In the late teens of March'13 I went to Taiwan and visited the Long Shen lug factory, which I believe makes the best lost-wax (investment cast) lugs, crowns, and bottom bracket shells in the world.
Lost wax casting is an ancient technique—at least 5,000 years old, and employed by Indians, Egyptians, Chinese, Romans, you name it. Long Shen has made other lost-wax items (years ago I saw a bunch of ear-piercers), but I think it’s been only bike parts for the last seven years, at least. Lost-wax casting is a common way to shape metal intricately, and jewelrs do it all the time. An intricate lug is more complex than an Elsa Perreti heart, though. I’m not an authority on how Elsa makes her hearts, but the smart money has to be on lost-wax.
In any case, Long Shen proprietors Alan and Shirley generously allowed us full access to the process and to share it with you, so here we do that, hoping you like it. —G
Throughout this presentation we will call these hanging brown things “trees,” because that’s the normal terminology. The brown part is wax, but they’ll get whitish. Inside the brown wax is metal. At the top of the tree is a funnel that is capped here with metal plugs.
This lady is removing cores from a multi-piece die so she can remove a freshly-made wax fork crowns—one of ours! Unseen behind her is the machine that shoots hot wax into the die.
The wax positives come out near perfect but not quite. Some of the wax squirts into tiny seams in the die and gets molded into the part and has to be trimmed off. EVERY piece is hand-trimmed. The wax is delicate, and you can’t trust a robot to do this. Human 1; robots 0.
Here’s another tree. The next step is dipping it into a ceramic batter several times—up to eight—drying each dipping before the next. This builds up athick crust of heat-resistant ceramic, which, after the wax is melted out (lost), becomes a mold for the metal.
Another picture of a wax tree, with somebody’s right rear dropout. Each one has been made with the same die-injection technique, and each one has been hand-trimmed. Never two at a time; only one.
These trees (of wax lugs) have been dipped once, and are on racks in the drying room.
Dipping a tree. This, actually shows-tho-not-in-detail, a secret lug we’re having made for our secret bike.
Working Name: Clem Smith, Jr.
It’s a year off. it’ll be too big for you. It’s a complicated lug, LS doen’t like to make them, and see how few fit on a tree? Sooo inefficient. And to add insult to injury, there is expected to be a high reject rate, due to the complication. All in all… not a smart move, but it will be a heck of a lug. We will not answer any questions about this bike. We might not even make it. Seriously, don’t ask. If you preface your question with, “I know you said not to ask…”…we still won’t answer. Back to the lug-making process:
Some battered-up (multi-dipped) waxed crowns on their tree. Trees are dipped up to eight times, drying each time in between.
Here’s a dipper with a tree. Them’s the Clem lugs again!
And here he is. I couldn’t pronounce his name. I will get it and eventually post it. I’m not presenting him as Generic Dipper or disrespectfully. I just don’t have his name.
This is Alan, who with his wife Shirley owns and runs Long Shen. We did an interview with Alan-Shirley-Long Shen in one of the earlier Readers. No, nobody here remembers which one. Alan is holding a finished ceramic tree full of wax bottom bracket shells. See the funnel atop them? Molten steel goes in there.
The tree-drying room.
Loading wax-filled trees into the melting-out oven.
In the oven, upside down, wax will melt out.
After molten steel has been poured and all’s cool. They’re full of steel castings.
Yep. Another shot of same, but this one showing the pouring gates.
The ceramic molds are broken open and out come…in this case, bottom bracket shells.
Used trees with castings broken off. These will be dipped into wax and reused as the future trunks of other trees.
You’d hope, after all that, that each lug would emerge perfectly formed. That’s not likely, but most are close enough. This one here isn’t close enough, and I picked it out of a reject pile.
Even after the unrejected lugs are culled, they still need to be deburred and crisped up at the edges.
On a related to lugs note—
Sean here has a 2tt Sam and there was the faintest bit of monkey business going on with the paint at the edge of the rear tt lug. Paint prefers flat or smooth surfaces, and a lug edge isn’t, and the paint was ruffled a bit at the edge and looked stressed or cracked. We suspected it was just paint imperfection, totally inconsequential, and you had to look deep into it to see anything, but to be sure we sent it to the maker in Taiwan who said, “That’s paint, not metal” about the ka-ka, then blasted it off to show it:
Paint, not metal, but here’s a close up of the nice brazing.