Joining metal components

[Garrett44]

I’m looking for advice in joining small metal components, similar to the nut and bolt sculptures you see online (https://www.google.com/search?q=sculptures with nuts and bolts&ie=utf-8&oe=utf-8&client=firefox-b-m), but I’m using some slightly larger components e.g. hinges, brackets etc. The components are steel (not stainless), aluminium and brass. Some are old and corroded, others are brand new.

Cost is starting to be an issue as I’ve had a number of failed tries. So far I’m limited to using a soldering iron and a butane blow torch, what I had available and what was low cost, have tried soldering (does not adhere), tried brazing (cannot get a high enough temperature. Not sure if I should try silver solder, this is what tutorials for nut and bolt sculptures advise but given soldering had zero success I’m doubting this.

What will work? What is suitable? Do I need to go to welding? Is there some welding solution that is reasonable cost, small scale and can be used indoors (no access to a workshop or outdoor space)?

 

[Phil Pascoe]

If you can't get it hot enough to braze, you can't get it hot enough to silver solder.

 

[ChaiLatte]

You might do some research on the materials you are using. Steel is iron-based. Brass is copper-based. Aluminium is aluminium-based.

There is only one method which will join all three together, and that is glue.

Soft soldering will join steel to brass. Silver soldering will join steel to brass. Brazing will join steel to brass. Welding will join steel to steel. You can buy specialised low temperature solder to join aluminium to aluminium (confusingly called lumiweld). Joining aluminium to steel or aluminium to brass is challenging.

Every joining method you use will work better if the item is clean. A flux will prevent the clean items oxidising in the atmosphere while they are heating up to the temperature of the filler material. Try to shortcut by joining dirty, rusty, corroded, tarnished items, with no flux, and you will cry.

Please read some of the items here:

https://archive.org/search?query=soldering+brazing

 

[ChaiLatte]

If you can't get it hot enough to braze, you can't get it hot enough to silver solder.

In this area of joining things together, we tend to be a bit fast and loose with the terminology.

You could have a low temperature brazing material that melts at a lower temperature than a high temperature silver solder.

By and large though, brazing is a hotter process than silver soldering (look up the temperature for Easyflo and Sif Bronze), so what you say is not necessarily correct - you could quite easily be too cool to braze but silver solder adequately.

Traditionally, 'braze' and 'brazing' are used to refer to copper-based materials (brass, bronze), but 'silver brazing' is also a term of art.

 

[niall Y]

Given the disparate metals you are attempting to join then I would have to agree that a glue of sorts would be your best option,The body parts of modern cars are often glued together.

If the materials in question could all be silver soldered then starting with the highest temperature ones you can ensure that components stay joined whilst you attach others with progressively lower temperature silver solders.

Getting it right can be tricky especially if there are different metals and they are of varying thicknesses. I have often found myself applying too much heat and melting through thin parts whiles adjacent, thicker parts, won't take on enough heat to melt the solder.

Of course, if one is talking of brazing and soldering the parts have to be scrupulously clean. And, dipped in a pickle to clean off flux and discolouration, afterwards.
So, if one is hoping to use components because of their particular patina or corroded surface. Then this approach isn't going to work. And, using glue would be a better approach.,


Epoxy glues are probably your best bet, and they will come undone by applying sufficient heat, should the need arise .I believe there are also some polyurethane sealants that can be used to glue metal parts together.

 

[Spectric]

For stainless you can use a tin - silver solder but silver solder is a good all rounder for many applications. Another option could be rivets which with different heads could form part of the look of the item.

