Build your own power hammer

A Word About Materials for the Appalachian Power Hammer:
          This power hammer concept means that you will build it from materials available where you live and work.

Motor: Generally, a used 1/2 hp, 110 v. motor will run the hammer if the hammer weight is under 30 lbs. You will want to use a 3/4 hp or 1 hp motor for heavier hammers or for production work. Older motors more than likely have heavier bearings and windings (and better torque) than the new models so don't be afraid to use an older motor. You should be able to find a used washing machine motor (1/2 hp) for free. A new 1 hp motor might cost $200 and up. If the 1/2 hp motor is too small for your power hammer, then you are not out anything if you took the time to find a free one. Try this approach first.

Anvil: The anvil post should be made from solid bar or round stock which can be found at a scrap yard. A section modulus of 3"-4" works very well. 2" stock would be too small and 6" would be overkill. But, if you find a railroad car axle for free, use it! You can also weld smaller bar stock together to make the anvil post.

You can also weld channel or angle irons together and cap it with solid plate but the results are not as good. Think about your blacksmith anvil when planning the power hammer anvil post. You really want some heft and weight in your power hammer anvil post.

The anvil height should be waist high or at a level where you don't have to bend over or reach up. Usually, a waist high levels allows you to comfortably hold the workpiece level and parallel to the floor. (See the RUSTY photo with Jerry Allen holding bar stock while demonstrating the power hammer.)

Hammer Head: By design of the machine, these hammers hit harder than you might expect. A 25 lb 'RUSTY' will hit harder than a 25 lb Little Giant.

You will want to look for a good piece of rectangular bar stock for the hammer head. The hammer head on DUSTY (as shown) weighs exactly 50 lbs which includes the bolt-on dies. The RUSTY hammer head (as shown) weighed about half that and did not have bolt-on dies--the head was slightly rounded for drawing out.

Most of you, especially if you are a hobby blacksmith, will be well-satisfied with a hammer weight of 20-30 lbs.

Flat springs: You may very well find flat springs at a scrap yard but they are becoming harder to find as automobile suspensions change. Thus, you may have to buy springs at a spring shop. Depending on their inventory, you will want springs that are 1/4" to 5/16" thick and about 2.5" wide. Length will depend on how you set up your power hammer but 38"-40" long for the center spring is a good guideline. (The upper and lower spring in the bundle will be about 4"-6" shorter.) Note: You may find that the spring shop only sells a standard length such as 48" or 60". Buy it and save the piece that you cut off for a special project.

Base plate: Steel plate from 1/2" thick and up will do although 1" seems to be the best all around. Highway and utility contractors use 1" plate to cover road excavations and the scrap yard should have an ample inventory of used 1" plate.

After you have positioned your finished power hammer in the shop, consider placing a thin layer of non-shrink grout between the base plate and (concrete) floor. This eliminates any 'walking' and transfers vibrations and shock to the floor or foundation. If you bolt the power hammer to the floor, be sure to grout under the base plate.

Center column: Most often, just weld two pieces of 6" channel iron together to form a hollow center. If you can locate square or rectangular tubular steel use that and save the welding rod (and time). The idea here is to fill the column with sand and wheel weights (free from tire shop) to add weight to the unit and to deaden sound. Don't fill column until the power hammer is where you plan to put it!

Wood base option: When Jerry built RUSTY, he was short on steel but had some timber blocks. So he shortened the steel work by 16" and made a timber base to make up the difference. See the difference between RUSTY and DUSTY.

If your anvil stock is shorter than you'd like, consider this option. By replacing steel with wood, this gives you more options when you are scavenging steel for the power hammer.

Your highway or street department will have used 6" x 6" pressure-treated guardrail spacer blocks free for the giveaway. They are about 12"-14" long. Bolt them together for a wood base if you do not have access to a sawmill's odds and ends.

KISS: Keep it simple, stupid!

Build yourself a 25 lb hammer with a 1/2 hp motor. If it's too small, you can sell it for a good return and then build a larger power hammer.


 

 

rusty logo
welding rusty  photo by matt giffels

Straightening Curved Leaf Springs

1. You can use curved leaf springs to build your power hammer--search the internet for forums and articles about straightening leaf springs. You'll find examples with the curve up (ends down) and the curve down (ends up).

2. To straighten a leaf spring, it is best to use a hydraulic press. If you don't have one, you can find a machine shop or welding shop that does. The best place to have this done is to go to a spring shop that installs and repairs truck springs. Their mechanics can also evaluate your springs as well.

3. Straightening should be done cold. If you do heat springs, you'll have to get them cherry red in a forge. Then you will have to anneal them and heat treat them to get the spring back into the metal.

4. Hydraulic presses exert tremendous pressure and can cause accidents if not set up correctly. This is a job best left to the people who know what they are doing.

5. Some smiths have straightened springs by placing blocks of wood under the ends (curve up) and parked a rubber-tired vehicle or tractor on them for a period of time. Regardless of the method, a spring has to be pushed beyond horizontal to correct the curvature. The placement of the blocks and the distance that you have to bend the leaf spring are a matter of trial and error, and this applies to hydraulic pressing as well.
 
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