Help with convave circle

[dan]

I want to make some sunflower. My center can be 4" 6" or 8" made our of 14 gage Mild steel circle. How do I go flat to my slight concve shape?

Any ideas?

Thanks in advance

[irnsrgn]

a drawing of what you want to do, would help understand what you want to accomplish

[Glenn]

Make a shallow depression in the end grain of a piece of wood. Place the wood over the depression and hit it with a ball pein hammer. Some armour's use large steel spheres welded to the face of a dedicated hammer for this work. The spheres may be of any size but the ones I have seen are about 2" in diameter.

[Frostfly]

dishing into the end of a stump of some sort works well, but I wouldn't use a ball peen unless you are looking for a textured surface, find a cheap 2 or 3 pound hammer (i use a driller's hammer) and grind one surface to a smooth radius (like half a sphere) use that to dish with (the process is called dishing) the larger radius on the hammer makes the surfaces stay much smoother.

the other way to do this is a process called raising, I'm not an expert on that check on anvilfire  for a description on that.

[IronFist]

Dan- I either use a dishing stump as frostfly mentioned but I also raise it using a forming stake that is a 5" solid steel ball ( various sizes at that) that I welded onto a 1 1/4" square stock, clamp in the vise, heat your material and shape away! Either is easy to make- out of the woods or from the scrap yard.

[ThomasPowers]

Actually for a sunflower I *would* dish with the ball end of the ballpeen and use one that has a more connical and less sphere like peen as the texturing will look a lot more like a sunflower center than a nice flat smooth dish like we generally try to make.

[dan]

awsome responses and suggestions.

I did carve yesterday a hardwood block with a diameter of 8" with a 7/8 of an " deep as a cavity for my concave shape. I will try to use a shere shape that I will weld to the end of an old hammer to get my desired shape

I will then make a male mold of the exact same shape out of soft wood that will be 8" in diameter and 7/8 " high .The idea here is to have my new shape facing down on the soft wood to the form my sunflower texture.

So I guess I will use both idea of a shere for the curve and the Ball pen hammer for the texture on the other side.

I will keep you posted on the results. I cannot thank you enough for your brain storming.


Dan

[Glenn]

The end grain swages (holes) I have used are about 3" diameter and shallow. Some were formed from cutting the end of a chain saw, some with a 4-1/4" grinder and some just burned with either ox/ac or hot forge coals. We even went hi-tech and use a wood chisel on a few.

The hole size needs to be sufficient to support two sides of the metal leaving the middle unsupported, which is where you hit it with a hammer. The depth should be sufficient to depress the metal without bottoming out. A 2nd hole can be used where the diameter and depth matches the shape of the bowl for another pass of hammering on (shaping) the metal. This is usually a little shallower and with a larger diameter.

Wood seems to give a "smoother" finished surface to work with later. After the general shape is formed, the surface is then refined with a variety of techniques. Finally if you are making armour or bowls etc, you can use files, sandpaper, buffing wheels, and all manner of things to achieve the surface you want.


Takes lots of photos, it sounds like a Blueprint to me.

[ThomasPowers]

The general rule when armouring is "hard on soft" or "soft on hard": If you use a wooden form use a metal hammer and if you use a metal dishing form use a rawhide, ironwood, etc hammer to dish.

Planishing of course is usually done hard on hard but with less force.

[Kristopher Skelton]

I like my panelbeater bag (heavy leather bag filled with sand) and a plastic forming mallet- one end with a large radius and the otehr with a small radius. I've made several of the shape you're describing for similar projects (sunflower, an iron 8-rayed Sun with a dished copper center, for example).
For the texture, I took an autobody hammer with the very pointy cone end (almost sharp) and blunted it then lightly hammered the inside of the dish over wood to give it a dimpled appearance.

[frogvalley]

I created these originally by simply forming the parts over the face of the anvil and horn. Its kinda hard to explain but concave forms can easily be made by hammering down on the face and sort of pulling up with the tongs. I could show you in person. I put the V in the leaves first (they are convex) and then put that "ell" shape against the edge of the anvil and just hit around the edge and backside of the work and make my way toward the vein. The flower is done the same way, rotating and reheating about 6 times or so for the dished part and about that many for the petals. The get formed backwards over the horn , btw. The sunflower is about 10in across and 48 tall.

By both the lifting/pullin action with the tongs and the spreading action of using a ball pein, the work can be made to be concave if worked from the backside. After all, if you expand the material, which you are doing with a ball pein, that material has to go somewhere. Make it go into a compound curve.

Can also be done in a similar way but in reverse by working the face of the piece over the horn and hammering downward and pulling down instead of up. I have a cone mandrel that can be used as well, it has a dome on top, not a point, just for this purpose.

Most important is to do this at the highest heat that you can stand to work it. Yellow or bright orange. Don't bother once its gone red. Especially with sheet metal. BE CAREFUL. The surface area of sheet iron radiates more heat than the same weight of thick bar stock. IR dangers can burn you pretty badly.

While I make dozens of bowls/flowers/other thingys a year, I don't use these methods very often. I have a swage block for dishing most things, and the big bowls that I make here ( 12, 24, and 36 inches across) are formed into a concave form that fits into my hardy hole. My most used ones are eight inches or so across and can be made to work small or large bowls. I have several for each anvil in different sizes and purposes.

Below are some pics of some things plus a pic of the tooling.

[Glenn]

There are several Blueprints that may be of assistance.

BP0169 Bending Saddle
BP0211 Making a dishing tool

And two more presented at last weeks Tuesday night LIVE that will be posted shortly.