Ted Ewert

Thanks for the info Frosty. I've started to build the foot control mechanism but I'm still working out how high I want the fulcrum position. I spend a lot of time staring off into space trying to figure out how I'm going to build one part of the hammer or another. Been a fun build so far. It's never a bad thing to build something which stretches your abilities a bit. Power was out all day yesterday, but supposed to come back on today. At least there haven't been any fires in my immediate area.

Matching the right amount of spring to the weight is going to take some fiddling. Getting the maximum amount of snap at just the right moment is going to take even more fiddling. I did manage to make a longer crank today. I'm trying to get in as much shop time as I can before #@&**# PG&E turns my power off! It's about 70 degrees with no wind here and they're threatening to turn the power off! Crazy times...

Thanks eseemann for the interesting history tidbit. The Zulu's are great warriors. I got my hammer mostly assembled and it came out at just over 30 lbs. The main body is 3" x 3" x 12", and is made up of nine 1" x 1" solid bar pieces welded and pinned together, with the center bar longer and used as the connecting rod. I decided to go with a rectangular steel tube as my hammer guide. For the bearing material I bought some UHMW (Ultra High Molecular Weight). This stuff is supposed to be better than PTFE (Teflon) as it is specifically designed as a multipurpose bearing material. It is self lubricating and engineered to work with metal surfaces. Sounds good on paper anyway, so we'll see how it holds up. Frosty, we're on the same wavelength. I just wrote the following and then your post popped up! It was mentioned earlier that most cranks are 3.5" inches, whereas mine is only 2". Theoretically it shouldn't make any difference as you can adjust the position of the drive point for any desired hammer throw. However, there is a catch. The closer you get your drive point to the fulcrum, the stiffer the spring is. This affords less shock absorption than if your drive point is further out on the spring. This is more of a concern with a speed reducer in the drive line than it would be with just pulleys. The armature in an induction motor will take a lot of shock load without damage. A worm gear speed reducer is a one way device and much more susceptible to shock damage. I may have to build a new crank.

Thanks Buzz, I'm looking forward to pounding some metal too. This design is a conglomeration of several different hammers. I'm still trying to decide if I want to use square tubing lined with plastic, or a T slot for the hammer guide. I'm leaning towards the T slot because it would be fun to build.

Thank you all for the input. I'm sure I will make many changes once the thing is up and running. I just got through building the drive linkage. I had to build a turnbuckle since none are available in fine thread. I used a couple of pieces of 5/8" square stock and a couple of nuts welded together. Works good. The turnbuckle will allow me to adjust the height of the hammer, and the clamp on top will allow for stroke length adjustment. The core of the hammer is going to be four 12" pieces of 1-1/4" square stock which weigh 20 lbs. Adding the end plate, connecting rod and other pieces should make it close to 30 lbs. I can always add weight if desired.

Well, thank you for the information. It's easy enough to swap pulleys if I need to. I'm still going to try it out at this speed to see how the whole mechanism works. I don't know how heavy the hammer is yet, so I'll have to see how all that pans out. Just for the sake of discussion, BPM does not necessarily dictate velocity. The velocity is dictated by the geometry of the lever times the BPM. The closer your drive arm is to the fulcrum, the more distance your hammer will travel. More distance equals more velocity at the same BPM. Also, raising the BPM rate requires more power for any set configuration, since more work is being done. So, I could shorten my stroke and raise my BPM, but the same amount of total force is being delivered to the work in any given time span. It comes down to a preference between big heavy thumps or a bunch of lighter thumps.

About 180. If it's too fast I'll adjust the pulley sizes to slow it down. What difference does it make?

I have had some difficulty trying to find heavy solid steel in my area. I don't own a truck, so whatever I get has to fit in my wife's minivan. Besides, I still think this anvil will work just fine. If I'm wrong you guys will be the first to know, and you can all take great satisfaction in telling me "I told you so". Until then, I'm moving on...

