Power hammer build

[Ted Ewert]

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

[ThomasPowers]

That hollow anvil throws me off; is someone on the "tube" advocating such nonsense?  Go with solid---or at least with vertically oriented stack of plates. The amount of steel under the hammer die makes a big difference.  (If nothing else to the concrete floor!) I'm using 5.25" dia solid just for a treadle hammer!

How do you plan to vary the size of the gap between the top die and the anvil?   (LG's, Champions, etc use a pitman you can adjust to change the gap.) Every hammer has a zone where it's most efficient; being able to move that zone up and down lets you use the hammer at it's best according to the size stock you are working.

[Ted Ewert]

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. 

20 minutes ago, ThomasPowers said:

How do you plan to vary the size of the gap between the top die and the anvil?

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.

[Frosty]

Ted: There is WAY too much flexion in structural shapes to make a decent anvil. Unless you plan on welding it solid it's not going to make a workable anvil, especially not for a power hammer. 

If you have to build one up then ditto Thomas on vertical plate, as thick as you can get and welded as deeply as possible full length. 

The anvil is the toughest part to come up with. Before I found my 50 lb. LG I was designing a self contained on paper and the thing I came up with for a reasonably good anvil were Rail car axles. They're just under 10" dia. x 48"+ solid 4140 for at least the last 30-40 years.  A good way to get a full length solid weld bead was my main headache. Now unfortunately the railroad operates on a single buyer contract for scrap so they're off my radar. 

I see you just responded to Thomas. No need to do it again, we're on the same page.

Frosty The Lucky.

[ThomasPowers]

I was working on inertia not stiffness---both play a part.

Turnbuckle like a Rusty?

Are you planning to "throw" the top  die---flex of the spring coming into play?

Anyway; it's fun to play with the various options; just faster to get hammering metal by optimizing from the start of the design phase.  My local scrapyard has an ex-navel gun that would make a great anvil for a large power hammer; as I recall, one chunk of it was 40K#.

[Ted Ewert]

21 hours ago, ThomasPowers said:

Are you planning to "throw" the top  die---flex of the spring coming into play?

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. 

22 hours ago, ThomasPowers said:

Turnbuckle like a Rusty?

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. 

 

22 hours ago, ThomasPowers said:

I was working on inertia not stiffness---both play a part

I understand both positions in this argument. We'll see how it goes. 

22 hours ago, Frosty said:

There is WAY too much flexion in structural shapes to make a decent anvil

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. 

[arftist]

Things that are a given;

Round wheels work best.

Fire is hot.

Hollow anvils are a joke.

Same with hammers.

Static load engineering is USELESS when working with dynamic loading. 

The simple fact is that your useless anvil post can be simply remedied. 

Determine what combination of flat bars (thickness) will fill the spaces between your H beam flanges.

Acquire them. Weld into place.

Why put so much effort into making junk?

[ThomasPowers]

The old powerhammer anvil to tup ratios were definitely worked out with a view to inertia, rather than flex; ( IIRC 15:1 or greater was suggested).  There is a paper that was published on this decades ago by one of the big name power hammer manufacturers---anybody got a link to it?

Ahh yes, some references to some good sources here:

 

 

[Ted Ewert]

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

[Ted Ewert]

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. 

[Steve Shimanek]

"You go on over there, General Custer" Little Big Man, Dustin Hoffman 70s movie

[JHCC]

9 hours ago, Ted Ewert said:

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.

Even with reinforcing, concrete is likely to crack or crumble from the hammer's vibration. Welding steel into the cavities would be a better idea.

[Ted Ewert]

20 hours ago, Steve Shimanek said:

You go on over there, General Custer" Little Big Man, Dustin Hoffman 70s movie

"A closed mind is a dying mind" Edna Ferber

[Steve Shimanek]

Funny you mention that, Ted; as you are the one vigorously defending your conclusion in spite of lots of experiences by others to the contrary. Anvil mass is an experiential fact that has been established by long practice, otherwise we would all be forging on I beam or rail instead of 125 plus pound anvils. But no one is stopping you from reinvention of the wheel (anvil).

[Judson Yaggy]

Mass of the anvil matters greatly.  Static load resistance to deflection, what h beams are engineered for, is different than resisting or returning the dynamic energy of an impact.  Concrete and steel react differently to the really exciting live loads we have here and don't couple well in a forging hammer.

[ThomasPowers]

Ted; do you have much experience with powerhammers; or are you coming up with a design based on what? 

Even my old powerhammer would bounce a garage floor slab around in use---you could feel the impacts just standing on the same slab.

I feel that you are re-inventing the jack hammer rather than the powerhammer.     However I am interested in the efficiency of what you build; perhaps an objective test of how many blows it takes to reduce the size of a known alloy at a known temperature to 1/2.  Something that could be run on other hammers as well? (May need to film so a proper count can be done in slow motion.)

[Buzzkill]

I have a question/concern regarding the gear reduction system.  Will there be a clutch or slip belt type system after this?  That looks like a worm gear reduction system and those tend to not "coast" once they are not powered, which in a direct drive situation would potentially be a problem when you shut the power off.

I've personally always enjoyed your non-traditional approach.  It seems you go in with your eyes open and realize it may not turn out well, but are willing to give it a shot anyway.

I've also been bit by the power hammer bug, so I'm watching this with interest.  I'm going to go small to begin with so I can understand things better, and if I am successful I'll have a small removable hardy hole mounted hammer which I'll use on my old-broken waist HB.

[Ted Ewert]

On 10/6/2019 at 7:40 PM, Steve Shimanek said:

Anvil mass is an experiential fact that has been established by long practice, otherwise we would all be forging on I beam or rail instead of 125 plus pound anvils.

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. 

 

 

On 10/7/2019 at 12:29 PM, Buzzkill said:

Will there be a clutch or slip belt type system after this?  

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.

[Ted Ewert]

1 hour ago, ThomasPowers said:

Ted; do you have much experience with powerhammers; or are you coming up with a design based on what? 

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. 

[JHCC]

32 minutes ago, Ted Ewert said:

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.

Pictures?

[Ted Ewert]

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.

[ThomasPowers]

Jackalope?---Mount horns on it!

I suggested an objective measure of efficiency test as; if you were inexperienced you would need a method of deciding if any changes you make help or not.  (I've run into folks claiming their cast iron anvil had a good ring---thud rather than !TING! as they had never heard a "good ring" and so assumed that what they had was good.)

Please think of visiting other smiths with various types of power hammers (air, mechanical, water powered...) to get an idea of what's out there already and how you can improve on it. (The tube is just not the same...)

[Ted Ewert]

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. 

[ThomasPowers]

The California Artist Blacksmith Association lists several members/officers in Sebastopol; have you contacted them to see if anyone is closer to you?

We had a fellow here once telling us that there were no smiths around him---till he contacted the local ABANA Affiliate and found that the president lived on the same road he did...

I have horns on my disreputable smithing hat---I tell folks that it keeps people from sitting on it when I use it to hold my chair.  Well at least not twice. Started with spikes; but when that hat fell apart I put 2 pointers on the new one.

I also have a deer mount in my shop---I was at a garage sale and they had it.  Nice rack and I thought of handles---but expected it was way out of my budget.  However the lady noticed my looking at them and asked me how much I would pay.  I told her it was way under what it was worth; but I had $5 in my wallet. I guess she was very tired of it---now it's on the wall of my forging shop storing the antlers till I need them.

[FlatLiner]

I for one am intrested in seeing how this powerhammer build ends up, and seeing how well it funcions.