Power hammer foundation follow-along

[anvil]

Do I have this right? You dont have much experience as a blacksmith, Your shop setup has been critiqued a poor, Your shop is pretty narrow, You dont know how to use these tools, and now you have a major expense trying to create a proper setup for one, but not all, of some rather large tools. I don't like to be negative but your project creates a real sinking feeling in my gut, you might say.

[Jarntagforge]

15 minutes ago, anvil said:

Your shop is pretty narrow, You dont know how to use these tools

Please don't comment on this thread anymore.

[anvil]

Did I say something thats not already been said?

[Frosty]

There's nothing about that soil that isn't labor intensive to build anything that'll support your power hammer without causing problems.

How large a diameter rod can you push to the bearing layer by hand? What diameter rebar did you push in the video? Maybe cap a larger dia. piece of water pipe and try that. The soil may have more lateral resistance than I thought from watching your video. It looked pretty effortless. 

How deep do you sink into the mud when you're standing in the pit?

I looked back and realized I probably confused you when I used the term cage earlier. What I meant was the steel welded around the pilings forming a cage like box to keep the angled piles from spreading under the weight and forces of the running hammer. It's not a separate structure like you  drew. 

I sure wish I could visit for some boots on the ground time, this is too easy for either of us to misunderstand. Distance and different languages aren't helping. 

Do you have or can you get enough I or H beam to make the pilings? It's much less likely to walk when the hammer is running.

Frosty The Lucky.

[Glenn]

2 hours ago, Jarntagforge said:

Please don't comment on this thread anymore.

If comments bother you, use the sites ignore feature and you will not see post from the members you choose to ignore.

Or do not choose to open the tread to see if there were any additional posts.

[Jarntagforge]

6 minutes ago, Frosty said:

I sure wish I could visit for some boots on the ground time

You're welcome to visit! The iron rod was a smooth iron bar, 16 mm. I went out again and stuck it down and bashed it with a hammer. It rebounds hard like it's bedrock. The depth of refusal is 170 cm below the pit floor. I can push a 50 mm pipe perhaps two feet until it starts getting tough. Haven't tried hammering on a pipe yet. The mud is such that one doesn't sink down more than a couple centimeters. Do you mean I-beam is better than a pipe? I don't have more than 2 piles worth of steel lying at home. I will have to source more somehow. I think it would be smart to put as many piles as practical. For example if one would catastrophically wander off.

[Frosty]

That's much better information, I hope I don't drive you crazy asking for more. 

Does pushing the 16mm rod get easier, harder or remain the same as you advance it? This will indicate if the material is consistent to refusal or is layered and can help determine a foundation strategy.

I'd like you to "map" the refusal depth with the 16mm rod and hammer. Just repeat the "test" in the corner pile locations and where the one directly under the anvil. Getting an accurate depth would be nice but a good estimate is a starting place. A reference mark you can measure from would make it as good as it gets. Level string lines corner to corner across the pit is pretty much standard industry. A laser level like I picked up at a yard sale would be perfect but not necessary. Anyway, when the rod stops and bounces just measure from the top of the rod to the string level and write it down.

Don't worry too much, 5-6 probes will tell us if the layer is: level, slanted, smooth, rough, etc. and give you a good idea how much steel you'll need for piles. 

Yes, I beam will be much better in this situation, not for it's strength but for it's shape. The I beam's profile has 8 flat surfaces and 4 inside corners to make it hard to shift sideways. Walking is a sideways shift in position. If you've ever watched a vibrating machine on a smooth paved surface you've seen what I refer to as walking. 

It's not sounding like as much of a problem as I thought at first. 

We'll get it mounted solid as stone.

Frosty The Lucky.

[Purple Bullet]

On 10/27/2021 at 11:56 AM, Jarntagforge said:

Does anyone know how to go about welding the lower level, if it's still wet then. I looked up welding in wet conditions on Google and every single page say it can be done but that it's life threatening. I know the current should want to go the shortest way so I should put the ground right next to the place where I weld. But I'm unsure of what makes it dangerous. Forgetting the ground is all I can think of?