Thanks for the vote of confidence, precious few here. I was watching a video of an old power hammer today and it also had hollow anvil. I'm not worried about it, but it seems to bother some folks.

I got the "transmission" part of the build pretty much done. This includes the pulleys, belt tensioner (clutch), and cam. I'm not entirely happy with this belt tensioner, but I'll see how it works. Here's the Cam. I built it from two pieces of 3/4" square bar. The reason for this was so that I could mill a key slot in the 1" hole after I drilled it. I then pinned and welded the two halves back together. I'm using two of these 3/4" rod ends with a turnbuckle for the link to the spring. These things only come in fine thread (3/4-16) so I'll have to build a turnbuckle for them, as most turnbuckles are in course thread.

Thanks, not a bad idea.

I'm in the process of building the drive train for this hammer and was wondering how heavy of a hammer this motor can support, so I did some calculations. The 1.5 hp motor produces 2.2 ft /lbs of torque. Converted to inch pounds: 2.2 x 12 = 26.4 in / lbs The speed reducer is a 10:1 ratio. The speed is reduced by 10 and the torque is multiplied by 10. Therefore: 10 x 26.4 = 264 in / lbs on the output shaft. I will be using a 2" cam which will half the 264 in/lbs to 132. So, I have 132 lbs of force when the cam is at 90 degrees to the load, which represents the maximum load on the motor throughout the cycle. Then the ratio of the distance of the drive point on the leaf spring with respect to the fulcrum, and the distance of the drive point of the hammer need to be considered. A 2" cam will travel 4" vertically. If I want 8" of travel for the hammer, that represents a 2:1 distance differential which will cut my force in half. 132 / 2= 66 lbs In this configuration a 66 lb hammer is my theoretical maximum. In the real world we have mechanical losses and other inefficiencies, so I'm thinking a hammer around 30 lbs would be reasonable. I'm also thinking that the more travel I have on the hammer, the more velocity I can develop. I would rather have a lighter hammer with more potential velocity to play with. Discovering the properties of the spring (springs) will determine the best configuration. Just some thoughts...

It's 34 inches high. That's a good working height for me. I figure another inch or two for the die.

The way I built it I don't think I'll have any trouble with the concrete. As I mentioned above, the concrete is not load bearing and merely serves as a dampener and stiffener. Here is a picture of the rebar config. There is also a solid 1"square bar in the middle on each side to support the point of impact. Here it is after the pour: When I hit the top with a hammer there is no ring at all, just a thwack. Concrete is a wonderful noise suppressor.

Me too! Thanks for your interest. Thanks, I'll look into it. I'm definitely putting horns on it. I'll make them as a first project on the hammer.

I like the horn idea! Maybe a horned woodpecker motif. I don't know any smiths in my area, let alone one with a power hammer. Like everything else I do, I'm just going to build it and see if it smashes hot metal to my satisfaction. The hammer weight is a big question for me right now. I'm thinking of building a hollow structure where I can add or subtract weight (I know, hollow hammer bad). I want to keep the weight under 50 lbs for now.

You can see the plates in this picture. I installed the two 1" bars from the bottom of the gusset to the base and also welded them to the web. I have another picture at home I'll post later which shows the column before pouring the concrete.

I have zero experience with power hammers and I'm designing this based on what I have read and seen on YouTube. I've earned a masters degree in YouTube watching ya know. This is one of those "here, hold my beer while I build a power hammer" experiments. I'm sure I'll end up rebuilding it several times, but I like doing that. Nevertheless, you have inspired me to name the hammer Jack.

