View Full Version : Which SS sheet will machine and form best

11-13-2015, 08:45 AM
I somehow find myself in the final stages of a scale model cannon build.
I decided to leave the cannon in it's naked state, and not put any finish on the barrel, which will probably be a bad choice for rust resistance as well as being maybe not a good idea to trust for firing. It is made from a piece of steel mystery metal roller gleaned from a bridge expansion joint.

Regardless, I have decided to use Stainless steel for the findings on the mahogany I'm using for the wooden base.
My entire stainless sheet supply consists of salvaged kick and push plates for door hardware. This stuff is not very user friendly. Doesn't cut well or form very well at all.
Looking at Online Metals website, http://www.onlinemetalsupply.com/stainless-steel/stainless-steel-sheet.html, I found this selection.

I would like to know which of these selection would be best for forming and machining. I'm leaning toward the 2D or BA.
The SS kick plate is just plain miserable to cut or machine.

11-13-2015, 09:18 AM
The selection in your link only gives finish, not alloy. They are likely 300 series. If your kick plates are non-magnetic they are 300's.
What you really need is the right tooling!

11-13-2015, 12:06 PM
Like most metals there are certain stainless alloys and heat treatments that are designed for ease of machining and forming. The specialty metals like these are made at the mill with careful alloying and heat treatment. They cost substantially more than off-the-shelf varieties, but worth the extra cost for ease of working.

If you can find 304 DQ (drawing quality) that'd be good. Problem is it's hard to find. Do you know of any spinning or metal forming shops in your area? If so, they might have some smalls they'd sell cheap.

I have a bit of 321 thin wall stainless tubing that I can flatten to sheet that forms like butter.

You could have a local heat treater anneal material for you. Still, if it's plain non-drawing quality it wouldn't do that much good.

Other than the above, it's a real problem. Stainless can be awful stuff to work with.

11-14-2015, 08:07 AM
Cam, the descriptions and alloys are linked to each of the samples shown. The two I chose are 430, the others are 304, I chose them because they were annealed. Probably all of them are ornery and I'm sure I don't have the proper tooling, but I never let that get in the way before.

DR, Thanks for the advice, I'm starting to get the impression that I should probably have decided on brass or just plain old steel. But, I like the look of the stainless, so for the few parts that are made from sheet I guess I'll just torture myself and tooling and just keep plugging away and try to make the best of it, even if I have to make a few changes to uncomplicate the parts, which are the trunnion straps that hold the cannon to the base.
I made up a die from white oak and pressed the half round into the straps, they came out fairly well. The real problem was trying to mill the 1/8 slots for the fastening hardware. I will probably give it another try with a carbide end mill.

11-14-2015, 09:37 AM
generatorgus It would help a lot if you'd put your location in, I have some thin wall tubing that is 2 1/2" D made from 316 316L that I might be able donate a little.

11-16-2015, 07:58 AM
generatorgus It would help a lot if you'd put your location in, I have some thin wall tubing that is 2 1/2" D made from 316 316L that I might be able donate a little.

Duckman, I'm in NE PA. I would much appreciate a small piece. The big pieces I need are 1/2" wide and about 3" long before forming. I'm sure a small USPS flat rate would do the trick, I would be very happy to pick up the tab and buy you a beer. If you want you can email me, generatorgus@live.com
Thank you for the offer.


11-22-2015, 07:50 AM
I think I solved my problem. I was putting things away in my shop and noticed a couple SS handicap grab rails that I salvaged from a job. About 1 1/2" Dia. Maybe? Not much to lose if it doesn't.
I chop sawed I about a 3" piece out of and then split it length wise into two pieces, it measured roughly .045 thickness. It didn't seem very promising, it didn't bend or cut well.

Last resort, I tossed them in the middle of the fire in my wood stove and let it burn, just feeding wood as usual and let them go missing in the ashes until the next day before I lit another fire. I've done that with some cast iron to soften up hard spots and it worked nicely.
I cleaned the pieces up a bit and tried bending a corner, and then drilled a small hole. Both tests told me there was hope. I pressed them flat in the hydraulic press and the tried shearing them in my old faithful Famco shear. I was quite surprised that it sheared very easy, so I sheared a couple pieces to the size I needed. Then made a die out of steel, and pressed the 1/2 round shape I needed. Came out perfect.
Today I'm going to rig them in the mill and see if the slots come out OK and I think they will.
I'm not even going to guess at what alloy it is, but I'm not going to put it in the scrap pile.

11-22-2015, 03:08 PM
to anneal 304 stainless steel, you heat it up to at least a dull red, then quench in cold water. It will get as soft and malleable as its gonna get.