I realize an alternative has been suggested so this may be moot. It has been many years since I did this, but this is what I recall for underwater welding: Use a DC machine only, small rod and high heat. Use only low carbon steel and wrap the rods with freezer tape to hold the flux on. We also had good success with airplane dope to coat the rods. You have to rub the tip off before you start the weld if you use airplane dope. Much of the time we had zero visibility, but we had something you may not have, a knife switch operated by a tender. We could rub the tip to expose the steel, feel the crack or the fillet to be welded, make contact and instruct the tender to "make it hot". That way current was always preferentially going through the rod to the grounded metal. We wore rubber gloves under cloth gloves but you would still taste your tooth fillings when the current was on. The technique to weld was to NOT try to work a puddle but try to hold a consistent angle and use the self-consuming method. If you have ever run jet rod it is the same technique. The weld will probably be bumpy and lumpy. Use an air grinder to smooth it over before putting at least two more welds on top. The heat from the top layers will give the metal below a chance to anneal a little. 

Without a tender and knife switch, I don't think I would try it. It would likely be easier to fabricate a clamp if you need to attach something reliably underwater. The main use we had for underwater welding was making sure anodes installed on an offshore structure had good electrical connection to the structure. For strength they were clamped. Any weld that needed strength was done dry inside a habitat.

[George N. M.]

I'll put my oar in and suggest that if it turns out to be too difficult or impossible to construct an adequate base given the soil/ground water conditions and the fact that you are doing this inside an existing structure that you may wish to consider some alternatives.  I have known of power hammers which were mounted on a wooden platform made of railroad ties or large timbers which were set on the ground or in a shallow pit.  Another option might be a large, reinforced concrete slab (think 100+ mm) poured in place or dragged in.

What all power hammer foundations do is provide enough mass and resistance to keep the machine from walking when in operation.  Any way you can provide that stability will work.

"By hammer and hand all arts do stand."

[Purple Bullet]

Thanks for posting that, George. When I got my 50# Little Giant, I just drilled through the wood floor of my cargo box, drilled about 4" into the concrete slab, welded an all-thread to extend the 3/4" Redhead anchors up through the air gap, 3/4' marine  plywood floor, through a 3/4" rubber mat (came with the hammer and the holes were already cut to fit) and up through the hammer base. I've been hammering happily ever after, but when I look at the lengths some folks go to it makes me wonder.  

[Jarntagforge]

The baby came knocking and so all work stopped for 2 weeks  A super healthy little girl with an inch long brown hair. Grows very quickly too! She's put on 2 pounds already. How amazing babies are!  All in all the hospital cost was 250 € for 2 days stay, food included. Not bad! The mother will get 9 months paid leave from the state, and that's a good thing because this baby is a full time job!

I found some time now and the foundation work progressed as shown below. I wanted to get rid of the water so I pumped it out and then installed a temporary drainage system. Temporary as in the black pipe which houses the pump will be removed later when all is done. The white pipe can stay. I built a wooden form to keep the walls from caving in. There's plenty of empty room around it, yeah, but at the brick wall we filled soil back behind it, more than it seems from the photo, so the dirt under the brick wall will stay put, at least.

I put a white filter cloth on the pit floor so I can fill gravel and get an even and stable floor. Dad cut it a bit too long.

But before the gravel I will have to drive down piles. I'm looking at 80x80x6 mm square tube. The professional pile driver said 90 mm round should be enough, and 80x80 has more steel in it so it should be good.

On 10/29/2021 at 2:59 AM, Purple Bullet said:

my 50# Little Giant

There's a big difference between a 50 pounder and a 165 pounder. Then there's the thickness of the slab, soil properties, etc.

[Purple Bullet]

Congratulations! Children are a blessing. Sometimes a challenge, but always a blessing. 

I wasn't disparaging your efforts or preparation. I have heard of similar efforts taken for smaller and lighter hammers such as mine and it makes me wonder if my foundation is sufficient. So far it is, but then again my shop is not what you would call a heavy production shop.

[Jarntagforge]

Since I last posted I insulated the walls and ceiling and I added a vapor barrier. I was worried the pit would freeze up. The greenhouse effect, ground heat and sort of airtightness will keep the shop a few degrees warmer than outside. I'm thinking of installing a single gypsum wall sheet so I can order a heat pump and have it installed it in its final place right away.

