Hello. Forgive me if this has been reported before. I recently broke the cleaning needle off the rack in an old (embossed tin) 111 burner. Although I have replacement needle racks and pinion/regulator shafts for these burners, I wanted this one to remain 'all original'. The repair was done using an Ernie Ball '10' (top E) guitar string which measured 0.25mm diameter. A hole was drilled in the top of the rack using the smallest drill I had (0.35mm), and the brazing set-up was as shown. A drop of Easyflo flux (mixed with water) and a sliver of Silver-Flo 20 braze rod were placed next to the needle. and brazed using an air-propane torch (Bullfinch) at a very low setting. Trimmed to size and fitted. Works well, and was a very satisfying repair to do.
Hi @Twoberth , Neat repair. I have often thought about it but never got around to doing such a repair. Did you have any problem drilling near the old needle,or had it already been removed? I think that some cleaning needles are held in place by crimping the brass once the needle was inserted into the hole and it some cases it has subsequently fallen out, or been pulled out. Best Regards, Kerophile.
Hi @kerophile, you homed in on the main problem - how to get the stump out. The needle was broken off flush, but fortunately the top of the rack was domed and I carefully filed around the dome leaving the stump proud. Then I gripped the stump with needle pliers with the rack in a vice and pulled gently. It came out easily and left a pilot hole for the drill.
Hi, here is a link to photos and measurements on a British Military No.12 cleaning needle: https://classiccampstoves.com/threads/british-military-no-12-cooker-–-cleaning-needle.27081/ You can see how a broken needle would be difficult to extract and replace.... Best Regards, Kerophile.
@Twoberth That is a fine piece of work. Your placing of the sliver of silver solder, rather than holding the brazing rod against the two parts, is a very good tip. Cheers Tony
Fine piece of work @Twoberth. Tricky getting the pricker rack hot enough for the silbraze to flow without vapourising the replacement wire. When the stub of the wire won’t come out of a pricker rod tip I’ve cut a groove down to it with a slitting saw wheel, then laid the replacement pricker wire in that to be silbrazed - or more often crimped it in place as @kerophile has suggested (not really feasible for the stubby shape of a pricker rack). John
@presscall , it’s also tricky not to melt the rack as the Silver-Flo 20 has a higher melting point than the more common Silver-Flo 55. @Tony Press , Using the sliver of rod not only controls the amount of braze melted into the hole, but also allows the braze material to heat up and melt more quickly than using a long rod which conducts heat away.
