Power hammer video, Kinyon

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

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Todd Rich wrote:

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

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

Is a kick hammer like a treadle hammer? Do you have a particular design in mind?

Pete Stanaitis

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Chilla wrote:

Same thing, different name.

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 wrote:

I have collected a few pictures of various kinds of treadle hammer. I 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:

Pete Stanaitis

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Chilla wrote:

You can never have too much information... information is my crack ;-)

Regards Charles

spaco wrote:

I just sent you an email with the pictures. I tried to keep the sizes down to manageable.

Pete Stanaitis

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Chilla wrote:

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.

Just got them thank you Pete :-) Just what I was thinking of, except now I don't have to figure it out for myself :-)

Thanks aga> I just sent you an email with the pictures. I tried to keep the sizes

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.

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!

Yes I was, the internet does that to me ;-)

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

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?)

If you are thinking of using a sledge hammer in a "treadle hammer" 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

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Chilla wrote:

On the surface of the Earth, weight and mass are pretty much interchangeable in conversation.

Weight =3D 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 =3D 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 =3D 2.45 m/s) imparts (2.45 Joules/kg * 30kg =3D) ~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

When Tozetre put fingers to keys it was 7/10/08 11:33 AM...

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.

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 wrote: (snip)

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

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