Talking to Frosty, he suggested making a depth map by hammering an iron rod down until it hits bedrock. I did so and I hit bedrock 1.5 meters down. I found 1.1 meter long pipes on an auction site which I welded end-to-end, giving me 2,2 meter long piles. 80x80x6 mm.

I made a pile-locating jig which I'm standing on in the picture. It was a good idea, but after looking at the depth map I shifted the piles around to hit the higher spots.

Just yesterday I got all the piles driven down. It went very easily with the tractor front-end loader and the bucket. We used it as a press first and a hammer at the end. The bucket weighs, perhaps 200 kg?

One of the outer piles kept going down, slowly with a lot of force. I don't know if it started skidding on a slope or what it is. I guess I'll either hammer it down more or pull it up again and push it down somewhere else using the tractor.

The next step is to weld angle irons and rebar between the piles to provide lateral support for when the piles start walking. It will also spread the load of the concrete between the piles and will give more bearing surface for the concrete to avoid point-loading.

[Jarntagforge]

I do wonder about anchoring the hammer. If I were to cast threaded plates inside the foundation with pipes going up to the surface, and insert threaded rods after the hammer is in place, then I would have to do that now. The other alternative is to drill the concrete after the hammer is in place and epoxy the bolts in place.

Back in the days they used worse steel, perhaps that's why they wanted the longer bolts. Long bolts that can stretch. Short bolts don't stretch much, they break. That's the only reason I can think of. But also a bouncing machine perhaps could do better with "stretchy" bolts? Hard to say. Long bolts are probably better but they're also a lot of extra work and I'm just a hobbyist.

I was told by Roger Lund, the industrial blacksmith, that the hammer should stand on concrete. It should stand on a few bearing points 30 mm in the air, and then be grouted in place. So there's no bouncy material under it at all. Then the bolts don't break. The anvil should move instead.

[FatBadger]

Looks awesome to me mate. Passion and drive are 3/4 of any project as far as I can tell. But I'm more of a rookie than you.  So I guess we'll have to try and power thru our shortcomings. I'll watch for more updates to see how you turn up.

Good Luck,

[Frosty]

I wouldn't worry about the one pile that kept going down, one out of six isn't significant. 

You don't have an industrial type power hammer, you don't need to do anything special to keep it in place. Grouting it in place might be just the thing if you're using a 500kg power hammer in a production shop but you're not near that league.

Mine sits on a concrete floor with one square peg in a gozinta and it hasn't moved enough to make the peg tight.

Bolting it down is a good thing so you need a bolt pattern template. Place a piece of plywood under your hammer that's several inches wider and longer. Trace around your hammer's foot with a felt pen or something to make a distinct mark. using the anchor bolts tap them into the plywood enough to make a clear mark. Is that clear? Drill the bolt holes in the template a little SMALLER than the bolts so you have to force or screw them into the template. This is what keeps them in place and straight. Make sense so far? The last thing to do to the template is make a largish hole or two in the center say 60mm or larger so you can see when the concrete is up to the template. 

You know where you want the hammer pad surface, IIRC level with the floor. Yes? Screw a couple boards long enough to reach across the pit and rest on the sides to the template. If you lay your template over the pit and measure you'll notice the template will actually be too low, it's top is flush the floor. Yes? Easy fix, screw scraps of the same plywood as the template to the ends of the boards. This will elevate the template till it's bottom is at floor level.

Make sense so far? Good.

The anchor bolts should be grade 5 or better though 5 is more than good enough. They shouldn't be tight in the bolt holes in your hammer foot but close. You need enough bolt sticking up to clear the hammer's foot farther than a nut and couple washers. 

The total length of the bolt needs to extend through the hammer foot and about 6" into the concrete pad below. A LITTLE more won't hurt but do NOT get carried away, you'd rip the foot off your hammer before pulling even one bolt up through 6" of concrete. Honest, I worked in a test lab and we did exactly that. That was an awesome machine, when it would break a 5/8" bolt it would shake the whole building. 

I suggest lag bolts that reach through your hammer foot and extend 6" into the concrete pad. Put ONE thick wide washer on each bolt and use a twist of wire to hold it at the hex end.

