Flux

Guys: Results are in. The flux is an improvement over the old flux, but, I had trouble getting enough heat with heat guns (yes, I used two!) I have a very powerful Milwaukee that has a strong fan-it got the guard hot enough, but, the steel seemed to need to be a bit hotter.
I soldered two 410 SS pinned guards to Mirror finished BG42 blades. With a little coaxing, I got nice fillets at the front of the guard, and, got wetting even at the top of the guard.

I applied flux prior to heating-it crystallized as the carrier evaporated. Eventually, it turned brown, but, I didn't have enough heat to keep it at temp as I reapplied flux, then solder.
The melted solder was "reluctant". I ran a carbide scriber along the joint to get it to wet out.

Inner surface of the guard was machined (end mill), blade finish was mirror on one blade, hand sanded (top to bottom direction) on the other.
The solder did not penetrate the whole joint. Bummer.
I did get a clean fillet around the joint, so, it wasn't a failure.

I'm gonna try again with a propane touch, the way I used to.

The flux turned the blade grey, but, cleaned up nice with no pitting.

Steve: Any further instructions for me????

RJ Martin

AYou seem to be doing everything about right, maybe all you can do is continue to, "practice." Sounds like you feel the job is an improvement, just need to refine your technique. If the flux goes brown that sounds like it may be getting too hot.

As mentioned in my initial "treatise," on soldering, I find it almost impossible to get the solder to flow throughout the joint ---- unless you use the paste and actually "put it there," during assembly, before you start to solder.

When the flux re-melts, you're at temp.

I generally have ample heat with the gun, unless it's a really big fighter-type. It is slower than the torch, but much more controllable. It'll take me 5-8 min. to do a solder job on a hunter. How large were the blades that you were working on? Keep on trying and tkae it slow, is all I can tell you. I surely hope you can make it work.

Steve: They were 4" hunters, 3/16" stock. My gun has a strong fan, and, I think that I was blowing the heat away almost as fast as I added it. I agree about not getting full penetration when using wire solder-it's like putting a 1/4" peg in a 1/8" hole-not gonna happen!
When I have gotten my best results, I have a nice fillet of flux along the joint when I apply the solder, and there is enough heat so the solder just melts instantly and flows out. When necessary, a final application of flux completes the job.
The force of the fan was blowing away the extra flux, and, the solder didn't melt quick-like.
So, I will try again, going easy with the torch.
What is the surface finish on your knife/guard when you solder?

Thanks,

RJ

Must be quite a fan!

I have my blades polished to the final finish and the guard either polished or darned close. Probably at least a 500-600x finish. I also will polish, on the buffer, the bottom lip, or extension, of the guard, on a hunter, both on a double guard, so that I can look into it like a mirror and, seeing the reflection of the blade/edge there, make sure that the guard is perpendicular to the blade, or at least as closely as possible.

So, the guard face, on the exetnsions at the choil area is generally polished to a bright finish, prior to soldering.