bikebasket

I'm kind of considering building a frankenstein tandem as there are basically zero touring bikes here in Cambodia, let alone touring tandems, plus it could be interesting. So i've got two options - ship one in, or build one.

I have plenty of experience with oxy/acet torches (normal steel rod welding, cutting), and arc welding, plus some MIG welding with a crap MIG welder. But very little experience with brazing or soldering, so not that confident doing that on a bike frame really. But i reckon i could tack weld ok.

But i was wondering if it would be possible to align the tubes myself and tack them myself with either a disposable MAPP gas or propane bottle and some solder at 4 points around the tube joints and THEN take it to a local full time welder to be TIG welded or brazed?

So some basic questions? - Is propane hot enough on its own to silver solder tack/spot weld steel bike frame tubing or is MAPP gas the way to go?

Solder or braze?

Would the silver solder or braze tack welds interfere/contaminate with the final TIG or brazing of the frame by the welder?

Would the silver solder welds melt and my frame move out of alignment, on any tack welds made by the full time welder?

Thanks for any help!

CliffordK

You can buy MAPP/Propane PLUS Oxygen outfits that would certainly get hot enough for brazing.

https://www.bernzomatic.com/Products...ition/WK5500OX

However, it is not a choice I would use. Compact sized full welding/brazing outfits just aren't that much more expensive. Or, keep an eye out for full sized tanks and used equipment.

https://www.walmart.com/ip/Arksen-Pr...Blue/112805092

Reading however, you might also look at a small inverter TIG outfit.

I'm not sure how low you want to go:
https://www.ebay.com/itm/2018-TIG-MM...f/323135909401

I assume this is missing the AC (for Aluminum), and High Frequency arc stabilization. But, it should allow you to tack weld steel just fine, and perhaps would meet your welding needs. You could probably even tack weld with a "stick welder", and thus not need the inert gas cylinder. There are cheaper stick welders without provisions for gas, but the TIG power supply might not be a bad starter system.

I don't think I would plan on TIG welding steel over a solder or brazed joint. You might get away with brass brazing over a silver soldered joint, but you're probably best using like metals.

bikebasket

Yeah, i see what you mean, that TIG welder is cheap.
How does TIG welding compare to arc or MIG, technique wise?

The plan is for leaving here permanently and heading west on the bike until we get knackered or bored. India being the first goal.
So maybe hiring a TIG welder machine, or oxy/acet for brazing is another option, if that's possible here.

So brazing or TIG welding - which is generally regarded as harder to master?

fietsbob

Another thread; Mig for farm equipment , Tig is used in bike frames ..

I learned brazing, but more, the silver soldering to fabricate Metal art works.. Jewelry lab at community college..






...

unterhausen

MIG is used by some recumbent manufacturers. Nothing wrong with it if the parts are stout enough.

bikebasket

Funny enough i did a fair bit of oxy/acet steel wire welding when i was a kid. Went on a night course so comfortable doing it.

Wasn't that familiar with what TIG welding involved but after reading : "If you can oxy/acet weld, then TIG welding should be easy for you" comments on the web, i guess it's just like that but with the electric arc making the puddle.