I know it can be done, and I've done a search and found threads related to it. https://www.bikeforums.net/framebuilders/162371-brazing-w-mapp-need-some-suggestions.html

My situation is similar. I cannot afford anything but a cheap MAPP gas torch like the ones they sell at the big box stores for about $40. I don't want to build frames with it. I *JUST* want to manage my own braze-ons. I do all my own mechanical work, and have no qualms about lighting a torch and melting some brass.

For example, I want to add canti bosses front and rear on a road bike I just got, and I might want to put track dropouts on it. That's about as complex as it would get, really.

So, what brazing rod would I use for this?

Edit: I found this in this thread: https://www.bikeforums.net/framebuilders/161694-velonomad-kof.html (Thanks Velondmad):
So does that pretty much cover it? Thanks for any tips and suggestions.



Don't worry I have junk frames to practice on...

Don't mean to contradict velonmad but I recommend you use brass (C-04 mentioned above) for dropouts unless they are socket type. Silver is good for tight fitting joints but for loose stuff, use brass. And I recommend brass for the canti bosses as well but this is not as strong a suggestion.

It's my understanding that MAPP gas is not hot enough to melt brass. I haven't personally tried it, but I've seen it come up in conversations in the past. I built my first frame with MAPP gas. Works great. If all you're doing is braze-ons then it's not worth investing hundreds of dollars in brazing equipment. All you need is the torch, flint starter, silver and flux.

I'd switch between 56 and 45% silver depending what your brazing.

Good luck!
-Chris

Awesome guys, Thanks!

So, would a cheap $40 mapp gas torch from x-mart work OK? Its got no variable flame, just on/off. I figure I'd control heat by how long and how far away I hold it. Would that work?

Thanks again!!

Yep. Get the kit with the 4ft. hose. Makes things so much easier.

You can control the heat by turning the knob.

It's not as though OA is the right heat, it's really too hot, you spend most of your time shooting it off into the air. All these things melt at below trans temps, 15-1600Fish, and you are in the 850plus range when brazing. The problem isn't how hot the torch flame gets, it's how hot the torch gets the tubing. Your not melting the rod, your heating the tubing that melts the rod. So there is a point at which the tubing simply draws away the heat faster than you can supply it. You can increase the heat with judiscious use of extra torches, and by heat containment strategies of using insulated brick bits or wools.

The one they have doesn't have a knob to turn. Just on/off and an ignitor. I am just trying to figure out if that will work or not. They don't have one with a hose, either.

In fact, this is the one that I am looking at:
https://www.bernzomatic.com/bernzomat...rnzoProd100012

I think I found what I need:
https://www.bernzomatic.com/bernzomat...rnzoProd100025

$22.99 online. $9 for a mapp cylinder at walmart. Guess I'll need a welding helmet?

Try this.

Unless you're cutting metal, you don't need a helmet. Gloves would help.

You can find brazing wire/flux on ebay if you don't have a welding supply store nearby.

-Chris

I am learning SO MUCH. Thank you VERY VERY much. I am buying this torch next month:
https://www.amazon.com/BERNZOMATIC-JT.../dp/B0006V6NKY

I am stripping the frame right now. I am going to learn to braze and do what I need with this thing. What fun!

I've used the bernzomatic products to make the following frame repairs:

a. replaced a crushed cable stop, and reinforced via fillet its slightly damaged companion stop.

b. mounted 2 new cable stops.

c. filled in some minor tube dents.

I still need to repair a couple dropouts.



I used this torch to cut frame parts off an old donor frame (mapp + atmospheric o2):

https://www.bernzomatic.com/bernzomat...rnzoProd100060

This works ok for this job but is slowwww. However doesnt require super expensive 5-minute-usage o2 bottles. I did not attempt to make repairs with this rig.



I used this torch to make repairs. It will melt the following berzomatic brazing rods, although still takes a minute or so to get up to melting temp:

https://www.bernzomatic.com/bernzomat...rnzoProd100044

This rig comes with 1 mapp and 1 o2. You better pick up 2 more o2 bottles to go with it. Then you'll still have leftover mapp gas. This little rig produces a flame temp near oxyacetylene. You can read the specs on the bernzo website or google research it.

Also, I found it a bit difficult to regulate the o2 on this torch. As i was trying to conserve o2, and not overheat my work, I was operating near O2 cutoff point. So it would light, burn 30 secs and pop off. Relight, repeat. It warmed up after 5 mins or so and worked good, at which point the o2 ran out. Learning is so much fun!



I used these rods, conveniently located next to the kits/gas in the display at home depot:

ni-ag

https://www.bernzomatic.com/bernzomat...rnzoProd100063

cu-sn aka bronze

https://www.bernzomatic.com/bernzomat...rnzoProd100065

The ni-ag is supposedly stronger. Its definitely harder and more difficult to file/dremel off. Seemed to melt about the same. Main difference is the ni-ag costs 3x as much as the bronze. Both these rods are flux coated so no extra flux is needed.

Bernzo doesn't have a brass rod. I looked for some of that fancy all-state rod. It was priced like gold, something like $18 for a few rods, and required special order and long wait. The bernzo rods are 2-4 bucks and sitting there. Since I wasn't doing anything structural/safety critical i went the easy route.

I may have skipped over it somewhere in the thread, but i believe you're going to have to devise a fancy jig to hold those canti bosses in place so that you can attach them. Its not something you can hold with a needle nose plier and achieve good results. Unless you've got a patient helper.

