Model Railway Forum banner
1 - 20 of 21 Posts

·
Premium Member
Joined
·
2,836 Posts
Discussion Starter · #1 ·
Why can't I get soldering right? Every joint seems to take three, four or even more attempts. Even then there's a fair chance that I'll find later that it's not right and have to do it again. I use a small modellers soldering iron with self-flux solder. I clean the pieces to be joined which are either copper wire or nickel silver rail. After every joint I have to file the iron because then end has gone black.

Is there enough information there for anyone to spot what I am doing wrong? Cheers, Robert.
 

·
Registered
Joined
·
574 Posts
Sounds like your getting dry soldered joints. Does the solder ball up, rather then run smooth into the joint?

First guess is you've haven't cleaned the solder area enough. After cleaning the joint up and dry fitting it, you then need to clean the area with a fibre stick, then chemically degrease it before applying the flex and solder.
 

·
Registered
Joined
·
4,497 Posts
Glass fibre 'pen' - has a refill which can be extended out of the body of the pen - the fibres perform a gentle rubbing action on the surface you are applying it to. (Can be used to remove coach numbers, for example, although it will remove the gloss of the plastic body.) Use Iso-propyl alcohol or similar afterwards to remove the resulting debris. Available from many model shops, tool suppliers etc. They are not only used by railway modellers.

But you mention that your iron tip keeps 'going black'. Do you clean and tin this at the start of a soldering session as a matter of routine? A damp sponge (vicose, I think, not an ordinary plastic one) on which the tip can be quickly wiped after each joint should suffice to keep the tip clean most of the time. I've a Weller iron - the stand has a recess to take such a sponge - the sponge I'm currently using was bought about 20 years ago!

The other main thing is to see that the tip is the right size/shape for the job you are doing - for example a small conical point when you're soldering to the side of rail so you get maximum contact between point and track. Allow the joint to warm up and apply a small bit of solder to improve contact between tip and object. When the object is hot enough apply the solder to give the amount of coverage you need.

A bit of practice on scrap track, circuit board etc with scrap wire is always a good idea.

Hope this helps,
John Webb
 

·
Registered
Joined
·
2,202 Posts
are you using a solder that doesn't contain lead?

I was once given the tip[?] of dunking the soldering iron tip into a glass of cold water to clean it.
when I do this, I notice a lot of black slag dropping off the tip.

suggest a look at Carr's soldering products?

but this sounds as much like the iron isn't big enough..or getting the work hot enough inthe time allowed?
 

·
Premium Member
Joined
·
3,614 Posts
i also often find that even with flux cored solder, a little more is very usefull. for jobs like this i use the really old traditional tin of gunge. i cant remember what its called but i have had it since i was about 8.

you might also find it easier to tin the wire before attempting the joint. it helps keep the strands together. but yes i agree with Al and John. the key to good soldering is a really clean joint. you dont need a monster iron for this kind of thing. 18 watts is enough. 25 is loads, 50 is too much. 80 is what i use to put stained glass windows together! 100 is what i use when i am feeling a bit cold and the heating isnt working!

Try and use a nice bit of fresh solder, not that bit that has been luying around in the bottom of the toolbox for 20 years.

Peter

P.S. if you are ever in london i would be happy to give a lesson or 2 in exchange for a packet of milk chocolate McVitties caramels.
 

·
Just another modeller
Joined
·
9,983 Posts
QUOTE (Robert Stokes @ 20 Dec 2007, 04:16) <{POST_SNAPBACK}>Why can't I get soldering right? Every joint seems to take three, four or even more attempts. Even then there's a fair chance that I'll find later that it's not right and have to do it again. I use a small modellers soldering iron with self-flux solder. I clean the pieces to be joined which are either copper wire or nickel silver rail. After every joint I have to file the iron because then end has gone black.

Is there enough information there for anyone to spot what I am doing wrong? Cheers, Robert.

***Hello Robert

I teach soldering schools so this is a subject dear to my heart :). Most modellers are frustrated not because they can't do it but because they don't have the right gear for the job.Its actually not too hard as long as we get the materials and tools right, so you will be an "expert" very soon!

Basically a soldering Iron tip has a fine iron plating on it and once that is gone, the tip should be replaced. The problem is that no matter how much temperature the Iron can generate, a bad tip can not transfer heat to the job to be done properly as you have found. A tip should never be filed - if it needs filing it should be replaced.

