Aluminium Brazing rod's

[kellystewart]

Hey guys,

Hope you can give me some advice as I have spent hours reading up and still don't really have a definitive answer.

So basically I am constructing an aluminium tubing A frame (for a 3 wheeled bike rig...think Husky racing). I have 1" OD 3mm walled tubing and lots of these aluminium low temp rods.

I bought a gas torch (screw in type that fit on cannisters) that uses propane/butane mix and the nozzle diameter of the tip is around 8-10mm so the flame isn't huge by any means.

The problem I am having is getting the tube anywhere near hot enough for the rod to melt on the metal on contact. People I have spoke to since are telling me I need pure propane and a gas torch with a larger diameter nozzle (at least 3/4") and others are saying I will absolutely definetly need Mapp or even acetylene.

Any experiences of using tubing this size and heating it to 400C+?

Thanks,

Kelly

 

[Shox Dr]

Yep, Mapp gas at the very least, though I doubt that will be enough. really you need a Oxy Acetylene set up

 

[shenion]

Mapp gas will work, that is what I used.

 

[kellystewart]

ok so Mapp will defin work that's great as everyone else was telling me I would absolutely positively need oxy-ace....but will propane work if I use a large diameter nozzle? (was looking at a set of 25, 35 and 50mm nozzles)

It's just I have a 10kg cylinder of the stuff sitting so would rather use that than have to buy a Mapp torch and gas etc.

Thanks guys,

Kelly


p.s if no luck then I will try and find someone who can just weld it for me....I have it prebolted up for ease as it is so I dont imagine it would be hard for someone to weld!

 

[shenion]

Propane will barely get hot enough for the rods.

Mapp, O/A or Oxy/Propane will work.

 

[hotrodder]

Bear in mind that those zinc rich rods aluminium brazing rods will contaminate the aluminium making it virtually impossible to weld

 

[kellystewart]

arrrgh I'm confused...what do you mean it will contaminate the metal?

Oh wait do you mean once I have tried to braze it with the rods it will be hard to then properly professionally welded?

 

[shenion]

Yes, brazing soaks into the metal. The rods are lead/zinc/aluminum/magnesium.

You can take a bar a aluminum and drop it in molten lead and it will dissolve. Probably same with zinc.

 

[hotrodder]

Oh wait do you mean once I have tried to braze it with the rods it will be hard to then properly professionally welded?

Yep, the zinc content will cause all sorts of problems should welding it ever be necessary (for example you call it a day because of issues getting it hot enough, cracked joints etc)

 

[kellystewart]

eeepp geeezo haha. ok well I shall test the temperature on spare tubing before I go anywhere near the real deal.

thanks for the advice guys it's really appreciated!

Kelly