Your favorite hammer

Google Hofi Hammer and you will get the clones as well as the higher priced ones.
Blacksmith depot calls it a Czech style hammer.
 
Stacy E. Apelt - Bladesmith said:
Google Hofi Hammer and you will get the clones as well as the higher priced ones.
Blacksmith depot calls it a Czech style hammer.
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Is there such a thing as the “real” one anymore. When I searched everything seemed to say Hofi “style” but not outright saying Hofi, so I assume these are clones. Prices were pretty wide ranging. Is there a true blue Hofi still being made or is it a case of finding a good quality reproduction of the style?
 
My go-to has been a 4# sledge after a few heats to warm up. However, that's probably from my general blacksmithing background.
JTknives said:
Also if anyone knows of a rounding hammer in the 3lb range that has a round “rounding” face and a square flat face I would love to know where to get it.
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Lately, for knife making, I've been going to my 3# sledge that I ground one face into a "rounding" face. So I guess that's my knife making favorite now.
 
With the price of good hammers in the $100-$200 range perhaps it’s time for me to start making my own. In the past, way back when I had free time at the machine shop I made 2 hammers. One I still really like and the other not so much but I do use it for a few tasks. Usaly with tang work. But with my big press I don’t think it would be to hard to whip up some hammers.
 
I am not sure Uri Hofi still makes his hammers.
A genuine Hofi has hebrew characters saying Hofi, the words Hofi Hammer, and the year of manufacture on it ( at least the older ones did). The clones are just as good in m0st all cases.

I would suggest getting a good quality clone and spending the difference on Uri Hofi's book/dvd on the hofi hammer and ergonomic hammer techniques. IIRC, it is also on youtube as a video with Uri showing its use. Uri is a hammering genius.
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A 4.5 lb Brazeal style rounding hammer with an octagon/beveled rectangle profile handle. I use it for everything but the finest or most specialized of work. My other go to hammers are a 4lb cross pein, a 2lb cross pein for fine work, and a collection of texturing hammers. My general process is to forge the blade and bevels to pretty close to final dimensions with the rounding hammer and (heavy cross pein if required), then clean up the bevels with the smalle cross pein. Use a texturing hammer at the end if I am going for that look. The smaller hammer is not required for precision, but it is a bit more forgiving. I recently made a small paring knife for a buddy that was forged almost exactly to final shape (very little bevel grinding was in order) with only the 4.5lb rounding hammer. He thought it was funny watching a knife be forged with a hammer whose face was nearly as broad as the blade was long, so I decided to skip the smaller hammer and just do it all with the larger one.

I see a lot of (blade)smiths who use a much lighter hammer for most work than all of the blacksmiths I learned with. Heavier hammers tend to be a lot easier to use once you get the hang of them. They save a ton of energy too as the rate they move metal is MUCH faster. And they are easier on the joints for heavy work. With a light hammer, you have to swing it very fast to get a similar amount of energy into a blow, which means you are expending a ton of energy on the downswing. With a heavy hammer, the only real work you do is on the upswing, and gravity takes care of the downswing force. All you have to do is guide the hammer to your intended impact point. The large head ensures that proportionally more of the energy expended ends up in the work and the anvil, and a smaller percent ends up reverberating through your arm.

The one "downside" is that until you build up some calluses, heavy hammers are more prone to causing blisters, but other than that they are faster and 'easier' to use once you get the hang of them.
 
The only reason I don't use a heavier hammer is because all the mistakes I make are magnified by the weight of the hammer :D

I think as I get better I'll likely start using a bigger hammer more frequently.
 
Most of the work involved in swinging a hammer is lifting it back up to the top. That is why you will never see any competition blacksmiths using heavy hammers. They just swing higher, faster and more accurately.

13-KineticEnergy2.png


In order to increase Kinetic Energy, or the energy contained in an object in movement, one could either increase the mass of the object or increase its velocity (speed). Because the velocity has a power of 2, the increase of speed leads to an exponential increase of energy, whereas an increment of mass is linear.

