What is the type of solder to use bonding brass to steel?

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ulgah

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Hope this is the proper forum to ask this question. What is the type of solder to use bonding brass to steel? TIA.:)
 
Stay-Brite or Eutectic 157. They melt at 430F. Use the specific flux that is made for them. Apply only enough heat to flow the solder.....too much heat will make the solder not flow. A heat gun works excellently.
Stacy
 
bladsmth said:
Stay-Brite or Eutectic 157. They melt at 430F. Use the specific flux that is made for them. Apply only enough heat to flow the solder.....too much heat will make the solder not flow. A heat gun works excellently.
Stacy
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Super!! Thanks much Stacy, for sharing your knowledge.:D
 
My heat gun [Milwaukee ] has 500F and 1000F temperatures .But I don't have an accessory to concentrate the heat .I don't know if it will be enough. I've used a propane torch all my life . Remember that you must heat the steel and the hot steel [and brass] will melt the solder. Don't melt the solder with the torch.
 
The 400-500 heat , carefully applied for one minute will not affect the temper, as that is the upper range of normal tempering. Also,the temperature does not go very far from the solder area if the flame/heat is carefully applied from the tang side. The blade edge areas can be wrapped in a damp cloth if you are not comfortable with your soldering skills yet. I usually clamp the blade, at the plunge line, between the copper jaws of my vise and it acts as a heat sink. I use a Smith (little jeweler's torch) Torch to do all my soldering. The trick is that you only need enough heat to bring the area up to the flow point of the solder.

Here is a tutorial:
Solder is mainly a sealant, not a structural component. Parts should have good mechanical support ( pins on bolsters, snug fitting guard to shoulders on hidden tangs, etc.)
Sand all surfaces to be soldered to 400 grit.
Make sure surfaces are a good fit. You only need a few thousandths of an inch for the solder to flow. Solder hates to try and fill gaps !!!
Clean all parts thoroughly. Wash with acetone, then wash with a good dish soap. Rinse well and dry with a paper towel. Don't touch the areas to be soldered after they are clean.
Assemble the parts, applying a good amount of flux while assembling. Once assembled, wipe of excess flux with a clean paper towel.
Put the knife in the vise/clamp/jig, apply a bit of flux, and using a heat source, ( small torch, plumbers propane torch, heat gun, etc.) gently heat the tang of the knife and the guard/bolsters. You want the tang to be the warmer of the two. Occasionally apply the heat from the ricasso, but not much.Try to avoid heating the bolsters/guard directly,too much. It will get plenty hot enough while you try to heat up the tang/ricasso.
Add some more flux, using a disposable flux brush or a Q-tip.As the flux just starts to bubble , remove the heat and apply the solder very sparingly, from the tang side,not the ricasso side. If it immediately melts and runs, apply the heat sparingly for just a second,from the opposite side of the joint from where you are applying the solder, and allow it to wick through the joint. If it doesn't melt yet, heat the entire joint a little more , and touch the solder stick to the joint again. Never directly apply the flame to the solder stick!!!It will melt and then resist flowing. Once it flows through the joint remove the heat . The joint will stay hot enough for you to work the solder. If it need a little more heat, just give it a quick shot.
Once the solder starts to flow and wick in, you can apply a little more flux to coax any spots that are not flowing right. If the solder is flowing, but not covering a particular spot, MORE heat will not make it flow better, and MORE solder will make a mess. Too much heat is the enemy of making solder flow.Too much solder is the enemy of a clean joint.Use the absolute minimum amount of solder needed to flow. You can add a tiny bit more much easier than you can remove the excess.
Have a solder pick handy. It is a sharpened piece of 1/8" steel or brass,sticking out of a 1/4" dowel handle. Take the solder pick and run it around the joint and the solder will flow in behind it. A little back and forth scraping (to remove the oxides/burnt flux that are preventing the solder from flowing) will usually get the solder to flow in any stubborn spots.Wipe off any excess solder with a clean dry paper towel while molten. Allow the solder to cool all on its own.Don't move anything. If you are worried about the edge temper,you can cool the blade edge by squirting some water on it, but never cool the solder joint quickly. It will make a cold solder joint ( the solder crystallizes too fast),and it will fail. Do not move the blade until the solder joint has completely cooled to below 200F. Wash off all remaining flux immediately after the blade cools.
Excess solder can be removed with a solder chisel. Make one from a piece of bronze or hard brass. It is just a 1/4" wide flat chisel, with a 30-45 degree bevel.Don't use a knife or steel tool - it may scratch the blade! The excess can be cut away nicely with the brass/bronze tool. Careful sanding and buffing will remove any vestiges left.

If the solder melts and refuses to flow, or you overheat the joint and the flux burns and turns black - STOP NOW. Don't keep applying solder and heat. Just dunk it in water to cool things off, re-clean everything as good as possible, and try again with less heat.

Hope this helps -
Stacy
 
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I should have said that I didn't know if a heat gun would work since I bought my first one only yesterday !!!...For capillary action to work there should be an optimum gap of .003" ! Take the time to fit things properly.
 
woodsman1031 said:
Thanks for all of the information,

What kind of solder do you guys use?

Tommy
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Stay-Brite for me. It works great. Stainless to stainless i.e. CPM154 blade to a 416 guard, Carbon steel blade to bronze, NS or SS guards, etc, they all work good using stay-brite solder & flux.

Excellent instruction Stacy ! Is the eutectic 157 the paste type solder ? The flux and the solder mixed together in a paste form ?

Has anybody tried Tix solder & flux ? I think it has an even lower melting point than stay-brite. I have been wondering about it for a while now.

I'm have also been told that most solders, like stay-brite etc. have a specific type/brand of flux that works best with it. Make sure and purchase that solders specific flux and you will up the odds of getting a sucessful solder joint. JMHO ;)
 
Those silver solders are all about the same .They are tin with about 5 % silver and melt just over 400 F. They stay bright and are approved for use with food so you can repair your wife's kitchen stuff !!...Another point - if you are soldering stainless steel make sure the flux specifically says 'for stainless steel'.
 
I use a lot of Tix at work, and occasionally on knives. It is good. Stay-Brite is also good.
Stacy
 
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