# Possible to braze small parts with a MAPP torch?



## bad mechanic (Jun 21, 2006)

Since I don't have a O/A setup, is it possible to braze small parts like cable stops or cage mounts using just a MAPP torch?


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## bobbotron (Nov 28, 2007)

MAPP, or MAPP/Oxygen?

I believe you could with MAPP/Oxygen for sure. The regulators and torch for those cheap MAPP/Oxygen are generally pretty cheap, and will give you more grief than a real oxy fuel kit... But it can be made to work.


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## bad mechanic (Jun 21, 2006)

Straight MAPP using one of these jobbies:


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## dr.welby (Jan 6, 2004)

Yes, back in high school I did a lot of cyclocross bike conversions with just a Mapp cylinder. The little Oxy/Mapp setups have a better tip than the plumbers tips like you show for doing brazeons so the upgrade might be worth it if you plan to do more than a one-shot deal.


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## Linnaeus (May 17, 2009)

I've even done a brake bridge removal and replacement (10mm higher) using Oxy/Mapp. Certainly works fine for small braze-ons. Canti studs are easy enough too.


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## unterhausen (Sep 28, 2008)

oxy/anything works without question. MAPP is a pain, but people use it, the difficulty is overheating because it isn't energetic enough. Seems backwards, but it's true. Propane might work but seems pointless given the ready availability of the more energetic MAPP. Acetylene/air also works. This probably should be in the FAQ


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## pursuiter (May 28, 2008)

I'd like to be able to replace dropouts and bridges, what about a kit like this mapp/ox:
Bernzomatic OX2550KC Oxygen/Mapp Welding Torch kit
http://bernzomatic.com/PRODUCTS/KIT...etail/mid/1147/xmid/6954/xmfid/3/Default.aspx

Or should I just spring for a Portable Torch Kit with Oxygen and Acetylene Tanks with a two regulators?
http://www.harborfreight.com/portable-torch-kit-with-oxygen-and-acetylene-tanks-65818.html


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## Linnaeus (May 17, 2009)

Mapp/Oxy:
Brake bridges: possible. You can also cut the bridges out and replace them with new, which might be easier because it is hard to get enough heat from that torch to melt out the filler metal and remove the bridge intact.

Drop outs: if possible, not easy, because you are going to have difficulty getting enough heat to melt the filler on both the SS and CS jxns. 

The oxy/acetylene kit can handle both tasks no problem, but you can likely find nicer (more versatile, more powerful) set ups on the used market (i.e. Craigslist) for less $.


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## pursuiter (May 28, 2008)

I haven't purchased used because I don't have a clue about getting ripped off and I don't want a big set of tanks. I don't want to use up a bunch of space, that's why I kinda like the portable/low cost oxy/acetylene. If I want to scale up to frames, I figure to spring for something electric that TIG brass brazes. $300 seems nice and cheap to mod old road frames for IGH use.

I promise I don't want to make frames with it, just braze-ons, bridges and disc tabs and have a little fun. If I pay someone to do braze-ons around here, I'll cost me $100 in labor easy just for one simple project. I've got 7~8 old frames that I can use as victims.

Is my thinking OK, please give me honest feedback?


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## dr.welby (Jan 6, 2004)

pursuiter said:


> I'd like to be able to replace dropouts and bridges, what about a kit like this mapp/ox:
> Bernzomatic OX2550KC Oxygen/Mapp Welding Torch kit
> http://bernzomatic.com/PRODUCTS/KIT...etail/mid/1147/xmid/6954/xmfid/3/Default.aspx


I started out with this and it will work, but those tanks don't last long. For braze-ons and dropouts, you'll at least get a frame per bottle though.


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## unterhausen (Sep 28, 2008)

used never is a good deal because the people that are selling it are selling their grandfather's tanks/torches and have no idea how much it is worth. So they try to sell it for more than new costs.


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## eMcK (Aug 22, 2007)

I've been wondering this too. I almost bought a Oxy/Acetylene set up, until I found out what it would do to my homeowners policy. No garage, so the tanks would be in the basement. The quote I got was double what I'm paying now.


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## tallsam (Dec 5, 2009)

eMcK said:


> I've been wondering this too. I almost bought a Oxy/Acetylene set up, until I found out what it would do to my homeowners policy. No garage, so the tanks would be in the basement. The quote I got was double what I'm paying now.


