AndyGrow

A few months ago I bought some scrap tube and lugs from Andy @ Strawberry Cyclesport (Terra Nova Bikes). I'm finally getting some time off from work, and want to start practicing brazing.

My problem is - I am limited to ONLY using MAPP torches. I live in government (Coast Guard) housing, and any sort of welding equipment is prohibited...except for handheld torches (propane, MAPP, etc).

So, working with that limitation...what are my best choices for rods and flux that will be most compatible with MAPP heat?

Thanks. And please - PLEASE - don't tell me I HAVE to get a big Oxy/Acetelyne setup. I can't!!

Nessism

Building with lugs is the easiest way to get started in framebuilding. If you use investment cast lugs with the proper clearance for silver (approx. .004"), 56% silver will work great. Use the appropriate white flux and have at it.

Good luck.

Ed

SoonerBent

I've never brazed frame tubes into lugs. I have however brazed and welded a lot. I really don't think you can generate enough heat with MAPP gas to get brazing rod to flow properly. The tubing probably conducts the heat down the tube too fast. If it can be done it would be with silver rod. Most silver rod melts at 1100 to 1200 F. Brass / bronze melt at 1200 to 2000 F. MAPP gas says that the flame temp is 2927 which sounds hot enough. But you have to get all the tubing metal at the joint well above the melting piont for the brazing material to flow into every little void. Which flux to use is determined by base material, rod material and temperature during brazing.

SS

Kogswell

MAPP brazer velonomad has a good list of rods/flux on this thread - look at posting #4

https://www.bikeforums.net/framebuilders/161694-velonomad-kof.html

Hartmann

Scroll down to the "re-cycle" thread. Velo shows how to fillet braze with mapp. I use to belong to the same MTB club as Velo . He has built some nice bikes with mapp gas.

mattman

Go to a plumbing or welding supply and get yourself an MC acetylene tank and regulator set with a turbo tip. Its fairly small not much larger than the mapp gas and the turbo tips come in various sizes.

bridgestone60

Hello from Marquette, Michigan! (A fellow Yooper on the shore of The Big Lake)

Just the other day I was looking around the web for interesting framebuilders and came across Circle A Cycles at https://www.circleacycles.com/. They're an interesting company in R.I. that builds frames and on their website they mention using MAPP gas. Good luck with the framebuilding. let us know how it goes.

tom porter

I.ve been using MAPP to fillet braze a couple of dozen cromo recumbent frames for almost 9 years. A properly done joint seems to be no problem. I even weld with MAPP.

Tom P

silversmith

If you ever find you need a little more heat than your torch provides you can use a heat reflector to capture a few more degrees. I use copper flashing.

mattman

The biggest problem i see with mapp gas is you hold the whole thing tank and tip. i have lots of experience brazing/ soldering and the ability to have the tip on a hose gives you a lot more room to work with.

raincrosswrench

This thread really got me interested! I've been wanting to try this for a long time, but never thought straight MAPP would do it... So, I figured, what the heck- give it a try - I've only got like 3 frames in the basement that I picked up for nothing because someone rammed a parked car or other tube tweaker. Sure 'nuff-- the stuff got it pleanty hot enough to pry the joints apart on a couple of lugged Reynolds 531 frames. I then managed to add a bunch of small braze-ons (cable guides and such) to a frame I've been meaning to take to a local builder. Saved at least $50, even after investing in a new self-igniting MAPP torch as advised. If mattman is worried about the weight, they (Bernz-o-matic) do sell a version with the nozzle on a hose. I guess he's never sweated water pipes in a basement before (all along the ceiling!)-- working on a bike frame at table top level isn't really that strenuous! ;-) I'm about to order up a few replacement tubes for the frames I've dismantled and see about putting these beauties back together. With luck I'll manage to get them lined up properly and they'll be good to go! You gotta love steel-- try that with carbon or aluminum!

mattman

Nope the problem is i sweat pipes for a living and when you do the amount i do even a mapp torch is bulky and uncomfortable. I use professional quality torches with long hoses and i just can not imagine why anyone making more than one frame would not invest the $100 or so for a decent setup. Its the difference in control between trying to write with a log or a pencil.

atombikes

I brazed this lowracer recumbent entirely using a Bernzomatic model JTH7 torch and mapp gas.



This torch has a hose that is several feet long, and DOES put out enough heat to fillet braze. I like the idea about using a shield to keep the heat near the joint. In the past I have used a second propane torch to add additional heat to bottom bracket shells, etc.

Cyclist0094

Efficiency and cost effectiveness is fine if you plan on building several frames a year. On average most home builders like myself will build 1 frame a year. The rest of the year the Benzo starts the charcoal in the barbeque grill

2 1/2 bottles of mapp? it wasn't the torch's fault.

I used less than a full 1lb Mapp bottle to build this frame using a standard Benzomatic tip. Just takes a little practice to learn how to control the heat.

AndyGrow

Once again...I let velonomad's pictures do all the talking I need to hear about MAPP!

Cyclist0094

Atombikes can you try posting the pic or link to your lowracer again? It doesn't come up on my computer

atombikes

velonomad,

OMG, that bike of yours is beautiful! I have an old Windsor (Mexican built) bike that has polished lugs like that. I plan on doing a restoration on it when I get some free time.

As for the pic, you're right, I can't get it to work either? Here's the link again (maybe this time it will work?)

atombikes

I don't think you will find too many people that would argue that an oxy-acetylene torch with proper tips and tanks, etc... is a better way to go for people that are doing this type of work in a more or less full time capacity. However, there are many that have never done this type of work before, and want to test the waters. Or perhaps they are only going to produce one frame a year, as velonomad states. Or maybe they work in a shop connected to their house, and they don't want to worry about the instability of acetylene or the cobwebs (soot) that it produces. Or maybe they don't want to sink a minimum $200-$300 for equipment, then pay for tank rental on top of that. Or maybe they would just like the convenience of going to WalMart to pick up a tank of mapp, rather than deal with going to a dealer.

For those people, there is mapp gas. And I can state that mapp torches are ESPECIALLY good and easy to use for brazeons. I have read that some professional framebuilders use mapp exclusively for all brazeons due to it's convenience.

Cyclist0094

It works as a link now.....cool bike!

My bike might be polished and pretty but your bike is much more interesting! You guys who are building recumbents and HPVs blow me away with the creative stuff you come up with!

atombikes

Thanks for the kind words. I am currently rebuilding that bike, I just finished painting it. I'll post pics when it is completed.

velonomad, can you give a brief description of how you painted your bike? It looks very good.

atombikes

I especially am interested in how the lugs were masked for painting, and how the decals (if they are decals) were made.