Cheers Ron, 56% wire what is the other 44% made up of ..... Silver? I don't have a clue on the brazing materials ,only just got my header around solder. Cheers tim
Tim, its 56% silver and I guess the rest is tin or sort. Works well anyway for me. The higher the silver content, the more expensive it gets In any case, I really do not use that much so 3 feet will last me a long time. Cheers Ron
Hi Tim, Silver solders,or brazes, are easier to work with than copper-based ones, and they do melt and flow at lower temperatures, but as you noticed, they are much more expensive. You can use copper-based braze metal, but you will need a higher temperature flux as silver baze melts and flows at lower temperatures (around 600 deg C) than does copper-based braze metal. Your new torch should manage the higher temperature required OK, but it would help if you set your workpiece on an insulator, such as a gas burner reflector from a scrapped Calor gas room heater. It is great that you have managed to recover a "dud" NRV, as they are expensive to buy new. Best Regards, Kerophile.
Ron George Thanks Things seem a lot clearer now. You need to be well set up working with higher temperatures,I did struggle a bit doing this job. I will keep a eye out for a burner reflector and have another go in a few days time . Thanks Tim
Hey Kero, thought all the while the silver requires something like 1100 degrees. As the propane torch puts out that much but with difficulty in melting the silbraze wire. Lance to the rescue please. Ron
Hi Tim, I use the same type of gas torch that you do, and found that a cradle or "parking station" was useful. Here is the prototype, constructed from wire and duct-tape: I was working on a Primus No.96 with a stuck NRV today. You can see that it was sitting on an insulator block: and yes I did get the stove operating and it did pass the Kerophile "tea test". Best Regards, Kerophile.
Hi, here is a phot of the 1950 Pr.96 operating: Tha flame is not perfect yet, but I believe that it is decades since this lovely stove last operated. Best Regards, Kerophile.
Hi George That's handy set up like having a third hand,is that MAPP or Propane gas canister. I bought my torch from the same place as you did,thanks for the link. The rotating head is a great feature ,add that to the home made cradle less chance of burnt fingers! Cheers Tim
Hi Tim, I am using Propane as it is cheaper than MAPP, and more than adequate for the work I intend to do. Don't worry too much about the burnt finger, I burnt a hole in my Cotton/Polyester boiler suit, below waist level, when working on a large tank. I now use the cradle more often, and once the flame is set-up, can bring the work to the flame, and still have a hand for the flux or braze. The range of adjustment possible with the burner on this gas torch, makes it very versatile compared with the more common pistol-grip style IMO. Hi Ron, you will notice that I used deg. Celcius rather than deg.F. when quoting the melting point of Silver-based braze. Best Regards, Kerophile.
Hi, I should have said, the second highest element in Silver solders is usually Copper, closely followed by zinc, and until recently, Cadmium. Here is some information on a popular silver solder, Easyflo No.2 made by Johnson Matthey: Easy-flo™ No.2 is a cadmium containing silver brazing filler metal. It is one of the lowest melting point and most free flowing brazing filler metals available. When used on a close and uniform joint gap of 0.05-0.15mm it will produce a neat joint with optimum joint properties. Easy-flo™ No.2 can be considered as the most economic cadmium containing silver brazing filler metal available offering brazing characteristics identical to the higher silver content alloys with only a marginal reduction in physical properties. As such it has historically been regarded as one of the best silver brazing alloys available. Concerns over user safety and the long-term impact of cadmium within the environment mean that this alloy should only be selected for use where no technically viable cadmium free alternative exists. In use potentially harmful cadmium oxide fume could be liberated. It should not be heated directly with a flame and localised extraction of fumes is essential. Companies should refer to JM as well as their national health and safety organisation for guidelines on its use. Cadmium containing silver brazing alloys like Easy-flo™ No.2 should NOT be used on automotive, electrical or electronic components, or in medical or food handling equipment. Composition: Ag 42% Cu 17% Zn 16% Cd 25% weight percent. Melting Range 608-617 °C Product uses: Johnson Matthey recommends that this filler metal should only be selected for use where no technically viable cadmium free alternative exists. Easy-flo™ No.2 can be used to join all the common engineering materials (excluding aluminium) such as copper, copper alloys including, brasses, bronzes, gun metal, nickel silvers, aluminium bronze, copper nickel, steels including, mild, carbon, tool steel, stainless steels, low alloy steel, tungsten carbide and PCD segments. Conditions for use: This filler metal is mainly used for brazing in air with a flux. In most cases Easy-flo™ flux can be used in conjunction with Easy-flo™ No.2. However, flux selection is application dependent. Please refer to JM technical department or flux product datasheets before selecting a flux. Cadmium-free Siver brazes are now available, and have similar working properties and characteristics. Best Regards, Kerophile.
Easy-flo No2 looks like the way to go. I thought about propane but I was unsure. Propane next time I think
Found some http://cgi.ebay.co.uk/Silver-solder-easy-flo-no-2-1-5mm-x-1-600mm-long-/360178071026#ht_657wt_1167 You make life easy for people George Thanks
nice show of how the NRV works. i didnt see it in the topic but you know that there are special keys to remove the valve. you can find them on the web. (i have one) are the valve's themselfs repairable ? mine seems to be broken. as far as i can tell the lead ring is intact and doesnt look wornout orso. And when i test it it sounds like the air (test only with air) is escaping trough the NRV. my test procedure. 1 close of the tank. 2 pump 5 times. 3 remove the piston. 4 listen the air very slowly starts to escape and ( i think when the vlave opened) there is a increase of noise and airflow out of the pumptube. i doubt if the NRV is repairable .. im searching for a new one .. Bart
thanks for that link makes me like a child in a toy store but i will first take the NRV appart maybe i only need the spring and i will have a look at the 3 other stoves at my parents house maybe they can be repaired to (idk the types) Bart
Hi Today I attepted to remove a pump tube from a Burmos 96. All was going well,slowly melting the solder from around the pump tube when the leg nearest the pump fell off To much heat from the new torch ..... need to be more careful there is a big difference from the mini torch I have been using! The leg and tube are back together now Cheers Tim
Hi Tim Oops! I pack the socket in the foot with water soaked tissue. You can also wrap the foot with a few layers of Al. foil. You only need enough heat to just melt the pump solder, you can then rock it slighly and gently pull it out. I'm glad its all back together again. Practice makes perfect. Best Regards, Kerophile.
I am amazed at the amount of soldering now being done. It seems to have started when i showed the repair of my Phoebus 30. i'm really pleased to see everyone taking on these wonderfull tasks so sucessfully. lance
does anyone know what the length of the spring of the NRV should be? i toke my nrv apart and the rubber is intact. only thing i can think of that is wrong is that the spring lost his strength. but i dont know that for sure .. Bart
Hi Bart, In my opinion it is the moulded NRV washer which is likely to be at fault. These become hardened with age and exposure to kerosene, and they do not make a good seal with the brass nozzle. Here is a post on manufacturing springs for NRVs: https://classiccampstoves.com/posts/50536 In the same thread, Doug, shows how he manufactures the better NRV internals which uses a brass bucket to carry a nitrile rubber "pip" instead of the "all in one" moulded design used in your stove. Best Regards, Kerophile.
