>
>What Ron G calls "shock" is vibrations in the helve that have large
>amplitude where your hand grips.  You can't eliminate vibrations but
>you'd like to have your hand on a "node" where the amplitude of the
>vibrations is (approximately) zero.
>
>A trick I was shown (so long ago I forget by whom -- Bert Shaw maybe?)
>is to make the handle with a gently tapered narrow neck between the
>grip area and the head.  Then saw the handle from the head end
>longways in both directions, (i.e. as if you were going to split it
>lengthways into quarters) down to a couple of inches below the head.
>Then mount the head and wedge with wood in both kerfs.  This makes a
>nice limber, good-feeling helve but either I haven't got the knack
>just right or the native ash available here isn't quite strong enough.
>My experiments with this have broken too easily.  Hickory (which
>doesn't grow here) or some other superior wood might be better.
>
>- Mike
>
>
>[1] See some nice animations as well as explanatory text at: [3]
>
>       http://www.gmi.edu/~drussell/Demos/bats/bat1-bend.html
>
>    It matters for some very light-weight hammers.  See:
>
>      http://mmd.foxtail.com/Archives/Digests/199911/1999.11.27.09.html
>
>[2] http://www.keenjunk.com/_junkyard/jp0012_2.htm
>
>
>[3] It has been said that using footnotes in email is pretentious. :-)
>
>  
>