Is this a stupid idea for a treadle hammer? - Update!

[East Branch Knives]

Just about all the treadle hammers I see online use a direct-drive system where you step on a peddle (or "treadle," I guess) that's connected by a rod to the ram/hammer. The ram takes the same path your foot takes. Kind of like this:

However, I wonder whether using the mechanical advantage of some levers may be beneficial, like this:

I'm not an engineer or all that handy with stuff like this, but I would like to build a foot powered hammer to give my elbow a break. I figure there's probably at least a few problems with my design that I haven't anticipated, and I don't know if it would even work. Any input would be appreciated!

 

[Mahoney]

In your lower drawing you lose the mechanical advantage you gain on the foot lever when it moves the hammer lever, the hammer lever puts you at an equal and opposite mechanical disadvantage. You could design a hammer linkage that would give you an actual mechanical advantage, but mechanical advantage comes at a cost: more movement. So if the hammer were to hit with twice the force applied by your foot, it would move only half as far as your foot did, and at half the speed. The force the hammer hits with is a product of mass and velocity, so the net force of the hammer hit is the same as you would get with no mechanical advantage.

You can use the power of oscillation to get some "extra" (not really, merely the recovery of a bit of energy imparted on the previous stroke) work out of a treadle hammer, where the rebound from the anvil helps lift the hammer head on a springy hammer arm a little higher for the second and subsequent hits than it starts at rest for the first stroke

 

[Stacy E. Apelt - Bladesmith]

Mahoney has it ... no gain from your lever system.

A treadle hammer is mainly used to free the hands to guide a piece of sheet metal under a small hammer. They make the foot the hammer hand.They are used a lot to do veining and decorative work on leaves and petals in artist blacksmithing. They are more about light controlled blows that pounding hard. They are not really all that useful for forging a blade in my opinion. A small power hammer would be far better.

 

[East Branch Knives]

Thanks guys, that's what I figured.

Stacy, I definitely want a power hammer, but it's way out of my budget. Even building one looks pretty expensive, and would probably require a beefier welder than what I have.

I had one more idea for a treadle hammer that uses the same principle as the kick drum pedal on a drum set (as a former drummer the foot pedal just feels like a natural way to go for me). I don't mind stomping on a pedal all day, it's the hammering that's giving me pretty bad tennis elbow. I've got some square tube lying around and figured I could put together something like this, with a sledge hammer attached to an axel that's also got a bike gear on it:

I may just throw something together to test out the idea, as I'm currently giving my elbow a break from forging for a while.

 

[Stacy E. Apelt - Bladesmith]

The sprocket acts as a pulley. This creates a pull on the spring. There is a loss in the two paths ( chain up and chain down). Additionally, the pull on the lever ( the hammer helve) is at the fulcrum, creating no gain at all.

Go back to your twin lever design in post #1:
Remove the link between the treadle and helve on the ends. Pivot the treadle where is shows the lower fulcrum ( eliminate the extension). Move the link to connect the treadle and helve to about 30% the length between the pivot and the foot pad on the treadle. This will give your foot mechanical advantage in making the down-swing. The link connector on the treadle should be movable to try different stroke power adjustment. The link attachment on the helve needs to be adjustable as well so you can find the spot to get a good action. Start at 50%.
Add a spring between the short end of the helve and a fixed attachment on the base. It should have a chain or other linkage attachment that allows adjusting the tension. It would be a good idea to make the helve attachment for the spring adjustable just like the link attachment. You want the helve to have just enough spring tension to hold the helve up. The spring doesn't need to be very strong. The farther the distance from the fulcrum, the more return power, but also the more foot pressure it will require to get the helve moving. Somewhere along the short extension is the sweet spot. Start at 50%. The spring power may need some experimentation, too. You want the lightest strength that makes the return efficient.

In operation, strong and rapid foot pressure brings the helve down and stretches the spring. The velocity and inertia of the hammer builds quickly, and upon the strike the rebound starts raising the hammer. The spring pull helps raise the helve and hammer so your leg gets a rest on the up-swing. With practice you will find the "period" of the hammer and can hammer at the rate that creates the most power for the least foot effort.

 

[East Branch Knives]

Stacy, thank you for those instructions! I will put something together and report back.

 

[East Branch Knives]

So I finally finished my treadle hammer. It's pretty low-budget but it works better than I thought it would (in that it works at all). The return spring is located under the anvil and links to the anvil stand. I really like the rapid fire action you can get, and it's really given my elbow a much-needed break. My next project will be a power hammer, but that will probably be a long ways away.

