How do you polish / finish stainless steel?

[DaveO]

I'm considering a little project using stainless steel, looking at an online source that gives this description:
304 Stainless Steel Rectangular Bar, Unpolished (Mill) Finish, Annealed, Standard Tolerance, Inch, ASTM A276

I've never worked with stainless before. What would it take to bring the "unpolished (mill) finish" to a shinier finish? Not looking for a mirror finish, just something pleasing to the eye.

Does stainless steel have an equivalent to mill scale that comes on carbon steel?

[Rambozo]

No mill scale, stainless is pretty much good to go for a lot of things. You can add a brushed finish or polished if desired. To polish you use a buffer and stainless buffing compound. A nice satin finish can come from scotchbrite wheels or pads.

[DVA]

I like the brushed look personally. I would use 120 grit to put on the brushed finish. Many sheet metal shops have sanders that can apply the finish and will not charge too much money. If you apply the finish personally, the brushed finish can be applied by a belt sander or block sanding in one direction.

[its_34]

This is a piece of 304 flat bar, as received. No scale as Rambozo said, very easy to finish and even easier to scratch!

[DaveO]

Thanks for responses. I wouldn't expect "easy to scratch"... does that vary between varieties of stainless?

[its_34]

Thanks for responses. I wouldn't expect "easy to scratch"... does that vary between varieties of stainless?

"Easy" is relative to carbon steel, but it can be a big issue if you selected SS for appearance reasons.

Grades will affect toughness, but your choices can be limited since you will be welding. The matensitic 400 grades are used for knife blades and tools when hardened. Welding is likely a complicated process, if possible, but I'd defer that question to some of the experienced folks.

[sportbike]

Do a goo0lle search for "flap drum", then click on images. It may give you some ideas.

[youngnstudly]

Just to be clear Dave, if you are just putting the grain on a small frame with legs, you could probably get away with doing it by hand with the Scotchbrite pad. No need to purchase a belt sander and the special belt just for that one (or 2) project(s)...unless you want to. Do you plan on blending the welded areas so it looks like the whole thing was made from one piece, or leaving the (pretty) beads exposed for all the world to see?

Do a goo0lle search for "flap drum", then click on images. It may give you some ideas.

I've never seen a grinder in that configuration before, that's cool and would be much easier to use than the setup we had at work. We always used the flap drums but they were mounted on a straight grinder (long, awkward, and a little difficult to keep steady while trying to blend just the weld bead and NOT the machine finished stainless around the weld!). They did work well mounted in a small electric drill though. The grinder we had was similar to this one:

[its_34]

I would agree that going with a hand-finish or a flap sander would be better than a belt. If the belt is wide and the plate is not very flat, you may end up with a heavy polish on the high spots and have diffculty getting a uniform finish without removing a lot of surface. I would expect the Scotchbrite belts to be much better than grit in this regard.

My vote would be for leaving the welds exposed and not blending. I did this with a small bathroom towel rack and thought it looked really good as-welded.

[youngnstudly]

My thinking was that if Dave's wife wanted to tell her friends about the fancy stainless work that was in her kitchen, Dave might want to make the part he's fabricating look like it's a factory built part. While I do enjoy pretty welds, I also appreciate all the work that it takes to make something look like it was machined from a single piece of material, instead of welded using several pieces of material. If the finish work was blended nicely, anyone that glanced at it would think that it was a standard kitchen accessory bought from large chain appliance store. But it's mostly the wife's call since she's your customer (so to speak).

Keep in mind that welding is like a drug....the more you build things for your spouse, the more projects they ask you to build later on (once they gain confidence in you)! The trick is to not get hooked and overdose.

[DaveO]

Right now I'm planning a rectangular frame in SS angle to support the raised surface, with a round rod bent in a square U shape underneath for legs. Legs would be under the "short" side of the rectangle only to allow sliding the structure from side to side. That's the reason for using angle, to support the long span of whatever the surface material will be, and to prevent the surface from sliding sideways off the support. It would be cool to find some marble, maybe, I just haven't got that far yet.

The amount of exposed weld would be minimal, determined mostly by whether or not I choose an inside or outside weld at the corners, and color or texture matching of the SS is a nice-to-have rather than a gotta-have. I'm thinking the most visual impact will come from the surface material.

Near term I'm planning to get some steel round rod to practice precise bends with an OA torch and welding a length of round rod to a flat surface. Not sure, though, what OA heating does to the SS... do colors from heating buff out?

[breakneckmot]

Do a goo0lle search for "flap drum", then click on images. It may give you some ideas.

That's awesome, I've never seen one of those before. New toy, do want!

[jakeru]

DaveO, consider getting a scotch-brite hand pad, (or 2 or 3) and do some experimenting to see if it will work for you. They aren't that expensive and they are very handy. I'd recommend the maroon color pads, and use an old pair of scissors to cut off whatever size piece you need from the pad. (You can make a single hand pad ho a long ways doing this...) You'll get a sense of how much effort it takes and whether it will work for your application, or if something else (probably more expensive) will be necessary. They can also put a "grained" finish on aluminum very easily, and are useful for pre-welding prep.