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
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