Screw or drive the bolts up through the template to the correct height and secure them. If a nut will screw to contact with the template use a washer and nut. If not wrapping a bunch of tape or wire will work though it's not my favorite.

Now what you have is your template adjusted for finish level with the anchor bolts in place. Place your template where you want your power hammer bolted down. This is where tracing the outline of the power hammer foot on the template comes in. You'll be able to visualize the hammer foot, front, back and sides so you can get it exactly where you want it. Yes?

Once in place tape it down to the floor so it can't get bumped out of position without you knowing. This is important, you'll be doing some hard labor right THERE and you don't want the template to move.

Now is time to pour the concrete. You'll need to push concrete under the template so it fills the space completely, be careful not to bump a bolt too hard. This is where the sight holes in the template come to play, you'll be able to see the concrete and air can't be trapped. You don't want to push concrete till it's pushed into mounds at the sight holes or you'll have to grind it flat once it's set.

I know that's a lot of explanation but I tried to cover as much as possible. Once you've done it once it'll be easy as eating scramble eggs.

If you have questions give a shout.

Frosty The Lucky.

 

 

[Jarntagforge]

Next up was steel reinforcements. I thought about using layers of mesh steel throughout, but Frosty reminded me to think like an engineer and put beams to resist the bending moments. The lengthwise beams resist bending in the lengthwise direction, the widthwise beams do the same for the width direction. Had these beams been close together resembling a cross, then the weak bending plane had been along the diagonals, that's what the crossways laid U-beams are there to resist. In practice I put the beams so spread out that there were no weak bending planes. The U-beams are also 3 inches higher up than the rest. Not much, but room for some concrete in-between. Too much iron in one spot weakens the block.

What bending, you might ask. Well the hammer is a 2 piece so the anvil will be in a pit. So the weakest place of the concrete is right under the anvil. What if water seeps up into the block and weakens it, and the hammer blows out the bottom of the pit? Most likely it would never break, but who knows. I feel better about it this way.

I found scrap 30x40 mm U-beams in the backyard which is perfect for reinforcement in the concrete block. I welded them to the piles using a stick welder, Finnish Kemppi Tylarc with long cables. I had pumped out the water previously. I was still standing in some water but I was wearing rubber boots, I was not on my knees or otherwise wet. I welded the rebar to the piles well because I want more bearing surface for the concrete than the tops of the piles. I wanted many places for the concrete to grab onto. Remember, there's no bearing force for the concrete from underneath. It's soft silt mud. Basically the concrete block will be floating on top of water, standing on the piles which stand on bedrock.

Today I put gravel in the pit on top of the filter cloth. It's impossible to get good compaction of the gravel when there's mud underneath but I went around the form with a 2x4 and compacted it as best as I could. I put the gravel there to get the pit floor to the level I want for the form. Concrete doesn't care, but my form needs to be at shop floor level. And the form will stand more stable on some gravel.

[Rojo Pedro]

Too cool.  Bet it works a treat. Thanks for sharing

[Jarntagforge]

Time flies. Our daughter got her name one weekend so we celebrated that. She got the name Freja, pronounced Freya with a rolling R. Then the next weekend I exchanged the 50 year old dried and cracked boards before the heat pump could be installed. I weighed all options and this was an easy install and the price fit the budget. It cost 2400 € with the install. I'll just have to cover it up if I do some REALLY dusty work, and turn it off when I do blacksmithing. Because it circulates the air in the room when it heats it up. It does have a filter, though, which needs to be rinsed every now and then.

I was told the U-beams I welded in place were too smooth so the concrete wouldn't grip onto them. And large cracks could start growing along the beams. So I cut them off and welded 12 mm rebar to connect the pipes. Then a mesh on top on top of those. On top of that two lengthwise rebar, two widthwise and two in an X. The X is some 100 mm higher up. I want these in place so that the concrete under the anvil for sure won't crack. Then I put mesh along the sides and I will put some near the top surface later.

The form is not done, obviously. I will put 2x4s on a few levels around the 9 mm plywood. Then I'm thinking I'll reuse the U-beams outside the form. I'm going to stick threaded rods out of the form past the 2x4s. Outside the 2x4s I'll put U-beams vertically and pass the rod through them, so the U-beams keep all of the 2x4s from bending and splintering.

