Construction Technique
Ybarrola and Persechini steel lugged frames are built the old fashioned way, mitered by hand, pinned joints and silver brazed.
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Hand Mitering Mitering by hand is a fast and very efficient operation. Using a file and a template or lug as a guide, a gap free miter can be done quickly. When doing a one off custom steel frame there is no need to spend lots of time setting up a milling machine and then risk tearing thin walled tubing with power machinery. There are times when a milling machine is helpful, but in most cases it is not necessary for custom small production bicycle frames. Notice the top tube head tube miter to the right. The top tube fits the lug perfectly. This will ensure a gap free fit with the head tube. Gap free miters are what give the frame its strength and help to ensure alignment.
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Pinned Joints I pin my joints because it allows me to make a better frame. With pins I can make a frame more consistently and with better alignment. A frame should be brazed outside of a jig to let the frame expand and contract during brazing. To braze outside of a jig, the frame must be held together and in alignment. It can either be pinned or tacked. Tacking involves doing small "welds" around the lug and tube. After tacking, a frame can be brazed outside of the jig. I choose to tack my joints mechanically.....with pins. The pins hold the tubes in alignment and allow me braze outside of the jig.
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| Silver Brazing
In my opinion heat is the enemy of steel tubes. Of course heat is needed to join steel to steel, but I believe that using as little as necessary will allow the tube to retain its original characteristics. Using silver solder allows me to braze a frame at much lower temperatures than brass brazing or welding. 56% silver melts at around 1,200F, brass melts at about 1,600F and tig welding is performed at even higher temperatures. The "critical" temperature of steel where steel can change characteristics is around 1,800F.
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Paint I choose to have my frames "wet painted", not power coated. It costs more, but there is no better way to show off lugs. I am lucky enough to live in San Diego where Brian Baylis and Joe Bell are the local painters. |
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