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JNewman

Could a sheet metal power hammer be used to make this?

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I saw a fellow make some mild steel bowls with a thumb die in a sheet metal hammer. It sure went faster than raising them by hand.


Ha Ha!

I've tried to run .125" mild steel through me Yoder with Thumbnail dies.

The result was 18 stitches on my fingers.

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I have a Eckold 665 Kraftformer that will shrink up to .250 steel plate cold. Will do .125" stainless no problem. It will work harden pretty fast so you need to anneal it so it doesn't kill the dies.


That's a pretty impressive machine. Is there a way you can work inside so you can shrink the edges so they end up straight up? The bottom die looks much thicker than a hammer like a Yoder.. That was a big part of my problem trying to do them cold on a forging hammer, Once I got to a certain point the opposite edge from where I was working was trying to hit the ram. Of course trying to stop that beat my hands up pretty well. I annealed them several times, they work hardened very quickly at which time they just stopped moving

Ha Ha! I've tried to run .125" mild steel through me Yoder with Thumbnail dies. The result was 18 stitches on my fingers.


So the 1/8 stainless would be to heavy for a hammer like the Yoder?

I have a similar project approaching where I will be making 80 shallow bowls 6" in diameter centered in an 8" square of 1/16" 304 stainless. The ideas here have me well on my way. What a great forum. Thanks to all for the input. Tommy


You might want to clamp the plate between 2 pieces of plate with holes in the center. That will help keep the edges flat. Doing it that way will mean you are not doing any raising, It will all be sinking.

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These are skimmers for the galvanizing line at a steel mill for galvanizing sheet steel. A retired blacksmith from another steel mill told me how they made these at the shop he worked at. Their method was VERY tooling intensive.

They had a bottom swage that was made up of layers of 3/4" plate that were doweled together and machined to a cavity of the outside shape and then a top solid steel plug. They would set the stainless plate on the bottom plate of the bottom swage then stack the rest of the plates on top. Then under the steam hammer the plug was used to sink the stainless the first 3/4 ". The top die of the steam hammer hit the top of the plates making up the swage as the plug bottomed out, flattening any wrinkles. They would then set a second plate under the stainless plate, set the rest of the plates on top and drive down the plug again. Then repeat till the bowl shape was done. Because the plates were not clamped during the sinking, there was probably some raising going on.

This tooling would probably cost more than a couple of years of making these would make. As well my dies are not big enough to hit the plates all the way around the outside like the steam hammer would.

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You might be able to get one that is close and rework it. Do they care what blank you start with?


They don't care, I will look for a similar one next itme.

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That's a pretty impressive machine. Is there a way you can work inside so you can shrink the edges so they end up straight up? The bottom die looks much thicker than a hammer like a Yoder.. That was a big part of my problem trying to do them cold on a forging hammer, Once I got to a certain point the opposite edge from where I was working was trying to hit the ram. Of course trying to stop that beat my hands up pretty well. I annealed them several times, they work hardened very quickly at which time they just stopped moving So the 1/8 stainless would be to heavy for a hammer like the Yoder? You might want to clamp the plate between 2 pieces of plate with holes in the center. That will help keep the edges flat. Doing it that way will mean you are not doing any raising, It will all be sinking.



The shrinking dies work the inside and outside of the material at the same time. You would hold the bowl with the open end down. As you shrink the piece( you are only going to work the outer .750 of 1" of the bowl) you want to help it down by pushing against the lower die slightly. This in turn will make the overall opening smaller, and put your sides at 90 degrees. Which is what I think you are after. I would think you could get it to 90 in two passes.

and yes 1/8 is to heavy for the Yoder.

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Thanks Jesse. good information to know. If i get a similar but different job to quote I will have to see if anyone around here has one of those hammers.

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If you restrain the edges adequately it will shrink them as the bowl is drawn.

Grant has a point, if you can order a near match out of the desired material, will they care if it looks a little different?

Phil

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You might also want to look at what Rory does with his bowls. He has a couple of videos and pics of him forming them on IFI somewhere.
I was going to suggest that you look at tooling that would push the rim of the bowl down rather than up to keep your hands away from the moving ram but I see Jesse already clued you in to that

You haven`t mentioned yet what kind of machines you have on hand John. If you already have a lathe then the suggestion of hot spinning might be the best option for you. Especially if you have a lathe that will allow you to spin one, part the bowl off, and then move the carriage with a steady rest and torch attached down and spin a second or third bowl from a piece of SS tubing or pipe.
If you already have a hydraulic press then doing it like Rory does Could be a good solution for you. A press might also be more useful for you in other work and allow quicker return on your money if you are looking to buy a machine
If you plan to do more sheet metal work in the future or there`s similar work like this knocking on your door then maybe one of those high dollar machines in the videos would be worth the investment.
One other option might be to ask the folks you`re making these for if they want to part with the tooling they already have on hand and will not be using. Believe it or not many of the places I worked with were happy to farm out jobs and supply the tooling to do that job. You never know till you ask and it`d be a shame to find out later it was sold for scrap when you could have used it.

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Much as I would love to have one of those high priced hammers and the skills to use it, I don't have a lot of that type of work knocking on the door. I am already set up as a pattern shop and blacksmith shop. It doesn't make sense for me to set up for sheet metal as well. It is good to know what kind of machinery is required to do it other ways though so if a similar but different job were to come through the door I could sub out to a shop that is set up to do that type of work. Alternately if subbing it out is incredibly expensive I have a baseline price that I can do it for the same price or SLIGHTLY cheaper.

The tooling to make these under a steam hammer was undoubtedly scrapped when they tore down the blacksmith shop. As well it was a different mill so the design was probably slightly different and the two mills seem to things made to their design for the same or similar jobs. As I said, I have the process down fairly well for making these and unless I can find tank heads that are very easily changed and are a reasonable price I am going to stick with my current process. At best this is a 4 parts per year job what I am doing works and makes me money now that I have the tooling I built last year, if there were lots of them it would be worth experimenting with the process

I learned what I could and could not do on my Kinyon hammer with cold sheet metal last year with experimentation. The point of this thread was to see whether a Yoder type hammer would do the job, not to change how I do this one but as background knowledge for the future. Thankfully Jesse answered that and also showed us the hammer that would do the job. There were lots of other good suggestions for doing these as well and hopefully that information will be useful to others.

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Oh, I see, a philosophical discussion. Never mind. (said in his best Emily Litella voice) :^)


Not philisophical knowledge, valuable knowledge just like the valuable knowledge I learned trying to do it on the Kinyon. I hope that was not a nose out of joint emoticon. I was not trying to hurt any feelings, I was trying to make sure my intentions were clear

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