Hey, we're both Jason

Shot peening a rod uses either glass or metal beads, not sure of the pressure though. Everywhere I'm reading says words like "smoothed" or "dimple" so I can't imagine this somehow leaving the ridge running up the side looking almost sharp on its edge. I'm not expecting it to be smooth enough to shave on, but if it puts tiny dimples in the metal I can't imagine it skips over the ridge.

Like I said though, someone with experience would know better. I wanted to call a local machine shop but nobody is open :?

From my experience, even the toughest media would have a hard time removing that ridge. It needs to be abraded down first. The simple description that the peening changes the surface color gray is indication that it'* not an abrasive process in the traditional sense. It'* a surface-altering process on a microscopic level. It'* not designed to remove features.

Yeah I reall dunno..I've had a heck of a time finding pictures of shot-peened rods with little to nothing else done. This is ALL I could find *phew*





I'm not expecting the ridge to disapear completely but maybe smooth out some?

Oh wait, this one was next to "Crack test & Shot peen rods"



I dunno, they all look a little different haha. meh, no idea. Where'* a machinist when you need one

You're talking with a machinist. The difference you see in all those rods is the media used to peen them. The more 'matte' less-reflective surfaces were created using media of varying grit and shape. The shinier finishes, if peened or blasted, were created with media uniform in size, and probably spherical.

The difference you "see" is simply the way the surface is altered to impede or enhance it'* ability to reflect light. Of course, that'* not the REASON it'* done, but simply a side-effect that your brain (eyes) pick up on.

Only thing I've read is they either use glass or metal beads..much like BBs which is what will give them the 'dimple' look.

I don't claim to know much about the reasons behind peened rods, but I'll venture a guess that it'* to increase the surface strength of the metal, and aid in oil retention? In that case I'd use spherical glass or steel balls or beads to do that.

Most finishes I use at work are totally random, and are intended to diffuse light or laser radiation on adjacent surfaces.

Finishes I create with lasers are typically for adhesion (rough, random finish under a microscope) or wettability (smooth, wavy, uniform).

http://www.shotpeener.com/learning/spo.pdf

The holy grail of shot peening...its long though maybe I'll read it at work monday

Like I said though, I'm not going off experience here so I could be way off. I'm just taking you along while I think about it haha

It seems most places I've read about agree that it will produce either a smooth or dimpled effect. Using those two "smooth" and "dimple" I can't imagine a ridge running along the side remaining relatively sharp and raised. Now flattened out a little without any real defined edges is one thing. But tall, skinny, and sharp after using the same process described above...it just eludes me how that could be. No clue though...at your work does it leave an obvious difference in the surface?

btw, I wish I could use "diffuse light or laser radiation on adjacent surfaces" to describe my work

p.*. maybe I just need a better pic of the rod?

Think of it this way.....it'* very difficult to affect the surface of most steels by more than .001" with a bead blasting process. Most people can't see that thickness with the naked eye.

Imagine that casting mark had a sharp edge. Could you see a change of .001" in it? To be fair, a corner or sharp edge is easier to remove than flat surface, but not that much easier. I would fully expect there to be no visible decrease in the casting mark from arm'* length.