What you call strike force depends on two things, mass and
acceleration. No acceleration only means hammer is not moving ---
no force.
I believe that what Leonid means, is not adding any shoulder into it.
If you hold the hammer moderately (not rigid in your hand) and bring
it down as fast as gravity accelerates the hammer, not adding any or
much of your own power, you have a proper blow for chasing or forging
of sterling or gold. This is why silversmiths and goldsmiths have so
many hammers, not just the shape, but the weight as well.
No, Leonid. There is no way that a punch, suddenly out of nowhere
will "magnify" force when you hit it with a hammer.We are not
talking about a lever so there's no "magnification" here at all.
In your example where you compare a punch with a 16mm^2 face area
and the striker area of 64mm^2 only tells us that the striker area
is 4 times larger...........
I stand to be corrected on my use of language. Pressure per square
inch is correct terminology, and my use of āforceā in strict
interpretation is misleading. That said, the gist of it it true.
Nobody talking about creating force out of thin air. Weight of
hammer, length of hammer handle, and goldsmith anatomy represent a
theoretical maximum of energy that system can create. When contact
with striking end of punch is made, energy remains almost the same (
some of it is lost as heat ), but pressure per square inch is
depends on the area of contact. The smaller the area, the larger PSI.
We can increase PSI even further by making face of the punch smaller
than the other end.
If this concept still remains confusing, think about concentrating
energy of the Sun with magnifying glass. Under normal circumstance we
can sunbath for for hours, but even small diameter magnifying glass
can concentrate Sun energy into powerful beam, hot enough to engrave
wood and even solder.
When contact with striking end of punch is made, energy remains
almost the same ( some of it is lost as heat ), but pressure per
square inch is depends on the area of contact. The smaller the
area, the larger PSI. We can increase PSI even further by making
face of the punch smaller than the other end.
Leonid, while changing the area of the end of the punch being struck
will change the psi being exerted on that portion of the punch, the
total amount of energy imparted to the punch remains dependent on
the amount delivered by the hammer (except, as you note, the small
amount lost to heat, due to the limited elasticity of the steel). If
you hit a smaller end on a punch, you are indeed imparting a higher
psi to that smaller contact area, but the total energy transfered to
the punch as a whole, and sent on to the working end of the punch, is
not changed. In fact, controlling the psi imparted to the punch by
varying the surface area of the struck end is not likely to work
well in any case, since usually, the hammer face, which is often
slightly domed, but even if not, will not be contacting the entire
striking end, but rather, most likely, a small portion near the
center of that end, assuming both punch and hammer face are properly
hardened. Only if either the hammer or punch end is soft enough to
deform to match the shape of the other upon impact, is the area of
the struck portion increased, and even then, usually the whole punch
end doesnāt come into play. Changing the area of the struck end of
the punch only affects the nature of how your hammer hits it, with a
wider end of the punch perhaps making it harder to direct the energy
straight into the punch, if a wider end is hit more off center; but
the slightly domed face of a chasing hammer for the most part,
corrects for this possibility. The way properly made chasing tools
are tapered at the striking end is not so that the force is magnified
or reduced. Itās simply easier to hit it correctly, and the lighter
punch is then also easier to manipulate, with less inertia when it
transmits the hammerās energy to the metal. With that said, the other
end of the punch, the working end, DOES change the psi imparted to
the metal. A smaller working end concentrates the force of the hammer
blow into a smaller area. The reason the working end of the punch
differs from the struck end in this is simply that the metal being
chased is soft and malleable, rather than elastic, so the punch
pushes itās shape into the metal, spreading the force delivered over
the whole portion of the punch that end up in full contact with the
metal. A smaller impression on the metal means the force of the blow
is concentrated into a smaller areaā¦
I believe that what Leonid means, is not adding any shoulder into
it. If you hold the hammer moderately (not rigid in your hand) and
bring it down as fast as gravity accelerates the hammer, not adding
any or much of your own power, you have a proper blow for chasing
or forging of sterling or gold. This is why silversmiths and
goldsmiths have so many hammers, not just the shape, but the weight
as well.
Dan, now that explains a lot why Iām not getting uniform impressions
I need to let the hammer do the work. No,ore, no less. And use the
correct hammer weight for the impression(s) I want. Thanks!
The way properly made chasing tools are tapered at the striking end
is not so that the force is magnified or reduced.