In other words, an increase of one unit of speed will result in greater kinetic energy than an the same increase in mass.

It took me years to figure that out, for myself. It wasn't until I started video recording at the anvil that I realized I moved metal faster with less work when I found that sweet spot between hammer weight, swing speed, length of stroke and accuracy of the strike.

I can finally admit that I move metal more efficiently with a 2.5 lb hammer than a 4 lb'er. That doesn't mean that if I go for it with a 4 lb'er, I can't move metal faster... it just means it isn't sustainable, for me.
 
Your basic summation that it will be easier for the average smith to do this with a lighter hammer is more or less true.

That equation is it is for a moving object striking a fixed object. It only takes into consideration the hammer on the way down which is inertia. Increasing the velocity requires overcoming the mass's resistance to movement, called asinertia.

The calculations for an object at rest to be lifted three feet from rest and then accelerated down three feet against an immovable object is pretty complex.
 
That was just to illustrate the relationship of mass vs. velocity with regard to kinetic output, at it's most basic. Any more elaboration would have been a bit frivolous, IMO. But you are correct and I think it would have driven the point home ever further had we attempted to work out the entire event.

Lift - Stop/Change Direction - Accelerate - Press - Recover - Repeat
 
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I get the kinetic energy equations, though there is definitely more going on here than that. Our goal is to move the steel, not to heat it up or make it pop. We move things by applying a force over a given time. More specifically, in the case of moving steel, we are generally worried about pressure over time (Thus why we use a pein for rapid forging). This is why a hydraulic press moves so much metal. It develops pressures sufficient to move steel over a much longer period of time than an impact. Momentum is another word for force over time.

Take two objects, one double the mass of the other and use equal amounts of energy to accelerate both. The lighter object will have about 41% greater velocity than the heavier, the heavier object qill have about 41% more inertia.

When hammering, you use some amount energy per swing. How much directly equates to how tiring the swing is. If you use the same energy to move a heavier hammer, it will have a lover velocity but a greater inertia, and thus apply a greater force over time.

There are complicating factors here. You may be able to apply more or less energy to a hammer over a given time depending on a number of variables. More, any given steel alloy at a given temperature has a compressive strength that requires a pressure to overcome, so any impact or portion of an impact that does not meet that minimum pressure will not cause the steel to deform. Imagine your hydraulic press pushing at 100 PSI, no matter the length of time you push for, nothing will happen. That being said, the pressure of the blow is really tough to calculate, and I need to go grab lunch, and I don't think that it is particularly relevant here other than to say that the lighter hammer will lose velocity (and thus pressure) more rapidly after the moment of impact, thus providing that pressure over a much shorter period of time.

Impact energy likely plays some direct role, but it isn't enough to compensate for the difference in momentum.
 
I’m not sure kinetic energy is the best “simple” equation to use to wrap your mind around the theory of it all (as Stacy states there are many factors really going). The force of stopping an object (impact) is a factor of the change in momentum over the change in time to come to a stop (this is why landing on something soft hurts less, it elongates the time to change your momentum), and momentum is equally dependent on mass and velocity. This would mean velocity is not more important than mass. Both matter about equally. There are some practical limits, like a human can only ever swing a hammer so fast, so a human is going to be able to make a greater impact with a sledge hammer than a jewelers hammer. There is also probably the factor of how many times can you lift and swing in a given time (more impacts more moves) and also how many times before just completely spent. Long winded way of saying within the common range of weights I’d guess it is as much personal preference as anything that generates effectiveness.
 
I'm going to agree with joe a bit, (not that it means anything). For me, swinging and hitting faster results in MANY more inaccurate blows. Heavier and slower is where I tend to go.
On the flip side, I've found often times that if I stay with the 4# as I get close to the final forged shape, I can easily forge too thin, so the last few heats I usually switch to a 2 1/2# hammer.

