Power hammer video, Kinyon
Todd Rich
http://www.youtube.com/watch?v=KkUFgoU_LO0
spaco
I wonder how many of those have been built by now. Looks like you
have more than enough air compressor for the job.
Pete Stanaitis
--------------
Todd Rich
> Nice solid sounding hammer.
> I wonder how many of those have been built by now. Looks like you
> have more than enough air compressor for the job.
> Pete Stanaitis
> --------------
Thanks! And yeah, it is probably about twice the compressor I need to run
this hammer. However everybody seemed to be telling me to find a used
Quincy compressor when I was looking and I couldn't find them anywhere
near enough at a cheap enough price. Then I tried one last time, just to
be able to say I did, and I found one about 20 miles away from where I was
for about 2/3rds the price of a new 7.5HP compressor. Too good a deal to
turn down.
Todd
Chilla
It is a good job, and that compressor is a monster :-)
I have compressor envy, mine is only 2.5, hardly enough to do anything
with :-(
Still thinking about a kick hammer.
Regards Charles
spaco
Do you have a particular design in mind?
Pete Stanaitis
----------------------
Chilla
Well I was thinking of something simple, like rigging up a large spring
and mounting a sledge hammer there in.
I've been thinking about ways to do it.
Regards Charles
spaco
can email them to you if you are interested.
Also, there are a couple of plans around for building them.
You can read what I have written on the subject at:
> http://www.spaco.org/trdlhamr.htm
Pete Stanaitis
---------------------------------------
Chilla
Regards Charles
spaco
down to manageable.
Pete Stanaitis
-----------------
bigegg
> Chilla wrote:
>
>> You can never have too much information... information is my crack ;-)
>>
I've seen a picture of a flypress converted to be operated by leg power.
Might be worth investigating.
I've been using a (smallish) hand powered type for a couple of years -
contollable enough that I can usually do a full forging without a hand
hammer (I tend to make door and gate hardware, so some big hinges, as
well as door knockers and latches).
I did have a go at making some laminated steel with it (cable damascus,
I believe it's called?), but it didn't turn out so well.
I believe Ron Reill's site has a page on using a flypress as a power
hammer.
--
BigEgg
Hack to size. Hammer to fit. Weld to join. Grind to shape. Paint to cover.
http://www.workshop-projects.com -
Plans and free books - *Now with forum*
Chilla
now I don't have to figure it out for myself :-)
Thanks again regards Charles
Chilla
bigegg wrote:
>
>> Chilla wrote:
>>
>>> You can never have too much information... information is my crack ;-)
>>>
>
> I've seen a picture of a flypress converted to be operated by leg power.
>
> Might be worth investigating.
>
> I've been using a (smallish) hand powered type for a couple of years -
> contollable enough that I can usually do a full forging without a hand
> hammer (I tend to make door and gate hardware, so some big hinges, as
> well as door knockers and latches).
>
> I did have a go at making some laminated steel with it (cable damascus,
> I believe it's called?), but it didn't turn out so well.
>
> I believe Ron Reill's site has a page on using a flypress as a power
> hammer.
My forge is in the non-powered shed, so manual systems are the go ;-)
Regards Charles
P.S. I have looked at power hammers and rolling mills, but would like
to keep things really simple.
bigegg
>
>
> bigegg wrote:
>> I believe Ron Reill's site has a page on using a flypress as a power
>> hammer.
>
> My forge is in the non-powered shed, so manual systems are the go ;-)
> P.S. I have looked at power hammers and rolling mills, but would like
> to keep things really simple.
>
confused :.(
the flypress I'm talking about is unpowered - swing a big handle with a
weight which is converted to vertical motion through a screw - not the
powered type with a couple of big flywheels driven by a motor.
hits with perhaps 1/4 a tonne, rather than 10!
Chilla
bigegg wrote:
> confused :.(
Yes I was, the internet does that to me ;-)
> the flypress I'm talking about is unpowered - swing a big handle with a
> weight which is converted to vertical motion through a screw - not the
> powered type with a couple of big flywheels driven by a motor.
>
> hits with perhaps 1/4 a tonne, rather than 10!
Well I figure I weigh in between 106-111 kg fluctuating week to week
(don't ask my body is pretty screwed up).
so if I can use a 6 lb sledge, and put a large portion of my weight
behind it I should be able to deliver a sizable whack :-)
Regards Charles
spaco
design, note that most of them have a MUCH heavier hammer head.