What did you use instead? I'm in a similar predicament.


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## dbohemian (Mar 25, 2007)

I know I have said this before but IMHO using MAPP cylinders for anything bike related is a big no no. 

Honestly, the stuff barely works....As in stand there for 5 mins and barely get what you need done all the while doing a shite job of it that may or may not work. This particular question is possibly the #1 asked question of all time and the one that newbs least want to hear but you have to have a at least a minimum of tools to make a frame and a Oxy-something is the only way to go. Once again IMHO.

If I had to consider another source other than acetylene it would be propane. Everyone can get propane and although it has a different flame characteristic it can still be used for nearly everything. 

As far as home-owners goes. Don't tell them.... treated correctly acetylene is practically bullet-proof. Your home appliances are far more dangerous. If I was overly concerned about it one could just take the tanks out to a little shed or something in the back yard and store them there in between uses. If you don't have a shed, I don't know what to tell you


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## mchimonas (Dec 19, 2008)

One can use MAPP-air for frame building provided the builder is willing to accept certain limitations.

MAPP will not work for fork crowns, brass brazing, dropouts made from thick flat stock (plate), thick lugs such as henry james mtb lugs, or thin ST-TT lugs with large eyes.

MAPP can work to silver braze lugged frames provided tubes are thin, the lugs are thin (without huge eyes), and dropouts have either plugs or sockets. If the user cannot get the subassembly up to brazing temperature in 3-5 min with MAPP-air then that subassembly cannot be brazed with MAPP-air. Another limitation is that subassemblies have to be brazed step-wise and piece meal with MAPP in sections 12-25 square cm. The area adjacent to this 12-25 square cm patch should be very near brazing temperature and reach brazing temp in just a few seconds with torch use, (otherwise the part cannot be brazed with MAPP). With MAPP the builder usually cannot bring the entire subassembly (for main tubes at least) to brazing temperature at the same time, which is what is usually ideal. Stepwise/piece meal brazing can result in voids unseen to the builder, which is okay only if the voids are small. 

So, in summary, some frames can be build using MAPP air, but only some frames. oxy fuels are better. However, if the newbe is willing to accept certain constraints on his design, he can build his first frame with MAPP to see if he likes frame building. If he likes it and wishes to keep witht he hobby he should by an oxy-fuel torch. (IMHO)


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## dbohemian (Mar 25, 2007)

mchimonas said:


> However, if the newbe is willing to accept certain constraints on his design, he can build his first frame with MAPP to see if he likes frame building. If he likes it and wishes to keep witht he hobby he should by an oxy-fuel torch. (IMHO)


I understand your POV and those were some good points you made.

I cannot agree though. Nothing you said was inaccurate but the fact that the theoretical person is a newbe and does not know what to look for and probably has very poor technique is exactly the reason NOT to give them a big disadvantage with a fuel source that is barely adequate. How does one know too thick from too thin? How do we know they do not have too many voids and although unlikely a failure could cause death in the right circumstances. No, IMHO one must have an adequate welding source and that is not a fuel/air torch. One can find these for somewhere between 200-300 dollars and if you don't have that kind of money you shouldn't be monkeying around with this stuff anyways.

If one did buy a decent torch setup and didn't care for framebuilding remember you could most likely sell it for near what you have in it, so it is not a total loss.


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## mchimonas (Dec 19, 2008)

Absolutely you are right in that you can recoup some or all of your cost of an oxy-ace torch by selling it on craigslist or what not, and you are also correct in that the newbe may not know his limitations. The purpose of this post is not to convince you to my point of view but rather shed light on an associated topic, specifically anyone learning to build frames on his or her own takes on a fair amount of risk in terms of safety and should take responsibility for said risk. Perhaps there should be a safety disclaimer in the FAQ's for the DIY builder (there probably already is one). An oxy-fuel torch in unskilled and unsupervised hands can also lead to frame failure (Don't get me wrong I am not trying to say that too hot a flame for the newbe is worse than too cold). For example, the first time I tried fillet brazing I totally boiled off my zinc and was left with (probably a wimpy) copper braze. Likewise, someone with an oxy-fuel torch could exhaust his flux by prolonged over heating, which could also result in dangerous voids in a lug. No matter how good your equipment, it is going to be dangerous in unskilled hands (Yes, some equipment is probably more dangerous than others). The safest way to learn to build frames is to have hands on instruction.


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