Power hammer vs. Striker comparrison

[Eddie Mullins]

I plan to build a power hammer this year so am of course doing some research. One of the things I have become curious about is the weight of hammer needed. I know bigger is likely better, but I would like to build a hammer of managable proportions. I want list out all of the reasons here unless needed, but given this is my game plan, the question is what size do I really need.

 

As point of comparrison, lets consider the amount of material that can be moved by a striker or multiple strikers swinging sledge hammers. For example I present this video of 3 srikers forming a tack from sizeable stock in about 1 minute and about 120 blows.

[ThomasPowers]

Power is tied to kinetic energy---1/2MV^2  now a powerhammer throwing the same mass will be doing so MUCH faster to get to 120 beats a minute.  Does that help?

 

Knowing what you will be using it for is probably the most important factor in sizing the hammer you need.

(money, time, skills and equipment factor into what you *can* build)

[trinculo]

Depends on the process and what you are trying to accomplish. Mathematical equations of force would not be very useful in my estimation for determining which is a better tool for a given application.. For drawing lengths of stock a power hammer wins, for punching a >2" hammer eye a good striker with a 12lb sledge beats my 75lb pneumatic hammer every time. Now if i had a 300lb utility hammer that would be a different story, Also know that the stroke on most smaller power hammers will limit the amount of force applied and the tooling you are able to use. Upsetting a hammer into a cupping tool with a flatter is much easier with a striker than under a power hammer.  I've tried.

 

 

My seat of the pants estimation is that the amount of metal moved in one blow is greater with a seasoned striker with a full swing of a 10-12 lb hammer than with a single full force hit with a <100' mechanical or pneumatic hammer. Of course the striker can't do 240 bpm.

[brianbrazealblacksmith]

Good answer, trinculo!

[Eddie Mullins]

Power is tied to kinetic energy---1/2MV^2  now a powerhammer throwing the same mass will be doing so MUCH faster to get to 120 beats a minute.  Does that help?

 

Knowing what you will be using it for is probably the most important factor in sizing the hammer you need.

(money, time, skills and equipment factor into what you *can* build)

 

I had found that equation, but also ran into discussions of hammer blow back or rebound and length of swing etc. It seemed to grow increasingly complicated. I also don't know the velocity of a striker in full swing and the up vs down stroke of the power hammer, etc...

 

At this point, I'm more interested in the theoretical or factual or practical comparrison of the striker and power hammer vs my requirements. However, we can certainly discuss my actual apllication and needs for my hammer in a different thread.

[MLMartin]

I will second Trinculo. I spent four years training with some great smiths, we would all routinely strike for each other. My common striker would normally use a 6 1/2 pound sledge or 9 pound sledge and she could hit much harder in one full swing than my 50 pound little giant can running full power. However my little giant only cost about 3000 then maybe a few hundred in electricity and oil for the year. The little giant will also hit maybe 250 - 300 beats per min. My striker can not hit that fast, and paying for a second full time employee in my shop is not feasible right now. I would love to hire my striker full time as she would be much more useful than the power hammer in my shop. A striker is just lovely for tooling and changing things quickly. A striker can work around a vise and swing at most any angles. Really having both options is best in a shop. Something like the KA75 is one of the best things I have seen that attempts to replace a human striker for smaller work. Still not a proper striker but great for punching and tooling work.

[brianbrazealblacksmith]

Well said, MLMartin!