You know that the speed of the hammer has a lot to do with the power
of the blow; it's a squared function, I think. (Energy = weight X speed
squared, or something like that). ----I always get confused about the
difference between weight and mass---
You can get a hand-swung sledge hammer going a LOT faster than the
treadle system will drive its hammer, so you need a LOT more weight to
make up for the difference. On the Gade-Marx and Clay Spencer designs,
the hammer head weighs about 65 pounds. That's a good weight in my opinion.
Pete Stanaitis
----------------------------------------
bigegg
>> hits with perhaps 1/4 a tonne, rather than 10!
>
> Well I figure I weigh in between 106-111 kg fluctuating week to week
> (don't ask my body is pretty screwed up).
>
> so if I can use a 6 lb sledge, and put a large portion of my weight
> behind it I should be able to deliver a sizable whack :-)
working alone @ 1 hit per second for a full heat?
my flypress only cost me £35 (about 70 U$) -
it's a bit of a no-brainer for me for the sort of work I do -
I simply couldn't do a lot of it without help if I used a sledge, plus
it was a lot cheaper than a kick hammer would have been, a lot quieter
than a power hammer, and it is (just about) light enough to transport to
site on a small trailer - weights about 3 or 4 cwt (350lbs?)
Tozetre
> squared, or something like that). ----I always get confused about the
> difference between weight and mass---
On the surface of the Earth, weight and mass are pretty much
interchangeable in conversation.
Weight = mass * acceleration (of gravity)
1kg of mass is 1kg of mass on the moon, but on the moon it only has
1/6kg of weight, since there's less acceleration. Being "weightless"
is what happens when one's "perceived weight" is zero- that is, when
there's nothing pressing up against us. At the top of a rollercoaster
curve, we have no upward acceleration- in fact since we started the
uphill climb our acceleration has been downward, but our velocity has
been upward. At the top, our imparted upward velocity runs out, so we
hover for a moment before gravity takes us back down again. In
freefall, while we've got full downward acceleration (at 9.8m/s^2) and
probably velocity (0 to start falling, increasing as we fall), we
don't feel the effects much because we don't feel anything pressing
against us to give us physical cues about our attraction to Earth-
until the end, anyway. So even an object in freefall on Earth (or at
rest on the ground afterwards) has an unchanging weight because the
force of gravity is always acting on it. In space, nothing's
attracting the object, so its mass is the same but its weight is 0
because it has no acceleration.
So, the weight of a hammer remains constant at the surface of the
Earth because its mass doesn't change and gravity's always pulling on
it. Its perceived weight (by itself, not us) is zero at the top of the
stroke, and all the way down if we just let it fall- but its objective
weight remains the same (1 lb, 2 lb, 5 lb) because gravity's still
working on its mass (W = mass (1 lb) * 9.8 m/s^2). The energy with
which it strikes the iron depends on how fast it's going when it hits;
if it falls for one second, its velocity will be 9.8m/s and its energy
will be 9.8 joules per kilogram; presumably your hammer falls for less
time than that. A 2lb hammer is roughly 1 kg; the acceleration is
constant, so 1/2 a second fall in Earth's gravity imparts 4.9 Joules
to the hammer. When the hammer hits the iron, that energy is
transferred to the iron- and then to the anvil, and some of it is
reflected back up to the hammer. Hot iron will absorb more of the
force and reflect less, which is why it deforms and the hammer doesn't
bounce back into your face unless you bang it against your anvil. Now,
this only calculates gravity's effect; your arm pushing down on the
hammer as it falls imparts more energy yet, because it's increasing
the net acceleration downward, like a roller coaster in reverse. When
you pull the hammer up, downward acceleration is 9.8 m/s^2, and upward
acceleration (your lifting) is higher than that, giving you a net
acceleration (at least at the start) upward, and a net velocity upward
until the hammer or coaster reaches the top (as it slows, it has net
acceleration downward). At the top, your arm starts giving the hammer
more acceleration downward, which adds to gravity. This means that the
hammer is going faster than 4.9m/s when it hits the anvil, which means
it's imparting more than 4.9 Joules to the hot iron.
Speed his how fast something is going (20 m/h).
Velocity is how fast something is going and in which direction (20 m/h
heading east).
Acceleration is how fast something is speeding up or slowing down (0
to 60 in 3 seconds).
Mass is how much of something there is (2 pounds on Earth, the moon,
or in space).
Weight is how much force gravity is giving an object (2 pounds on
Earth, 4 ounces on the moon).
Force is how much it's going to hurt when it hits you. (2 pounds of
mass hitting your thumb at 4.9m/s hurts just as much in space as it
does on Earth. The difference is that on Earth you can drop it, but in
space you have to swing it.)
