Usually if a magnet sticks the grade is cheaper, but if it's in a house and you polish it up nice it should last forever.

Considering the rust/corrosion that I see on the parts on most pinball games I would say very little is actually stainless. I think a large portion of the parts that look like stainless are mild steel plated in chrome/nickel. I can always spot a well used pin when the lock down bar has the plating missing by the flipper buttons and it is starting to show some rust.

Stainless is a bitch to work with compared to mild steel. It is harder on tools and a lot more expensive. Pinball games just don't need that level of fancy material. They were not made last that long and the environment they are in is very gentle relatively speaking (inside and dry, hopefully)

Steve Ritchie would disagree. On a number of levels.

Is that you Gary?

I would hazard a guess at an austinetic stainless like 304 or 316, but could easily be something in the 200 series, which I personally have never used buit would serve the purpose as well I believe. I would guess most of it is likely cold worked or spring tempered to bring its hardness and strength up a bit... I havent's seen much deformation on inlane returns like in the old days and I don't THINK most of it is magnetic so it's likely austinetic with a temper, and not cold worked.

Anyway thats what I intend to try to use as my first shot at lane guides, wireforms, ball guides, etc.

I'd go with 304 stainless steel (A2 in the UK). 304L if you plan to weld it.

316 is typically used in a salt water/swimming pool environment so is a bit overkill.

Phisrace is right, stainless is definitely a bitch to work. I particulary enjoyed the fact that, with the larger diameter fasteners, you could be threading a nut down a bolt without any load on it, and the nut would suddenly cold weld to the bolt. How I laughed as I took out the hacksaw

Andy

I would stay away from stainless fasteners wherever possible if you are using stainless components unless you can avoid pressure and contact between the fastener and the part

I don't know anything about metals so can't advise but looking at my metals, of which at least one of everything had some mild rust spots/pitting, there was definitely plating on it all.
(Edit: except maybe the wireforms...memory escapes me)

Could be because it's a Gottlieb sys3 though