 

[Fergie 307]

You would certainly make your life much easier by avoiding Aluminium.
If you want to join rusty parts for their appearance then clean the areas to be bonded first so you can solder or low temp silver solder them. You can solder steel easily using the products available from car body restorers. You could try plumbers solder and plumbers flux paste, works on very small parts, not really tried it on anything bigger does work on Bowden cables to stop ends fraying or make nipples.
You can make the steel go rusty again afterwards.
Either just leave them outside or speed the process by putting them under an upturned bucket with a small container, the glass tureens GU puddings come in for example, containing a few teaspoons worth of spirits of salts. The vapour will make them rust pretty sharpish.
You can justify consumption of said puddings as a necessary evil in order to obtain the required pots
You can do similar with brass or copper, get bright and shiny in the areas to be joined so your solder will stick, then use an antiquing fluid to patinate them afterwards.
If you are not squeamish urine works well.

 

[Garrett44]

Many thanks for all the replies. Sorry I've been a little slow to reply. Will try to reply to all the key points above.


@ChaiLatte and @niall Y
Glue is not option for me. Brass is definitely in the minority of what I'm trying to join. It's mostly steel and aluminium. Cleaning is something I should have been more thorough with - I wasn't because the parts are so small and fiddly. Is there any solution to cleaning small parts? I did purchase wire brushes but it's didn't really seem to help.


@ChaiLatte
"You could have a low temperature brazing material that melts at a lower temperature than a high temperature silver solder."

These are the brazing rods I tried (https://www.ebay.co.uk/itm/195626916763). They are supposed to be low temperature and the range of my blow torch is supposed to surpass that but as I said I couldn't get it to melt on the heated metal (steel).




"we tend to be a bit fast and loose with the terminology...brazing is a hotter process than silver soldering (look up the temperature for Easyflo and Sif Bronze)"

Yes terms online in tutorials and on products have been confusing. So I looked up Easyflo here as you suggested - https://matthey.com/products-and-ma...ity/pgm-industrial-products/easy-flo-products, "white general purpose silver brazing flux" - what is this referring to here? Is it flux for ordinary soldering or is the "silver brazing" referred to what we are calling silver soldering? The flux I purchased for brazing was Sif Bronze flux in powder form.


@Spectric
>For stainless you can use a tin - silver solder but silver solder is a good all rounder for many applications.
>Another option could be rivets which with different heads could form part of the look of the item.

This is why I was gravitating towards silver solder as many of the tutorials I've found demonstrate this. Can you recommend a specific brand that is available in the UK? Everything I've seen online recommends US brands that can only be ordered via eBay from the US. This is the tutorial I used as reference. He uses Safety Silv 56, struggle to find this in the UK so I need alternatives, and he seems to barely clean it.

()


@Fergie 307
>the products available from car body restorers.
>plumbers solder and plumbers flux paste

Any specific brands or places to buy from (links would be great). I've attached a photo of what I've tried so far with solder and flux. None of it was very good and the liquid flux I used seemed to be useless.



>"You can make the steel go rusty again afterwards...speed the process by putting them under an upturned bucket with a small container, the glass tureens
>GU puddings come in for example, containing a few teaspoons worth of spirits of salts. The vapour will make them rust pretty sharpish...If you are not squeamish urine works well."

Yes, that's the plan. Good tip. Noted and thanks. (Aldi do an imitation version of the GU puddings - more cost effective)

 

[Fergie 307]

Eastwood restoration products I think do the body solder sticks and flux. I too have found liquid flux to be pretty useless. Paste flux can be found in Screwfix, or any plumbers merchant. Then there are powder fluxes for brazing etc, but a huge variety depending on what you are using in the way of rods, temperature and time. Solders and fluxes.co.uk are a good site to look at for guidance and products.

 

[Fergie 307]

Not aware of any means of attaching aluminium and steel by brazing or soldering, but never tried it. Think it will have to be glue or mechanical, nuts and bolts, rivets etc.

 

[Jake]

Epoxy glues are probably your best bet, and they will come undone by applying sufficient heat, should the need arise .I believe there are also some polyurethane sealants that can be used to glue metal parts together.

I think glued cars often use structural acrylic glue - methylmethacrylate (MMA). Amazing stuff (but smells awful).

