Advice for attaching brass to steel ?

   / Advice for attaching brass to steel ? #1  

Jeff Lary

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I am thinking about attaching a finger guard to a knife I am making and need some wisdom.
I know a lot of people talk about silver soilder and I did some knife making research and found out that it can be very messy if your not proficent at it. I was courious if there is a diffrent type of soilder I could try ? I have acetylene torches so I could try brazing? ( I of course have Propane torches as well ) but I have never delt with trying to braze brass ? not sure if I could with out the finger guard melting along with the rod? I am very inexperienced in brazing so just know that up front.I use the torches mainly for cutting. The steel is about 1/8 thick and so is the brass stock. The steel is from a saw mill band saw if that matters in your reply. Thanks Jeff
 
   / Advice for attaching brass to steel ? #2  
You are better off using silver solder more so than brazing as silver solder (depending on the type) melts at a lower temperature than bronze rod. True silver soldering is called silver brazing because of the temperature but it's still lower than bronze. You are close to the melting temperature of brass when you use bronze so you get into the possability of melting the fingerguard, it probably isn't that big I wouldn't imagine? Not only that but silver solder flows better.
If you decide to go silver solder get the coated rod, here's a pic of them, 56% Flux Coated Silver Brazing Alloy x 5 rods | | AusWeld it's the first link I found so it's not necessarily the right rod, just a picture.
Only thing to watch out for is to not get the base metal too hot, once it does you'll have to stop and clean off the oxidized area and try again as the solder won't stick to the oxidized surface. There is a fine line between hot enough and too hot. It does require a bit of proficiency(sp) but if you keep touching the rod to the surface of the blade while heating it with a slightly carburizing or neutral flame it'll melt when you get it gets hot enough. Don't melt the rod onto the metal (dropping molten blobs), let the heat of the metal melt the rod as you touch it.
You don't want an oxidizing flame, it'll prematurely oxidize the surface and the flame will be hotter in a more concentrated area. It sounds harder than what it is really.....Mike
 
   / Advice for attaching brass to steel ?
  • Thread Starter
#3  
Thanks Mike I have seen carburizing or neutral flame pictures some place I will have to try to find them . I almost stopped by the welding shop today to ask them but I really did not know what to ask for ,so I thought I would get some advice before i go in.
 
   / Advice for attaching brass to steel ? #4  
hello i havent done any silver soildering but i asked my dad who is and old time mashinist and has done a lot of silver soildering he said yes it can be done, it wount be to strong,if the saw blade is hardend it probably wount stick, he said the way they do that in your aplication is they spot or but weld it together. i would clean it good and flux it and give it a try.
 
   / Advice for attaching brass to steel ? #6  
Silver soldering brass to steel is very common. I do it all the time for model engines. Here is a crankshaft I made. The shaft is 1/4" steel drill rod and the webbing is brass.

First clean and flux the area. Then put some small rings of silver solder around (or on) the joint.

DSC05384.jpg


When heating - I use a MAPP torch - Make sure the solder flows in, around and through the joint. After soldering, it looks pretty messy.

DSC05388_zps36f25d54.jpg


Cleaned up and ready to go. The joint is very strong. This crankshaft went into a model gasoline hit and miss engine.

DSC05389_zps136981e3.jpg
 
   / Advice for attaching brass to steel ? #7  
You're welcome Jeff. Truth be known a neutral flame is the best but an oxidizing flame is the worst so just for safety's sake go with carburizing, that why I had put carburizing in italics. You want just a tiny bit of feather on the inside flame, just barely so you can see it and you'll have a carburizing flame.

Nice looking crank Dennis. You're right tho, when you first look at something that's been silver soldered it looks like crap until you get it all cleaned up........Mike
 
   / Advice for attaching brass to steel ? #8  
There is also silver ribbon that can be cut with a scissors, flux'd and inserted in areas that are difficult to reach. I like the black higher temp flux, Seems to stay put better and you need less.
 
   / Advice for attaching brass to steel ? #9  
Hi For a neat almost no clean up joint. Make sure your brass & steel are both clean. Heat the brass (flux coated) until your sliver solder melts when touched to the brass. Flux should start to turn clear when your at the right temp. Quit let cool or quench. Lightly file the silver on the brass, flux both pieces, position. Have a small pick to reposition the brass piece should it move or You can hold it in place with the pick. Use your torch & direct most of you heat to the larger piece. If do correctly and you don't use too much solder there will be almost no clean up, just a nice little fillet around the brass piece.

Spent over 30 years silver & gold soldering. We called it welding as solder sounds like something cheep. Did lots of brass & copper as well.
 
   / Advice for attaching brass to steel ? #10  
Hi For a neat almost no clean up joint. Make sure your brass & steel are both clean. Heat the brass (flux coated) until your sliver solder melts when touched to the brass. Flux should start to turn clear when your at the right temp. Quit let cool or quench. Lightly file the silver on the brass, flux both pieces, position. Have a small pick to reposition the brass piece should it move or You can hold it in place with the pick. Use your torch & direct most of you heat to the larger piece. If do correctly and you don't use too much solder there will be almost no clean up, just a nice little fillet around the brass piece.

Spent over 30 years silver & gold soldering. We called it welding as solder sounds like something cheep. Did lots of brass & copper as well.

We always called that technique "sweating" the pieces together.
 
 
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