tsappenfield

I've been trying to figure out how the lugs on my 1980 something Colango Nuovo Mexico were placed onto the frame and welded into place. There are two beautifully sculped chrome-plated lugs, one running from the top tube and then encircling the head tube and another running from the down tube and encircling the head tube. I see no seams on either one. They certainly weren't Super-glued into place. If the tubes for the frame were first welded together, how were the lugs placed onto the frame. I don't see how that could be possible. So the lugs must have been slid into place over the head tube first, but then how were the welds accomplished without ruining the chrome lugs? Also, is it possible to have the lugs re-chromed without cutting the frame so that they can be removed? I DON'T GET IT!!!!

TSAPP

Kactus

The tubes are inserted into the lugs and then brazed. This is similar to soldering but is higher strength.

BlueDevil63 

As Kactus says the frame is brazed not welded. Think of brazing kind of like the soldering you do to join copper pipes in plumbing. The tubes are cut to fit together, inserted into the lugs and fluxed, then silver or brass rod is melted and drawn into the joints. The chroming happened after the frame was brazed and actually covers more than the lugs. When there are chrome sections on the frame large sections of the frame are chromed and then those areas which the builder doesn't want to show chrome are painted over.

Captain Blight

The frame is assembled by silver-soldering the lugs in place over the tubes, using a system of jigs and reference points to keep it as true as possible. Then the solder is cleaned up, with files and abrasives and then the frame is either fully or partially (head tube/first few inches of the DT/TT, and an appropriate amount on the rear triangle) chromed, the lugs masked off and the frame painted. Dollars to donuts that if you scratched through the paint on the head tube, you'd find chrome underneath... maybe a little rough, as they intended to paint over it, but chrome nonetheless.

gmt13

Coulda just googled "Lugged bike frame" and saved us some time.

miamijim

They're assembled like a puzzle with the seat tube being the last. Chroming is done after the tubes r joined and then paint.

Bianchigirll 

Kinda of like copper plumbing right?

The fact you don't see any seam or other imperfection in those lugs is one of the reasons Colnagos command such a high price

rhm

Don't listen to them^^, they're just pulling your leg. As for this whole interwebs thing, you know that's a liberal conspiracy, don't you? The frame is actually cast in tin by a lost wax method and then converted to steel by alchemy.

Scooper

fender1

This thread is way more informative than the "Why Are Bicycle Wheels Round Thread" started by nlerner last month!

busdriver1959

It sounds like the reason for your question is that there is rust on the chrome lugs of your Colnago. If I'm right, you will want to search this forum for OA or oxalic acid. You can get very good results removing rust with the techniques you will find there. Also, even though it sounds unbelievable, rubbing the rusted area with aluminum foil soaked with vinegar works great too. Maybe a search for rust removal would show some other techniques. Post pictures so the experts can tell you what your chances for a good result would be.

sailorbenjamin

Yeah but how do you get them to be round?

repechage

I really doubt they are silver soldiered. Every Colnago I have seen sans paint has been "brass, bronze" take your pick, brazed. Silver is way too expensive in a production environment. Silver is a thing the Americans embraced.

ColonelJLloyd 

+1

I like how OA has become the de facto answer even when there is no question.

Captain Blight

I've no doubt you're correct... but, silver solder for bicycling use runs from 48-53% silver and even at the higher concentrations looks like brass when cooled. I don't know if I could tell the difference without really looking at it closely.

busdriver1959

Colonel, if you read the original post, you will see that the question is really about figuring out how the bike is put together so it can be taken apart to remove rechrome the lugs. All the talk in the world about silver and brass brazing won't really help the OP.

big chainring 

Questions like this and basically all the stuff you needed to know about bikes used to be available through "Bicycling" magazine. Fred Delong informed readers of all this kinda stuff. And how to fit a bike to a rider. And the differences in components, and everything you wanted to know. You would feverishly wait for every issue, either delivered to your door or for pick up at the LBS. And if you were a kid like me, you could figure stuff out by looking at the pictures. Reading was optional. If you read the articles, man you really were informed. The interwebs sorta ruined all that. Now, the question is, "I have $10,000 to spend, what kinda bike should I get?"

Michael Angelo 

+1

Michael Angelo 

Silver Braze looks like brass when looking at a Silver brazed lug. I like Silver brazing over Brass. It melts at a lower temp and seems to flow better.

repechage

In the efforts I have done, silver is much easier to insure it has flowed through the entire joint. But it is much more expensive. Much. Brass can be made to flow almost as well and in some instances such as dropouts of the traditional form is better and almost necessary in gap filling. I have ordered some alloy that is designed to create a fillet in silver, but I have had no time to use it yet. Some guys use brass for forks as there is technically a stronger joint, I think given what bad workmanship I have seen on bikes that have held together over time, a well built frame is overbuilt in general.

For stainless, silver is the choice, and for braze ons too. Now for cantilever studs I am not that sure, unless they had a large contact area, the old Mafac stamped mounts would push me to brass.

busdriver1959

Did you get some Fillet Pro? There is one builder I know of that uses it for silver fillet brazed bikes. Much smaller fillets but still a strong joint. I think it's really good stuff.

Scooper

It's not clear to me what the OP's question is; the rechroming question seemed almost like an afterthought.

In any case, the frame and lugs are brazed before any chrome plating is done, and then cleaned up (flux removed, excess braze material on the tubes and around the lug shorelines are filed and sanded, and finally the areas to be chromed are polished to a high finish and then plated. Typically, if the head lugs are to be plated, the whole head tube along with the head lugs and an inch or so of the top tube and down tube are plated. After the final plating is done, the frame is baked to reduce the potential for hydrogen embrittlement.

Rechroming plated head lugs on an existing frame first requires removal of the chrome by a "deplating" process, then cleaning up any corrosion, highly polishing the lug surfaces, and replating the head tube and lugs. The areas of the frame that were painted around the head lugs would also require repainting.

Much of the chrome plating and rechroming processes are described on the CyclArt website.

Over the past few years, there has been a trend by framebuilders to use polished stainless steel lugs instead of chrome plating mild steel lugs. With stainless, there are no problems with toxic waste disposal and you never have to worry about pitting/peeling/rusting chrome.

Polished stainless steel head lugs from Dave Wages.

busdriver1959

Unfortunately, stainless only stains less. It isn't stain free. Stainless lugs require some care and feeding, especially if the rider sweats all over it. Ask me how I know. Having said that, the work being done by guys like Wages, Dave Anderson and Darrell McCulloch (Llewelyn) is just incredible.

jr59

Me like that Ellis bike!

I like it a lot! So much so I bought my own!

And yes the lugs can be redone. But it's not cheap.

Oh yea, mine only has a chrome fork!

Oldpeddaller