 

[Fergie 307]

I think glued cars often use structural acrylic glue - methylmethacrylate (MMA). Amazing stuff (but smells awful).

Aircraft too

 

[MorrisWoodman12]

I found initially when brazing with a MAP-X blow torch I couldn't get things hot enough. Solved this by building a corner out of three fire bricks. It must reflect the heat back/ stop the drafts/????, well somethin' like that. Worked a treat.

 

[bp122]

Epoxy glue is the best option in this case. Gives you lot of control and the curing time is short.

 

[Vulcan]

I’ve seen lots of these sculptures in the past and all of them have been welded. I’ve wanted to have a go myself but can’t justify the cost of the required equipment. I did look into it though and concluded that TIG welding would be the best but also the most expensive way to do it. I’ve seen many beautiful TIG welds produced by skilled welders.

 

[profchris]

@Garrett44 you ruled out glue but without explaining why. You might want to reconsider, as JB Weld (and the other metal epoxies I'm sure) can make a joint which is strong enough to hold a sculpture together. With care you can get near invisible joints.

If there's no structural reason I'd give it a try. Th stuff costs around £6, and if it doesn't work there'll be household repairs for which it's useful.

 

[Fergie 307]

I’ve seen lots of these sculptures in the past and all of them have been welded. I’ve wanted to have a go myself but can’t justify the cost of the required equipment. I did look into it though and concluded that TIG welding would be the best but also the most expensive way to do it. I’ve seen many beautiful TIG welds produced by skilled welders.

Happy to be corrected but as far as I am aware you cannot weld steel to aluminium, vastly different melting points.
Glue is definitely the way to go if you want to join steel and aluminium.

 

[Garrett44]

Many thanks for the advice and tips.


@Fergie 307
>Eastwood restoration products I think do the body solder sticks and flux. ...Paste flux can be found in Screwfix, or any plumbers merchant...Solders and fluxes.co.uk

Many thanks. There is a screwfix around the corner from me here so will investigate.


@MorrisWoodman12
>Solved this by building a corner out of three fire bricks. It must reflect the heat back/ stop the drafts/????

Will get some some firebricks. Have got a paving slab in the last week to use as a surface indoors as yes I suspect the draft is an issue.


@Vulcan
>I’ve wanted to have a go myself but can’t justify the cost of the required equipment...TIG welding

If I have to weld then I arrived at the same conclusion, that TIG welding seemed to be the most versatile. TIG welders don't seem that pricey (and are compact) but the gas cylinders and my constraint of doing this indoors makes this impossible for me. My own way to follow up on this would be to see if there is a local workshop that does training/provide space for doing this.


@profchris
>you ruled out glue but without explaining why. You might want to reconsider, as JB Weld (and the other metal epoxies I'm sure) can make a joint which is strong enough to hold a sculpture together. With care you can get near invisible joints.

Sorry, should have mentioned why. A number of reasons - it's not so much a structural reason these will be so small I think epoxy would be fine, it's for sculptures so there is an aesthetic reason, I actually want a visible weld on the sculptures and when they are done I will be corroding them so am concerned the corroding process will remove the epoxy or weaken it.

 

[Vulcan]

There is another option that may work for some joints, and that is to use small fasteners like nuts and bolts. In some cases it may actually enhance the appearance of the finished piece. I’m a big fan of Socket Screws and these are commonly available in quite small sizes in both High Tensile and Stainless versions. Just a thought.

 

[RonnieI]

Not aware of any means of attaching aluminium and steel by brazing or soldering, but never tried it. Think it will have to be glue or mechanical, nuts and bolts, rivets etc.

You can join steel and aluminium by brazing (gas or TIG) using something like Al-Still flux and a filler rod that's got copper and silicon in it like BCup5 or 6. If TIG brazing make sure you get zinc free rods (traditional gas brazing rods) because the zinc vapourises instantly and buggers everything up. Ask me how I know