I have a job where I need to dish 12 gauge steel into rough depressions. I am making a 36" tall Buffalo.  I have been doing it in the dirt with a sledge hammer. It works but is slow going. i am wondering about a small electric jack hammer. I can stand over the steel with the hammer and drive the steel into the depression dug into the dirt. The jack hammer has 60 joules of force. I think that is a lot less than swinging a sledge but at 1900 BPM I think it will work and be easier for me. 

I have attached a pic of the model that I made which is 6" tall. It was mostly done with a ball pein, First textured the outside and then created volume from the back. it is two pieces of 12 gauge welded along the midline.

 

Crazy?

I have attached a pic of the model that I made which is 6" tall. It was mostly done with a ball pein, hammering from the back.

 

Most of the jackhammer forging I’ve seen has been in thicker steel than 12ga. — that is, bar and plate stock. It might be doable, and you could certainly give it a try with some scrap pieces.

Two thoughts:

(1) You’re not going to be able to hold the workpiece and the jackhammer at the same time, so get at least one helper who can position the stock and hold it in place with long-handled tongs. 

(2) It’s going to be very easy to go too far too fast, crumpling your workpiece. Go easy, and perhaps limit yourself to doing the gross work with the jackhammer and doing the fine work by hand when the rough shaping is done. 

Let us know how it goes!

9 minutes ago, JHCC said:

(1) You’re not going to be able to hold the workpiece and the jackhammer at the same time, so get at least one helper who can position the stock and hold it in place with long-handled tongs. 

(2) It’s going to be very easy to go too far too fast, crumpling your workpiece. Go easy, and perhaps limit yourself to doing the gross work with the jackhammer and doing the fine work by hand when the rough shaping is done. 

Good points:

My helper will be holding the steel and it will be set into depressions in the dirt so it should locate reasonably well. His job will be more to stop if from bouncing, rather than horizontal control.

I will be working cold so I am hoping that the small electric hammer I am looking at wont be too aggressive. It weighs 45# so should be pretty manageable. The Buffalo head and shoulders need to be highly texture so i think it will work. If it is too fast, I can make wider and textured heads for the hammer bits so the forces get distributed and be less aggressive. 

I will let you know. Thanks.

Albert Paley used jack hammers for some of his sculpture but never so small and fast. When Paley worked on a heroic scale he used tools to match.

1,900 bpm will work harden mild steel quickly and it will crack long before you reach your desired depth. 

Find or bend a steel ring from round stock with about a 18" ID and dish over that, it will give you fine control of depth and smoothness make a smaller one for smaller features like the head. 

Dirt is a poor backing for repousse, REALLY stiff fine mud might work IF you cover it with a heavy rubber mat. Traditional is a shot bag for the gross work and pitch and punches for fine work.

Even though you're doing repousse you're doing it in steel, at least normalize regularly or work hot. 

Frosty The Lucky.

I think that to do this kind of work a sturdy frame to hold the workpiece and a rosebud type torch are in order.  Forming could be done in air with small localized heats where you want to move metal with the cold parts being the resistance.  You could also work from both sides this way.  Nice buffalo by the way.

I agree that spot-heating with a torch is the way to go, whether you work on dirt, some metal form, or a block of wood. More efficient metal-moving, less stress on the smith.

19 hours ago, Frosty said:

Find or bend a steel ring from round stock with about a 18" ID and dish over that, it will give you fine control of depth and smoothness make a smaller one for smaller features like the head. 

Thanks Frosty, totally agree,  I have a good assortment of rings/dishes for working specific areas. I use dirt to do larger depressions that need less definition.  Fingers crossed. Because these are big pieces heating up 3 ft sq of material is a challenge with my rosebud. I have turned my gas forges so that they point up and laid the still on top to heat larger areas.  I am hoping to work cold because it will be easier to manage large sheet cold but understand the need to anneal in between steps.  Thanks for all your great advice

Th

Matthew Harris Studios did something similar.  I know there YouTube short of him making the tooling.  I believe I saw the longer video of the actual project, but I can't put finger on it.

Here is a report of my progress. I used a flat nose tool with a 3/8" radius. I was easily able to texture the surface of cold 16 gauge making dimples that added, I think,

a lot. Here is a video of my buffalo maquette and the body parts nearly completed. The head and horn are to come

 

 

I'm afraid 12meg is too much of a file size to want to watch, I have a high speed connection and that'd still tie it up.

I'd intended to post a pic of one of my only repousse pieces done on a Christmas cookie tin lid. The border around the bear is 8 1/2" x 6 1/2". Altoid and cookie tins are good for repousse because they're a deep draw very low carbon steel but you still have to normalize pretty frequently. So frequently I stopped waiting for it to cool before going back to work. This was done on Bees wax and even then it was pretty easy to punch through.

Frosty The Lucky.

Here is a pic of the buffalo. In between the two bodies is a 10" version completed. The larger pieces still need the head and horns. When finished it should be the size of a big Newfoundland.

 

Frosty,

Your Polar Bear and Hunter are fantastic. Well Done!

Steven

I was scratching my head wondering where between them the 10" bison was until my focus changed and HOLY MOLY your finished sculpture is going to be life sized!  I've stood next to a woods bison and they're huge. There's a wildlife center about 35-40 miles S. of Anchorage that maintains a breeding herd as part of the project to reintroduce them to the wild. The herd in the interior is small enough they need to get more bloodlines in the mix for a long term healthy population. 

I love it, grand projects make me smile.

Thanks, I didn't get lots of things right. Perspective isn't there, it's obviously a 2D picture pooched out but it was a lot of fun. For a while there was quite a group of people sitting around each other's living room with a pitch bowl, hammers and chasing tools happily tok tok toking away and talking. 

Good times.

Frosty The Lucky.

The perspective was great. I totally got the humongous Bear and the fearless/foolish hunter. I recently went to an Inuit Art Gallery in Quebec City and your piece would have fit right in. Their work seems less interested in being anatomically correct and more focused on the feelings you get when you see it. Totally works.

Yeah, it's that kind of picture, I've never shown it to anybody who didn't get it immediately. I wish I remembered who the original artist is, there's a good chance he was Inuit. (trans polar) Perspective wise I missed the bear's posture, I over raised it's belly so it almost looks like it's slouching, the original emphasized the chest and head in a proper loom. Little things like the claws on it's paws facing back instead of out was because I didn't know how to do it and settled.

In the original painting the hunter doesn't give the impression he's brave or foolish, he gives a strong impression of confidence. His back is arched looking almost straight up like a window washer sizing up a 3 story job, no problem, just another big job. The bear of course is sizing up the nibblit to see if it's worth bending over to eat.

I wish I'd known more about bears back when so I could've made the impression of a particular bear Polar bears have longer muzzles and narrower heads where Grizz are wider and blunter, blackies are more middle of the two. Now though, I'd like to try a short faced cave bear, the proportions are close but it'd have a much scarier loom. The short wide heads are scary as fossils, let alone going up against one with a sharp stick and club.

I don't dwell on the mistakes and outright blunders in the present tin, I'm actually pretty pleased it came out so well for not having a clue what I was doing at the scale. I should've drawn out the areas that were to protrude farthest, the head and maybe paws, then shoulders and chest, lastly belly and feet.

Draw the hunter's head way out almost looking at the top of his head, a large nose might be neat. Draw the shoulders less so with his almost back dishing inwards and butt sticking out.

I almost never look at the tin without reimagining the piece. I still have the hammers but I think I gave my chasing punches away. But I DO have plenty of garage door spring to make another set. . . If that is I were to loose grip on my sanity farther.

Frosty The Lucky.