(1) You need a new tip at least - but you will be well advised to buy a good quality soldering Iron. 25 watt or more is important - any smaller and the Iron will take too long causing all sorts of problems from heating the job too much (melted plastic sleepers) to simply being so slow that oxide build up stops the jint ever happening as you have found. More power is good as long as the Iron is handlable, less is not for ANY reason!

I strongly suggest an ANTEX XS25 which will be reasonable in cost, excellent quality and has an excellent tip structure which transfers heat very effectively. This tip structure is excellent as the tip sleeve totally surrounds the element and the large surface area makes sure the tip temperature remains stable. The XS25 is supplied with a 2.5mm chisel tip which is perfect for modellers as used one way it has a good surface area for things like rail soldering/droppers and used the other the sharp side of the tip is small enough for fine work in electronics. (tip replacement is easy though, so you might want to get a 1mm pointed tip for PCB work - they are quite cheap.

(2) You need a very clean rail and a liquid flux. The flux is important as you can't hold three things at once - ie Iron, wire and solder, and if you try to transfer solder to the joint on the tip of the Iron, the internal flux will have burned off long before the iron gets to the joint.

The flux to buy for general use is carrs ORANGE which is a no clean flux.

(3) You need carrs 179 solder. This is excellent for electrical or soldering to rail - much better than standard 60:40 and far, far better than lead free solder.

A joint on clean rail with a good Iron and flux plus good solder will take less than 2 seconds and be good every time.

Procedure:

make sure the Iron tip is properly tinned. It should be bright and shiny all over

before every use, wipe it on a damp sponge. as long as you keep it damp, a standard cheap kitchen sponge is just fine.

Clean rail add flux and tin the area with a little solder

strip wire and tin the bare end.

bend at a right angle to meet the rail nicely and apply a little more flux to the area

wipe Iron tip on sponge than add a small amount of solder (NOT a big blob)

take the Iron to the joint and remove Iron as soon as the solder flows.

keep the parts totally still until the joint sets - this will be MUCH quicker withthe Carrs 179 than with the standard solder as it has a narrower melt range.

if you DO have a failure then clean the area and re-tin before trying again - don't just nag at it.

if you have more questions then plese don't hesitate to ask.

Richard
DCCconcepts

(2)
 

·
Registered
Joined
·
303 Posts
Richard,

I hesitate to take issue with someone who teaches soldering, but I feel that I must in this case. The use of liquid flux is OK as far as the actual soldeing operation is concerned, but on the long term, liquid flux is an acid and it attacks the joint unless it can be washed off. Clearly this is not a problem if you are building a loco. An overnight soak in a neutralising agent such as bi-carbonate of soda would be enough.

At our club, soldered track built with a liquid flux ten years ago is now beginning to fail because we did not wash off the flux.

When building track, or soldering electrical joints, it is not possible to wash your work. In these cases we now use paste solder such as Fluxite.

Colombo
 

·
Just another modeller
Joined
·
9,983 Posts
QUOTE (Colombo @ 20 Dec 2007, 19:55) <{POST_SNAPBACK}>Richard,

I hesitate to take issue with someone who teaches soldering, but I feel that I must in this case. The use of liquid flux is OK as far as the actual soldeing operation is concerned, but on the long term, liquid flux is an acid and it attacks the joint unless it can be washed off. Clearly this is not a problem if you are building a loco. An overnight soak in a neutralising agent such as bi-carbonate of soda would be enough.

At our club, soldered track built with a liquid flux ten years ago is now beginning to fail because we did not wash off the flux.

When building track, or soldering electrical joints, it is not possible to wash your work. In these cases we now use paste solder such as Fluxite.

Colombo

**Colombo, the orange is a resin based flux, not an acid, which is why I recommended it.

Richard
 

·
Registered
Joined
·
4,497 Posts
QUOTE (pedromorgan @ 20 Dec 2007, 05:59) <{POST_SNAPBACK}>.....Try and use a nice bit of fresh solder, not that bit that has been luying around in the bottom of the toolbox for 20 years.....

I'm still using some 22SWG Multicore solder bought in 1968 - a 8oz reel I think, the labels have dropped off - and which I've carefully kept in the top of my various toolboxes. I reckon I've still got two or three year's worth of solder to go, unless I build a really large new layout, which is a bit unlikely.

I've never found the need for extra flux, by the way, careful cleaning to start with seems to eliminate the need, particularly if the wire has been 'tinned' beforehand as well.

For those who don't like waving soldering irons about, there are various alternatives. It is possible to buy fishplates (rail-joiners) with wires already soldered to the underside for connecting power to tracks. For under-baseboard connections there are 'choc-blocks' and various crimped connectors including 1/4 inch tabs and various plugs and sockets.