So you agree with results, but disagree with underlying reasons. You
are entitled to your views, but my advice would be to review them. I
also would be interested in how many punches did you make in your
career? And what is your formal training in this area?
Dan, now that explains a lot why I'm not getting uniform
impressions from my stamping or chasing. I was wondering what I was
doing wrong. I need to let the hammer do the work. No,ore, no less.
And use the correct hammer weight for the impression(s) I want.
Thanks!
That is correct, but still takes practice. If you are going to do
this for long hours, for many years, you need to protect your joints
by minimizing the impact. I have hammers from a few ozs. up to 5
lbs., each with an intended amount of work to accomplish. I donāt
recommend buying too wide a variety of hammers all at once. As your
skills and strength (lifting the hammer up against gravity)
increase, you will want different hammers. When I forge flatware
after a long time off, I often start at 1.5 lbs. and over several
days increase my way up to 3 lbsā¦ I remember spending some time with
Allan Adler when he was 82 and still forging flatware (he was an
impressive man), and he was using about a 2 lbs. hammer. For stamping
I have seen people using chasing hammers which I always thought was
too light. Chasing often is progressive and overlapping but as you
have said stamping is one hit one impression; preferably. You can
experiment with borrowed hammers, if available, until you find which
weight you like and then buy hammers with that weight and the face
you think is appropriate. Just so you know, you can get hammers
custom made, so you arenāt limited to what you see in a suppliers
catalog.
I believe that what Leonid means, is not adding any shoulder into
it. If you hold the hammer moderately (not rigid in your hand) and
bring it down as fast as gravity accelerates the hammer, not adding
any or much of your own power, you have a proper blow for chasing
or forging of sterling or gold. This is why silversmiths and
goldsmiths have so many hammers, not just the shape, but the weight
as well.
Thatās a very reasonable answer.
So in theory you could put a pivot on the end of your hammer, so the
hammer swings freely, raise it up and drop it onto the work.
So in theory you could put a pivot on the end of your hammer, so
the hammer swings freely, raise it up and drop it onto the work.
Actually, this is exactly what happens if geometry of hammer and
punch are correct. When I started this thread, I said that it would
not be possible to go in all details, simply because email is not
conducive to pictorial representation. But we can dabble a bit.
To facilitate power transfer from hammer to punch, hammer face is
made spherical, with specific radius depending on other features of
hammer design. Striking end of a punch also made spherical, and again
radius is very specific, depending on punch application. In this way,
when contact is made it is only between small area of hammer surface
and small area of punch surface ( ideally it is point to point ).
Because surfaces are spherical, no matter what is the angle of the
hammer is, the energy transfer is always at 90 degrees. This is a
foundation of technique of texturing, when one can rapidly apply
multiple blows, without even looking at the punch, and never misses
it.
I was wondering what I was doing wrong. I need to let the hammer do
the work.
I guess itās a bit of a teaser to even tell the story, because you
all canāt see it, but why not. I had a friend who was a machinist -
aerospace quality. He had a hammer collection of some several
hundreds of pieces that he would show now and again. It was really
fascinating to see the breadth of things people have done with such a
simple tool. The thing was that they werenāt HIS hammers, like he
chose them for work. He chose them as a curator for a museum would,
for their unique properties and features.
Really interestingā¦ Heās gone now and I imagine his son has
the collection, but weāre not in touch anymore.
For stamping I have seen people using chasing hammers which I
always thought was too light. Chasing often is progressive and
overlapping but as you have said stamping is one hit one
impression; preferably. You can experiment with borrowed hammers,
if available, until you find which weight you like and then buy
hammers with that weight and the face you think is appropriate.
Just so you know, you can get hammers custom made, so you aren't
limited to what you see in a suppliers catalog.
I guess im in the dark as to what you mean by stamping? Can you
explain?
Stamping to me means an industrial process with a drop hammer and
dies. Repusse, chasing, raising, forging on stakes and anvils are
silver and goldsmiths hammer driven processes.
Ive never heard of stamping by hand? unless you mean hammered coins?
Thats a moneyers technique before industrial coin making was
developed.
Ive never heard of stamping by hand? unless you mean hammered
coins? Thats a moneyers technique before industrial coin making was
developed.
In this case we are talking about stamping impressions like you would
stamp numbers into the side of a die set for identification. In
jewelry there is a whole field of stamped items from earrings to belt
buckles. This is very popular in American Indian crafts. Never heard
the term moneyers but I would think we talking about very similar
things.
