Why am I failing at alumnium brazing?

[Matchless]

I have repaired the oil union hole in Matchless single engines by techno welding in a brass union fitting, techno / Lumi weld sticks to brass but not to steel, you can form a crude thread by techno welding around a steel stud, when it cools and you remove the stud you have a thread! I have also repaired a casting blow hole deep inside a BMW cylinder head inlet port that would have been impossible using tig, mig or much else, it needed heating in a big oven to get up to temp. and careful slow cooling but it worked, main problem with even small casting repairs is getting enough heat into the piece.

 

[Hopefuldave]

I have repaired the oil union hole in Matchless single engines by techno welding in a brass union fitting, techno / Lumi weld sticks to brass but not to steel, you can form a crude thread by techno welding around a steel stud, when it cools and you remove the stud you have a thread! I have also repaired a casting blow hole deep inside a BMW cylinder head inlet port that would have been impossible using tig, mig or much else, it needed heating in a big oven to get up to temp. and careful slow cooling but it worked, main problem with even small casting repairs is getting enough heat into the piece.

Yep, repairing threads / cracked bosses on the likes of oil coolers and radiators worked well for me, I think it was the sticks from a ?Polish? bloke at a Motojumble I used - as above, removed the stud and a pretty decent thread resulted! Also managed a repair on a carburetor body (Mazak?) but the casting was starting to get soft by the time it was up to temperature...

Fillet brazing on ally sheet wasn't that difficult, but needed my Bullfinch torch to get it hot enough, little nozzle-on-a-can wasn't up to the job, and I've put a backing plate behind and filled a few large-ish holes in diecast ally electronics boxes that were the right size/shape but secondhand. That does go through a lot of stick though Must buy some more.

Chinese motorbike "cast ally" parts seem not to be too easy, full of muck? but CAN be brazed, wouldn't trust it on anything safety critical (brake levers etc,) but that's down to the original material, not the rods...

Dave H. (the other one)

 

[skotl]

I contacted the seller last night and they have confirmed they are TIG rods

To be fair to them they have offered me replacements (on a slow boat from China) or a refund.

Sigh...

 

[Brad93]

I’ve got sif555. Not for me. They work but they’re Ugly and it’s just not right. I had some very problematic castings which I tried them on. Safe to say the casting was scrap by the time I’d finished with it.

 

[Pigeon_Droppings2]

Amazon sell a pack of durafix for £18 for 5. Not cheap but they work and usually what I'm fixing would cost more that the rods.

If I was doing a lot then I'd find a cheaper supplier...but to do a test it's worth getting good rods.

I seem to remember seeing a video where they tinned 2 sheets then just put them together and heated to join.

At least you know for sure now that it was the rods

 

[JEZGUZ]

I think the size of the torch may have a bearing on the success of brazing, I was using Oxy/Acetylene. The flame from a propane or butane torch won't be localised enough which is probably why the sheet/plate you were using melted, even though that is what they demonstrate using the rods with. You could try Oxy/Propane with a suitable torch to get a more controllable flame.

 

[Mr Roo]

Oh... that's a shame about sheet - I was hoping to use this technique for some (very light) fabrication of covers, boxes, etc.

Oh well - ordered some lumiweld, and another 2mm sheet, so will have a play!

Any thoughts on whether it helps or hurts to have the 2mm plate sat on top of a 40mm cube of aly to sink the heat?

maybe better to weld them rather than duffing about with this temperamental-sounding braze?

I’ve a good-sized lock-up about 10mins from you if you want to come and get a shot of my TIG plant to weld some ally sheet - lies doing nothing most of the time

 

[skotl]

maybe better to weld them rather than duffing about with this temperamental-sounding braze?

I’ve a good-sized lock-up about 10mins from you if you want to come and get a shot of my TIG plant to weld some ally sheet - lies doing nothing most of the time

That's very kind. I actually went looking for the temperamental brazing option as I didn't want to spend the money on getting set up for TIG

I'll see how I get on with the actual sodding rods when they come, but might take you up on that offer if it turns into a disaster - thanks

 

[Pigeon_Droppings2]

I use map gas (yellow cylinders) with a plumbers torch.

Never tried with blue....I always use map as it's my soldering torch and also what I use to get rusted nuts loose

 

[Mr Roo]

That's very kind. I actually went looking for the temperamental brazing option as I didn't want to spend the money on getting set up for TIG

I'll see how I get on with the actual sodding rods when they come, but might take you up on that offer if it turns into a disaster - thanks

Then you’ve struck gold - i’m armed to the teeth with welders, torches, tungstens, collets, and miles of filler wire for stainless, ali, etc!

I’m in there most nights and near enough every weekend so feel free to pop by and get a shot of the kit - just shoot me a PM!

meantime, i hope you have better luck with the new rods!

 

[mtt.tr]

Pre ac tig days me and dad used these but found we needed O/A to get enough heat

 

[skotl]

Then you’ve struck gold - i’m armed to the teeth with welders, torches, tungstens, collets, and miles of filler wire for stainless, ali, etc!

I’m in there most nights and near enough every weekend so feel free to pop by and get a shot of the kit - just shoot me a PM!

meantime, i hope you have better luck with the new rods!

Cheers mate - will drop you a PM to make contact. I've never tried TIG so it might be good* to give it a go

Spoiler: Definition of "good"

...or terrible, as it will almost certainly convince me that I need to rent a bottle of pure argon and then spend ages learning TIG

 

[Wallace]

Cheers mate - will drop you a PM to make contact. I've never tried TIG so it might be good* to give it a go

Spoiler: Definition of "good"

...or terrible, as it will almost certainly convince me that I need to rent a bottle of pure argon and then spend ages learning TIG

That's you on the slippery slope of Tig ownership once you enter Mr Roo's den of Tig temptations!

 

[skotl]

That's you on the slippery slope of Tig ownership once you enter Mr Roo's den of Tig temptations!

Aye - that's what I'm worried about...

 

[northwest]

I too have used this Duraweld or whatever it masquerades as with some success. It is not ally welding as such but what a terrific get out of jail card the few times I have used it.

 

[hunter27]

After turning up an alloy spacer to fit between my boats prop shaft flange and the gearbox flange I cut slightly too much off the male register that went into the flange, I used this process to build up the spacer and then successfully turned this down to the right size. Saved me starting from scratch again.

 

[skotl]

I too have used this Duraweld or whatever it masquerades as with some success. It is not ally welding as such but what a terrific get out of jail card the few times I have used it.

That's what I'm shooting for!

 

[MattF]

, I thought I was rubbish at it

I was trying to resist making that suggestion.

 

[northwest]

That's what I'm shooting for!

It will work fine for you. I was a bit skeptical at first but it really does work well with a bit of practice.

 

[Pigeon_Droppings2]

Couple of times I've used it definitely saved my bacon.

Using a steel mould will help if you need to cast it onto something. If you shape the parent part correctly you can get a mechanical lock as well as a bond.

It shapes up well too...a lot of tin I imagine?