Today I welded up 3 mm sheet steel for the elevated "platform" for the hammer. I bought these pieces ready-made. Which saved me a lot of headache. Slowly but surely it's all coming together.

[Frosty]

That looks a LOT better than all the structural steel. It's going to be way more than strong enough for your hammer and the piles will keep it where it's supposed to be.

Well done.

Frosty The Lucky.

[Jarntagforge]

My apologies for not sharing the progress sooner. When I got this done I relaxed and started thinking about all the other stuff I need to do. For example, rip out the concrete floor in this workshop so I can put polystyrene under, and pour a new good floor with floor heating. Also I need to renovate a house...

In the pictures below you can see the platform with reinforcements. I welded the rebar to the sheet steel so all of it became very rigid. I took measures to avoid the bolt holes.

Next picture is the form with mesh steel near the top surface and sides. I welded threaded rods to some rebar and stuck that out of the form, past the 2x4s into channel iron, to brace the sides. We welded them on the spot.

Third picture shows the box for the anvil hole. I made it from plywood with wood braces inside. It was nailed together from the outside so it all comes loose from the inside with a crowbar. The bottom plywood sheet of the box was put inside of the standing sheets, so as not to get jammed in the concrete. Hundreds of small details with all of this. I hung the platform on top of the form by welding 50x50x5 mm angle iron to it with 3 thick weld beads. I figured the form would be strong enough to hold the platform with a bunch of weight on top. I put about 2 screws from inside the plywood out into the 2x4s around the box. So they work together and are rigid. The weight on top is also the reason I put the topmost 2x4s standing on edge. Just improvising. This could be done in many ways.

Fourth picture shows the box in place. I simply screwed boards to the 2x4s sticking up out of the box and lowered it in place. I put some extra 2x4s there to share the load of the weight I put on top. I also screwed the middle boards to a board that was fastened vertically to the form. So the anvil box can not float up without lifting all of the form.

At first I put about 100 kg weight on top. Then I added more so the total weight was 210 kg. I figured it would be enough as the volume of the anvil hole is about 210 liters, which if it were water would weigh 210 kg. Turned out it wasn't enough.

[Jarntagforge]

Then there was the day of the pour. The company called and asked if they could come sooner than agreed. I said no, then I got a text message: "We're on our way!" 45 minutes too early. Hehe. It was fine. These concrete trucks are enormous! We started using the vibrator as soon as there was some 20 cm concrete in the form. We didn't use it nonstop, but short bursts throughout the pour to make the concrete flow everywhere. The elevated platform kept its concrete without problem. The concrete didn't sink down in it.

Then at some point we noticed that the box for the anvil hole started lifting up!!! The weight wasn't enough! We hurried and carried an anvil on top and two batteries. Fortunately the box was screwed in place!!! That's probably what stopped it from rising further. Talking to Frosty, I was told 150 lb weight per cubic foot displaced concrete is a good rule of thumb. Following that, I would have needed 500 kg. About the same as the amount of concrete that would fit in that same hole. I had 210 kg. Well, I was lucky. The end result was only about 8 mm difference in hole depth. I can compensate that with the wood I'll place under the anvil.

The concrete I wanted to use would have been SR-concrete, sulphur resistant. Because as the ground here is an old seabed and full of dead organic matter it's also acidic. I think that's why, at least. Acids eat steel and concrete. When they make bridge footings around here they do piledriving with stainless steel pipes. I used regular mild steel pipes. They didn't have SR-concrete in store right now but they had "bridge construction concrete" which was K45 xc4 xf2. 4 classes higher strength than regular, high water tolerance and some acid tolerance. I was happy with that. The pipes rust some 1 mm per 20 years, or was it 50? So it'll stand 120 years. Good enough.

[Jarntagforge]

That's my dad in the pictures above. On the picture where the form has lifted one can see I put some pieces of sheet steel between the platform frame and the 2x4s. Small details. I thought maybe the boards would sink into the frame and I would have no control of what I'm doing otherwise.