One thing to consider with the Hofi hammers (I have a Mermelstein version) is that the handles tend to be short (IMO), but more to the point, the distance from the hammer face and the handle is short, and with the shorter handle, I end up banging my knuckles on the anvil face with certain forging blows.
 
I like a further distance from the handle to the hammer face. I don’t think kenetic energy really works here. Smaller and faster does have the same or more energy but the advantage of a larger hammer is the larger momentum is slower which gives the steel time to move out of the way. Slap the surface of water as gas as you can then half that speed and compared the differences. Yes steel is not water but it takes time to move out of the way and if the smaller lighter hammers inpulse of energy is to short then the steel will not have time to move.
 
For what it’s worth for others looking, I found an old post from Uri Hofi on another site where he says that he taught the gentleman at Big Blu Hammer how to make his hammers. That’s pretty good for me. I’ll take that of the apprentice if I can’t get my hands on that of the master. I’ll just need to decide between the 2.5 or 3.5 lb version. Then hopefully I’ll be able to come back and post a reply here in the future with a new favorite hammer ;)
 
It is not about what the hammer does to the metal, it is what it does to you in the long term. The whole point of my post was not to make the case that a smaller hammer swung faster would move metal better. It was to find that happy medium between weight, speed and accuracy to allow you keep working without damaging your body. Of course, a heavier hammer will mean fewer swings.... but at what cost? Will you be hunched over your anvil, swinging from the elbow? Isolating a joint to do most of the work is probably not a great idea. And the bent over stance is not sustainable either.

I had a 5th generation Master Blacksmith attempt to school me(publicly) on technique at a hammer in. I told him my technique works for me but that wasn't good enough for him. So, I suggested we both get in our ready stance with hammer held in mid stroke. after about 30 seconds, he asked "what next?" I said "Nothing, we just see who gives up first." As he waddled and grunted back up straight, he winked and called me an a-hole under his breath. We became good friends and he now has an alternate anvil set higher and uses a lighter hammer. He is pushing 70yrs old and has major joint and back issues.
 
Rick Marchand said:
It is not about what the hammer does to the metal, it is what it does to you in the long term. The whole point of my post was not to make the case that a smaller hammer swung faster would move metal better. It was to find that happy medium between weight, speed and accuracy to allow you keep working without damaging your body. Of course, a heavier hammer will mean fewer swings.... but at what cost? Will you be hunched over your anvil, swinging from the elbow? Isolating a joint to do most of the work is probably not a great idea. And the bent over stance is not sustainable either.

I had a 5th generation Master Blacksmith attempt to school me(publicly) on technique at a hammer in. I told him my technique works for me but that wasn't good enough for him. So, I suggested we both get in our ready stance with hammer held in mid stroke. after about 30 seconds, he asked "what next?" I said "Nothing, we just see who gives up first." As he waddled and grunted back up straight, he winked and called me an a-hole under his breath. We became good friends and he now has an alternate anvil set higher and uses a lighter hammer. He is pushing 70yrs old and has major joint and back issues.
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Common sense & wisdom can make ones life so much easier.
 
My favorite hammer is the one I can no longer use. I knew it was to big but I did it anyway. My love for hand forging and seeing steel move with each swing became a drug and common sense went out the door. After right shoulder surgery to repair my rotator cuff at 69 and then having my right wrist fused at 70 my desire to make knives had left.

This past January my desire to make knives started coming back. It was mostly putting knives together by using left over blades I had made over the years but something was missing. I knew what it was but I didn't want to get involved since I was sure I could no longer do it. It was my anvils calling me. You can use smaller hammers, we don't care. I couldn't resist. I lit up my forge and put a piece of steel in it and a couple minutes later I was hammering on it. I could feel a smile starting to grow and my old love coming back.

Things will never be the same now that I no longer have a functioning wrist. Don Hanson III said it all, common sense and wisdom can make ones life so much easier.
 
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