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How do I repair aluminium using aluminium soldering rods and a blow torch? An idiot's guide is really what I'm looking for: preparation, technique, finish etc.

There is no idiots guide to something as skilled as this. Practice, more practice and then a lot more practice required.

[quote="Pars"]How do I repair aluminium using aluminium soldering rods and a blow torch? An idiot's guide is really what I'm looking for: preparation, technique, finish etc.[/quote]

Surely there must be a way of passing on the basic processess involved? What do I clean the area to be repaired with? After heating the area, how do I introduce the rod? Is there a way of checking that the area is hot enough? How can the repair be tidied-up if required? If repairing a hole, how do I block the void so that the flux doesn't drop right through? Are there any useful general tips?

from what i can gather ur asking for a how too on a very very hard job many "skilled" people cant do this even after full training i know a few welders/boilermakers but only one bloke who says he USED to be able to do it (and he is an awsome and very experienced welder)!! sorry mate i think u may struggle ? good luck anyway though

Soap the block type not soft soap does go black just before aluminium melts but in the main just lots of skill required.

How do I repair aluminium using aluminium soldering rods and a blow torch? An idiot's guide is really what I'm looking for: preparation, technique, finish etc.

Simple answer don't! If you know a welder the best method is tig welding using reverse polarity or mig weld it. If not find a small fabrication workshop and get them to do it. I've never heard of fixing aluminium in this way until today and 15 years experience tells me not to.

I saw a hole in a piston being welded up and assisted in the re-build on a Denis Pax gully emptier back in the early 1970's while we were waiting for the new engine to arrive. A oxygen/acetylene welding touch was used by a very skilled motor mechanic called Tegid Morris who was the Superintendent for Flinshire County Council maintainance depot at the time. He was welding good quality aluminum with the best rods available at the time. It lasted only a few weeks but that was all that was required. Since then I have seen aluminum welded many times but mig is the main method. But again for the council they use to make draining boards covered with aluminum for schools and used a special flux and soldered them. So yes it can be done but it requires skill and right type of flame on touch. Seem to remember slightly smoky. Not oxidizing. But this was 30 odd years ago I am sure today they would use inert gas welding either mig or tig although never seen latter used. And would have to be DC or HF not a standard welding set.

The radio and television chassis were mostly made of aluminium and as an engineer I had to solder connections to the aluminium chassis.

I was told by my contempory 'expert' engineers, that one couldn't solder aluminium with tin/lead solder; so I found out why; then solved it.

The main problem is that although you can clean aluminium ready for soldering, it starts to oxidize immediatly it is exposed to the atmosphere. You cannot solder to oxidized aluminium.

What I did, was clean the aluminium first. Heat it up whith a soldering iron, then melt a pool of solder over the area. I then used the hot soldering iron to remove the oxidation layer, by scraping through the pool of molton solder. no oxygen from the atmosphere could get through, and I was able then to solder later to the previous 'wetted' surface.
I hope this helps.

It is possible that arc welding of the type which provides a non-oxygen gas shield may be the main answer you were looking for

Hi Pars,

the process of welding or using a low melting solder type repair is one that takes quite abit of practice..
welding is best done with a ac tig set, using argon gas, the metal has to be very clean, no trace of oil/grease or such like...
takes a reasonble amount of power...but depends on the thickness..

Yrs back we always welded and repaired ally with gas welding before tig sets were generally available...flux is very corrisive and you need quite abit of skill so as not to melt the ally part before the welding or aluminium brazing is complete...
the trick with the soap is a good one...usually used for anealling ally...as it work hardens as u work it..

boc did produce some low melt solder type brasing rods...i do still have some in the workshop...but with the advert of inverter tig welders i usually tig the ally without any probs..

Its a skilled job that takes alot of practice...if you want to try then get some scrap ally plate and try ur hand..

Stainless steel wire brush is needed to clean the surface of the plates etc..& it can also be used to clean up a nice weld when its done...

hope the above points you in the right direction...alot of practice is needed to get good results...
old saying ..practice makes perfect..

cheers

smithy..(blacksmith)...

The process of welding or using a low melting solder type repair is one that takes quite of practice.

Hello,
good to have some proffecional advice on the matter, clearly coming from someone with experience