A trip hammer weighing 65 pounds and falling for 1/4 a second (9.8 m/
s^2 * 1/4 = 2.45 m/s) imparts (2.45 Joules/kg * 30kg =) ~73 Joules. To
hit with the same force using a 2 pound hammer a smith would need it
to be traveling at 73 m/s. A boxer can punch about 8 m/s, and I think
our hammers aren't as fast as that. If we assume we can get the speed
up to 4m/s, then we're imparting about 20 Joules per blow. For
comparison, 1 Joule is roughly what it takes to lift a small apple 3
feet in the air (and the same force you'd feel when that apple hit you
coming back down). If you took 20 small apples, compressed them into a
small area, and dropped them 3 feet onto your hand, that's about how
much it ought to hurt when you smack your hand with a hammer- seems
about right to me.
Keep in mind that while the calculations are out of science texts, the
numbers (1/4 a second, 4m/s) are rough guesses. Also, I'm not a
physicist, so take my assertions with a grain of salt.
/endsciencelesson
/relurk
Carl West
>> ... it's a squared function, I think. (Energy = weight X speed
>> squared, or something like that)...
OK, so this _is_ the formula? The speed at impact is the important part,
the acceleration is only important 'cause that's how we get the speed.
Got it.
So I can explain to a student that if they can _swing_ the hammer
instead of _pushing_ it, and get it going twice as fast, they'll hit
with four times the force?
I can say "Force equals Speed squared times Mass"?
Hrmmm... I know the formula F=MA, but now it seems flawed because it
doesn't include time, and A requires time. I'm missing an assumption,
Yes? It's been a long time since I studied this stuff.
> A boxer can punch about 8 m/s, and I think
> our hammers aren't as fast as that. If we assume we can get the speed
> up to 4m/s, then we're imparting about 20 Joules per blow.
Speaking of swinging...
The boxer's punch is a fairly linear thing, thrown that way because it's
harder to block. If you get to swing your arm through an arc you can get
a lot more speed on your hand. Add a handle with a weight on the end and
swing _that_ and I bet it gets going pretty darn fast. 4m/s is only
about 9mph. I _know_ my hammer head is going faster than that.
--
Carl West
http://prospecthillforge.com : The Blacksmithing Classroom
Reduce. Reuse. Recover. Refurbish. Repair. Repurpose. Recycle.
Todd Rich
(snip)
> I can say "Force equals Speed squared times Mass"?
> Hrmmm... I know the formula F=MA, but now it seems flawed because it
> doesn't include time, and A requires time. I'm missing an assumption,
> Yes? It's been a long time since I studied this stuff.
Yes. If A has a time component, F has it as well.
Start out with distance. 8 meters
Add a time component. Speed = Distance over time
Or 8 meters per second.
Add in another time component, and you have Acceleration.
Add in the mass to get the force with F=MA.
Add in distance again, and you get work.
Add in time again to work and you get Power.
Here is a refresher if you are interested
http://en.wikipedia.org/wiki/Elementary_physics_formulae
John O. Kopf
Assuming a solid anvil/target, the force applied by the hammer is the
mass of the hammer times the (de-)acceleration of the hammer (change of
velocity) Assume a 4-lb hammer *DROPPED* onto the anvil - it will have
2x the force of a 2 lb hammer dropped the same distance. *SWING* the
same hammer, and you'll have a lot more velocity to slow down; the
slowing from full-speed to stop will take about the same time, and
impose a lot more deceleration (= force) A 50-lb "Little-giant" will
probably move about as fast as a good swing, but must decelerate 50 lbs,
and so applies a lot of force. Also, if the hammer bounces, it must be
decelerated and then re-accelerated in the opposite direction - more force.
John Kopf
Chilla
Tozetre wrote:
>>of the blow; it's a squared function, I think. (Energy = weight X speed
>>squared, or something like that). ----I always get confused about the
>>difference between weight and mass---
>
>
> On the surface of the Earth, weight and mass are pretty much
> interchangeable in conversation.
Yeah, I wish this was the same for air pressure.
I bought a Whisper Momma and it basically cost me $1500 landed :-( The
forge only got hot enough to forge weld when I adjusted it, by adding an
extra fire brick base (effectively reducing the size of the fire box.
Apparently this has to do with the altitude where I live (although I
can't fathom why), but others with the Whisper Momma swear that it's the
best thing since sliced bread.
About a month later I figured out that making a better furnace was a
piece of piss. I still have the whisper momma, and when the lining
wears out I will "fix" it :-)
Regards Charles
Tozetre
> >> ... it's a squared function, I think. (Energy = weight X speed
> >> squared, or something like that)...
