Mauricemonge

Hey guys, I’m having a frame built for me using some lugs that the company no longer has casts for.

I’m wondering how hard/expensive it would be to get moulds made from existing lugs so they could potentially keep making these in the future. They only have one road and one track set left, and I’m taking the track dropouts.


In case anyone is wondering, the company is cherubim, and they’re making me a 3rensho (same family, they own the rights) using 3rensho modeulo lugs. And it’ll be pink with rainbow flake.

Thanks
Maurice

Calsun

What the fellow did for my custom bike was to take lugs and cut them in half and then make the necessary adjustments and braze them back together. Talk to a couple frame builders as this is a situation they encounter and have already solved.

unterhausen

It's very expensive to have the tooling for investment casting made. I'm designing a lug to be 3d printed. That's about the same price as buying cast ones. Probably can 3d print for investment casting patterns, at least I have seen talk of people doing that.

I suppose they could get those lugs scanned now before they use them. But I think I could copy almost any lug pretty closely just by looking at a completed bike

bulgie 

Consider making lugs out of steel tubing, mitered and welded (or brazed) together then smoothed to look like one piece. Time-consuming, bit still probably cheaper than IC, for a one-off.

For example see the perfect clone of a 1961 Masi Special, made by Rob Roberson, commissioned by Richard Byrne (of Speedplay pedals fame). The Flickr album shows in-process shots of the lugs being made. Some of the photos have terrible focus, Roberson is a better framebuilder than he is a photographer, oh well.

Once, for Davidson, I made a complete lug set including BB shell that way, that was sent to Takahashi Japan to be used as master models for a new line of IC parts. I think I spent most of a week just on the BB shell, but I am slow. I never took pictures of anything back then, sorry. The parts I made could have been used to make a frame rather than sending them away to be copied as castings, if it were a one-off frame. The bastards never sent the masters back, claimed they "lost" them. Of course we had the cast parts, but those hand-made masters had sentimental value to me, and they were actually better than the cast parts in a couple ways — they screwed up a bit. That's always a risk with IC parts, you never know how they're going to fit until they're done, and if they're terrible, you have to just use them anyway because of all the sunk cost.

Mark B

unterhausen

I think OP is more thinking of the future of those lugs, not for their bike. Unless I misunderstood that Cherebum wanted to keep them. Anyway, in the future we will all be using 3d printed lugs and wondering where we're going to get tubing. I found some companies that will use a 3d printed model for investment casting. I'm not sure if that's superior in anyway to just having them printed directly.

Andrew R Stewart 

I have read that when casting lugs there's a shrinkage on cooling that has to be accounted for when making the master. So a lug that is the correct to braze up dimension would not be the right size for the mold master.

For a one off I agree with just making one's own lugs with thinned down tubing and a lot of cutting and filing after the filets are done. Andy

dsaul

I agree with Unterhausen that 3d printing is the way to go for small batch items like that. I know people that love lugged frames think that there is a huge market for them, but the reality is that it is a very niche thing and not profitable to continue to produce them with investment casting.

Mauricemonge

Thanks for all the replies. Looks like the builder probably came to the same conclusions when getting more of these made.

As far as making one off lugs that look like these. there is some cool webbing that would take some time to braze, and there are 3 spikes (don’t know the technical name) that attach to the tubes, instead of just a top and bottom.

I’ll just be happy I’m getting the last track bike made with these old lugs, and leave it at that

thanks again!

unterhausen

I found this thread from someone who had those lugs 3Rensho Reproduction / Frame building Diary
They would be easily 3d printed. It's not that big of a deal to braze or weld some up either.