Modifying the forkends.

Beginning steps - deciding what you want to build.

Materials - what to use and where to get it.

Tools - a bare bones set of tools.

Modifying the fork-ends with stainless faces.

Modifying the bottom bracket shell to work with my mix of angles.

Mitering the tubes.

Soldering the main triangle.

Soldering the rear triangle.

Cleaning up the lugs. Complete with lots of pictures of the naked unpainted frame.

Making transfers.

Painting.

Addendum.

I agonised for a while about how I wanted to deal with the fork ends. On a track bike, it's necessary to move the back wheel forwards and backwards a little bit to accommodate various gearing combinations. If the parts of the fork-ends that come into contact with the axle and nuts are painted, this paint will be destroyed fairly quickly, leaving the metal underneath exposed, which subsequently rusts.

In order to create a more useable fork-end, I thought it would be neat to solder stainless steel plates to either side of the fork-ends. This way, the nuts bite into the stainless steel, which isn't painted, and won't rust, thereby keeping the paintwork pristine.

However, the fork-ends were already 8mm wide. I played around with a track hub, and decided I really didn't want to add to that width. Thus, I was going to have to remove as much material from the side of the fork-ends as I would later add. I did this on the inside of the fork-ends using a file, however I was unable to do this to the outer face because the chain stay and seat stay sockets were in the way. I cheated a little, and conned a friend with a mill to remove the lip for me. I took 1mm off each side.

I then cut four 1mm thick sheets of stainless steel to the correct outside shape of the mounting faces. I drilled some holes in the middle, so I could clamp them either side of the fork-end by passing a pair of small screws through the middle.

Next came my introduction to brazing. This was done under the tutelage of an experienced welder from work, who watched over my shoulder through much of the process, and offered lots of advice. I first put plenty of flux on all contact faces of the joint, and carefully clamped the stainless pieces to either side of the ends, using screws and nuts.

In order to join them, I next used the oxy-acetylene torch to heat the job. I used a reasonably large tip, and kept the gas flow on the low side. The flame was just right when you could barely hear it. First I heated the whole fork-end gradually, in order to bring it close to the right temperature. The flux spattered a bit, then settled down and took on a transparent, glassy appearance. Gradually the colour of the metal changes, so it takes on a sort of straw colour (hard to describe in writing, but easy to see in practice).

It's time to add filler when the joint is almost glowing. There's a knack to getting just the right temperature. When you get it all right, the filler flows right through the joint, and there's minimal coaxing with the torch to get it to flow around. On this joint, I had difficulty getting the thin stainless plates and heavy fork-end up to temperature simultaneously. The thin plates would invariably get hotter quicker.

Once the filler was added to each side, they were left to cool and then cleaned up a little. The flux cleans oxides from the join, but deposits these oxides at the edges of the join, where it's cooler. If like me you take a while to get it to work, you end up with a lot of hard black gunk that's very difficult to remove.

After they were cleaned up a little, I cut the slots with a hacksaw and file. They ended up looking like the following picture: