Has anyone here ever built a frame using internal lugs?

Trek's early aluminum and aluminum/carbon frames used internal lugs (and epoxy bonds); my road bike (an '85 Trek 2000) is one example. I'm a big fan of the clean look the internal lugs afford, and I have the dream of one day building an internally lugged titanium frame. The biggest hurdle would seem to be acquiring the lugs, as I haven't seen internal lugs available anywhere online. Machining internal lugs wouldn't be that difficult, except for the bottom bracket cluster, which might take a bit of thought.

If anyone else has tried to build a frame this way (or has an opinion) I'd love to hear about it.

I have the feeling it would be cheaper to have a company cast your titaniium alloy inverted lugs than machine them...

Has anyone here ever built a frame using internal lugs?

I'm a big fan of the clean look the internal lugs afford, and I have the dream of one day building an internally lugged titanium frame. The biggest hurdle would seem to be acquiring the lugs, as I haven't seen internal lugs available anywhere online.

If anyone else has tried to build a frame this way (or has an opinion) I'd love to hear about it.

Internal lugs result in a frame that looks almost identical to a well made TIG welded frame with ground down welds. Why bother with lugs if you don't like the look?

it is actualy stronger, and welding TI is suposed to be a *****

Internal lugs eh?

Oooh, cool.

Masi (who owned it at the time I have no idea) did it in the early-mid 80's. Looked good too.

it is actualy stronger, and welding TI is suposed to be a *****

welding TI requires an internal argon purge of the tubes and an extremely clean environment, other than that it's the same as any other DC tig welding procedure. I'd say welding aluminum (AC) may be considered more difficult, especially if you're coming from a steel (DC) background.

i second the steel to alum comment

nice design thylacine.. have you got any of these made yet? would the fishmouth cut on the tubing have to be mostly hand cut and filed, or do you have an idea how to machine cut this profile??

cool stuff.

!Steve

nice design thylacine.. have you got any of these made yet? would the fishmouth cut on the tubing have to be mostly hand cut and filed, or do you have an idea how to machine cut this profile??

cool stuff.

!Steve

God no. As nice as these would be, they're not the most practical design. The design would allow the builder to use .5mm straight guage tubes but I have no idea how practical it would be to massage lugs of this design to change the lug angles. Probably no harder than the current lugs, but I have no idea.

This was just a bit of fun I had with a couple of other bike designers a while back. I was thinking out loud 'What would be the natural progression of the Masi internal lugs?' and that's what I came up with.

The tubes would be laser mitred, a very common thing in the mass production world, but obviously not something Joe Custom has in his back shed.

I'm not interested in framebuilding just the "internal lugs" caught my eye as I went by.Several of my Antique bikes have Internal lugs. I think schwinn started out with this method and in the 30s went to fillit brazing.But the early internal lugs were not the hi-tek luggs shown here---they were simply tubing cut and fish-mouthed into the head/bb stock--not sure how they bent the fish-mouths inside the head/bb stock---somehow the flared them against the sides.---sam