Norris,
Thanks for sharing your experiences of framebuilding in the days of old. Some fascinating information in your text. Like you mentioned, part of framebuilding is learning to adapt to the materials and situations at ha nd. I especially like the mention that frames were built withing using a frame jig. Many people do not understand that quality frames are built by quality framebuilders. The jigs and fixtureing are simply an aid and a time saver. The quality of the outcome depends on the builder, not the jigs.
I try to encourage young builders to take on the construction of a frame without a fixture and using only and alignment table or something simil ar. There are thousands of ways to do that. It aids their understanding of what they are trying to accomplish in terms of frame alignment and ho lding specified angles and dimensions. Also helps them not rely complete ly on the fixture and take things for granted.
Thanks for helping people to understand the world of framebuilding a lit tle more.
Brian Baylis
La Mesa, CA
John Clay raised the problem of filling the voids that occur in th e i nternal joints created by frame tubes and badly pressed steel lugs.
Framebuilders become well aware of the shortcomings of many of the frame co mponents that they have to use when constructing a frame; in particular the tolerances and accuracy of many pressed lugs leaves much to be desired. Th e void between the radiused internal angle of a lug is probably the bigg est problem..or at least filling it with brazing material is, as John has h igh lighted.
I was around in the early days of the 1950s when frame components wer e in short supply, and the choice when building a frame was often either to adapt as best as possible old style and slack- angled cast lugs, or con str uct the frame without lugs..or use the bilaminated technique. But with t he
easing of the supply of raw materials along came supplies of pressed lug s,
notably Franco-Suisse, Prugnat...in very short supply..and Oscar Egg Sup er
Champion.
All these lugs suffered from the internal radius problems ie voids or em pty pockets in the joint that did not exist in cast lugs. The way I was tau ght to overcome the problem was quite ingenious, but it made more work., but it was a technique that was easy to employ, in a sense, because we b uil t the frames without the aid of jigs.
We started the brazing process by brazing the top head-lug to the top-tu be, and by brazing the bottom head lug to the down tube. Note that the head tu be is not mentioned. We would braze these joints by applying the filler rod from inside the lug and drawing it through the joint and along the tube . T he void would then be over-filled. When cool the surplus braze material on
the inside of the lug would be carefully filed to ensure that the void no longer existed and that the joint had a perfect mitred profile so that to
all intents and purposes the inside of the lug was as accurate as a cast on e. Later on we bought an expanding reamer that gave more precise profile s a nd diameters. When we had filled these joints we carried out the same pr oce ss by attaching the seat lug to the other end of the top tube, backfilli ng
the joint with braze material and then filing away the surplus Once the top-tube head-tube and down-tube were assembled and ready for b raz ing we would carry out the process with silver solder that melted about 230 degrees lower, thereby ensuring that the braze material in the voids wou ld not be melted and the integrity of the joint not compromised. Th e s ame process was applied to the seat tube joint. As for the bottom bracket joints and chainstays, the brazing rod was app lie d from the inside of the shell and sucked up the tubes. Back-filling any ra dii in the bracket was quite easy.
In later years and following training with the British Oxygen Company I bec ame much more proficient in controlling the movement of brazing spelter
with the torch flame within a lugged joint and also outside on lugles s f rames. I abandoned my early void-filling technique and became very ski lled at filling the voids by using an externally applied rod of thick er
than normal diameter, say about 1/8", and a smaller than normal nozzle, usu ally a No1. With the much smaller flame I could almost stroke and coax th e slightly pastier filler rod into the voids, by controlling the heat an d t he rate of flow of the braze material at the same time. As my tutor at t he
BOC always said...Always use the smallest nozzle possible. It may take a li ttle longer..but a craftsman with a lighted torch in his hand should n eve r be in a hurry.
Hope this helps, John. Neither way gives rise to any real difficulties.. it' s all a question of time..and practice...and control.
Norris Lockley....Settle UK
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