Soldering stainless

[JackOfDiamonds]

I want to solder 304 stainless to copper or aluminum to make a heatbreak for my 3D printer. Is it possible?

 

[Firebrick43]

I don't think you can do 304 to aluminum that I know of?

You certainly can do 304 to copper(brass and bronze as well which would machine better than copper) with a silver brazing alloy such as Safety-silv 45, 50, or 56. I would suggest 56 for the easiest job.

https://ch-delivery.lincolnelectric...t/5198ad9d11c8447a9b1baf1167a72375?v=7b0de2c2

https://harrisweldingsupplies.com/harris-safety-silv-56-brazing-kit-56kpop/

 

[jaw22w]

I do a lot of soldering for stained glass projects. I know you can't solder anything to aluminum. I've tried. Unless there is some special flux or something.
You can solder steel to copper easily, but it seems to my hazy memory that I tried soldering stainless steel welding rod to copper for a stained glass deal and was unsuccessful. If I recall correctly the solder wouldn't stick to the SS.

 

[Firebrick43]

I do a lot of soldering for stained glass projects. I know you can't solder anything to aluminum. I've tried. Unless there is some special flux or something.
You can solder steel to copper easily, but it seems to my hazy memory that I tried soldering stainless steel welding rod to copper for a stained glass deal and was unsuccessful. If I recall correctly the solder wouldn't stick to the SS.

I have silver soldered lots of SS to copper/copper alloys such as brass and bronze. I assure you it works just fine.

 

[JackOfDiamonds]

Looks like the bigger problem is finding copper.

It has to be copper... conductivity of copper is 400, aluminum is 200, brass is like 60. I didn't know conductivity of brass was so bad.

 

[OccupantRJ]

What form of copper do you need? A flat sheet can be obtained by cutting a length of copper pipe, splitting it, then flattening into a sheet. Annealing helps with this.

 

[jaw22w]

I have silver soldered lots of SS to copper/copper alloys such as brass and bronze. I assure you it works just fine.

Well, I guess my memory was hazier than I thought. I was a certified arc welder but have no experience with gas torch welding. Is the brazing operation an oxy/acetylene process? My only experience with soldering is with an iron. It must take a lot more heat for the brazing operation.

 

[PCustoms]

Looks like the bigger problem is finding copper.

Why?

You should be able to buy copper all over the Internet....

McMaster
Online metals
Metal supermarket
Etc.

 

[Firebrick43]

Well, I guess my memory was hazier than I thought. I was a certified arc welder but have no experience with gas torch welding. Is the brazing operation an oxy/acetylene process? My only experience with soldering is with an iron. It must take a lot more heat for the brazing operation.

I always did it with a oxy/acetylene torch.

It’s also done on ovens and induction heaters(with iron/steel)

 

[Rusty Wrench]

I have soldered copper to stainless and brass many times. Many swear by Harris Stay Clean flux. I've used both Harris and paste flux successfully but for copper to stainless I'd prefer Harris. For stainless, depending on thickness, regular propane my not provide enough heat but MAPP gas or whatever it is now works fine. If the work is delicate hammer the solder flat for better control of application.