If I were to do this again I would do it differently. The angle irons would be welded some 50 mm higher up on the frame so they wouldn't be in the way for finishing the concrete. Same with the wooden boards above the anvil box. To handle a 500 kg load on top of the anvil box I might have braced the form differently. Maybe two diagonal braces from the top middle of the sides down to the bottom corners of the sides.

I removed the form the following day. The block was warm from the chemical reaction. Very cool. When I removed the anvil box it steamed from under it. I put a thermometer there and it read 33 °C ! My dad suggested we'd cover the anvil hole box in plastic so it would come off easily. I wasn't keen on the idea but I thought let's try it. The plastic fused to the concrete. Don't know what to think of that. I watered the block some, one time the day after the pour, then again 3 days later. Yeah, I realized later that I should have watered it every few hours for the first few days. But I did go back a few times more to water it. I didn't realize how much watering it needs. I read it becomes about 50 % stronger from proper watering. But then today 2 weeks later it stood in 30 cm water, however. It has been raining. We pumped it out.

The block turned out fine! It became quite uneven around the anvil hole due to the boards, but I can grind that flat. The angle irons also left marks. All in all I'm happy with it. This is as far as I can go at the moment. Now I'll saw the floor in pieces and start working on a new one.

I've decided to leave the black drainage well pipe in place and lengthen it up to floor level. But I'm not sure how to think about that. When the floor is done and the hole is all filled in, who cares if there's water down there? The concrete doesn't. I think I'll run a small diameter pipe from the drainage well to a floor drain. From there it would then flow onwards and out. So if I want to I can leave the pump in the well, pump water up into the small pipe, which goes to the drain, and then it would flow out by itself. The other alternative is to rip out the drainage well and do nothing. It feels right to pump out water, but perhaps it's futile.

The weight of the block is 6,7 metric tons. In my opinion it is 1 ton too much. But I wanted and was told to put a lot of concrete under the anvil. I was told 1000 mm under the anvil, I put 560 mm. I wanted a lot of weight in front of the hammer, so the anvil would stand in the center of mass. I think this resists the block tilting, if corner pipes would start wandering. So that leaves the sides as spots to save on concrete. I could have shaved off 100 mm per side of the block. But it felt proportional like this. Who knows. Perhaps a lot of mass absorbs the impact of the hammering and doesn't transfer it so directly to the piles. Helps keep the piles from wandering? Proper professional piles would have a hardened solid steel tip, that would dig a small cavity in bedrock and make it stay put. I guess this is just mental gymnastics! It will be fine. If I start blacksmithing so hard that I ever get a problem with this, I'll be happy. Thanks for all the help everybody! I'll post some pictures of the floor here also later because why not. I can't say when I'll be installing the hammer. I need to renovate a house first...

[Frosty]

17 hours ago, Jarntagforge said:

The other alternative is to rip out the drainage well and do nothing. It feels right to pump out water, but perhaps it's futile.

REMOVE IT! Pumping water out from UNDER the floor and foundation is worse than futile, it WILL cause the floor and foundation to settle!

DO NOT PUMP WATER OUR FROM UNDER YOUR SHOP AND HOUSE! DO NOT PUMP WATER AND OR FLOOR DRIPPINGS IN! 

You'll be manufacturing a sink hole, hopefully a slow one but B A D regardless. 

Why haven't you backfilled and compacted around the block yet? The sooner the better! Cover it with old blankets or similar so it will stay wet. It will continue to cure for decades but the first week is the best return but keeping it wet until it's under soil or more concrete is good. 

Then again that block is so strong it doesn't matter.

Frosty The Lucky.

[Jarntagforge]

17 hours ago, Frosty said:

Pumping water out from UNDER the floor and foundation is worse than futile, it WILL cause the floor and foundation to settle!

That's very reasonably. One could perhaps think of it as the ground here consist of some % water! So if I remove 10 % water then there is less ground and the buildings sink. I'll remove it.

17 hours ago, Frosty said:

Why haven't you backfilled and compacted around the block yet?

Lack of experience, planning, some laziness, I guess. I'll get to it in the next few days. Last weekend I sawed the floor in pieces. We'll leave it the floor in place until we have backfilled the hole and then we'll start lifting out the pieces with the tractor.