I am a frame builder AMA

A seagull?

Use long horizontal dropouts.

It's what they were designed for: the hanger was a later adaptation while we waited for someone to invent vertical dropouts.

It is by no means impossible to do it, just bear in mind it's another thing to go wrong. Awful for biting off more than I can chew, so if it was me I'd just do it!

Because we have gone back in time and it's 1935? ;)

Is it possible to carefully cut off a screwed up lugged B.B. shell and fillet braze another in? Leaving the lug tips but removing the main cylinder and end up with something a bit like bilaminate

Anything is possible ;)

Yes should be perfectly doable with a bit of work holding

Can someone make me something that looks like an 2007 Litespeed Vortex with a flared diamond downtube? I'll kiss you if you can

What’s the pros and cons for Oxy-acetylene or Oxy-propane?

I've never used propane, only acetylene, but the obvious benefit of propane is costs and availability. Acetylene is expensive to buy and relatively difficult to get hold off without having to hire the bottles and have a contract with someone like BOC. The downside of propane is that acetylene has a hotter flame and so is better for things like fillet brazing where you need a lot of heat in a small and accurately defined position.

Propane is ok for framebuilding and I started like this. TBH I much prefer the hotter flame of Acetylene now though.

Acetylene is very explosive and scares landlords shitless. I have been knocked back for workshop's because I use it.

@danstuff @Markgee
Thanks for the information guys.
I think propane may be fine for my hobby stuff and the lower entry cost makes sense.

I think you are probably making the right choice. I started out with this kit https://www.weldequip.com/oxy-propane-brazing.htm

Thanks dude, that’s a great help.
So for all but fillet brazing this should be fine?
Could fillet brazing be done with this set-up at a push? I know you’re saying it’s not ideal but I’m just thinking about tinkering.

I always found it ok to fillet braze with this set up personally. Lugged BB shell's were harder to get hot enough and seemed to take forever. I switched to Acetylene for this reason as I do mainly lugged frames.

I just had a look at you instagram. I love that lugged wishbone seat stay on the Flanders Flyer.

Thanks man. They are a pain to get right but look good when they are done.

Can I tig tubes onto this cast bridge?

Don't see why not. It'd be like any other butt joint. Won't it look a bit fugly though? It'd rather ruin the clean smooth lines of the wishbone, even with most excellent welds.

Could grind a vee and fill it up with weld, grind back so it’s smooth... I’m more concerned about TIGing cast parts though. Seem to remember reading somewhere that they’ve got lots of impurities so the weld is wack.

I might be tempted to drill some holes in the tubes and do some plug welds too. If you're going to be grinding the welds smooth, will it matter if there are some impurities in the cast part?

I had thought that it was best to use bronze when brazing lugs and silver on little things like cable guides etc.
I now think I’m wrong as I saw a photo of someone using silver to braze a fork to crown.
If that’s the case what are the rules of which to use, on what bit of the frame etc?

Silver flows better, you need silver for stainless, other than that both are adequete for most things.

Thanks, that makes sense of the photo as it was stainless.
I want to have a go at a lugged frame, if I go with an Oxy-propane set-up should I just try some test pieces with bronze and some with silver and make my choice based on which I prefer? Or are there parts of the frame where one would be a better choice than the other?

Welding cast stuff is a shit. It acts like it youre welding with bad argon.

I use brass for the lugs/ends and silver for the braze ons. SIF 101 has a low melting point and seems to be the best brass but the Cycle Design brass is cheap from Ceeway and will probably be good enough to get you started.

Ceeway does test lugs and cheap tubes to practice on mate.