TANK BRACKETS

Thanks,

Pretty easy, but, once again, StayBrite IS NOT silver solder, it's silver-bearing (4%) solder and nowhere near the strengh of real silver solder. Silver solder cannot be melted with any electric soldering gun or iron. The metal underneath must be heated to red hot before it will melt, and that will take a torch. Real silver solder is completely unsuitable for this application, and every solder joint in the tank will be melted and all the tin will be vapor long before you get the metal hot enough to melt silver-solder.

However, StayBrite is plenty strong enough for this application. The flux is really the trick with StayBrite. It's extremely aggressive flux and *will* remove all the tin plating from the metal. I think this is unnecessary in this case, and I would expect it to eventually eat through the tank no matter how well you clean it off.

For this application, regular old 50/50 Rosin core electronics solder will be fine, no extra flux will be required. That's what I recommend, and that's what I use for building tanks, too. It's plenty strong enough, not likely to damage anything, and easy.

When you get done, be sure to check the tank for leaks afterwards, because the heat of soldering on the brackets will probably also result in the existing tank joints being melted.

Right, the flux is what I have a bit of a problem with (at least, for this). The solder is nothing special, particularly, you can get the same thing (4% silver-bearing solder) with a rosin core at any hardware store.

>The sta-brite is definitely more vibration resistant than
>conventional solders. I've seen data on this (but don't
>currently have it), that was done in the early 1980's. You
>are, of course right about "silver solders". They are
>typically reserved for specialty applications and jewelry
>and can be compared to a brazing process.

REAL silver solder works well for soldering the uprights on control horns. StaBrite or other low-silver content solders are not really good enough for that unless you do something special to reduce the load on the joint.

Bob --

Being a good welder is likely a handicap in good soldering technique. In soldering, the focus is not melting the solder, but "sucking" solder into the joint by getting the joint area HOTTER than the area where you are introducing the solder. The heat radiates from the hotter joint area to the place you need to apply the solder, and when that area is hot enough to melt the solder, the joint is made as if by magic! Whether soldering a 3/4" copper plumbing pipe with a torch, or a small brass washer to a landing gear as a wheel retainer with a small iron, the principle is the same. Get the joint area hot, and feed in the solder when the joint area is hot enough to suck it in.

As Bill Sawyer pointed out, the kiss of death is a cold joint. Normally, that is only a problem when melted solder is hotter than the metal to which you are soldering. You can tell a cold joint in a heart beat, as it doesn't shine, and looks like old people's skin.

Make sure you jig is firm, so that parts don't move after the liquid joint is formed, and starting to cool.

Yes, tinning is a must. Cleanliness is a must. Materials matter little. Most any solder (including lead free) and paste (PASTE!) flux will work for our needs. Rosin core turns me off. No logic on the rosin core, just prejudice.

Do lots of sanding / steel wool to get bare metal to solder to. A necessity, as you can not solder to any oxide, no matter how clean it is.

Good solderers stick a dab of spit on the joint to speed the cooling.

Larry Fulwider
"An effective birth control method for senior citizens is nudity"

"i ain't got it! really, i ain't got it!!!"

Kreth --

The "spit" comment was a little "tongue in cheek." (Or maybe, "tongue out of cheek.") It is a ritual for solderers, akin to the Eucharist. It is a confirmation of your faith in your solder joint. It is more spiritual than physical.

As to the rosin core, Brett has likely soldered a lot more tanks than you and I have (or ever will)! My prejudice comes from house plumbing where solder joints have to withstand high water pressure, and I have never had a fluxed solid core solder joint fail, even after many years of use. No plumber would ever consider rosin core instead of flux! As I admitted, it is a prejudice, and I don't know of any problem with rosin core in model applications.

I do know that with half inch copper water pipe soldered into an elbow, I would be uncomfortable expecting to get the needed half inch solder penetretation required for the joint to withstand 100 pounds of water pressure. I have flux and solid core on hand, and see no advantage for me to buy special rosin core for models.

Make sure you understand that this is in NO WAY a criticism of those who prefer rosin core. I like flux because it takes little skill. For applications like tank mounts (the original question), I know the solid and flux works fine, will not fail, and looks good. I am not debating that other methods might not work just as well.

Larry Fulwider
"The key to winning races is never to come unsoldered at critical moments" -- Al Unser

The only thing wrong with acid flux is that it completely removes the plating, and it tends to corrode the metal (and the iron - one session with StaBrite flux can just about wipe out a Weller gun tip. They're cheap.) So you can never use regular solder again. If the tank plating is thin to the point that the steel is poking through (like most Veco/Perfect tanks), then, you might need to use some more aggressive flux. Clean tin plate (like the K&S material), using acid flux is unnecessary and probably counter-productive.

