Model Railroading > Soldering Question

I've never been any good at soldering. How in the world do you tin the tip? I've been trying and trying, and all I get is a molden glob of solder that wants to roll off.

Thanks for any advice.

As soldering requires a bright, tinned tip on the iron, this is the first step to successful soldering. To do this, use a fine file to remove all crust from the face you wish to tin. Heat the iron, and apply a very little flux to the end of the solder and touch the iron to it. The flux should spread ahead of the solder, cleaning the surface and allowing the solder to adhere. Repeat on each different soldering iron tip face you wish to tin. For a soldering "gun", there are two small faces which can be done at the same time. From personal experience, I suggest use of "Sal-Met" flux, obtainable from Henry Mfg. Co., 117 S. Crawford St., Danville, Illinois 61832, Tel. No. (21`7) 442-3846 (as of the last information I had). I have soldered Zamac to Aluminum with it, a job generally impossible with conventional fluxes. For use on brass, apply very sparingly, as too much will carbonize, interfering with the solder sticking to the metal. It may be cut with ammonia for use exclusively on brass; the solution will turn very dark, but still cleans sufficiently to allow solder to adhere.
It all cases, the surface to be soldered should be clean and relatively "bright", an abrasive rubber block will do the job. Apply flux to each part, hold the tinned and heated iron face to the metal and touch with the solder, which will flow when the metal heats beyond the solder melting point. (Note that there are many different solder types, with different proportions of lead and tin. 60-40 is the most common.) Some solders contain their own flux; if you use such, brush away the remaining flux with water, as it will keep on working even when cooled, though at a much slower rate. This may eventually weaken the soldered joint, especially where the contact point is very small, as in soldering fine wires on a brass steam locomotive to represent pipes. On brass, if you use solder containing its own flux, always select a resin-core type, and never acid-core, which should be confined to soldering iron parts. It should always be washed away after the joint has cooled, or the acid will keep on "working", eventually weakening the joint. Nveer try to substitute pressure for heat, (I have seen some people try to press the iron so hard against the work that the work broke, and it still didn't solder together).
The rules, in sum, are: Bright iron tip, tinned; clean the area to be soldered, use a small amount of flux of the proper type, Separately tin parts if possible, and heat the parts until the solder touching them flows. Don't press, it will not transfer heat.
Other points: If you get too much solder on fastening detail to a model, you will have to remove the "blob" with a scraper or wire brush on a motor tool. You can transfer solder from the iron tip, but again, use sparingly. ALL iron tips will eventually need to be re-tinned, and on soldering guns, the flux WILL eventually erode the small tip to uselessness; keep a spare on hand. I hope this will help.

It was the simplist thing! Why isn't it covered in the must-do's in model railroading?

A few further suggestions; When soldering details on a locomotive, that are close together, you can prevent the heat from the second application un-soldering the first detail, in two ways. FIRST: pack the first, "frozen" joint in wet tissue to keep it cool: SECOND, buy an aluminum heat-sink clip (Radio Shack has them) and apply between the first joint and your second soldering location. One important thing to learn, is how to get the iron OFF of the material quickly. As soon as the solder at the second joint melts and flows, get the soldering iron OFF the material. Otherwise, you will melt the first solder joint, and have that job to do over.
It is a good idea to wipe the face of the iron every time after it is applied to the work. The flux will build up, and soon corrode the tinned face into a hollow, preventing the contact of a sufficient area to transfer heat onto the work. On a soldering gun, you will have to file the contact face flat, re-tin it, and soon replace the entire tip. While not so serious with a large soldering iron, it becomes annoying when you have to file away a good amount of copper to avoid a pit on the face.
Just as knives work best when sharp, soldering irons work best when bright, shiny, and un-pitted.

Solder comes w/variety of temperature ranges(eutectic temp). So own several types if you intend to do much locomotive modelling, or similar type requiring sequential work. Obviously, use higher temp solders initially , working your way toward firewire(or similar match melt types) at final stage. If possible avoid acidic fluxes, which you should be able to do and still build models.

Nice job there, A.Wallace, on being genuinely helpful. That's what makes this BBS a good place. Thanks.

Hi,
Not all soldering irons can you file the tip.My Weller says-do_not_file_the_tip!Ok,ok,... :-)
But it does get dirty and the solder will "bead",so I add solder,let it sit for a few seconds,wipe it clean,re-tin wipe.I now always do this before I turn off the iron,so it is ready to go next time.
My old iron,once I did file it it worked fine but the tips do(eventually) wear out.

KB

Thank you for your great primer!

kbdb wrote:
>
> Hi,
> Not all soldering irons can you file the tip.My Weller
> says-do_not_file_the_tip!Ok,ok,... :-)
> But it does get dirty and the solder will "bead",so I add
> solder,let it sit for a few seconds,wipe it clean,re-tin wipe.I
> now always do this before I turn off the iron,so it is ready to
> go next time.
> My old iron,once I did file it it worked fine but the tips
> do(eventually) wear out.
>
> KB

KB is right. Some tips are plated with iron, which does not disolve in molten solder (copper does, that is why your uncoated tips pit and slowly disappear.) For these tips, a quick "steam cleaning" before you tin them with rosin core solder can do wonders. You can steam clean them by dragging them across a damp viscose sponge. Viscose sponges are sold for cleaning, and look sort of like real sponge, right down to the holes being all different sizes, except they come in party colours.

As KB says, clean it before you turn it off. And NEVER use a coated tip to melt plastic etc. It can contaminate so badly that it will never tin properly again.

-trainman-