Über ßike #4

25 08 2009

Still working on Uber bike…..Had to get some “real” work out of the way. You know the kind that pays you. Show bikes are awesome but represent a huge undertaking that doesn’t pay you right now and das bills have to be paid.

So where am I. I am finally brazing this frame together. The front of the front end is brazed and I am going to do the finishing down to the last bit with it partially finished. Then I will joint this in one operation to the seat tube-BB- and chainstays. Why? mostly because it is just easier to work with a smaller piece. A full frame is always banging into everything and is cumbersome, especially because I have some real detail work to do.

So the first thing is that I have to braze all the sleeves to the tube and then braze/weld the tube together. We generally call this a Bi-lamminate. This idea dates way back to the early bicycles in England and France. That is you have a sleeve to add structural reinforcement and then you fillet braze that to either the head tube or visa versa. First I did the seat tube and then the other eight sleeves.

This is the same piece cleaned up

Seat stays:

Then I made up the head badge.

made up some inlay for it:

Brazed head badge and head tube rings…..

Polished the seatpost. Most of this is good ol scrubbin’ mostly done in front of the TV at night.

 

Then I brazed the top tube to the head tube. A little info about this. This is stainless steel and it is quite sensitive to filler metals and heat. Stainless absorbs heat a lot faster than some other materials and if too much is used serious distortion of various things can occur. Silver not only bonds well but reduces distortion to nearly zero because of the low heat needed to melt it. You don’t often see this technique used. This is high content silver rod specifically made for this purpose (Fillet pro silver rod) and it can be a lot more expensive than brass or “nickel silver” which is a mix of brass and nickel and has no silver.

Silver requires a completely different technique. It’s melting range is super narrow compared to bronze and therefore does not build the same. Torch control is paramount. The upside. A super strong joint. Upwards of twice the strength of bronze and 50% more than nickel silver without distortion and a very low heat input which retains more of the original properties of the material.

Just brazed:

flux cleaned off:

finished

whole head tube finished

Now I am going to completely finish this, then join it all together. More to come….

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One response

26 08 2009
Kevin

Hi,

just found the flickr pics. Now I understand. Just amazing!

Cheers
Kevin

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