One very important point is, that if you do have nice solid plating, DO NOT "clean" it with steel wool, Scotch-brite, sandpaper, wire brush, etc, because you will remove the plate, expose the underlying steel, and then be forced in to using an acid flux to make the solder flow out. Anything I have ever seen on clean tin plate can be cleaned off by heating and rosin while you are doing the soldering. Don't use ANY abrasive method, you will just make it harder in the long run.

We are really talking about two different things here - the type of flux (rosin core or acid) and the type of solder (lead/tin, lead/tin/silver). If you could get the metal perfectly clean and keep it that way, you wouldn't need flux and the type of flux wouldn't effect the strength of the joint.

StaBrite *solder* is noticably stronger, than 50/50 electronics solder, but in practice, on .008 tin-plated steel or brass, the difference is irrelevant. I have made dozens of tanks with 50/50 rosin core solder, and, *if you use good technique*, it's far more than adequate. I have seen and had numerous crashes where the fuel went forward and hydraulically ballooned the front end of the tank until it looked like a sausage, and the solder joints were intact. When the joints do break, its because the tin plate was pulled off the steel, not because the solder itself failed.

Soldering is all about *technique*. Solder, to be strong, has to be heated until it is the consistency of *water*.

If you don't want to solder then consider using JB weld to attach your brackets to the tank. I've done that for the last 4/5 profiles that I built and not one of them has had them come loose. Also not a danget of unsoldering any other part of the tank. just enough to cover the base of the part and attach to the tank. Done properly and it looks just as neat as a solder joint.
Dennis

Aha! I just figured out why we are "pretending" to mildly disagree. Reading my posts and your posts, I think we are 99.5% in agreement! Let me tell you where we agree.

>The only thing wrong with acid flux is that it
>completely removes the plating, and it tends to corrode the
>metal (and the iron - one session with StaBrite flux can
>just about wipe out a Weller gun tip. They're cheap.)

I never recommended acid flux, nor shall I ever! It doesn't work well, and it eats metal, as you said. I was VERY SPECIFIC and emphasized PASTE flux, the same stuff as is in rosin core solder.

>One very important point is, that if you do have nice
>solid plating, DO NOT "clean" it with steel wool,
>Scotch-brite, sandpaper, wire brush, etc, because you will
>remove the plate, expose the underlying steel, and then be
>forced in to using an acid flux to make the solder flow out.

Again, I was VERY SPECIFIC and stated that you should not solder to OXIDES. Brass and copper, particularly, readily form protective oxides. Plating can form oxides also, but not likely much of an issue for model soldering. We both know we want to solder metal to metal, not oxide to oxide. I stand by my original statement, remove the oxides, and that may require some abrasion. I agree that a guy with an eggbeater up his a$$ and a wild man turning the crank could remove more than the oxides. Never remove the plating! I know of know way to get rid of the unwanted oxides other than abrasion.

>We are really talking about two different things here -
>the type of flux (rosin core or acid) and the type of solder
>(lead/tin, lead/tin/silver). If you could get the metal
>perfectly clean and keep it that way, you wouldn't need flux
>and the type of flux wouldn't effect the strength of the
>joint.

Correct! Rosin fluxes are what we want, and what I advocate. My point is whether it is in the core of the solder or in a separate flux tin matters little. You seem to have the opinion that the only way to get a rosin flux is to buy rosin core solder. That is simply not true. Rosin flux is readily available in tins. I prefer the flexibility of choosing when I need flux and when I need solder in a joint. Hence, my preference for solid core and a separate tin of rosin flux. Depending on the size of the joint, when you want flux, and when you want solder is a little awkward with rosin core (my opinion), but no big problem. You just automatically get more flux when you add more solder. With solid core, you get no more flux when you add solder.

>StaBrite *solder* is noticably stronger, than 50/50
>electronics solder, but in practice, on .008 tin-plated
>steel or brass, the difference is irrelevant. I have made
>dozens of tanks with 50/50 rosin core solder, and, *if you
>use good technique*, it's far more than adequate. I have
>seen and had numerous crashes where the fuel went forward
>and hydraulically ballooned the front end of the tank until
>it looked like a sausage, and the solder joints were intact.
>When the joints do break, its because the tin plate was
>pulled off the steel, not because the solder itself failed.

This is where we agree so strongly! A good solder joint is a good solder joint, and if it proves stronger than the plating, we have achieved a good solder joint.

> Soldering is all about *technique*. Solder, to be
>strong, has to be heated until it is the consistency of
>*water*.

Yeah, more agreement.
> Brett

We were?