www.artistblacksmith.com
January 2008
Newsletter

Air Hammer Techniques

The transition from December to January each year is a time of reflection for me. Things I have done well. Things I could improve upon (there is always room for improvement). Things I should never do again (once again that black heat on a bar is still hot!!!) but probably will. I think we barge through life without doing enough retrospection.

You may not have an air hammer or a power hammer and are doing all your work by hand. This is how I started and how most smiths start. If you are doing this strictly as a hobby and time is not important and your arm is still good you may not be worried about an air hammer.

If your arm is sore and starting to give out and you are trying to make a living it is a completely different matter. My air hammer is why I can make a living at this business. Without it my arm would get too sore, projects would take too long to make, and most of my work would be 1/2 inch square bar and down.

A few years back I was at Quad State Blacksmith Round Up and Uri Hofi was demonstrating his air hammer techniques. I was facinated and the light bulb went on! Up to that time I used my air hammer for primarily drawing out, and decorative punching. Uri was using some very different techniques.

Later he produced a video called Free Form Forging. I whined and complained about paying I think about $50.00 for the video. It opened my eyes about how under utilized my air hammer was. What I could do with it was much more fun than what I had been doing. So you will find the following information biased towards the Free Form Forging concept.

The air hammer that I use (and sell, see air hammer for sale) is a 75 lb Kinyon style with modifications. The basis of an air hammer is "it goes up and down and it hits hard" as a friend of mine once said. It also has to have the control to feather the surface of the bar. All the rest is structure that holds everything in alignment.

As air hammers go this is on the light side. Many are 150 lbs or more. The industrial hammers were 1000's of lbs (this is the weight of the ram not the machine).

This small air hammer allows me to work 1.5 x 1.5 inch square stock effectively. It will move 2 x2 but it is slow.

So what can be made using the air hammer.

Leaves are one of the things that come to mind. This Ginko Leaf is 5 inches wide and was made out of 3/8 by 1.5 inch flat bar.









This is another form of leaf again made out of the same material but it is 3.5 inches wide. I like making organic shapes so lots of different leaf types








This a more stylized leaf. This uses different dies under that air hammer. This was made out of 3/4 round bar. It is 2 inches wide and about 9 inches long.








How do I use the air hammer to create these forms. We start with the basics just like starting at the anvil. The first is drawing out.
Not the clearest picture sorry about that. The video will make things more clear. The techniques I use revolve around keeping flat dies in the air hammer and adding cap dies or other tooling between the dies. I save a huge amount of time switch dies with this technique. I do loose on effeciency of energy transfer. I tend to make componets in the tens not hundreds. If I was doing one form over and over again I would take the time to make speacialty dies.

So to draw out with flat dies I nibble at the bar. I will take a bite of 3/4 inch at a time. Then nibble back further and further, then smooth the bar out and work the next side. Drawing out is done square. The bar in the photo was 3/4 by 1 inch flat bar and this much draw out (about 9 inches) can be done in one heat with the flat dies.

If I wanted a longer drawout I would switch to rounded cap dies that pull the metal much faster.
This is an early style of cap die that I made. You can see that it is rounded and would act like the horn or cross pein for drawing out quickly.










This is how I constuct my cap dies now. I find this a bit more versatile. They can loosen up a bit where as the above die didn't loosen very much, but alignment was more of an issue.








This finial is shown in the video and is made only with the flat dies. I pointed the bar, made steps in the triangle of the point, shouldered the stem portion and rounded it off. The last step is turning the work on an angle and using the courner of the die to pinch out the lobes. This offset process and using the courners of the dies is not used by many smiths.



This finial is almost the same process. Point the bar. Shoulder about 1.5 inches back from the begining of the taper. Then offset the bar and use the side of the die to pinch out the blob in the middle. Flip to the other side and repeat.







Another useful technique is the use of spring fuller dies. These are like two cap dies but they stay in constant alignment. I use mild steel for the spring and the dies. Yes it will break but quick welding and I am back in business. The spring breaks after 1000's of hits so the 5 minutes to repair it is not an issue for me.






The spring tool or "clapper dies" I use in the video is a ball swage. It is very imortant to radius all edges on the dies so it doesn't leave any cut marks. There are two ways to make clapper dies like these. The first is to make the spring and the flat plates all welded together. Heat the dies up to bright bright yellow and put the master (in this case a ball on a stick) between them and hammer them together to create the depression. This is tricky as you are balancing things, trying to hammer and keep everything in alignment.

What I do instead is take the individual top and bottom dies and hammer the master into one at a time. I have to pay close attention to alignment but only one at a time. I make the spring structure (bent only leave annealed) then weld the dies cold after I have generously radiused each. I use the master for alignment top and bottom.

The ball that is produced has a bit of a point on the top as the metal is pinched out. This is simply ground smooth.









By creating different shapes in you clapper dies or fullering dies you can get many different cross sections of the steel that then can be bent or twisted to your design.








Going back to the flat dies I can use small punches on handles to create decorative punch work or to punch completely through the bar.

These punches 1.5 inches to 2 inches long and have handles about 14 inches long. See the video for examples of their use. The punch marks you see on the bar took one heat to do. The hole was also completed in one heat.



Speacialty shaped punches can create many different patterns and shapes.









The use of speacialty shaped top and bottom dies can create different textures as well as shapes in the bar. This flat bar has been worked only on one edge thining it and curving it at the same time.







The following video shows many of these techniques. The video is about 9.5 minutes long and on dial up will take a couple of hours to download. Highspeed a few minutes. It is 75 Mb in size.

Tip: This tip applys to hand hammering as well as air hammers. Use modeling clay, plasticene, or playdough to create shapes to be duplicated in steel. Watch how your fingures stretch and manipulate the clay. Can you duplicate these movements and shapes with simple tools, punches fullers etc. Try using punches you already have to make shapes and designs in your modeling medium. Steel is not much different except it is self supporting over long distances. Modeling clay is not. Some shapes you generate will be very hard or perhaps impossible working with the steel, but they may lead you to other shapes. Part of the whole point in being blacksmiths is creating interesting shapes in the steel. Things that people normally wouldn't see in a mass produce world. That is part of the art.

Up coming blacksmithing courses.
For more information see www.artistblacksmith.com/courses.htm

2008 Calendar is up on the website
Basic Blacksmithing Course
Members price $275.00

Intermediate Blacksmithing Course
Member's price $275.00



copyright 2008 David Robertson