lemondzurich

So here's my idea.

1. Buy stock stainless 304 or 316 tubing with wall thickness around .75 to 1.0mm depending on the tube.
2. Miter with my grizzly tube notcher.
3. Fillet braze with nickel silver or 45% silver and MAPP gas.

Is this a horrible idea? I was also thinking about putting in additional bracing at the joints. TT to HT, HT to DT, DT to ST, and ST to TT. Maybe also ST to chain stays and seat stays as well.

This would be a super heavy bike and probably won't be pretty, but I don't really care about the weight or the aesthetic. Just thinking it might be a fun quirky bike that won't kill me and won't cost me an arm and a leg.

Pocko

I know of a guy who built a BMX stainless-steel bike frame, TIG welded. Apparently it gets easily bent because the stainless-steel tubing he used just turned out to be too soft. Mind you it was being used for BMX racing, jumping and stuff. Maybe for commuting it might be OK?

Just be aware of this, because it's very conspicuous that none of the bike manufacturers offer stainless steel bikes in their product line up. Well, none that I know of anyway...

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white folks

how about using 953 for the main top and down tubes and seamless non butted stuffed that you mentioned for the ST and everything else? would cost that much more and would be a much more rideable bike. your going with lugs yes? make sure your miters and lug/tube fits are spot on for silver brazing, the silver dont like gappy fits and miters...

After seeing how much work it takes to get one SS fork crown all polished up like the big boys have it, I would never build a whole bike from SS, it would just take too much time.

NoReg

Tubes could be spun in a lathe, etc... to polish them. Lugs are hard to polish because people want them at near chrome levels of shine, and because they don't come all that well finished to start with. Getting a brushed stainless look might not be all that bad.

I would agree that stainless tubing is not going to compare to Chromo. it is normally compared to 1018 structural type stuff and even there it comes up short. The key is lots of work hardening, so you would need to find a DOM type steel that is work hardened, you can tell this if it is smooth finished inside and out. There are some very fancy stainless tubes that have higher tensile properties, but they cost. We use them for rudder stocks on sailboats, and doubtless various military application.` It would be simpler to go to some SS bike tubes like 953 (is it now sold to the public?).

The bottom line is if you can find an SS DOM, and go to twice wall thickness you would be in the ballpark that means walls nearer to 1/16" than what you are looking at. Think of .9MM being a baseline for straight wall tubing in Chromo, which is way stronger stuff, a regular high strength steel needs twice the wall thickness. I am not an engineer, familiarity with different parts has made me notice how often the Chromo version is identical save for the wall thickness being half that of some 1018, so at least it is a starting point spec. None the less, unless a stainless tube is work hardened it wil be below even simple mild steel in yield strength.

MAPP and 45% will do this, but probably not in the tubes involved. Remember the thicker walls are a deeper heat sink, and a single MAPP torch is at the limits on 3/8" rack tubes, in my hands. There is 6 times the material in a plain steel 1.125" tube. I think the cheaper option would be stick welding. A rig can be had for 100 bucks, to weld thin metal as involved here. Stick is easy to weld 1/16" stock thickness with. You need a delicate touch to do .9mm chromo, but stuff for plain steel frames is a lot simpler to do. Find electrodes designed for sheet metal repair. Cut them in half so they aren't as whippy and hard to control. And try the 5/64" electrodes

lemondzurich

I was actually thinking about going lugless. I'm pretty sure I can do it with lugs no prob. That's why I was going to use the additional bracing and asking about using nickel silver or 45% silver for some small fillets.

NoReg

I think we get that, My guess is that WF was just talking about the time it takes to polish the lugs alone, they being smaller than tubes. The stainless tubing I have bought didn't look half bad as I bought it, since there isn't any need to leave a crudy surface for protection against rust.

Desperado cycles has some pics of a bike filleted with 45% silver in stainless. But his methods are not typical, so you are venturing out on your own.

Nessism

Silver is not for fillet brazing, although some people are known to do it. From what I understand, when silver fillets are built up there can be micro cracking on the interior of the fillet.

My opinion is that your idea of building a frame like you describe is silly. What's the point of using stainless when carbon steel tubesets specific to bicycles are superior in every way other than corrosion resistance. If you want corrosion resistance, get the frame plated and send it off to powder coat. This would be a far better solution in my opinion.

lemondzurich

Silly? Absolutely. Pointless? Yes, if the main goal is to just build a normal bike. But I already have three normal bikes. So even though the idea has little merit from a practical standpoint, I'm thinking it would be a fun exercise as long as it doesn't kill me and cost me an arm and a leg. Plus, it would be stainless! (Which again, isn't really worth anything except for the novelty of it.)

Anyway, thanks for the input everyone. I'll let you know if anything comes of it.

porschetoyz

btw, Dahon (folding bike co.) made some stainless steel folders some years back. They can now be found on ebay, and usually command a relatively decent prices. Because of the added corrosion resistance (?) the bikes seem to be shipped to Pacific Rim locations or end up on boats.

Good luck!

NoReg

"Silver is not for fillet brazing, although some people are known to do it. From what I understand, when silver fillets are built up there can be micro cracking on the interior of the fillet."

That is certainly the conventional wisdom, and I don't mean anything by that. On the other hand one can only hope that this wisdom is more solidly founded than the bike brazing industry's views on welding, etc... A while back there was a thread on this in the FF, and Don Walker of NAHBS and framebuilding fame mentioned that he had done a lot of silver frames at one time, and he might bust out the 45% and fillet one up just for old time sake. I can't remember whether he credited the idea that silver cracks etc... or not. But he certainly didn't seem too traumatized by the possibility. In another thread where I was pushing the idea of filleting with 45%, just to evaluate the push back, there seemed to be the view that the main reason it had fallen out of favour was that the end result is too TIG like in look, and that the silver is expensive. At one point people filleted/lugged bikes because there weren't alternatives, not in order to make a 6000 dollar sale/fashion statement. Bikes were brass brazed simply because it works and is cheap, and bonds nicely to the steels then in use.

That said my interest in silver was largely to find an option for the home builder since the heat requirements for fillet brazing in silver are doubly lower. I have no reason to believe it is actually superior to brass, or not. I just figured it might work for those who have neither Oxy/Fuel, nor welders to play with. I will leave the actual promotion of it to those like Desperado.

Thorlak

If you do go with 304 s.s., it looks as good as chromed if you have it electro-polished. Free machining that grade of stainless sucks, so does 316.