shot peening ti

[eddief]

besides what one can read on the net and what IF says about shot peening ti, does anyone here have an opinion about the cosmetic or other effects of this process for finishing ti?

[wasfast]

<large snip>.....sorry, double post

[wasfast]

As with any abrasive process, start with media FINER than you think you'll want and experiment in an area that's at least partially hidden, like between the chain stays. Use VERY LOW pressure and gradually move up. Better yet, get some scraps of Ti and experiment on those first. Once you go too heavy, it's a big mess to fix and potentially damaging to the frame if you make a weak spot.

Most folks think of silica sand but there other softer medias as well. Web search if you're not sure.

Be advised too that the rougher the surface, the more difficult it will be to clean since the dirt and grease will sit in the low spots created by the media hitting the surface.

[Needs Help]

It looks horrible?

[quattro]

I have a IF Crown Jewel Ti that is shot peened. It is pained 3/4 and the rear end is unpainted. I think the shot peened surface looks great. I had a custom seven Ti stem made and had IF shot peen it to match the unpainted portion, I love the look. IF says it strengthens the Ti, I can't tell, I'll take their word.

[Fixed]

bro is that where you use a ballpeen hammer ?
cheers

[dbrk]

I've seen a slew of these frames and they sure are purdy, if you like unfinished ti (and I do). It's a brushed, soft look, not unlike the way we ordinarily see Moots frames. As far as strengthening or affecting the metal, I am sure something happens but they don't break and people seem to like the ride. If ti is properly welded it will out last any of us by a few hundred years or longer. Shot peening may be a distinction but I can't figure it affects the ride.

dbrk

[Endless Goods]

I'm an architect, and often specify a "glass bead blasted" finish on stainless steel. It's a very tough, scratch-resistant, and impervious to fingerprints. You may want to look into this...

Glass beads are used as media to blast the surface.

My only beef with certain Ti finishes and unfinished are the ^#@$#@! fingerprints!

[Lunar Probe]

bro is that where you use a ballpeen hammer ?
cheers


That would be ball peening. :)

[victoryfactory]

Be advised too that the rougher the surface, the more difficult it will be to clean since the dirt and grease will sit in the low spots created by the media hitting the surface.

Wasfast is right. A shot peened surface holds the grime and is a pain
to clean, this is one of the main reasons I went to the "polished"
finish on my Legend after a "matte" finish on a concours.
Of course the choice of media they use determines the degree of
nastyness in a shot peened finish. My concours was from 2002.

VF

[11.4]

The theory of shot peening is sound. The big issue is that ti framebuilding isn't an exact science, and a tig'd ti frame will have a huge transition in wall thickness from the tubing into the welded joint. That transition is so significant that it transfers the stress out to the tubing proper. With currently used ti alloys, and good welding, those areas (say, 1-3 centimeters from the edge of the weld) are very unlikely to crack anyway (or if they do, it isn't the welding but rather the use of, say, a far too light top tube in a large stiff frame, that is more at fault). Shot peening does it's thing best for relatively slight thickness transitions or where localized heat is accompanied by relatively minor changes in thickness. The transition from a 0.8 mm or so wall thickness close to the join to 3-4 mm in the weld is simply too much to overcome with shot peening. Examples of where it might possibly have more benefit would be in a curved piece of tubing, chainstays around the bottom bracket (where everything is a lot thicker), or around heavily worked tubing.

One can shot peen with metal shot, sand, ceramic beads, or even with soft plastic beads. Even the plastic beads can have a significant effect on the metallurgical properties. IF seems to use something like fine metal shot; it causes a very fine pattern of roughness which, as folks have pointed out above, picks up dirt, sweat, and oil like crazy and is hard to clean out again. If you get shot peening from IF, my personal recommendation (based on experience) is to get it painted so you don't have this problem. I have no problem with a polished ti finish on a Serotta Legend, but my IF ti cross bike really looked awful. No complaints about the bike per se, but it never looked clean after it came out of the box.