All together i spent ~75 bucks on this stuff. I used it to salvage an otherwise unusable 1990 trek 950 mtb frame (lugged, pretty). Eventually it will become a commuter bike with fenders, rack, light. I'm using a like new 1993 deore dx group for the build plus araya polished rims. Pretty polished parts, but they are heavy. But then so is the trek frame.

ps - make sure you have a well vented area to work - mapp gas smells like you're in the immediate vicinity of a pig farm

I wouldn't use this stuff to cut out tubing. You will only have to cut it again when you want to use it since the prolonged heat is not doing the tubing any favour, Sounds like an interesting experiment though.

Thanks for all the suggestions. SO it sounds like I'll want to braze with silver then. I do want to replace the dropouts. What rod would I use for that?

Try wire first. Harris Safety-Silv should be easiest to find. 45% for the d/o's. I'd suggest picking up 1 troy oz of both 45% and 56%. I havent brazed with a flux covered rod yet, so I can't suggest any particular one.

Working with flux is really interesting. It goes through a series of different stages which tell you what temp the metal is. Its fun to watch.

As far as flux goes, try Harris Stay-Silv or just order a jar of T-6 from Fred Parr (www.cycledesign.org)

Have fun man,
-Chris

Well, I think I have all the information I need. I am very excited about this. Thank you everyone for the help. I am sure I'll be back with more questions in a couple of months when I get the torch and all.

Thanks again!

Ryan

You can do it. I did it with the MAPP torch with the hose on it, (pictured above in another post). I was a rookie too. I put in a set of water bottle bosses and removed the cable "looms" from the top of the top tube and mounted cable stops under (on the side) of the top tube on an old Guerciotti. After a little practice on some junk frames it went fine. The hardest part was getting the vice grips in position to hold those cable stops in place while I heated them. They slightly deformed as I mounted them. So keep the vice grip pressure light. I tried the bronze, silver and also experimented with some steel rods on some of my junk pieces. I would not try the steel rods on anything of high value with MAPP gas. But it's a fun experiment to try to get steel hot enough. It's good practice for managing the heat.

Steel rods are welding territory and you need intense focused heat like arc or OA. I'm a little curiouos about the Benzo Oxy rig. There seems to be more than one thing wrong with it, but people complain mostly about the O2 cost since the little O2 bottles run out pretty instantly. On the other hand, A real rig costs between 800-1000 dollars. I'm looking at 300 for the bottles, and in this case rental probably isn't an option, 100+ to fill them, 400 for the torch and accessories I want. So for a few frames I could buy a lot of O2 bottles. Anyway, I have TIG, and I can do the rest with propane.

A normal full size OA rig looks too big to me for bike jobs. You'd have to add accesory tips suitable for bike brazing. There are a couple makers selling mini OA rigs with small bottles, hose and multiple small tips, even a cutting torch - this is more what you need. These go for 250-350. I have seen them recc. by a few bike builders. Cant recall name. Come to think of it i think my local home depot had one of these.

The bernzo rig is a hobbist toy. Very expensive to operate and slow too. But its all you can justify when just doing simple repair jobs.

Paying someone could be cheaper, but hard to find an experienced bike brazer. There's a guy near me who builds bmx. He looked at me with a blank stare when i started talking brazing. Evidently all this guy knew was tig-ing heavy bmx tubing. That seems to be the norm - tig and mig. Relatively few use OA. And brazing is not suited for anything except bike frames, jewelry and other specialties.

Well, I want to find out if I even want to get into brazing at *all*. This will be a cheap way to find out. Expensive? For $9 a bottle for mapp gas, I think it'll be cheap enough for me. It'll take a lot of $9 bottles to add on to the $30 purchase price of the torch to add up to the $250 for the cheapest OA setup I can find (at harborfreight.com).

But, if I really do like it, I *will* get a small OA setup and start building my own frames and doing my own metal work. I like the idea of brazing *much* better than welding. I don't know why. Seems more "organic" or something. And, doesn't require electricity which I happen to like.

Thanks for the input guys, I really appreciate it.

Oh, btw: I checked on adding two brake bosses to my rockhopper by a local frame builder who builds fillet brazed steel frames. She would charge $100 to add the bosses and cable guides. I can buy the mapp setup and a couple of bottles and the braze-ons, do it myself, and still be under half what she charges.

gas temp comparisons

https://www.bernzomatic.com/bernzomat...parisons.jhtml

metals melting point, degrees fahrenheit:

Cu 1984

Zn 0787

Sn 0449

Fe 2800

Ag 1763

Ni 2651

Ti 3134

Al 1221

6061 1145

4130 2610

Wow. You are going to attempt to braze dropouts with MAPP gas?! Good luck buddy.

seeker333 Thanks, man. If I go the OA route it will be the Tweeko, which is even smaller than the popular model amoung bike builders. It doesn't have the round handle that seems to fit brazing well, but it''s great for welding tubing, not too thick aluminum, and will do all the brazing tasks also. The only drawback is having to use Acetalene, but then most probably do use it.

You can forge weld a knife blade in a bernzo powered propane forge. Google "one brick forge". So you can probably melt the whole assembly, the jkey is to hold in place the heat that otherwise leaves. I haven't tried it myself, on a bike, but there has to be a way, and when someone figures it out it will make stuff a lot leasier. Probably just uisng two bricks positioned aorund the tube with an access hole would do it. I think people are doing drops with propane, but I'm not sure of the details. They must be using silver or something. The other option is improving the quality of the propane burnner. I have a bunch of really high capacity propane burners from above bernzo leve up to melt your own car parts. Best site is either Zoeller, Hybridburners, or Ron Reil.

These were done with MAPP. It worked incredibly well for the time being, but I'm interested in building more frames so I want an oxy setup for the future.

MAPP is great for doing small jobs

-Chris

https://www.homedepot.com/prel80/HDUS...p?pn=100054748