Roger Smith

My Feedback: (2)

Can anyone help me solve a problem I'm having with soldering. About half the time it works perfectly and the rest does not. I sandpaper the metal and rub it with alcohol, then bind the joint (say, a landing gear) with copper or steel wire, then smear with flux and heat the part with a Weller iron. I've also used hobby-sized and full-sized blow torches. The silver solder flows on to the joint and then flows right off again. In any case, the joint fails. The problem is usually with wire-bound joints. Should the wire be wound closely or wider apart? Should I be using a better flux? I used to use a liquid flux that got better results. Any tips would be appreciated. Thanks.

Augie11

Roger-

I hate to admit this but my batting average on soldering is about the same as yours. I have produced both the absolute best and worst joints using the same materials and techniques one after another. It's uncanny.

I'm sure you know cleanliness is of great importance and you seem to use the same tehniques as I do except in place of alcohol, after sanding I generally use acetone. My best success is with Stay Brite silver solder using the liquid flux they provide. Make sure to clean ALL the wire, including the copper, before you start. I use a small torch and find it's just as easy to get the joint too hot as it is not to have it hot enough when you apply the solder.

Since I'm sort of in the same boat as you are, I'll be watching the responses you get to this inquiry.

Best of luck!

Dr1Driver

Some of that wire is either galvanized or has some type of coating. You gotta sand/steel wool through that to get a good joint. Sounds like you:

Might not be heating the joint enough.
Don't have enough flux.
The wire is dirty.

Clean all the metal parts with sandpaper or steel wool.

Construct a solid mechanical joint.

Apply the flux liberally. I use the blue paste type.

Heat the joint. If the landing gear wire is larger than 5/32", I'd use a propane torch. Even the big Weller 140w gun won't do the job on large wire. Wave the tip of the flame over the joint, heating it evenly. When it's hot enough, touching the solder to the wire will cause it to melt and flow into the joint. Never heat the solder itself. When the crevices of the joint are all filled, pull the solder and heat away.

Let the joint cool naturally. Don't move it, and don't apply water or air to cool it faster.

Good soldering comes with practice. Keep at it.

TFF

Make sure you are using Stay Brite silver solder like Tower sell. The silver solder at the hardware store in the plumbing department is not the same thing; they attached that name for plumbers who have to use it instead of the old lead type. Both parts have to be just as hot or it wont work. Sounds like you have the clean part down.

ARUP

I use Stay-Brite silver solder and its liquid flux. You might get a MAPP (or similar) gas torch. They are inexpensive and the heat is intantaneous (almost). Your technique sounds perfect in all phases but I suspect there isn't enough heat (likely), you are melting the solder but the parts aren't hot enough to sustain it (very likley) or the heat is too localized and the flux/ solder is 'boiling' off (most unlikely). I 'waft' the torch back and forth over the part to be soldered to get everything heated uniformly then heat the parts opposite where the solder is applied. Use care to not burn the flux. The solder will flow toward the heat of the torch. You will see the metal got thru some color changes when it gets up to temp. Red hot is not what you want, here! There is an 'art' aspect to it but is easily mastered with practice.

Laird SS

Make sure your flux is the correct one for the type of solder you are using. You shouldn't need a mapp gas torch. Ordinary propane produces more than enough heat for the soldering you are doing.

ARUP

You are correct! That's why I have in the post 'or similar'. MAPP is what I have on hand.

abufletcher

My silver soldering problems largely disappeared when I switched to StayBrite solder or any of the other 3% silver solders. I use a liquid flux (the one that comes with the StayBrite kit). And all I need is a large soldering iron. No gas torch needed. But there's also a bit of a magic touch to soldering and somedays I have it and other days I don't.

CanDo

1. Soldering is similar to welding, a lot of folks can melt solder and get metal to stick together, some can make a nice solder joint, but only a few can make consistent, excellent solder connections. Good soldering comes with technique and experience. As some have mentioned, you have to use the right materials (flux, solder, wires/metal), but the solder iron and tip are also very important. The techniques change depending on the materials and the material mass.
2. Temperature: the iron must have sufficient wattage and temperature regulation to quickly heat up the connection, but not over-heat the connection (which torches and unregulated solder irons tend to do). To compensate for an unregulated heat, you have to guess when the temperature is just right. If you guess wrong, you end up with a cold solder joint or a grainy, over cooked connection. Either way, you have a weaker connection.
3. I have soldered landing gear with a Weller soldering gun and got good results, but you have to be patient and the technique has to be right-on. For landing gear especially, when you solder smaller wire to larger wire, try to position the solder tip to allow it to transfer more heat to the larger wire. You may have to move the tip to adjust the wire's temperature. Practice on some extra wire before you solder your gear.
(I'd better get back to work now!)

