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Brazing Aluminum?


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  #1  
Old 06-26-2018, 11:55:59 PM
Railroads Railroads is offline
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Default Brazing Aluminum?

Hi everyone, I was wondering if anyone has any experience using the alumiweld brazing rods and a map torch for small hobby projects?

I want to make a water block out of aluminum just like this fellow only thicker. https://www.youtube.com/watch?v=h0nL3NIJxUU I want to do some experiments with TEC cooling cycles.

These are the Ally brazing rod welding methods I have found.

https://www.youtube.com/watch?v=QLAjeSa6CqI

https://www.youtube.com/watch?v=5HF47xulteo

https://www.youtube.com/watch?v=mIpPBwoEDDs To flux or not to flux? What would work better? Using flux or just wiping the alumiweld rod method?

Robert
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Old 06-27-2018, 10:14:56 AM
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FWurth FWurth is offline
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Default Re: Brazing Aluminum?

I tried to use those bare rods once but couldn't get it to flow and mix. I think it needs some sort of cleaner/ flux to get it to work.
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Old 06-27-2018, 01:01:05 PM
Andrew Mackey Andrew Mackey is offline
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Default Re: Brazing Aluminum?

You must clean the area you want to weld with a stainless steel brush, and weld immediately. Oxidation is a killer for this product Cleaning with a brass or 'regular' steel brush or emory will leave contamination and the lumiweld wont stick. It works OK on thin surfaces but for heavier work, more than about 1/8", it is difficult to get enough heat to make the lumiweld bond and flow properly. The rod will melt but wont stick to the aluminum. In the demos I have seen, welding aluminum cans and thin (1/8") aluminum engine block material seems easy, but thicker materials, not so much. Unless you find a way to heat the entire work evenly, with Mapp Gas, the best you will get is a surface bond - no flow beyond the surface, and a weak joint at beat. I believe that a higher heat source, such as Acetylene will not work, due to the carburizing effect (carbon formation). If you are working on a small area, you might get lucky.
Andrew
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Old 06-27-2018, 05:29:20 PM
mcostello mcostello is offline
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Default Re: Brazing Aluminum?

I have used it to plug a hole in 1/2"x!"X6" electric heater blocks. What I found out was the Luminaweld seems to either concentrate the heat or dissolves the Aluminum and will penetrate about 1/8" and leak out the bottom. I solved the problem by plugging the cross hole with a sliding fit piece of steel rod. Saved the part. Nothing like seeing the bottom dropping out of Your part to get the blood pumping.
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Old 06-27-2018, 07:02:28 PM
mihit mihit is offline
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Default Re: Brazing Aluminum?

Always flux. I can think of no good reason not to.
Gas welding is entirely feasible on aluminium of any type, shape, thickness. I'd say it's preferable over TIG as the it's a less severe heating/cooling cycle so less thermal stress, usually wont need annealing.
Managing heat is a big one, as it conducts away from your joint really quickly.
Mapp gas should absolutely be hot enough, and a slightly reducing flame on an oxy set also works.
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Old 06-27-2018, 07:44:15 PM
Railroads Railroads is offline
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Default Re: Brazing Aluminum?

There are a lot of brands of the aluminum brazing rods. https://www.youtube.com/watch?v=aj0NjwBqsSg

Robert
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Old 06-27-2018, 08:06:21 PM
J.B. Castagnos J.B. Castagnos is offline
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Default Re: Brazing Aluminum?

I bought some aluminum brazing rods at a show one time, guy was demonstrating welding holes in a beer can. I found the only thing I could weld with them was a beer can. If I have a beer with a hole in the can I'm going to get another beer, won't try to weld the hole.
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Old 06-27-2018, 08:14:48 PM
Railroads Railroads is offline
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Default Re: Brazing Aluminum?

I am looking to weld 1/8 and 1/4 aluminum into a thin water block about 2 inches wide and 12 inches long about 3/4 inches thickness minus the thickness of the two outer pieces.

I also need to weld two end caps to a length of aluminum square tubing that will make up part of my heat exchanger contraption. The tube is 2 inches wide and 12 inches long. The trick is everything needs to be water tight.

Robert
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Old 08-23-2018, 09:46:30 AM
Tracy T Tracy T is offline
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Default Re: Brazing Aluminum?

good luck is all i can say! my experience with aluminum is that a tig is best followed by mig being second best. i prefer the tig 10 to 1 over the mig, better heat control. clean, clean, did i say clean very clean or you will be disappointed.
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Old 08-23-2018, 05:41:58 PM
IronworkerFXR IronworkerFXR is offline
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Default Re: Brazing Aluminum?

I might have some extruded thin wall rectangle aluminum stock , have to check dimensions if that would work.
as far as the magic rods , I tried that as a kid , before I could afford a tig machine , great for beer cans , only

JC
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Old 08-23-2018, 06:34:02 PM
Pat Barrett Pat Barrett is offline
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Default Re: Brazing Aluminum?

Son had an engine loose a piston, Brodix heads. We sent the head back to them and when we got it back no indication of the former damage. It looked brand new. Don't know how they fixed it, but they worked a miracle.
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Old 08-23-2018, 11:48:32 PM
JoeCB JoeCB is offline
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Default Re: Brazing Aluminum?

The no flux "beer can" rod is not aluminum, its a zinc alloy. The stuff is capable of making a strong joint on aluminum. I have used it successfully for repairing small broken cast alum parts. Parts must be CLEAN, scrubbed with a clean stainless steel brush. Careful heat control, parts must melt the rod not the flame. The resulting filler material is darker than the alum and much harder. Because of the heat control difficulties I don't think that you could do a project like the OP "water box" where there are multiple joints on the same piece. And besides this rod will not flow into a joint, it's to be used as a filler like in a "v" joint.


Joe B
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Old 08-24-2018, 07:56:39 AM
I like oldstuff I like oldstuff is offline
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Default Re: Brazing Aluminum?

I did a lot of semi automated machines to induction braze tubes to heater cores and auto air conditioner condensers Sold these to Ford, Chrysler etc.

The problem brazing aluminum besides cleanliness is that the braze alloy often melts 100 to 200 degrees below the parent metal making the process very tricky. Something you can try is using a flux called Nocoloc. http://www.aluminium-brazing.com/noc...iumbrazing.php

I'm by no means an expert on brazing aluminum
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Old 08-31-2018, 08:03:05 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Brazing Aluminum?

Quote:
Originally Posted by Railroads View Post
...I want to make a water block out of aluminum ...
Meh. Without a TIG rig, and some experience good luck getting leak-free joints.

I'd skip the aluminum in favor of copper (where thermal conductivity matters) and brass (where it doesn't), and soft-solder it.
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Old 08-31-2018, 10:56:16 PM
Charley K Charley K is offline
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Default Re: Brazing Aluminum?

Like Tracy T said, best of luck! I've been welding aluminum almost 50 years, I can tell you all the high dollar aluminum welding rods made for gas torch work I have used have been disappointing. To put it mildly, good for making a mess. Welding anything thin IE 1/8" to something thick like 3/4" can be challenging even with a tig torch. The heat transfer is difficult to master. Nothing like welding mild or stainless. Just my 2 cents. CK
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Old 09-06-2018, 11:41:53 PM
Railroads Railroads is offline
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Default Re: Brazing Aluminum?

Guys, Thanks for the replies. I haven't even thought about this project for quite some time.

Robert
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