Blacksmithing Tips – What Type of Power Hammer is Right For Your Shop?
Blacksmith Power Hammers or Trip Hammers
If you have ever worked with a power hammer you see the blacksmithing world through different eyes. Power hammers really fall into 3 basic categories, Hydraulic Presses, Mechanical Hammers, and Air Hammers. They are all designed to increase the amount of force that you can apply to the steel. This means you can do more work in a given amount of time and you can work bigger bar. Suddenly this opens a whole new creative reality with the steel.
I don’t use one in my shop but I have used one years back in another smiths shop. Hydraulics have tons of power (literally) and can force the metal into many different shapes very effectively. They are useful for extreme controlled force applications such as forcing steel into preshaped dies, or cutting at specific lengths or angles etc.
This is not an impact machine such as mechanical hammers or air hammers, and is not fast. It can be used for drawing out steel but this is tedious. Although it would save time from drawing out by hand and allow you to work bigger bar I would go crazy with the slow process.
Essentially the machine is a hydraulic ram mounted on a frame with an electric pump. You use a foot control to squish the metal. Step with the foot apply more force. Release the foot the dies back off then you can move the bar and apply the force again in a different spot.
There are a couple of positive aspects of a hydraulic press. They have a small footprint, and require no special foundation. Prices are manageable for this type of tool. About $2000.00 in my area. There is no impact noise or vibration with this type of machine. The whine of the hydraulic pump can be loud but it doesn’t have the same annoyance factor for neighbors as the impact from a hammer. Presses are rated by the number of tons pressure that the ram can produce. 20 ton, 40 ton and 60 ton are common sizes.
All mechanical hammers work on a variation of the same principle. A rotating crank shaft lifts the weighted hammer head that is counter balanced, then forces it down on the next half of the revolution. The attachment on other hammer head has to be a spring construction of some sort so that the impact is absorbed in the spring not the crank shaft. The counter weight relieves some of the strain on the motor.
There have been many different configurations of mechanical hammers over the years. Little Giant comes to mind but this is only one style. Others include Helve Hammers etc. Mechanical hammers are rated by the hammer head rate. So a 25 lb Little Giant has a 25 lb hammer head weight. The heavier the head weight the larger the steel that you can work under it but the larger the motor that you need to run it.
Something to think about. If your shop is in open air but has no electricity you could run a mechanical hammer off a small gasoline engine. A little expensive but compared to the amount of work you could do this way, it might be worth it.
I have only worked a little with mechanical hammers but a 1 hp motor will run up to about 50 lb Hammer head weight.
The beauty of a mechanical hammer is that it is relative simple to build or repair. The concepts of the movement are very simple and easy to follow in slow motion. Mechanical hammers were relatively common in industrial settings in the late 1800’s and early 1900’s so you may be able to find one for a good price in your area. The downside is that parts may be impossible to find and you may have to fabricate your own.
You can also build your own mechanical hammer. It will take some tinkering but a good working hammer can be made pretty economically. They don’t take up a lot of space. Perhaps 2 feet by 3 feet for a small one. They are a bit noisy to run and have an impact sound to them. They do need a good foundation, although a small one can get by with a small foundation. They are a bit limited by the tasks that you can do with them. If you are creative with your tooling you still can do a lot of work and save your arm.
My personal favorite. The air hammer was originally conceived as a steam hammer for huge industrial applications. Like the mechanical hammers they are rated by the hammer head mass, and usually range from 50 lb to 1200 lb or more. The upper end of the scale are massive machines that require mammoth foundations to work properly. These are poetry in motion to watch a skilled smith use.
The principal behind the air hammer is fairly simply. Air pressure lifts a weighted hammer head then some thing shifts the air pressure and the hammer head is dropped under air pressure force then it is lifted again. The air on the bottom of the air cylinder acts as the cushion replacing the springs in a mechanical hammer. This process creates a cyclic hammering of the steel. The weight of the hammer head and the pressure of the air both contribute to the force applied to the steel.
Most smaller blacksmithing shops use 50 lb to 150 lb size. There are two subclasses of air hammers that you should be aware of. The self contained and the air compressor version. The self contained uses two air cylinders. One is the compressor cylinder and is driven by a motor. This cylinder provides air to the hammer head cylinder. So every up stroke of the drive cylinder forces the hammer head cylinder down and every down stroke forces the hammer head cylinder up. Valving causes the air to be either exhausted or sent in varying amounts to the hammer head cylinder. This provides the control on the stroke and force applied to the steel. This cyclic timing is governed by the speed of the electric motor.
The air compressor reliant air hammer feeds off a constant line pressure and has a feed back circuit built into the design. The hammer head travels up and trips a switch that tells it to go back down. Once it reaches a certain travel point another switch tells it to go back up. The amount of the exhaust dictates both the speed and the force applied to the steel.
Although air hammers appear to be a bit more complicated than a mechanical hammer there are actually less moving parts and less to wear out. I find them to be more versatile. You can adjust your stroke and force just by moderating your foot peddle. With a mechanical hammer you have to make a mechanical adjustment to change your stroke height. Your force is controlled by the speed of the impact or the speed of rotation.