Roger Smith

My Feedback: (2)

Many thanks to all for your valuable advice. I will definitely get the Staybrite solder with liquid flux and try both a Weller iron and a small torch. Try, try, and try again!

TedMo

Sort out your replies and try them they all have some merit. Myself I have found by using acid core solder works great. Don't use it on electrical connections though.

carlbecker

My Feedback: (3)

It is important to get and keep the metals clean. It is also important to get the metal hot enough to melt the solder. Either can cause the solder to roll off the metal.

jaka

Hi!
As has been said earlier...Use "Stay Brite" silver solder!!!
This sweet solder is much much easier to use than any other sweet solder. It's also much stronger.

Using ordinary tin/lead solder is also very easy but you must clean (sand) the surface first and then apply flux and then heat again and pre solder the surface. With Stay Brite nothing of this is necessary!

dcflyer001

stay-brite is excellent there is no better but it's the flux that makes it work so well. i used there flux with at least 15 different solders and all of them worked excellent. there flux is like no other it's hydrochloric acid and that's the key. remember to heat around your soldering area, dont burn the spot where the solder is going to go. i use to be just like you guys and after a couple of years useing stay-brite, it's really the hydrochloric acid i can weld anything, i even weld aluminum but i don't use solder.

abufletcher

That's a very good point! It's the little bottle of liquid flux as much as anything else. I've now switched to Novak Racing Silver solder which is EXACTLY the same stuff at StayBrite but you get more of it. And the little bottle of flux from StayBrite goes a long, long way. So get yourself one of the StayBrite kits about about three packs of the Novak silver solder (from Tower).

ARUP

I build fun scale antique and WWI types mostly which require lots of functional struts, wires and fittings to replicate. Wish I had more pics to show the 'shiny' soldered joints. If the joints are dull and 'globby' then the joint is not a good one. Heating and adding flux can cure it but a lot of times the parts need a good cleaning and filing to get the oils and/or surface oxidation off. These pics demonstrate wrapped wires, wire in tube and butt joint with fillets. I build jigs out of hard balsa to hold my parts and I get the jig wet to keep fire possibility to a minimum. Sometimes parts to be soldered are near previously soldered parts and you have a possibility of them 'un-soldering' much to your chagrin. If a jig can't hold everything or I am feeling a little lazy I wrap the part to be preserved and not un-soldered in wet toilet tissue to act as a heat sink. Remember, the flux is acid so it will 'eat' stuff it gets onto. Have a clear work surface and make sure any clothes you are wearing are from the 'Hobo' section of the wardrobe. There are other ways but I've been doing this for 40 years and it works for me! After you solder your parts wash them with spare tooth brush, soap and water then dry them immediately. I 'taste' the part with my tongue and if it is sour (flux is acid = sour) then I wash it some more until I only get a metal taste (clean). Yes- I have 'strong white teeth' (quoting a Benny Hill bit part!) and haven't dissolved them out of my head, yet! You are now the proud owner of soldered parts ready to be primed and painted! Good luck and practice makes.... an acceptable part!

bunsen

HiCouple of minor follow up suggestions to all the fine comments with Stay Brite solder and Flux.1. Be sure not to overheat the solder joint. If the Stay Brite Flux turns black it is too hot.2. If the solder is not flowing well then give it a small shot of additional flux, even while hot, and most of the time the solder will flow nicely.3. When done, and the joint is cooled off, give it a small shot from a small plastic bottle of Baking Soda and water solution to neutralize the acid.4. Then clean the joint in running water and it should be bright and shiney.For music wire solder joints I find that a propane torch is way too much heat. Most of the time I use a BENZOMATIC small handheld torch. Can control the area that is heated very well. For brazing using real silver solder a MAPP gas torch works well with white flux. Both from McMaster CARRJust some suggestions.Ray

abufletcher

Great tip. I've heard soaking in soda pop does the same thing. But I have noticed that there's often a "waxiness" that doesn't wash off easily.

ARUP

Soda pop? Some of it is made with phosphoric acid!!! I know it will make car parts 'shiney' and eventually dissolve them to molecules in sugar suspension! 'Drano' is a base and would nuetralize acid- don't recommend that- period! Water and soap is quick. Baking soda a good idea but that' just one more step I could do without.

dadragon

first things first.you have to get the mill scale off,get down to raw metal the rest will come with what your doing