It is worth while to take a fresh look at framebuilding material options because it is always possible something new can be learned. Just a bit of history to help put things into perspective. When I started to learn how to build frames in the 70’s investment casting had just started to be an option. Its disadvantage was that it was a lot more expensive than what was commonly available. Before that lugs were made out of sheet metal by stamping and welding (or sand casting). As frame production techniques changed to tig welding, lug companies that made a profit by volume found their market had disappeared. Custom framebuilders were supplied with investment casting products by Henry James and Richard Sachs and others. Now even those suppliers are disappearing as the number of builders using IC products has continued to decline. Hank has retired and the investment casting houses in Taiwan that were used by other suppliers have stopped production.
Several years ago I persuaded the Nikko company in Japan to make some blank lugs. Instead of stamping and welding they are bulge formed so there are no seams. Trek used Nikko lugs when they first started framebuilding in the mid 70’s because they required less clean up before and after brazing. These lugs are a little more malleable for changing angles than investment cast lugs. I had a graphic artist create a template of each lug socket twice its normal size. This large template makes it easier to draw a design. This big design can be reduced to life size on a copy machine that prints out the pattern onto a sheet used to make labels. This is sticky backed paper that can be bought in places like Office Depot. Once the template of a socket is cut out, the backing paper is removed and placed on the lug for cutting with a jeweler’s saw. Dremel cutting discs and jeweler’s files help complete the task.
Bilaminate construction is the most common way a builder makes a lug. This is where 2 sleeves are fillet brazed together to form a lug. Claude Butler frames in England used this method because lugs were not available right after the war.
I visited an investment casting company some years ago. Individual wax pieces are put on “trees” so that each pour can make 10 or so pieces. One of the challenges of doing an investment cast lug is that shrinkage has to be calculated into the mold. In other words the wax lug has to be a bit different size than the final product so that after the melted steel has cooled it is the right size. This is why engineers have to help design the lugs.