Process

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Power hammers can be a Blacksmiths' best friend in the shop.  You are limited to the size of material you can efficiently work with, by the amount of force you are able to apply.  Some of the earliest power driven hammers were run off a water wheel, while others connected to an electric motor via flat leather belt. This one, a Nazel 3b was developed around 1905 and was used in large industry through the 1940's.  Mine was pulled from the General Motors plant when they updated their facility.  I've had many power hammers over the years and this one has such good control and flexibility that  I can safely hold tooling  in place while controlling the hits to create difficult shapes.   
I make a lot of my own tools to use under the power hammer.  These next 4 pictures show how I forge holes. This traditional way of pounding a thin punch into the metal  pushes the material  that's in its way, off to the sides, so little is lost. This method allows me to open the slot created to a size even greater that the width of the material, while retaining its strength. Plus it is just a great look.
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I then use a tapered  drift punch to open the hole to the desired size and shape
This finished hole allows for another bar of the same size to pass through
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I'm pounding into a depression in a stump that allows me to create the soft curves of a leaf without damaging the surface texture. This is the final shaping over a forming stake that I made from a jackhammer bit.