Thanks for all the help Stacy and Mahoney!

 

[S.Alexander]

Well now we need a video of you using it!

 

[Stacy E. Apelt - Bladesmith]

That seems to have all the required parts. Mechanical advantage should provide a more powerful blow for less effort ... and it is your strong leg muscle providing the force.

That machine qualifies for some sort of Red-neck engineering award ... and man, look at those welds

I will point out one engineering error. You ran the floor braces only to the back support legs of the anvil. This makes the front legs able to try and move away from the back ... which they will do ... and the welds at the anvil base will likely break. The front legs get more force due to leverage and load sharing, so they need as much or more bracing than the back does. Add two more angle iron braces between the front and back legs to give the machine more rigidity.

Optimally, the anvil should have a support column extending to the floor like the rear support column. As it is, part of the force supplied by the hammer is dissipated by the non- rigidity of the support system. You can still add this and have it pass through the treadle foot bar. A 4X4" column like the rear one would be fine.

 

[East Branch Knives]

That seems to have all the required parts. Mechanical advantage should provide a more powerful blow for less effort ... and it is your strong leg muscle providing the force.

That machine qualifies for some sort of Red-neck engineering award ... and man, look at those welds

I will point out one engineering error. You ran the floor braces only to the back support legs of the anvil. This makes the front legs able to try and move away from the back ... which they will do ... and the welds at the anvil base will likely break. The front legs get more force due to leverage and load sharing, so they need as much or more bracing than the back does. Add two more angle iron braces between the front and back legs to give the machine more rigidity.

Optimally, the anvil should have a support column extending to the floor like the rear support column. As it is, part of the force supplied by the hammer is dissipated by the non- rigidity of the support system. You can still add this and have it pass through the treadle foot bar. A 4X4" column like the rear one would be fine.

Stacy, thank you for the additional info! It's details like the ones you identified which are especially helpful to me because of my general lack of engineering/mechanical knowledge. I would have used this contraption until it collapsed, most likely sooner rather than later, and the anvil probably would have pulverized a few bones in my foot when it landed. As it happens, the whole anvil stand will jump around because of the non-rigidity you pointed out, and I think running the floor braces all the way to the front will help w/ this (in addition to keeping the whole thing from coming apart). After adding the extra bracing you recommend, I'm going to place the whole thing on a piece of plywood to shield the floor and perhaps secure it down in a couple places.

And yes, I definitely need to practice my welding! I'm going to see if there's a welding class I can take before embarking on my next project...an "Appalachian" power hammer.

 

[Lieblad]

After you get that stengthened & "tuned up" a bit, it will be fairly easy to motorise it.
Or build another with motor in mind.

Mechanical powerhammers are basically two designs. One is DuPont linkage like Littlegiants, the other is a Helve design much like your contraption.

 

[Stacy E. Apelt - Bladesmith]

I was going to ask if it was jumping all over the place in use. A 1" plywood base would be a good idea. You might even want to set the sheet of plywood down on rubber floor matting to dampen the vibrations even more (HF has interlocking shop floor mats).

The next change after the basic ones needed would be to change the helve to something stronger. I don't see a long life for that handle. Your setup would allow a 2X4" of oak/hickory/ash/maple to be substituted for the hammer handle ( do not use a regular 2X4). Fit the end of the 2X4 into the head and run a lag screw with a big washer in to hold it tight. Put epoxy on everything and tighten the lag screw down to make the head solid.

Other things usually done on builds like this are filling the columns with sand to dampen vibration and add some more mass.

 

[Storm Crow]

Yep, that anvil stand looks highly suspect. I have discovered that you cannot overbuild a power hammer or forging press. I like the rest.

For something along those lines with some help from a few inconvenienced electrons, take a look at these creations of the late Grant Sarver:

http://blacksmith.org/forum/power-hammers-and-presses/50-oliver-or-50ver-grant-sarver-jack-slack/

I particularly like this one. I'd use an eccentric wheel with a tire clutch instead of an engine crank with a slack belt clutch, but the basic design is great.

https://www.youtube.com/watch?v=-tPTLwmxsWc

For one step up in complexity you can build a guided helve hammer. Rather than swinging in an arc and therefore hitting the steel differently depending on how thick it is, the ram moves in a linear fashion so it is hitting more consistently even as the steel is getting thinner. Do a Google search for the Rusty power hammer. The original one had a 15 lb. ram and was powered by a 1/2 hp motor. The one I built (Gunnhilda) is a 100 lb. ram and is powered by a 3 hp 3 phase motor.