Which solder

[Herbiev]

Hi all. I am just after a few words of wisdom regarding the joining of a cast iron cylinder (1.25" O.D 1" I.D) to a 1/4" piece of steel plate. I was thinking silver solder but which one to use. 45% silver? I shall be using mapp gas for the job.
Thanks in advance

 

[tel]

Yes, 45% silver solder and No.2 Silver Solder Flux

 

[BillC]

Use borax and 50/50 brass brazing rod. Using silver for this joint is overkill and will form no fillet.

 

[tel]

50/50 brass brazing rod? Don't think I've ever seen that here - the commonly available brazing rods are either tobin bronze or manganese bronze.

 

[Herbiev]

Please forgive my "newbieness" but what is 50/50 brass brazing rod. Could you elaborate for me please ???

 

[Maryak]

Herbie,

I used what tel said.

Best Regards
Bob

 

[Herbiev]

Thanks Tel, BillC and Bob.
Bob, I shall take your method as it seems to work well and is very neat. I too will have to buy a larger burner. One weekend of soldering coming up

 

[BillC]

Please forgive my "newbieness" but what is 50/50 brass brazing rod. Could you elaborate for me please ???

I've been trying to get back onto this site - keep getting the message that a connection to the server here could not be established - about 10 - 15 tries. No sure why this is happening but it happens all the time......I don't visit here too much anymore due to this connection problem - sort-of aggravating.

50/50 brass is the lowest and cheapest alloy found in most shops for gas brazing. The alloy is a bit more complex than the 50/50 would indicate but it is basically Copper/Zinc (Cu/Zn). It works well with the basic borax flux and will skin onto cast iron as well as any brazing alloys containing Ag. The ability to work a fillet is very good since it freezes without direct flame contact so it can be manipulated and hot formed quite well.

 

[Jasonb]

But I doubt a MAPP gas torch would get it hot enough. So stick with the Silver solder as Tel suggests or if you don't want it containing cadmium then 55% silver will be the nearest.

Jason

 

[BillC]

But I doubt a MAPP gas torch would get it hot enough. So stick with the Silver solder as Tel suggests or if you don't want it containing cadmium then 55% silver will be the nearest.

Jason

Mapp/air will reach 2300° and mapp/O2 will reach 5300° - 50/50 brass is liquid at 1640°

Cadmium in sliver solder? Maybe phosphorus (which is not used with ferrous materials - makes the joint brittle).

 

[peatoluser]

sometimes its not the temperature of the flame that matters, but the heat output of the torch.
All those different nozzles Primus-Sievert sell don't make Propane burn any hotter, but they sure do pump out a lot more energy. Thats why the nozzles are labeled with thier KW output
I think this is what Jason is refering to, although given Herbiev is only brazing a 1/8 flange to 1/4 plate he should be O.K.

peter

 

[Jasonb]

Peter its a 1 1/4" dia of CI tube to 1/4" steel plate and yes although the temp of the flame may be above the melting point of the solder but I doubt a small map torch will get enough heat into the metal for use of 50/50.

The 50/50 braze is usually used with oxy acetalene though I do occasionally use it with carbon arc rods on a MMA buzzbox. I also don't see the reason for being able to form a fillet, on a fabrication like this its better to have silver solder that will flow into the joint rather than a fillet of braze around the outside. Now if it were a repair in a piece of CI then this would be the right material to use with the right oxy-gas mix. My uncle was a well respected bicycle frame maker and well versed in the art of smooth fillet brazing and did show me a thing or two about using this type of alloy.

Bill as for silver solder (not silver plumbers solder)containing cadmium the model engineers silver solder of choice in the UK and many parts of the word is Easyflow No2 (AG303 or L-Ag42Cd)which is a cadmium bearing silver solder that melts at 1150 deg F approx. This is now becomming harder to obtain as the H&S are making it harder to obtain thats why I said a 55% silver rod may be prefered if Herbiev has health concerns.

 

[BillC]

Well, I just checked because I thought that cadmium bearing silver solder had been 'outlawed' due to its health effects. Apparently it is still available but may soon be pulled from shelves. I believe the UK leads in this banning but I understood that it had already been banned - not yet...

Oxy/Mapp works OK but using the small propane sized bottles doesn't give much time to do much, but it gets plenty hot to flow the brass. Just don't pause to tend to an itchy spot. ;D

 

[peatoluser]

yes, Jason, but it does have a 1" hole in it and I'm assuming the 1/4 plate isn't too big!
but on reflection, I'd follow your advice and stick to the solders. there's nothing worse than not having just enough heat and ending up with overworked flux and a pasty mess of filler. Solder may be more expensive, but you need less heat , and if you only need a bit why risk ruining the job?

hope Herbiev tells us how it went

peter

 

[Jasonb]

I don't think Herbiev has Oxy/MAPP more likely just a small blowlamp type MAPP torch if what he said in another thread is anything to go by

My mapp gas doesnt seem to deliver the heat required for 1/2" copper tube to 1/4" steel plate

And that was trying to do it with 42% Silver so not much hope getting the extra 500deg F needed for brass.

J

 

[Herbiev]

Thanks to everyone for your response to my question. I will let you know how i went (with pictures ;D )

 

[Herbiev]

http://i1237.photobucket.com/albums/ff463/Herbiev1/Snapbucket/th_6E53369C-orig.jpg
As promised here is a photo of the 1.25" cast iron cylinder soldered to 1/4" steel plate. I used bbq gas blow torch and a mapp gas flame to get things red hot. The 45% silver solder flowed very smoothly. I could not get the 50/50 brazing stick to melt. It must need oxy acet. The photo is a bit too close up but its looking down along the cylinder on the right showing how the solder fused the cast iron to th steel. Thanx again for all the help