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I Forge Iron

Hammer Efficiency

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I see homemade hammers all the time with heavy rams but usually they fall dismally short of the 25:1 anvil to ram ratio targeted for optimum efficiency, this ratio doesn't include the total hammer weight. 

Question : will a 50lb hammer (ram) with a 1500 lb anvil do the same work as the same hammer with a 100lb head and a 1000lb anvil?

i am questioning the value of making a 100lb hammer with all of that extra ram mass getting thrown around if the anvil is only 10 times the ram weight. i believe it would be more prudent to invest the money in the optimum anvil weight of 1500 pounds for a 50lb. ram weight if i have better efficiency.

Any engineers please speak up if there is any value to building a larger hammer without the best anvil ratio

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Chambersburg published the ram/anvil ratio vs. Efficiency chart that is widely used as the basis for your statement. Find that chart and you will be able to quickly determine how much difference there is in efficiency between the two scenarios you describe.  Though I don't remember the exact details I can tell the graph is not linear. Once you get to about 20:1 additional increases in anvil mass have a negligible effect on efficiency. You need to keep in mind the difference between mathematical efficiency and getting work done. Even with a smaller ratio I think you will still be able to do more work faster withe the 100# machine. 

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actually weight is not the sole factor.   velocity has an influence.  Also consider the number of strokes per minute.   The ability of the anvil to resist the transfer of momentum is dependent on the weight but the ability to return the energy of compression also is a factor.   Just saying that there are a number of factors that can be used to define efficiency.   The word itself in the term as used by the Krush  is very restricted in application.  When thinking about various designs of User built hammers there is not single simple method of comparison.

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Best paper I've ever found on this subject.  Fig. 2 is very similar to the CECO chart seen on anvilfire but with explanation, and they have a theoretical 100:1 off on the end of the graph.  Best of all for us blacksmiths it talks mostly about open die forging.  Even has an equation for calculating hammer energy capacity.


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thanks patrick i will see what i can dig up on that chart, i understand the velocity play a part in what can be done one the speed you try to move material also plays a role as there is material resistance when trying to move steel quickly like with a hammer or a standard press compared to a linkage drive press or a hydraulic press. 

my specific question was just in regards to build a homemade hammer. i wanted to understand if there is any value in building a heavier ram which if its a mechanical hammer will have more moving around in comparison to building a smaller ram head and ideal ram weight if i can get the same job done.

If i can dig up the info from chambersberg i will see if an old contact of mine who was a hammer designer for AJAX hammers may be able to clarify.

thank you

interesting paper Judson thank you for posting it

My last post is kind of incoherent! Im going to build my own hammer so want to ensure i maximize energy efficiency and lose as little through the anvil as possible. Im definitely going to look for the chambersberg info and see if one of my old contacts at AJAX can help me with any other outstanding questions i might have thereafter. 

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