Welding/Soldering

[Andy in Germany]

I'm still looking for someone able to weld or solder parts onto my bike frame. As I understand it, soldering is the way to go because welding involves too much heat and can make the frame brittle, and a client recently suggested I rent a soldering machine from the local DIY shop and solder the items myself.

I'm cautious; I've soldered models before but this would seem to be a big jump up. On the one hand I can see how the principles are the same but on the other it seems a bit unnerving. Has anyone else soldered parts onto a bike? What do you need to be a ware of or watch out for? I'm thinking I'd get an old frame and some offcuts to practice, but any tips would be welcome...

 

[ColinJ]

Brazing, not soldering!

Soldering is a lower temperature (< 450 C) , lower strength version of brazing, and brazing is a lower temperature (> 450 C < melting point of tubing) , lower strength version of welding.

 

[ColinJ]

Actually, I just noticed that you are talking about parts, not tubing... Er, is that done by brazing or soldering?

 

[Andy in Germany]

Brazing, not soldering!

Soldering is a lower temperature (< 450 C) , lower strength version of brazing, and brazing is a lower temperature (> 450 C < melting point of tubing) , lower strength version of welding.

We could be having a language issue here: In German we use the word Löten, and I think that could mean either. Perhaps I mean Brazing.

 

[classic33]

How much weight is going to be on the parts.

Maybe Hartlötung or hartlötend is the way to go.

 

[Randomnerd]

I've done a fair bit of brazing in my time, and welding. And a bit of soldering.

There is quite a bit of know-how to get your head round, even for a beginner.

What are you trying to put on what, with what?

Soldering and brazing can both deal with dissimilar materials. Soldering needs less kit, but is not always so strong as brazing (which is generally heating metals with gas torch over 450 celsius, and sticking them using various filler rods)

Soldering is good for thinner parts, but in the right hands a brazing set-up is better for pretty much all mechanical and stressed parts in thin and thick materials, similar or dissimilar.

Start out with some soldering kit and some scrap pipe and bits. And a decent book on easy technique. Leave aside twenty weekends and you might make some decent stuff.

Welding is high temperature - around 3500 celsius. Specialist kit for tube construction, and years of training

 

[Andy in Germany]

What are you trying to put on what, with what?

A very fair question. I want to fix some of these:

Onto this:

 

[midlife]

BITD we would braze with brass or a lower temp silver (more expensive) braze. We had special clamps and jigs to hold them in place.

 

[Randomnerd]

These ought to be brazed. I'd say that's a job for someone who has done it before. A framebuilder. That would lead me to imagine it's an expensive job. Is the frame worth it?
Rivnuts for the bosses?
But the stops will need ocyacet. Mapp gas won't get hot enough. DIY soldering will not keep stops in place. It's a lot of gear to own, hire etc if you haven't used it.
You'll need to lose a lot of paint. A good area of tube has to get up to heat to get a good solder

In short, you need someone who can braze using brass or silver solder.

 

[Andy in Germany]

These ought to be brazed. I'd say that's a job for someone who has done it before. A framebuilder. That would lead me to imagine it's an expensive job. Is the frame worth it?
Rivnuts for the bosses?
But the stops will need ocyacet. Mapp gas won't get hot enough. DIY soldering will not keep stops in place. It's a lot of gear to own, hire etc if you haven't used it.
You'll need to lose a lot of paint. A good area of tube has to get up to heat to get a good solder

In short, you need someone who can braze using brass or silver solder.

I've had it done before on this bike rebuild:

Unfortunately the person who did it is in Stuttgart, and I'm not.

I may have a possibility locally but it will be a few days before I can follow that particular lead.

Thanks for the replies; this saves me a lot of time and stress trying to make this work myself...

 

[wafter]

Brazing is typical on bike frames and uses a bronze filler rod, silver soldering (which IIRC can require temperatures between brazing and lead / tin soldering) uses a filler with silver content and is somewhere between the two in terms of strength too I imagine. Welding is totally different as it fuses two similar / identical metals and requires melting of the parent metal.

Any of the non-welding techniques will probably require a torch which with it will carry the risk of over-heating the frame. This is likely to be more problematic on frames that have been heat-treated such as 725.

While I'm all for having a go, personally this is something I'd leave to a pro.

 

[midlife]

Brazing is typical on bike frames and uses a bronze filler rod, silver soldering (which IIRC can require temperatures between brazing and lead / tin soldering) uses a filler with silver content and is somewhere between the two in terms of strength too I imagine. Welding is totally different as it fuses two similar / identical metals and requires melting of the parent metal.

Any of the non-welding techniques will probably require a torch which with it will carry the risk of over-heating the frame. This is likely to be more problematic on frames that have been heat-treated such as 725.

While I'm all for having a go, personally this is something I'd leave to a pro.

753 tubes / lugs had to be brazed with silver stuff to stop overheating, one way to tell if its genuine, what would that be?

 

[wafter]

753 tubes / lugs had to be brazed with silver stuff to stop overheating, one way to tell if its genuine, what would that be?

I think filler rods for all these processes are available in a wide range of alloys which affects their properties - including melting temperature; so it could have been bronze rod with a high silver content to lower the melting point perhaps..

 

[midlife]

I think filler rods for all these processes are available in a wide range of alloys which affects their properties - including melting temperature; so it could have been bronze rod with a high silver content to lower the melting point perhaps..

Thanks, had a hunt around and the filler rods had a high 56% silver content.

 

[wafter]

Thanks, had a hunt around and the filler rods had a high 56% silver content.

no worries and thanks for confirming that