I was reading some of the comments on other posts regarding soldering, and rather than hijack a thread, decided to put down some thoughts, tips and a bit of advice from 10+ years of soldering various metals.

1. A bells and whistles soldering machine is nice, it's not essential unless you do this sort of thing for a living. I use 2 irons. The first is a 15-45 Watt iron with interchangeable fine and medium point tips, I use around 17.5 Watts for white metal, 25-30 Watts for general soldering. The second is a 60 Watt brute with a large chisel tip that is used when I'm soldering primary assemblies, frogs or thick (20 thou') brass with high temperature solder.

2. Solders. I use 4 solders. Low Temperature, around 70° for white metal fittings and small castings; Low temperature, 100°, for white metal (tinning not required); General, 183°; and High, 243°, for primary assembly. All from C+L Finescale. I do not use rosin-cored solder. I chickened out of using the solder for MAZAC after reading the ingredients in the flux. A very good ventilation system is necessary for this (better than my Heath-Robinson affair).

3. Flux. Liquid general purpose no-clean flux. Witches brew re composition, but nice to use. Based on weak organic acids (citric, maleic, which etch the metal), an organic surfactant (which lowers surface tension and allows flow) and an alcohol. Most compositions are patented, so be careful if you make your own from a published recipe  and use it commercially.

4. Preparation is the key. Wash the metal, I use the cheapest possible unscented dishwasher powder and a hard and new toothbrush (not dishwasher liquid, it it leaves an aliphatic residue), extensive rinsing with water, followed by several wipes with 99% IPA (rubbing alcohol, not the Burton-on-Trent stuff), and key the surface where necessary. I use 800 emery wet and dry, followed by another wash to get rid of the glue from the paper, and once clean keep my fingers away from the surfaces to be soldered. Old kits will often have a patina of oxidation (both brass and white metal), this needs to be removed as it will result in a "cold" joint. Score the surface with a craft knife to increase the surface area on large pieces of white metal. Do not use cream pastes as they can leave a residue. Same goes for Brasso. It needs a lot of cleaning to get the residues off.

5. For white metal, I always test the iron on a small piece of scrap from the kit. This is essential when dealing with old kits, as the actual composition of the white metal varied considerably, with corresponding changes in melt temperature range. Unless a no-tinning solder is used, soldering white metal to brass requires that the surfaces be tinned.

6. For white metal castings, which in old kits can be large lumps of metal, it's often impossible to get the metal surfaces sufficiently hot to allow solder to flow. In this case the solder has to be chased into the joint to follow the flux. Some of the parts in old K and Wrightlines kits (especially O-scale) often have to be spot welded first with a hot iron, rather than soldered together.

7. For white metal and brass details it's often easier to use a low viscosity CAA applied with the end of a bit of wire. Only a very small drop is needed. CAA shears with relatively low lateral forces, if the fitting is a peg/hole attachment it's as good as a soldered joint.

8. Heat sinks. I have a supply of metal clothes pegs with flattened ends that I clamp around where I am working.

9. Hard wiring DCC decoders. I do not. After frying 2 ESU Loksound V3.5's and a Soundtraxx Tsunami (even with heat sinks on the wires) when I first got into DCC conversions, I settled on hard wiring 8 pin plugs to the engine, and having decoders with pinned wires. 21 pin or multipin PluX boards can be soldered up quite easily. Use heat shrink to cover soldered wires. Electricians tape does not stay put.

10. Solder in a well ventilated area. Just because it's "lead-free" doesn't mean it's any safer. Some of the metals used in solder are quite toxic in vapor form.

11. Solder melts over a temperature range. Old solder should be recycled, new ones have a much better defined melt range. If possible get rid of any old solder with copper mesh when rewiring, for example putting a decoder into an old non DCC engine where there are often large lumps of solder on the motor terminal.

12. Re-tin the tips after soldering. I use a tinning paste.

13. I read somewhere that it's best to go in hot and quick, rather than warm and slow. Do not linger, especially with white metal, otherwise all sort of interesting things will happen.

14. Some sort of support jig is useful, as trying to hold 2 pieces together in one hand and soldering with the other will also result in all sorts of interesting things happening.

15. When dismantling old white metal kits already assembled with 2-part epoxy, put the whole thing in a can of paint stripper for a month. it will dissolve all the paint and the epoxy glue (it requires a mix of methylene chloride and methanol, or similar). I use a "green" stripper that can go down the sink. One can is good for 2-3 strips. Use a strainer to catch all the detail bits, otherwise you will be dismantling the sink S-bend while undergoing a domestic interrogation. A good clean afterwards and it's all ready to be soldered up rather than glued.

16. When soldering power jumpers to RTR track, cut the plastic web and move the sleepers well out of the way. Plenty of methods described, I now use a wire bent into a right angle and soldered to the foot, rather than the side, of the rail web. That way it is not visible from the side when ballasted. And looks a bit neater. Power jumpers every 3 feet.

That's it, I'm sure others have more tips and pointers.

Nigel

Thanks for that Nigel.That's a pretty comprehensive explanation on how to solder and what to use.:thumbs

Thanks Nigel thats a very helpful post. You and Nick (Woody) have helped answer most of my questions. I have soldered masses of wiring and quite a few decoders but I have never attempted building a kit.

It seems I need a few accessories (eg tinning paste which I had never heard of before:oops:) and a new tip for my ancient 25W Weller. I guess I need to dig around for a Canadain source.

Thank you again for taking the time to write such a useful post

Hi Alan,

Thanks. Hope it's useful for other members getting into this side of the hobby.

Nigel

Hi John,

It's a bit like Nick's toolbox (the Dean Goods thread) - you don't need that much. Unlike John (Brossard) I was a great fan of Radioshack cheapo irons, especially the variable setting ones. At $12-$15 a pop and a tip life of 2 years if kept away from corrosive fluxes (phosphoric acid and the like) and tinned regularly they served me well. Alas no more, looks like I'll be moving up to a Weller or similar as I'm on my last one. I must check out my local electronic discount store later this week to see if they carry an equivalent cheapo range.

Cleaning (wiping on the damp sponge) and tinning the tip after a session while the iron is hot (no pun intended but it's apt) will maximize the life of any tip.

Nigel