Silver Soldering :Good and Bad :Flux sometimes a black mess

Hello,

Following some encouragement on another thread I had a go at Silver Soldering today. I think the end results are okay, but I had to totally clean and redo some joints 3x due to flux turning to a black charred mess before the copper was up to temperature. Flux is Easyflo. Solder is SBA 245 with a soupcon of Cadmium. Torch is average handyman small general purpose and is shown in one of the photos.

When it works I don't know what I did right and when it doesn't work I don't know what I did wrong ..... Is it a bit like using a parting tool ? One day you go to the shed and realise you can do it and its not a problem any more ?

Sometimes it is easy to indirectly heat the flux from the other side of the joint, but depending upon workpiece size and geometry sometimes the flame has to play directly upon the flux, that's when I seem to have more problems.

Would value any comments / recommended reading / websites etc please.

Its a Jenny Wren boiler from Tubal Cain book "Building Simple Model Steam Engines"

Photos here

...... and yes the flue is crooked ..... decided to press on with all mistakes included and get maximum learning from first attempt ..... will repeat from the start and do a better one.

Bill

Edited By JasonB on 16/04/2019 10:35:46

Edited By BW on 16/04/2019 10:45:37

Edited By BW on 16/04/2019 10:50:00

Bill,

Seems like something awry here; when I click on your link & 'open in new page' I get my albums coming up?

George.

When I click on the link I get my pictures.

Martin P

Clicked on your link again, seems to have resolved itself... ?

George.

Jason Fixed it - this post redundant.

Edited By BW on 16/04/2019 10:50:40

Fixed the link

With a small torch like that it will take a while to get things upto temp so use a flux more suited to longer heating such as tenacity No5 or Cup Alloys HT5.

Those blocks are not the best but you would do better arranging two of them to form an internal corner and stand the boiler about 1" clear of the corner, that way any heat that misses the part will get thrown back. Adding a few small vermiculite blocks infront of the building ones will help.

Got to your albums, click "view album" for the one you want and then copy the url displayed at the top of your browser. Slightly quicker option is to right click the "view album" and select "copy link address" then use that when linking in your post.

My mini hearth...

George.

Thanks for the help and the comments. Will try a different flux and placing the workpiece in a corner as suggested by Jason. Will look for some of that Woolly stuff that George uses as well.

When you chaps are soldering something as small as the M3 threaded socket in my photos would you still use a bigger torch than mine ?

I guess you don't bother trying to focus on one small part in one location just wash the whole surface with flame. Gotta admit I was hoping to be able to learn by doing small workpieces with my small torch before splashing out on a big one.

Just noticed that the solder ran into the steam outlet hole and completely blocked it, I guess thats a rite of passage that all soldering novices have to experience ....... will buy a bottle of tippex.

Bill

You need to heat what you are soldering teh bush to so don't just heat the small part. I seldom fit a smaller burner to do a small part..

I think Keith appleton did a few videos on silver soldering on his youtube channel as did myfordboy - might be worth your while to have a look . I find it easier ( most of the time ) to show how to do something rather than explain it in writing . There tip sheet from Cup alloys somewhere on this forum that i found useful .

Hello Bill

The process is simple as long as you understand the basic principles and STICK TO THEM.

You will be successful.

Read the book from CuP Alloys. It is the result of 50 years experience in the silver soldering business. Or why not simply ring them and get help from the UK's number 1 supplier to the model engineer.

Talk to them face to face at Doncaster next month

The help is there. Just reach out for it!

Keith

Hi BW

Have a look here; it's where I got mine from, from their stall at Donny' exhib couple years ago.

**LINK**

George.

Thanks for all the tips.

Am getting there, had another go today and managed a lot better.

Bill