A few weeks ago I asked about this and was given some excellent advice, including PM's. Yesterday I returned to the project. One statement about this solder "no harder to do than lead/tin" certainly does not match my experience.

First I washed the parts with Carburetor cleaner, and rinsed with acetone. I applied flux, heated slowly with propane, and managed to get one bead of solder stuck to the stainless. OK, I heated from wrong side, and burnt the flux. My bad.

Second, washed burnt flux off with water, wire wheeled the part, and washed with acetone. Reapplied flux, heated from inside cylinder, and stuck half a dozen beads onto the outside of cylinder. No way these beads could be coerced to flow, but they were stuck on hard.

Third, washed flux with water and bead blasted between beads before applying more flux. again, I heated from inside. No flow. Tried pushing and stirring the beads with a screw driver. No flow.

Fourth, washed flux with water and washed a file with acetone. I filed a white streak across top of cylinder, immediately applied flux, and laid a stick of solder in the flux. When heated, this stick melted and bonded nicely, but refused to flow.

By now, I know that this is possible, and if I can't find a way to make this solder flow, a major pain in the ass.

Searching YouTube, I saw some guy using "silver solder" on gun parts with a propane torch. His procedure was to frequently reapply flux while brushing the solder onto the gun surface with a stainless steel brush.

So, I find a stainless steel brush. Clean it with acetone. Clean and bead blast my part. apply full coating of flux, and heat gently from inside. When the solder softened, I started brushing, eventually achieving a fully tinned OD.

Well that wasn't so bad. If only I'd known that to start. Next weekend, after my new round brushes arrive, I can attack the ID of the other part.

Is this solder really supposed to flow over a surface wetted by flux, or was brushing the trick I needed all along?

What are you using for flux? You need to use the recommended flux, rosin burns at too low of a temp. to use with hi-force 44.

Yes you have to brush the solder; it won't automatically fully spread on its own.
I don't solder stainless steel.

In my experience the parts need to be tinned.

Tinning is good advice. You can also hammer the solder into thin sheets. Buff them with steel wool. Apply flux to each piece. Sandwich the solder between pieces and apply slight pressure with steel spring clamps. Apply indirect heat.

quote:

Originally posted by Jim Kobe:
In my experience the parts need to be tinned.

Jim,
I totally agree -- not everyone does, though .

quote:

Originally posted by Dans40XC:
Clean,Flux,Fixture,Braze.

If you burn the flux....start over.

If you need to "TIN" parts....seek a professional.

I solder quite a bit of stainless; some are easier than others. The acetone works sometimes, but not as good as you think it should.
Try this; after acetone scrub it down with very hot water and ivory liquid. Works way better than acetone.
Test; clean a piece of glass with acetone,then pour water on it. It will bead up. with the ivory it will sheet out like you want.
For steel to stainless I sand clean and solder,right now. If a longer than 30 minute wait, it gets soapy water. Practice on something junky is a good idea.
Just my 2cents on it.

Clean parts to be soldered by mechanical means (filing, scraping, ect). Don't depend on chemical cleaning to do the job. It doesn't seem to work well IMO. Maybe it drags contaminants from the surrounding areas with it and leaves it on the surface you want to be clean.

Apply flux and Tin both surfaces. Easiest way I've found to do this on gun parts is with the old style electric soldering iron, or even a newer pistol grip electric soldering gun.

Tinning the tip of the 'iron' first is important too so it'll hold the solder to be transfered to the part(s).

The iron will apply no more heat than necessary to tin the surfaces and little or no chance of burning the flux or overheating in general.
Both of these issues,,and parts not being clean,,are the major causes of soft solder failures.

Once both parts are tinned,,and they only need a flash of solder on their surfaces,,
flux them both again and clamp together.
Now reheat with either the iron or this time a torch. Don't play the flame directly on the parts if using the torch or you'll overheat and burn the assembly/flux.

Heat till it melts and flows. Gently tighten the assembly if needed and let it cools on it's own.

The Force-44 silver bearing solder works fine using this method. The tinning done with the electric soldering implements applys it easily to the surfaces.
I use common plumbers paste flux. Nothing fancy.
I've re-ribbed a number of SxS's using the above method and using Force44. No problems soldering.
I don't care for the for-ever brite white look of the solder line though. So I've gone back to using plain old lead/tin solder.

What will really make the Force44 and other silver bearing soft solders flow is the use of 'acid flux'. Sold under different names, most are Zinc Chloride and they work remarkably well even for lead/tin soft solder. They clear even a slightly dirty surface and with a little aggitation and scubbing,,most any solder will flow on them.

The problem with these acid flux products is the after rust conditions they can set up. Since they are Metallic Salt compounds, they will rust metal very aggressivly if not completely removed and flushed from the surfaces afterwards.

That would seem to be a simple thing to do, but in reality it isn't. More than a few projects show the heavy live rust still crawling from the soldered joint well after the job was completed.
I stay right away from their use. No real need for them anyway if you prepare the surfaces right in the first place.

I'm using the flux Brownell's recommends for the High Force solder. Nasty stuff. After using the brush to tin the part, I got to wondering if the flux was really necessary, since the brush worked so well, and reapplying more flux still wasn't letting the solder flow. I am tempted to get a piece of scrap and try brush only without flux. I'll still need flux to get the first bead started, but then I'll stop reapplying and see how it goes.

I have been tinning with the comet acid flux and then thoroughly rinsing and joining with rosin seems to work pretty good. A stainless carding brush works well for scrubbing to tin the parts as does degreased steel wool sometimes I even use a heavy cotton flannel patch

Force 44, hate the stuff! I can't get it to work well either. I wonder if regular silver solder flux would work? I don't think the melting temperature is too high.

https://www.amazon.com/Oatey-3...-Ounce/dp/B000BQPX8W

This is the flux I use for tinning with HF44 solder. Very nasty stuff and you must wash it off prior to adhearing the parts using pine rosin as flux. I’ve laid 100’s of ribs with this stuff, no SS though.

You must pre-tin HF44. Anyone who says otherwise...

I’ve found you have to rub the molten solder onto the part with steel wool when tinning. After that it flows ok.

quote:

Originally posted by metal:
I’ve found you have to rub the molten solder onto the part with steel wool when tinning. After that it flows ok.

it has so far gone without saying .. but i'll say it ..

degrease the steel wool!!!!

When I dabbled in making handmade knives years ago, I soldered brass and nickel silver guards to the blades. I read all about pre-cleaning methods and one that worked well for me was the Dove dish soap. Hot water, scrub and rinse. Pre-tinning I had good luck with either steel brushes or a small piece of degreased steel wool used to rub the solder on the part using COMET acid flux and then washing afterwards before joining the parts.

I've used the hi force for years with no trouble and never had it fail. I use the recommended flux and although I sometimes tin both parts, I've also just clamped them together and had the solder wick completely between the parts. It's good stuff. I am careful to degrease the parts and keep my greasy fingers off of them. I think cleanliness is the key.