Fabricating Stainless, Question for the Experts

[choice]

Hi all. Please bear with me on my unsophisticated terminology.

I want to take 20 gauge stainless strips measuring approximately 1 inch by 6 inches and bend them into roughly a "C" shape. The curve is not of a constant radius. Also, there needs to be a slight dome to the item. What I mean is that if you look at the "C" shape from the side, it is not flat but rather has a curvature which is regular and is elevated about .25 inches in the middle. If that is not clear, then think of a piece of steel which would fit to the surface of a 4 inch diameter ball.

I am looking for an efficient and economical way to do this. My thought is that I could have dies made for an arbor press and use that. Would that work or do you have a better idea? If using an arbor press: 1. Would a 1 ton capacity press be adequate? 2. Would I have to account for the material "springing back" toward its original shape when I have the dies made? 3. Somewhere I have read that working stainless with steel tools will make it prone to rusting. If I have dies made, should they also be made of stainless?

Any ideas and suggestions are appreciated

[nett]

Wood mandrels and a light deadblow mallet? Practice and experiment to discover how much memory the strip has and compensate that amount in your wood shapes. Stainless steel is odd in that you can easily bend it once, but you will have a dickens of a time bending it a second time. Experiment. 20 gauge seems doable without presses and dies.

[Frosty]

Lets see if I have this right. You want a compound curve, bent in two dimensions instead of just one.

You could do it by first bending the strips on edge (the hard way) and then putting the major "C" bend on the flat.

OR, bend a tube of the correct radius from SS and then cut the strips on the desired curve. A good 24tpi bimetal jigsaw blade should have no problem.

OR, cut the strips with the desired curve, THEN bend the "C".

The last method probably being the easiest and the first the hardest.

Frosty

Edited February 11, 2009 by Frosty

[HWooldridge]

Ries may chime it here - he has worked SS extensively. I have machined a lot of SS so I can recommend that you have the pieces passivated to remove free iron from the surface. Anytime you work stainless with some type of carbon steel, it will have a propensity to stain - rather than try to make every tool from stainless, just send it out for chemical treatment. Passivators are located in most large urban areas; the prices are usually reasonable.

300 series SS will workharden so a great deal of cold work may require normalizing but the amount of work you are describing is probably not enough to need it. In any case, I think you will need to make a C-shaped mandrel out of pipe with the proper inside radius so you don't lose the "dome" across the material.

With regard to the fabbing process, I tend to agree with Frosty's recommendations.

[Frosty]

Ries is hanging here? He's usually not so quiet as to be totally below the radar.

Speak up why don't you?

Frosty

[wyvern]

I've worked and welded alot of stainless on the industry side of things and found kind of stainless a man or woman is working has alot to do with ease of how its worked

[Warren Nakkela]

I am reading 'choice' differently than others. I think that he wants a stainless strip bent/rolled with a crown, like a section of a cylinder. like this: ( Like a metal tape rule. Then he wants to form this section into a "C" shape. Like bending your measuring tape belly out around a pipe. Without some special tooling I have no idea.
Warren

[NeatGuy]

This is an ideal job for my nibbler since it is so easy to make the dies... but one could also use a hydraulic press or a break press too.

brad

[devon blacksmith]

I have made this shape a lot of times for replacement fire places. In my forge we would hand roll something like this with shaped rolls or forge under the fly press a small piece at a time,