Masterclass: Lugs and lugged framebuilding with Llewellyn Custom Bicycles

Welcome to Masterclass, a series where we take you behind the scenes with renowned artisans to share the effort that goes into their craft. In some cases there will be tips and tricks to help you practise at home, other times we’ll simply provide an advanced understanding of how something is created. In this edition of Masterclass, we look at what’s involved when working with lugs to build a frame with Darrell McCulloch from Llewellyn Custom Bicycles. There was a time when all road bike frames — indeed, all bicycle frames — were lugged. This method of construction, which can be traced back to the earliest steel frames, is an easy one to grasp: just match each purpose-built socket to the tubes, and the whole frame can be assembled like a child’s construction kit. Brazing is used to bond each tube in its socket, and provided there is an accurate fit between the two, it produces a very sturdy and durable joint. From the outset, it was a sound strategy, so it persisted for many decades until the industry discovered TIG-welding in the 1970s. TIG-welding was not only quicker than brazing lugs, it gave framebuilders more freedom to vary frame angles. Nevertheless, some framebuilders p...

Finding HVAC Techs to Properly Diagnose TXVs Is Necessary but Problematic | 2019-02-04

The basic components and function of a thermostatic expansion valve (TXV) continues to play a role in HVAC service. “Long, long ago in a faraway place, TXVs had very little impact on service technicians because they seldom gave any problems,” said Carter Stanfield, who currently serves as lab assistant at Athens Technical College in Athens, Georgia, after retiring from full-time teaching. “The contaminated compressor issue, the switch to POE oils, and lack of nitrogen brazing have all combined to make TXV problems fairly common.” Not only does Stanfield have over 40 years of experience in the industry, but as co-author of “Fundamentals of HVACR,” from Pearson, he literally wrote one of the books on the components and functions of modern HVAC systems. In one of its sections on TXVs, the book points out that “this component is widely used for nearly all types of air conditioning and refrigeration systems. The advantage of the TXV is its ability to automatically adjust to match the load, as it is designed to sense changes in the refrigeration load and respond to them.” A member of the metering valve family — which includes the likes of capillary tubes, automatic expansion valves, ...