Lugs. Those fancy bits that builders used to strengthen the brazed joints between the tubes. Over time they became more elaborate, almost a fashion accessory by which bike builders showed off their skills and differentiated their bikes. Carpenter used a variety over the years, occasionally hand-cut from sheet steel (which was very laborious), more often bought in and then modified and fettled to a close fit. Once Nervex introduced their pretty investment-cast lugs Carpenter, like most lightweight builders, adopted those. The following examples illustrate the trends. Also shown are some examples of dropouts, lamp brackets, bar stems.
1936 #3115 Chater-Lea; 5/16″ Bottom bracket
1937 #3257 Cut-outs in chromed head lugs. Super Champion rear dropouts.
1949 #4296 Ekla
1955 #4898 Nervex lugs, b/b shell. Fluted wrapover seat stays, track rear dropouts.
1955 #4908 Hand cut lugs (Oscar Egg?). Fluted wrapover seat stays, which became a consistent Carpenter ‘signature’.
1956 #5012 Back to Nervex Pro lugs, wrapover seat stays, Campagnolo road dropouts
1957 #5071 Nervex Pro II lugs, wrapover seat stays