A traditional blacksmithing anvil and a power hammer anvil are two different animals. Working the horn or side (or anywhere else) of a small anvil vs a large anvil is where mass plays a big roll. In that case, mass prevents movement (inertia). This is why a bigger anvil works better than a smaller anvil. It all hinges around resistance to movement. A power hammer anvil has to resist movement in only one direction, which is vertically. It has none of the lateral or leverage forces of a traditional anvil to deal with. Therefore, it's design can be significantly different and still be functional. Resistance to a repeated vertical shock load is the only requirement. Mass and inertia are irrelevant since the anvil is bolted to the floor and is not moving anywhere. Strength and rigidity are the primary considerations. The only failure this type of anvil is susceptible to is deformation, which consists of flex or compression. An H beam is highly resistant to any form of flex due to its configuration. It will ring, but it will not fail to perform due to excessive lateral flexing (at least not one of the size and length I'm using). That leaves compression. I don't know what the vertical load rating for this particular beam is, but it's far beyond any force, let's say, a 50 lb hammer can exert. This beam can easily support 10 tons of dead weight. I understand that the hammer hitting the beam is a dynamic load, generating far beyond 50 lbs of force, and a shock wave can cause deformations which a static load cannot. Nevertheless, I have taken steps to minimize any localized deformation by spreading the shock load to the entire beam through the use of thick steel plates. I have also installed two 1" solid bars down the center of the beam to further reinforce the point of impact. Vibration and noise are the other concern. To mitigate this I have poured heavily reinforced concrete into both cavities to lower the resonant frequency of the column. This concrete is NOT load bearing, but rather serves to stiffen and dampen the column. If you guys think I have missed anything here, I would be glad to hear of it. As mentioned above, the argument of mass and inertia is a moot point, unless you think the earth moving itself is significant. If it makes you feel any better, this anvil now weighs around 100 lbs, so it does have some mass. Yes, I will be using a slip belt clutch between the reducer and the cam. I'm still waiting on parts, which should be in this week. I did see a video where a guy used a gear box in a direct drive configuration and it seemed to be working alright. The leaf spring will absorb any sudden loading, but it seems to me it would put a lot of stress on the drive train anyway. Plus, there's no way to control it except off and on.

"A closed mind is a dying mind" Edna Ferber

I'd like to make a comment here. I occasionally use materials and designs which don't conform to the traditional or generally accepted way of doing things. In doing so I'm not attempting to reinvent the wheel. Rather, I think to myself "why not?". I then go through an extensive analysis of what is needed in the material or design to adequately perform the intended function. An H beam is a solid steel structure which has been intelligently designed to provide maximum load bearing properties with a minimum amount of material. It's geometry is such that it can not only bare a substantial vertical load, but will also greatly resist any form of lateral deformation. So, why not use it? How is it going to fail in the configuration I'm using it in? I have an inch and a half of steel plate on top to distribute the shock load from the center to the flanges. I have two 1/2" steel gussets to minimize any center deflection in the top plate. I am going to fill in the cavities with reinforced concrete, mainly to quiet it, but also to add a measure of stiffness and mass. The column is welded on to a 12" x 12" x 3/4" plate to distribute the load out. I will then bolt it to my concrete floor which rests on bedrock. Where is the weak link? "hollow anvil bad" is not a valid argument. Give me some logical reasoning why you think this won't work and I'll certainly listen.

Thank you both for your thoughtful comments. I never intended to leave the anvil hollow. Thomas: inertia should only be considered if the anvil has movement. For instance, an anvil which is just sitting on a stump. This anvil will have no movement since it will be securely bolted into concrete. Therefore, stiffness (rigidity) is the only criteria, other than noise, to be concerned with. I received the motor and speed reducer, and built a mount on the rear post. The motor mounts vertically due to the right angle of the reducer. If anyone decides to buy one of these rigs in the future, I recommend buying the reducer output shaft (which is an accessory) for $15. It slides in easily and has a snap ring to hold it in place. You also have to be mindful and make sure your motor has the same NEMA mount as the reducer. These two fit together perfectly. I plan on making an additional support bracket for the reducer so all the torque load isn't on the part which connects to the motor. It might not be necessary, but there's a lot of torque and a cracked housing is the end of the reducer (as they are filled with oil). The motor will be on the back of the column, along with all the pulleys and linkage bits. Ted

