Question #2: Soldering Stainless?

Archive ... when asked by members ...

First off, pertaining to SS for fittings: I've used un-heat treated T416, almost exclusively,for many, many years with complete satisfaction. The engravers, as noted elsewhere in this "Arena," love it and, if I know that a knife is going to be engraved, I even use T416 screws, if I can remember to do so. Don't ask where to get them, I don't even know who'd make them. I had some made special a long time ago and only have a few on hand.Secondly: Maybe, Tom, I'd reverse that statement to say, "I do exactly the same way as with nickel." I haven't made a knife with N.S. fittings in so long, I can't even remember when it was. But....I do use the same procedure: Fit guard/tang as close as possible, although a really tight fit isn't essential for the soldering to work. I clean it, before assy., or after, with acetone.Then you can either heat it up and then brush on flux, or flux first, then heat. I'll usually warm it up a bit first to try avoid, to some degree, the chance of burning flux. The flux, as you know, is your temperature guage. It is liquid at first, then it crystalizes when approaching temp. Then it will "melt" again as it reaches 430?F. You have to watch carefully for this "melting" to happen. This is it, don't go applying much more heat, or things will start to burn and blacken and get all messy. If this happens, it may be wise to stop and start over, although you can, sometimes, save it, if you're lucky. You also get more of a flux etch on the ricasso, the hotter you get things. As you hit temperature, apply the solder, it'll be a bit hesitant to melt, but resist the urge to apply more heat to speed it up, until you've given it a bit of a chance to melt and the heat to be conducted throughout the entire guard/ricasso/joint area. It takes some practice. It's easy to go too far and pass the right temp. If you add heat, make it slow and a little at a time, checking with the solder as you go to use the minimum amt. of heat needed. I then run the solder around the joint, dabbing/punching the brush into the joint and brushing slightly in the direction you want the solder to flow as you coax it around the ricasso. You need to use more flux here, but try to keep it to a minimum. Dip the CORNER of the brush into the flux. It doesn't take much, unless it's being obnoxious, then it takes some fiddling. Try to do this before it cools down, but you can add heat, as needed, not overdoing it. The longer you mess with it, the more chance you'll have of it getting messy. When it's flown all around the front of the joint take a PAPER STEMMED "Q-Tip" and wipe, carefully, the excess flux and solder away, you can "flip" it off of the guard to get rid of it. You can "smooth" the fillet a bit with the "Q-Tip," also. Now........ IF IT FLOWS THROUGH THE JOINT, GO TELL YOUR WIFE THAT YOU LOVE HER AND THANK HER FOR YOUR GOOD FORTUNE. She, being more worthy than you, is the ONLY reason the solder will flow through the joint. You owe her a night out and the washing of ALL the windows in the house!!That's why I slip my guards into a notch with rounded corners and use a 3/32" or 1/16" stainless pin. 'Cause the solder joint, even though Eutecrod 157 is dang tough solder, isn't likely to be as strong as a tool steel/N.S. joint, where the solder has wetted and flown throughout the entire joint. SS, as you know is difficult to wet and the solder won't flow easily, like it does when soldering tool steel and nickel silver, for example. With the pin and the notch, the guard is stable and strong and the solder seals the front of the guard and strengthens the whole joint.Then, to hopefully, eliminate trapped flux in the joint, I boil the knife/guard/joint, (after burnishing/smoothing with the knife-like edged "BritghtBoy or Cratex, 80-P disc and buffing with the sharp corner of a buff), in soapy water with some baking soda added to neutralize the flux that is inside the joint. Usually, even if you try to solder front AND back, you'll have a gap at the back for water to get into. This goes a long way in helping to eliminate the "flux leakage" that's sure to "pop up" sometime within the next year, if you don't boil it.. I even continue my hollow grind of the tang into the area under the guard to allow the water to get under there. Then wash all the soapy water off and blow it dry with the air hose. The problems arise with too much heat, dirt in the joint and trying to get the solder to flow like it does with a tool steel and a brass or N.S. guard. SS is an "anti flow" material, you might say. Any help? If not, get back to me. I have never tried the soldering iron approach of Bob Loveless, referred to by Mike C. This is the technique I learned from Bob and it's been good for me for many years. I did tell you of the early days when I spent 8 hrs. soldering two guards, didn't I? I think that they were N.S. guards at that! Practice, practice, practice.... I am sure, however, there are other ways. And Bob Loveless will find a better way if it's out there, that's for sure.


Another maker had this comment/advice:

I have some experience with the paste solder that I would be happy to share with you all. Get you some Allstate 430 Flux and their paste flux. Mix some of the flux in the solder jar to the point it is runny (you want it to be thick enough to stay on the guard but thin enough to spread evenly). coat the inside of the guard and slide it on the knife. If it is a double guard, coat the ricasso area before putting on the guard and then wipe off the excess. Make a pin from your guard pin material (I use 303 for the guard and 309 welding rod for the pin, 416 is harder than 303 and will stay "raised up" when you go to finish the guard)and put a THIN bead of flux around the guard at the joint. Keep in mind where ever you put flux, the solder will stick, guaranteed!!! I then take a heat gun and apply heat to the bottom of the guard. I used a tourch for years, but the heat gun is a lot easier. When the flux starts to bubble, put a VERY SMALL amount of solder at the joint and run it around the guard with the pin you made. Use a flat piece of brass to clean up the joint. Works great. GenO Denning taught me this, and it has saved me many hours of work. Good luck Mark Hazen.

Then Mike Connor says:
Where do you get this solder? I have two heat guns, but never thought about using them for soldering guards. What a neat idea, thanks for sharing it with us.
Mike

From SRJ:
The heat guns are great, at least I think so, so far. They are bit slower than a torch, but MUCH more even in the heating and less messy, you'll love 'em! You can actuall see what's happening with the flux/solder, etc.

All-State's distributor locator is at: www.esab.com/html/esabna01.html

I've used some Allstate paste and also a sample of Eutectic's 157PS paste. However they, and Jim Poplin, recommended also using a bit of their EutecSol #682 flux to get a better wetting on the SS. You can get in touch with Eutectic at this site:

www.eutectic-usa.com/distributors.html
They sent me to Salt Lake, who sent me to a Tech. Rep in the next town south of me and he got me a small sample bottle to try. It's expensive stuff, you should know, so see if asample is available to see if you like it first.

I'm going to try the suggestions from Mark, above, too.

Maybe there are specific item numbers we need to know, Mark? Thanks.