>
> OK, so this _is_ the formula? The speed at impact is the important part,
> the acceleration is only important 'cause that's how we get the speed.
> Got it.
Short answer; nope, the formula for calculating the force that's going
into hot iron is; energy = (how heavy the hammer is) times (how fast
it's going).
Long answer; Newton's second law is F=ma, but this means; the rate of
change of momentum of a body is proportional to the resultant force
acting on the body and is in the same direction. In other words, once
you stop accelerating something (and it's moving at a constant
velocity), it has no more F, or *rate of change* of momentum.
Acceleration is not speed squared, either; m/s is speed, and
acceleration is m/(s^2), not (m/s)^2. I think what we want is
something more like his explanation of impulse, that the impulse
granted an object is force F exercised over time. Other posters have
stated this with more clarity than I did.
> a lot more speed on your hand. Add a handle with a weight on the end and
> swing _that_ and I bet it gets going pretty darn fast. 4m/s is only
> about 9mph. I _know_ my hammer head is going faster than that.
True! I forgot about pivots and levers, sorry. Well, like I said I was
picking those numbers out of thin air.
> Also, if the hammer bounces, it must be
> decelerated and then re-accelerated in the opposite direction - more force.
Nope. The amount of force available doesn't change, just where it goes
and what its direction is. It's like a wave in a pool; when the wave
hits the edge it gets reflected back. Some of its energy is imparted
to the wall, and the rest goes back into the water. Your wave is now
smaller and heading in the opposite direction, right? but just because
it switched doesn't mean it's going to capsize boats. Same thing with
a hammer; you swing, it hits, it bounces back. It may bounce back
higher than it started, because you gave it more energy than gravity
alone, but it doesn't have more energy coming off the anvil than it
did coming down. My apologies if you didn't mean that and I'm holding
forth on something you already know.
> Yeah, I wish this was the same for air pressure.
Living nearer the mountains, here, elevation 2000ft. Advantages:
easier to find coal mines. Disadvantages; less air to burn it with. I
feel your pain.
Carl West
> Short answer; nope, the formula for calculating the force that's going
> into hot iron is; energy = (how heavy the hammer is) times (how fast
> it's going).
Having just gone back to that wiki page of formulae it looks like we
want to be talking about Kinetic Energy, Work, and Power
(ignoring gravitational potential energy)
KE = 1/2 x m x v^2
W = /_\KE (trying to make a 'delta')
P(avg) = Work / /_\Time
So, getting the hammer going twice as fast does quadruple the Kinetic
Energy of the blow, which quadruples Work and approximately quadruples
Power (I'm sure contact Time increases slightly for a heavier blow. How
much? no clue).
>> Also, if the hammer bounces, it must be
>> decelerated and then re-accelerated in the opposite direction - more force.
>
> Nope. The amount of force available doesn't change, just where it goes
> and what its direction is.
If it doesn't bounce, that means all the energy has left the hammer and
gone into the piece (for practical values of 'all'). It it bounces, it's
carrying some energy away with it.
The colder the work, the more the hammer bounces, the less energy
imparted to the work, the less it is deformed. Hmmm...
spaco
Pete Stanaitis
Tozetre
> Ah. After all is said and done, it's 1/2 MV^2.
>
> Pete Stanaitis
Blow me down, so it is. My apologies for claiming otherwise!
CGraf
> I have compressor envy, mine is only 2.5, hardly enough to do anything
> with :-(
>
> Still thinking about a kick hammer.
>
>
> Regards Charles
>
This is probably too obvious, but no power hammer should be running
directly off the compressor any way, so why not put in a larger storage
tank?
I ran my bull hammer for a short while off of one of those little
compressors that roofers use and a larger tank.
It was very hard on the little compressor as they have short duty
cycles, but the hammer didn't care at all.
For the small one person shop there is usually enough down time between
heats for the smaller compressor to refill the tank.
I have since gone to a big honkin' two stage, but that is because I now
am set up to run other things off of air and have the potential of
having more than one tool in use at a time.
For a short while I considered twinning a smaller compressor into the
system and setting the switch at a higher on point than the two stage.
Running the numbers it looked like the energy consumption would not have
changed much. Compressing a given volume of air to a set pressure just
required the same amount of energy.
I do have the smaller unit piped in as a backup at the other end of the
piping, but not turned on, strictly a reservoir. This also helps
alleviate possible pressure drop issues due to piping size, if I fire up
too many pieces of equipment at the far end of the piping.
Mike Graf