Regards,
John Webb
 

·
Premium Member
Joined
·
2,836 Posts
Thank you all for your advice. I will try to put it into practice and see whether I get better at it.

Thank you to Pedromorgan for your offer, but I do not envisage going to London in the near future (ever?). I grew up there as a child but left at 18, which was 45 years ago. On the few occasions I have returned I have wanted to get back to saner pastures as quickly as possible. Couldn't stand the noise, fumes, crowded roads and the general rushing about - and that was the last time about 20 years ago. What it must be like now I don't even want to think about.

Cheers, Robert.
 

·
Registered
Joined
·
312 Posts
Good advice above about tips and heat, most electrical irons are too small to get enough heat so 25 watt or more is ideal. Go for a decent iron with a stand and a reasonable size bit, remember you are joining to rail not just wires so you need to transfer the heat efficiently.
Lead free solder is bloomin useless see if you can find some old resin core lead solder just use adequate ventilation! Flux is useful but not essential for a good joint if you clean it well with the aforementioned fibre brush.

Clean the bit on the supplied sponge, tin it with a drop of solder only - not a great ball of solder.

Apply iron to the joint,

then when hot apply the solder to the iron and joint and it should flow into the wire and onto the rail.
You don't need much, first it just soaks up the heat rather than making a better joint and second a big blob looks awful and can cause shorts in a tight space.

The most common fault is to apply solder to the iron and then put it onto the joint and you've already burnt off the resin flux before you even touch the job.

Signs of a poor joint are frosting or long tails of solder as you take the iron away.
 

·
Registered
Joined
·
233 Posts
Jenolite rust remover is one of the best fluxes that you can use.

The comments from PaulRhB really hit the nail on the head and he knows his stuff, especially about iron capacity. Never attempt to use an iron less than 25watts when solder to anything such as rail as PaulRhB has described, this is the heart of the matter.

Tim
 

·
Just another modeller
Joined
·
9,983 Posts
QUOTE (72C @ 21 Dec 2007, 08:38) <{POST_SNAPBACK}>Jenolite rust remover is one of the best fluxes that you can use.

The comments from PaulRhB really hit the nail on the head and he knows his stuff, especially about iron capacity. Never attempt to use an iron less than 25watts when solder to anything such as rail as PaulRhB has described, this is the heart of the matter.

Tim

***Hello Tim

Yes, Jenolite and most rust removers will act as quite good fluxes however this is simply because they contain relatively high proportions of phosphoric acid.

They really aren't at all suitable for use on electrical or trackwork wiring for this reason. Additionally, they are skin irritants and addition of heat gives off noxious gasses that will affect more sensitive people, so good ventilation is needed if they are used as a flux.

All acid based fluxes will need neutralisation after use with something alkaline such as an ammonia/water mix.

This is why I recommended a resin based flux to Robert. It can be used with no need for cleanup afterwards and will not hold any long term risk to the quality of the joint.

Kind regards and best wishes for a happy Christmas and a New Year full of smiles

Richard
DCCconcepts
 

·
Registered
Joined
·
233 Posts
The reason why I favour Jenolite for larger work (we were discussing soldering track) is due to the aggressive nature of Jenolite in cleaning the metals but this must be neutralised after use (it says so on the tube) therefore this must be taken into account.

Resin based fluxes also contain active chemical agents and these must also be neutralised, if you don't bother, you will watch your paintwork lift and solder joints rot.

All soldering should be carried out in a well ventilated space whilst wearing a face mask and eye protection, the face mask is essential due to the lead content (yes, I know that the EU has banned it but it is still available) in the solder. Therefore even using resin flux requires a mask.
 

·
No Longer Active.
Joined
·
13,319 Posts
[quote name='72C' date='21 Dec 2007, 09:45' post='42783']the face mask is essential due to the lead content (yes, I know that the EU has banned it but it is still available) in the solder.

From the way I interpret the EU regs regarding the lead content in solder you can use solder with lead content for private use but you must use lead free solder for commercial use. Therefore, if you carry out work for commercial gain you have to use the lead free stuff.
 

·
Registered
Joined
·
70 Posts
Lots of good advice here! One very simple, additional tip - Wipe the solder wire clean and bright before use. You'll notice that older solder, and indeed, your previously soldered stuff goes a dull grey due to a thin layer of lead oxide, which is detrimental to sound joints. I pull the last 6" through a piece of 'green-rub' scourer if it looks at all dull. Good luck!
 
1 - 20 of 21 Posts
Top