avhed

Wonder why I do not see lugged frames for this? Seen welded Somas, New Albions, and Surlys.

Andrew R Stewart 

How old are you?

Really lugged Prestige was popular enough until tig became the go to joining method. Tig is faster and cheaper to produce a bike with. As soon as mountain bikes established Tig as The Way Modern Bikes are Made road bikes followed soon enough. Andy

avhed

Where is the significant labor savings? I can see the reduced cost of the lugs and elimination of silver brazing rod.

Brian25

Welp, I really have to completely agree with Andy. With the advent of the mountain bike, frames needed to built faster. The tig welders are quite skilled and can whip out frames really fast. Dealing with fluxing/ brazing and the post brazing clean up is worlds slower, at least from my experience.

Andrew R Stewart 

Lets see what makes TiG faster. (And this from a non Tig hobby guy). No lugs to prep or do any shoreline follow up finishing. No flux to remove (or add to begin with).

Cheaper- The above time savings and fewer pieces to handle/stock.

However the lack of silver really isn't a production factor as I don't know of any production bike that uses silver for just about any joining. It's too expensive and wants better prep to be as sound as brass. Trek stopped using silver decades ago.

Side bar- A long time ago Bicycling published a comparison of the three joining methods popular at that time. Lugs with silver, brass fillets and TiG. They tested the Heat Affected Zone (HAZ) and stressed bent) the test joints to failure. They all failed but in somewhat different ways. The TiG joint failed right up against the weld. The HAZ extended only a very small distance from the joint. The brass lugged joint failed rather far from the lug's edge, it's HAZ extending further from the joint's root (maybe at the butt transition). The silver lugged joint failed pretty close to the lug's edge as it's HAZ was minimal with the cooler temp. They commented on not just the temp level but also the time at temp, the longer the time at temp the more the changes to the tube's strength. (I might have some details not correct but do remember seeing the photos of where the tubes bent at failure). The HAZ added strength at the expense of lower elongation (greater brittleness).The conclusion was any of the joining methods done well were strong enough and the forces to deform the joints were all greater then those seen when riding (excepting impacts). Basically a wash, pick your poison. Andy (trying to remember 30+ years ago after a couple of beers)

fietsbob

Taiwan..

Andrew R Stewart 

And further savings as Viet Nam, mainland China and other depressed labor rates countries are sought out as sources. But this is not what the OP was asking about, not countries of origin, but joining processes. Andy

avhed

TIG welding cleaning is faster only because you do not have to follow the lug edges?

avhed

I sure would like to see that late 80s issue.

Brian25

There is absolutely no clean up at all after tig welding. Assuming that the frame passes all quality control, it's ready to paint. When a frame is brazed, there is residual burned flux. At least the flux that I use, from the heat, ends up hardening, almost like glass. Initially, I spend a considerable amount of time with some files, removing said residual/ remaining flux. Sometimes I refer to this as playing "crunch goes the flux" after the flux removal the frame requires sand blasting. After that, I spray the lugs with rattle can aluminum colored paint. The light colored spray shows any "bulbs" of flux that I missed filing/ sandblasting. Another reason for the alum paint is that solvent takes it off really easy before the frame is painted, So there you have it Lugged frames are more of a hassle.

Andrew R Stewart 

The actual time spent getting up to and staying at heat is usually vastly less for TiG then flame brazing. The prep of fewer pieces (no lug) also saves time/cost.

This question is like many that have already been answered in the real world by those who's money is on the line. If flame brazing was faster or lower cost that would be what's done today as the common and we'd be debating about why TiG isn't done. After the thousands of smart people have tried every method and the masses have settled on a way it's usually for real reasons, even if you're unfamiliar with the reasons. Like natural selection. you might not agree with it but it works. Andy

Andrew R Stewart 

I'll exclude the filing and sanding that what we call builders do to their brazed joints as it's only cosmetic and instead say that a welded joint still needs some surface prep before painting, like sandblasting or a pickling bath. Andy

unterhausen

if the flux is like glass, you're using the wrong flux. Gasflux, Harris, Cycle Designs all sell flux that will wash off with hot water. Actually, the glass will come off with water at near boiling temps.

BITD, Trek had 7 chemical tanks for prep. I forget how many they used to prep the tubes beforehand, but it was a good day when we stopped sandblasting the tubes and they were prepped chemically. They went through another subset to get the flux off between operations. Then when they were finally done, the frames went through all of the tanks. It was definitely an expense, but not that big of an expense given the benefits. There was a passivation stage that kept the frames from rusting, which is good because Wisconsin in the summer is really humid.

I was just thinking about the time the electrician fell in the first acid tank and wondering if I cleaned him up enough. It was really mild acid, but maybe we should have given him a better shower.