I have been getting occasional adverts for some “welding rods” that are used to weld aluminium and I was wondering if anyone had used them. They are marketed by a company called Millionus. They appear to be really easy to use so, as I have couple of pannier lids that I need to get welded up, I was wondering about getting some but if they are rubbish then I will get someone to weld them up for me. Yes, I am so sad that I have made my own panniers - it has been good fun actually.

https://www.millionus.co.uk/products...30961102159923

They seem too good to be true which makes me think that there is a catch somewhere - they aren’t very expensive and I guess they could be used to fill holes on crankcases. If no-one has used them I will get a set and do a review - maybe even do my own video.

I'm sure there's some people on here who have a lot of welding experience and for whom these things are second nature. I'm not one of them, but I've done welding courses in the past and become passably familiar with arc, gas and tig (using someone else's decent equipment) and pretty good (for an amateur) with my own mig. I've even tig welded aluminium bike bits (with the instructor leaning over my shoulder!), but I can't do anything at all with those aluminium 'welding' rods.

I've tried several times to repair stuff with them without success and there's a few projects that could do with their help right now. I have a load of rods and other bits - including the instruction DVD - sitting in my tool chest waiting for the day when I figure out where I'm going wrong (probably via a good youtube video). I suspect my heat source isn't good enough but that costs money whereas the rods are cheap. The feeling I have is that the heat margin between success and disaster is too close for comfort.

Give it a go and video it - I'll watch it, but practice on something of no value first.

Does this mean that you have tried them but to little success? If that is the case And you think that it is the parent metal temperature that is critical then I can see a case for getting a cheapish laser thermometer - I am thinking of getting one for work anyway but this would clinch it.

I have every intention of getting good first before doing something that matters.

Yes, I've tried a number of times to get the rods to 'weld' but not managed it. It's been a while now since I last tried it but from memory there's a number of reasons why that may be the case - I may have useless technique, I may not have cleaned everything sufficiently, I may have been getting / able to get the workpieces hot enough or the alloy I was trying to repair may not be suitable. Again from memory, the last thing I tried it on was some cracked Kawasaki alloy manifold clamps. I couldn't replace them (unobtainable) but I didn't want to ruin them either.

The rods are more like high temp soldering than true welding and it was getting them to melt and run into the alloy that was the issue. Like normal soldering you can't just blob the stuff on, it doesn't take. The alloy needs to be clean and hot - much hotter than normal soldering but I was worried I could overheat the whole thing and just end up with a puddle on the bench. Aluminium doesn't give you any warning - like glowing red etc, so you have to use other methods. I have an I.R. thermometer but I'm not sure it goes high enough (?).

It was on my list of things to revisit but, prior to your post, fairly well down it.

Ally welding is a pretty skilled process, as BoB says, you don't get any warning when it's going to melt, it just goes, so you need to know how much heat you're putting in or you'll either melt holes in it or just blob metal on top which will be useless. Another complicating factor is that aluminium oxidises very readily so if you don't weld it in an inert gas atmosphere (Argon is the usual gas shield) you stand a good chance of ending up with a spattered lump of alumina instead of a weld. Finally there's the Heat Affected Zone (HAZ) that develops where the recrystallised grain structure meets the original grain and that's where it tends to break, adjacent to the weld rather than through it. I'm not a welding expert but I believe if you preheat the weld zone or post heat treat the entire component you can avoid a lot of the HAZ problems - but again it's a question of knowing how hot and how long.

The thermometer I have looked at goes up to 550C and the melting point of aluminium is around 660C but the rods talk about a temperature of less than 480C so there is a decent amount of wiggle room there. I suspect that it is a two person job - one to heat and monitor the temperature and the other poised to apply the rod. The thermometer is a laser infrared job so non-contact and instant - the trick I guess is to get the temperature just right across the workpiece.

Aluminium oxide starts to form quickly at around 450C so the final 30C gain needs to be done quickly. The other thing is making sure that the aluminium doesn’t anneal - in my application for my pannier lids this is not a big deal but other applications may not be so forgiving.

That'll be a posh thermometer - mine only goes to 380C. You don't need to get the aluminium up to melting temperature for the rods to melt and flow. The instructions say there's a 200+C 'safety margin' between the temperature you need and the aluminium melting, the idea being that once you get the ally that hot the rod will flow onto it.

You can't melt the rod in the flame you're using as the heat source and 'flow' it onto lower temp ally - it won't do that, it just balls up or runs off. The problem is that in a hot flame that 200C margin can vanish in seconds and there's no way of telling how close you are. Maybe with a decent IR thermometer it'll work but last time I tried it I didn't have mine and it was all guesswork.

I saw this video some time ago, and thought he did a very good review:

__________________
Grant Johnson
Seek, and ye shall find.
------------------------
Inspiring, Informing and Connecting travellers since 1997!
www.HorizonsUnlimited.com

I'm going to have to have another go at this sometime soon. I checked my rod supply yesterday and there's half a dozen half used ones as well as a load of new ones, so enough to try again. I don't want my ineptitude to colour this conversation though so it would be great if somone who has managed to weld / braze / solder with them to chip in.

An interesting review. So it has its place - temperature control is clearly a key factor as is preparation.

Agree, it's clearly not "easy" like grabbing an old arc welder and sticking a couple of pieces of steel together.
Perfect Prep has always been the biggie from my limited experience with aluminum welding.