That's an interesting topic. I do plan on some throw since I think that will be optimal for power generation. A golf club is basically a hammer on a spring. As you can see in this illustration, the shaft is pretty straight at the point of impact. This would indicate the point of maximum velocity, which makes sense if you think about it. K.E. = 1/2 m v2 (Kinetic energy equals 1/2 (mass X (velocity squared) ) It's the velocity squared part which matters most. I might have to take some videos of the hammer to see at which point the spring is straight. Don't know what a Rusty is, but a standard turnbuckle using threaded rod is what I was envisioning. Perhaps some 5/8" or 3/4" rod with a couple of rod ends on them might serve. I understand both positions in this argument. We'll see how it goes. I'll have to respectfully disagree with regards to an H beam on end (which is specifically designed for vertical loads). Again, we'll see.

I couldn't find any solid stock, so I'm going to see how this works. I've been down this road with the whole anvil stand argument, so I do have an understanding of the physics involved. Unless this H beam deforms, I don't see how it can be any less stiff than a solid piece. It will also be bolted onto concrete. I will ring like a bell, so I plan on filling in the hollow space with reinforced concrete to dampen, and dare I say, stiffen the column. If it all falls apart, or fails to perform, I'll go to plan B. It will be an interesting experiment in either case. I was thinking of using a turnbuckle in the drive side connecting rod to make those adjustments. The initial length of the rod will take into account the size of the dies I eventually come up with. I'm sure there will be a lot of tinkering involved once I get it running. Thanks for your input.

I watched a lot of power hammer builds on YouTube so I decided to build one myself. I really just like to build machines, and this one will also happen to be useful. I went to the steel yard and bought a bunch of "cutoff's", which they sell for 60 cents a pound. I got some H beams, 3/4" plate and some other heavy bar stock. I built the anvil first, which I'll reference everything else to. It has a comfortable working height and is composed of a 5" X 5" H beam on a 3/4" thick base. I beefed the top up a little by adding some inserts inside the beam as well as a couple of gussets. The top plate is attached by 4 bolts which screw in from underneath. I will need to have some sort of mechanism to hold dies, which is easier to build when the plate is detached. I also built the top rocker assembly for the springs. This allows for easy spring rearrangement. This should keep the springs aligned as well as providing a strong pivot point. I'm not sure how much lateral stress is going to be placed on the 3/8" bolt, but I can beef it up if need be. I'm using an I beam for the taller support piece. This will also be on a 3/4" plate which will be bolted to the floor. The general plan is to use a 1.5 hp motor @ 1750 RPM coupled to a 10:1 speed reducer. That will produce approximately 3 cycles per second. I then plan to use a couple of pulleys to transfer the power to the crank. I will also use an idler pulley between the two drive pulleys for a clutch. I can adjust the cycle frequency in this pulley assembly, and would welcome suggestions since I'm not sure what the optimal frequency is. I decided on a speed reducer because trying to get a 10:1 reduction with pulleys is just too many pulleys and bearings, and the total cost isn't that much more. It will also be a simpler and cleaner installation. I though about using Pneumatics, but I don't want to have to buy a new air compressor and the valve control mechanism made my brain go fuzzy. Frankly, I have never even used a power hammer. I'm going into this semi blind but I have a pretty good grasp on the mechanics involved. I've built other similar reciprocating devices (don't ask), so I'm familiar with the concept. The leaf spring came with 4 separate leaves, so I can mix and match to suit the hammer weight. I'm using 20" of the I beam for a hammer, and I have a piece of rectangular tubing which it will fit nicely into (with space for (PTFE?) lining). I can add steel in the channel of the beam for weight to get somewhere around 40-50 lbs. Frequency vs weight vs spring tension vs stroke length all have my head spinning. I figure I'll sort it out as I go. Helpful suggestions are always welcome! Ted