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Cutting cast lugs for bilam?

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Cutting cast lugs for bilam?

Old 04-03-24, 09:41 AM
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Cutting cast lugs for bilam?

Is there a reason why you can't miter cut a cast lug for use as the sleeve in bilam construction? It seems to me this would save some labor as compared to filing down the standard 1.125 sleeve to make it less chunky.
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Old 04-03-24, 01:11 PM
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I'm confused why you wouldn't just get one of the lugs that's meant for carving at that point. Lugged mtb?

I can't imagine filing down a piece of tubing, I do it on my lathe. So in a way, I agree with your question.
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Old 04-03-24, 01:42 PM
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Oh I kind of just forgot about those! The "lug blanks" are thinner than 1.125 x .058?

I guess partly I was curious because there are some very nicely 3d shaped lugs, like the "web" types, that would be difficult to replicate carving a blank.
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Old 04-03-24, 05:37 PM
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You can always add whatever flourishes you want with extra metal. It's pretty common to do that with lugs too. We have gotten used to pointy tops on seat lugs, for example. On vintage lugs, that has to be added. Peter Weigle has posted pictures of some lugs he has done that with, for examples
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Old 04-25-24, 02:03 PM
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This might be worth watching:

youtu.be/uK9yeHU14rk?si=XA6mv83doSaaYv9r

Paul Brodie,bilaminate construction
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Old 04-25-24, 02:23 PM
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Sure, using a lug as the start of a bilam joint is not at all wrong. It has all the limitations that using a lug with a pre cut shape has when not doing a bilam. People work around those limitations all the time (as Eric mentions).

So the time saved by only cutting off one socket from a lug against the time to make a single socketed sleeve is the next question. One that I think would depend more on the builder and less on the parts.

The one detail that I can think of is the process of brazing the three parts together. Do you braze the single socket lug to the tube (head tube with most bilams) then attach the top tube? Or do you do the entire joint at one session? The way many make a bilam with a self made sleeve/lug is to leave the material that the end of the top tube will touch alone, so the top tube touches the sleeve and the sleeve is touching the head tube (as an example) with no direct tube to tube contact. But when using a premade lug that has had one socker removed the two tubes will want to touch. How any filler that is already in that top tube contact area interferes with the fit up depends on skill or clean up if the joint is done in two steps.

My choice would be to make the sleeve to insure best tube end contact and better control the lug shore lines shape to one I like. The sleeve would get brazed onto the head tube first. Andy (who isn't attracted to the whole bilam thing anyway)
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