Air hammer

[myers4768]

i am trying to plan out a hammer that can hit harder when needed. is it possible to make a hammer that that can hit 50# all the way up to 80 or 100#. by adjusting air pressure or makeing a ram that you can change out. have plans for good air cylider for a 125# max ram. and will have to make it fit a design to come up with later. also to adjust ram stroke is for micro switch?
thks

[tech413]

I am no expert on this topic, but when I went on my course, the hammer we used was very controllable. It had a 75# hammer and the instructor demonstated decorative puchwork and then tapering 1.25" H13 round just by controlling the air flow and adjusting the stops. He sells plans for the hammer if you are interested.

[Shane Stegmeier]

The fall weight of the hammer doesn't normally change, but by amping up the PSI you can get a bit more force out of the ram. A lot of hammers run on low PSI I've seen some old steam hammers run on air between 35-100 PSI. BUt to be honest in my experience the difference with big flat dies is practically negligable. If you want to hit "HARDER" think smaller. With all smithing opperations, but with power hammers especially you need to understand VARP: Volume, Area, Resistance, and Power... All increases in the first three result in a greater need for Power... And by reducing one or more of those first three you can work like you have more power. It takes 4x as much Power to forge 1" square than it does to work 1/2" square. But by reducing the Area you are striking you can functionally increase the power you have. Resistance can sometimes be over come by working hotter, (be carefull with high carbon or alloy steels on this)and quiting when you drop below a certain level of acceptable work heat. Generally when the steel trys to jump out of the tongs and attack you then you are working TOO cold;-)

That is why small hammers have SMALL DIES, the Area that a small air hammer can reasonablly be expected to be effective working IS smaller.

Tooling is another area where you can focus your energy and get the most bang for your buck. You can do a lot with top tooling, and that gives you a geat deal of control.
But the spring fullers and swages can be designed to really give you an advantage. You can also put stems on them that will allow you to make a fixture that clamps to your bottom die and locks the spring tool down

[steveh]

I know with the Anyang hammers the more you push the foot pedal the harder they hit,so you can barely tap the piece or really hit it with great control.They are a very responsive machine.

[Shane Stegmeier]

I suppose this is just semantics, and how you conceptualize the way the controls work... ;-)

Selfcontained hammers are cool because the system is balanced, and using this to good advantage is pretty easy on most hammers. Most of them have wonderful control and you can vary the force deliviered by how long a stroke you allow the hammer to attempt to make. By precisely controling the length of the stroke you can just barely "tap" the stock you are working, like when you are breaking corners. This is the point where the hammer is just beginning to pull ram back up, so the vector on the ram is shifting, so in a way it is zero-ing out, ie a lighter blow. The hammer hits "harder" when the ram is accelerating past the surface of your stock, think follow through. The closer the turnaround point is to the surface of your stock the "lighter" the blow will be. Steve Parker regularly pencils some of the tong reins down to a shade over 1/8" on a Nazel B4, which is slinging a 450# Ram. Now that is control!

A selfcontained hammer will hit a weaker blow if it isn't allowed to develop much of a stroke. If you have too much tooling between the dies, or the stock is too thick the ram cannot travel far enough to have much punch, and will hit weakly. Having more daylight between the dies will tend to make a hammer slower, but will tend to make it hit harder, and give you more options as far as tooling goes. Try fitting a good sized V-block onto your bottom die, a goodsized piece of stock and a top tool shaping things up and you will understand;-)

Edited March 10, 2009 by Fionnbharr (finn:-)
Clarifying language and concepts;-)

[myers4768]

thnks yes i would like any address you can help me with. thanks to all for your time!

[Iron Falcon 72]

I am no expert on this topic, but when I went on my course, the hammer we used was very controllable. It had a 75# hammer and the instructor demonstated decorative puchwork and then tapering 1.25" H13 round just by controlling the air flow and adjusting the stops. He sells plans for the hammer if you are interested.

I'd like to have his address. PM me if you'd like. Thanks.

[Jamesrjohnson]

If any of you want to stop by my shop, I would be more than happy to demonstrate some of these concepts... I can take my 165 lb Anyang (or any of the smaller ones) and just barely crack an egg or you can go full force and pound 3 or 4" stock onto a pancake. Finn is right, you can also control the amount of force by concentrating the hitting by using different dies. A smaller flat die or a fullering die will give you more impact than a large flat die because you are focusing the same energy on a smaller area. Again, if anybody is interested, my shop is open for a demo. When things slow down, I am going to do a set of videos showing some of these concepts and the use of dies to create different textures.

[Mike Ameling]

Jay Hisel over at Big River Forge took the air hammer plans that ABANA offers, and then ... tweaked ... the valve system a bit to work better for him. He put some of that tool/die/engineering education/experience to work. I don't know how the original valve system worked, but Jay had his hammer tweaked to work pretty well. I could just lightly tick the dies together, or slam them together with all that 100+ pound force. The control of the power of any hit was there - all off of the foot treadle. The more you pressed the treadle down the farther the cylinder/ram cycled - until it would travel far enough to start hitting your work or the bottom dies. And we still could adjust the pressure some up by the valves. (A lot like a Nasel or most any air hammer) Like any hammer, it took some practice to learn how that particular hammer worked, but after that it ran well for me (and much better than it worked for Jay - but that was just a matter of experience using it).

He (we) ran that hammer off of his regular shop air compressor - which also ran the plasma cutter. But we had to plumb in an expansion resevoire tank right beside the hammer - to help even out the pressure and air draw when things got really running. We plumbed in an old 100# LP tank in the line. Never did get that "smell" out of it (the stuff they add to LP gas to help detect leaks). Never did bolt it to the floor - just put it on a large rubber mat and "walked" it back into place when it shifted too much.

So you might want to consult the ABANA plans for an air hammer. All the stuff is already figured out for you.

Mikey - that grumpy ol' german blacksmith out in the Hinterlands

p.s. I can't remember if Jay has a picture of the air hammer on his web site. He might. Big River Companies

Edited March 30, 2009 by Mike Ameling