Soldering the rear triangle.

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.

This was the trickiest bit to align correctly without a proper jig. After mitering the chain stays, and cutting them to the right length, I fluxed both ends, as well as the fork-end and the bottom bracket socket, and assembled one side.

To hold it at the right angle in the socket, I again used my 40mm square aluminium tube. Recall that the top and seat tubes are both 28.6mm diameter. If I clamp the tube to the side of the top tube and seat tube, so that it passes where the rear axle would be, it provides a handy in-plane reference. A little math tells us that we simply need to add 5.7mm of spacing between the inner face of the fork-end and the outer face of the square tube to get 120mm spacing between fork-end faces.

Slightly harder was getting the angle of the chain stay in the vertical plane right. I used a flat steel bench as a reference surface, and sat the frame on the bench so that the down tube was horizontal. A little math then gave me the angle of the chain stay to the bench, which I set with a protractor. I engaged the clamp, checked everything twice, and then set to soldering.

As with the other bottom bracket sockets, I added filler to the top, and then flowed it around. I then went back to the fork end and soldered it to the chain stay.

Once it had cooled, I swapped my square tube to the other side and repeated the process. I additionally checked that the fork ends were parallel and at the same height before soldering, and that the chain stays were inserted exactly the same depth into their sockets.

The frame was now at a stage where I could put a wheel in. I did this, and was relieved to see that the wheel was nicely centered with respect to the seat tube and the chain stays.

This collection of tubes was now starting to resemble a bike frame. The final bits to attach were the seat stays. I had fitted the seat stays to the fork ends, but had not done the miter between the seat stays and the seat lug. This miter was really difficult to get just right.

Rather than just stick a cap on the seat stays and solder them to the side of the seat lug, I wanted to fit them to the rear of the seat lug, in a fast-back configuration. My seat lug had additional material at this point to attach the seat stays, but didn't have any sockets cast into it. I had to miter the seat stays so that they fit neatly on the back of the seat lug.

This is easier said than done. I started by cutting a seat stay a tad long, and then drawing what I thought the miter would look like on the tube. Then I set to with my half round file and removed metal. I made sure the seat stay was always a few millimeters too long. I figured I could remove the last millimeter from the other end of the stay once the miter was right. After literally dozens of trial fits, the miter started to close up. When it was close, I inserted the other end, and pulled some emery cloth up between the seat lug and the stay, while pressing the stay into the seat lug. This improved matters no end.

When I was satisfied with the first stay, I taped a bit of paper around the end and cut the paper to the shape of the miter. I then taped the paper upside down on the other stay, so the miter was mirrored, and cut the miter with my hacksaw and file. Again, when it was really close, I finished the job by drawing strips of emery cloth up through the seat cluster - seat stay join, while pressing the stay towards the seat tube. I could now put a wheel in the fork ends and check that it was centered in the stays. I drilled a couple of small holes at the bottom of the stays to allow hot air to escape the tubes when I soldered them.

After a lot of careful checking, and measuring both stays against one another to ensure they were the same length, I fluxed both ends and put the stays in position. I started by soldering the bottom end of the stays, with a bar clamped across the top where the brake bridge would end up, to hold the stays in the correct place. Once this was done, I moved to the top of the stays. There was no need to move the clamps, as this join was all ready to go. This was a little tricky, as the stays shielded the back of the seat lug, and made it difficult to heat the seat lug between the stays to a good temperature without overheating the stays. I managed to get it to work reasonably well by alternately heating from above and below, then ran solder from the top of the join. It formed a really nice fillet around the base of the stay, but a smaller fillet at the top. A wheel showed everything was nicely centered.

The very last bit to add was the brake bridge. Although this frame will probably not be used with brakes, I thought I'd allow some provision for them. The brake bridge was simply mitered with a round file, then fitted in position and soldered. These were my neatest joins. Just the right amount of solder flowed straight around the join, with no fuss at all.