In this case we are talking about stamping impressions like you
would stamp numbers into the side of a die set for identification.
In jewelry there is a whole field of stamped items from earrings to
belt buckles. This is very popular in American Indian crafts. Never
heard the term moneyers but I would think we talking about very
similar things.
Ahā¦
a slight difference in our language. So thanks for putting me right.
here in the UK we call that punching in designs or whatever. I cant
remember why, but is must have been some 30 yrs ago when I started
making my own punches? with designs on them? to make pictograms
incised into strip metal, usually about 1/8in thick. mainly bronze,
but also silver and copper.
For example, a friend is a farm tractor enthusiast. He wanted a
bracelet with a pictogram of his hobby on it on the outside, with his
name and D of B on he inside.
Ive some 50 or so different punches so can make up almost any design
with these.
These punches were made from chisels or center punches of 01 steel.
all different sizes. annealed, hand filed up then hardened and
tempered. As there is quite a thread running on hammers right now,
the best hammer i found is in fact a boot makers double headed
rivetter. the faces of this hammer are on a line with the end of the
handle., not parallel with it. Made by Dixons of Sheffield from about
1875 0nwards.And!! they still make them today.
Makes it much easier to strike accurately without looking at the
punch head, as one is concentrating on where the punch is locating on
the metal being incised.
So you can imagine a miss placement buggers up the whole item.
Yesterday, at our local car boot I found a definitive guide to
Egyptian cartouches.
Lots of new designs of punch to be made up from that reference book.
To facilitate power transfer from hammer to punch, hammer face is
made spherical, with specific radius depending on other features
of hammer design. Striking end of a punch also made spherical, and
again radius is very specific, depending on punch application.
What variables affect the radius of a punchās striking end?
Charles et all: Have you ever listened to a master silversmith when
he is moving metal. It is a constant tap tap tap tap. not a BANG BANG
BANG and the blows are delivered like a rapid trip hammer. This is
the proper technique and if you are doing anything else you are
FORCING the metal not moving itā¦ Just an observation from one loves
to listen to what the metal has to say.
Charles et all: Have you ever listened to a master silversmith
when he is moving metal. It is a constant tap tap tap tap. not a
BANG BANG BANG and the blows are delivered like a rapid trip
hammer. This is the proper technique and if you are doing anything
else you are FORCING the metal not moving it.. Just an observation
from one loves to listen to what the metal has to say.
I actually havenāt, but you bring it to life.
The design students that I hear through floors, seriously go to
town.
Regards Charles A.
P.S. Hitting softly is a hurdle that a blacksmith finds difficult to
overcoming, mind you when Iām doming sterling using a dapping set, I
can usually do it in one strike
What variables affect the radius of a punch's striking end?
You may need to draw pictures, if my answer is confusing. If we have
true spheroid surface, than any point of contact will necessarily be
on a tangent to such surface and radius of the surface must be at 90
degrees to such tangent. This been the case, a power vector ( the
direction of energy transfer ) must coincide with the radius.
We can take great advantage of this by designing our punch in such a
way that origin of the surface radius lie on punch axis. This insures
that there are no lateral forces interferes with control of the
punch. In another words, when such punch struck with a hammer, there
should not be any side to side tendencies, which are very tiring for
fingers.
That is as far as location on axis. By changing length of the radius,
we can also move origin up and down the axis. If we move origin
closer to punch face, we gain in stability. It may be good for
punches struck once (stamping). For punches designed to be used for
creating overlapping textures, it is advantageous to move the origin
towards striking end. We loose in stability, but gain in
maneuverability. And it goes without saying that the thickest part of
punch should always correspond to location of the origin.
There is also dependency between radiuses of striking end and the
face. If full impression is required ( which is not alway the case )
than if origin is equidistant from both ends, than radiuses must be
the same ( for partial impressions it does not matter ). If we move
origin towards striking end, than length of face radius must be
increased and vise versa. If this requirement does not make sense,
make a drawing to clarify it.
I have to mention a special case. Sometimes it is not possible to
have shared origin between two surfaces, and such punch would have
two origins. This invariably causes vibration of the punch center. If
one works with such punch for a while, the fingertips start having
tingling sensation ( the thinner the punch, the more pronounced the
effect ). Forcing rubber tubing over the middle of the punch can
remedy the problem. Even couple of layers of electric tape can be
helpful in such situations.
