Keith Hale | 23/06/2015 14:20:39 |
![]() 334 forum posts 1 photos | Hi Andrew, Silver soldering of steel takes longer. Steel requires more heat to reach brazing temperature than copper. It takes longer. Be patient! Watch the flux. When it goes into a colourless liquid you are at brazing temperature The answer is to stop heat loss (brazing hearth/insulation blanket) and burn more gas. Fit a bigger burner. The 2941 burner generates 7.7kw heat at 2 bar. It might not burn enough gas to generate the heat required. Or using the regulator, increase the gas presure or fit a 2942 burner. Use a long life flux eg HT5 that accomodates the slower heating rate and matches the melting range of your solder. Fluxes have a very long shelf life but I suspect 35 years is pushing it a bit! Replace it. Borax is fine if you are using brass as the filler metal. It does not start to work until the joint is at 750 deg C. Brass melts at 830 degC. Your silver solder melts at what 650 deg ? The alloy may well melt but it will not flow until the flux works. A real concern is that if your alloy is 35 years old, then it probably contains cadmium. Getting the alloy to the temperatures required for borax will definitely give rise to the production of harmful metal fume. The alloy will also take on an "orange peel" appearance. Overheating a joint is one of the most common reasons for poor results. Do not use borax flux with cadmium bearing solders. Getting the heating right is the skillful bit associated with a simple process! Get it right and it's simple. Get it wrong and it's frustrating (?) For more info go to **LINK** Keith
|
Andrew Johnston | 24/06/2015 11:34:09 |
![]() 7061 forum posts 719 photos | Keith: Thanks for the advice. I have read the notes on the Cup website. Having bought some HT5 flux and 455 grade silver solder I had another go over the weekend. Another complete failure. To hell with the workshop, I'm going to take up knitting instead. Andrew |
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
Sign up to our newsletter and get a free digital issue.
You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.