__________________
Grant Johnson
Seek, and ye shall find.
------------------------
Inspiring, Informing and Connecting travellers since 1997!
www.HorizonsUnlimited.com

Technically, these rods do not "weld". A general definition of "Weld" is to melt two pieces being joined along with the deposition of welding material (ie the rod or wire) and the result being the two pieces fused together.

What you are showing us there is a form of "soldering", where the two work pieces are not melted or fused, the only thing that melts is the rod itself, that is melted and flowed and adhered into the joint.

So What? Will it hold? Yes.

Since the material in the rod has a lower melt temp than the two pieces of aluminum being joined, the "weld" material is obviously a different metal than aluminum. The weld metal would probably have a different coefficient of thermal expansion/contraction than the aluminum pieces, so repairing a crack in an aluminum head or block that sees high stress at a wide range of temps will probably crack and fail.

I initially bought a few rods of it to repair a punched-in oil-pan on a VW ALH Jetta. I got mine off e-bay for like $3. The 2.5cm triangle shaped chunk of oil pan was knocked out and missing. I fashioned a patch from 1/8" thick aluminum plate. Wire wheeled both pieces to a clean surface, not shiny. Heated both pieces up with hand-held torch with MAPP gas, and wire wheeled again. Then held together in the press, using a big 3/4 drive socket on the inside perimeter of my repair area and a small socket on the outside in the middle of the patch. Not tons of pressure, just enough to hold it. Watching the videos, you can see that one of the things that happens is the heat applied by the torch is transferring away into the rest of the parts, so your torch has to be able to add heat faster than it transfers away. If clamping parts together, be aware of the heat transfer capacity of your clamp, a chunk of steel with lots of contact area will take away a lot of heat. In my case, the perimeter-edge of a socket is round-ish, and the actual contact area is quite small, so heat transfer is minimal. That was several years ago, and I still see that Jetta driving around, and the owner tells me the oil-pan is still holding. Fixing the oil pan was a waste though, replacement oil-pan from a self-serve wrecker is like $20.

The other thing I've repaired is a stainless steel ladle or dipper. It was a stainless steel cup with a handle-strap of stainless steel spot welded to the side. The spot welds had let go. Its a vintage useful/ornamental item that hangs on the woodstove that we use for ladling hot water out of the heater tank. I carefully ground the surfaces, held them together, and applied the alumafix solder, and its holding well.

So to repair the pannier lid, I say have at it. The danger is that the pannier lid is super-thin, and applying heat may distort it forever. The other possibility is that the lid is not actually aluminum, but some alloy that melts lower than you expect, in which case you will be warming up the pieces to apply the solder and your pannier lid blobs onto the floor.

As with any solder/braze process, surface-prep is key to success, clean, and microscopically rough so the material can adhere. As mentioned, your torch has to be able to add heat faster than heat transfers away. A standard hand-held propane torch may theoretically reach the melt-temp of the solder, but will lose the heat transfer race. You pretty much have to use the more expensive blended MAPP gas torch.

Good luck!

Yeah I think he covered the main points pretty well. It is soldering not welding, since there is no melting of the parent metal, and that makes it a process that needs to be a lot less closely controlled. As he found, it isn't as strong as the parent metal, it's only as strong as the solder itself, and is dependent on getting a really clean surface to bond to - but still, it's not a bad performance at all.

As he says, it's definitely not something to use on anything structural like a frame, but for some applications it *may* be a viable get-you-home. And for non critical items a good one for the more creative to have in their shed

As an aside, when I was racing years ago I had a Mk4 Seeley, and I got a spare tank made by the same guys down in Dartford who built the originals for Colin Seeley. They gas welded all their ally tanks, and the workmanship was superb. I never understood how they did it, given the propensity of aluminium to oxidise when heated in air, but I wonder now if they soldered it using the same sort of stuff as this. Whatever they did, it certainly worked and didn't suffer any distress despite 10 years racing including the Manx GP.

Interesting.

Grant's video pretty much shows it's pros and cons.

Great for DIY and i'm sure plenty good enough for panniers.


I think i'll stick to my TIG welder though.

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Can't say anymore.

The rods have arrived and they seem pretty easy to use. Surface prep is important as has been rated by others - the kit I bought cam with a toothbrush sized stainless steel wire brush - the brush is very abrasive on aluminium.

Points to note so far:
The size holes you can fill is limited to about 8mm diameter in my very limited experience and as you move towards 8mm the thickness of the covering gets thinner so ends up more like a film towards the bigger holes so if pressure is involved for big holes forget it. I think I would braze a patch of aluminium over the hole if bigger than, say, 5-6mm.

If I was to be putting a patch over a large hole then I would prepare the surface around the hole and the the patch. Apply the rod to form a “puddle” around the hole and then do the same thing for the patch contact area. Finally heat the patch and hole area to get the puddles liquid so that the patch can be placed over the hole sealing it.

Ensuring the piece stays still during the cooling process is important as the filling metal stays liquid longer than I expected. My fault entirely.

For a butt joint it is better to have access to both sides of the joint to put a “weld” bead down both sides.

You can easily make smooth looking joints easily and they seem to be relatively strong - it is NOT welding so it is weaker but it could be a simple remedy to carry out a bodge repair until such time as a proper repair can be done.

The rods are lightweight and don’t take up much space so I can see myself taking some on a trip - the heat source can be from a plumbers torch so should be simple to obtain locally.

I still plan on doing a video but that will have to wait for a quiet day at work and some time to prepare samples.