Soldering Advice #2

SOLDERING INFORMATION & ADVICE #2

The Black Art de-mystified

Part 2a: Flux

What is it & why should you use it – how & why does it help?

Part 2b: Preparation

Cleanliness, fluxing, tinning and the post soldering cleanup

Part 2c: making a start on that first kit

A detailed “how to” for soldering your first Brass kit.

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First, lets talk about the various fluxes…...

There are several Definitions of flux - Not all even relate to our subject of soldering metals, but all are correct for the purposes they refer to.

Each kind of flux is different and its creation depends on the job it has to do... Fluxes provide active cleaning, especially when heat is applied, they improve heat transfer, encourage solders etc to flow and they also aid formation of the important inter-metallic layer when used with solders.

It is important to use the right flux for the right job.

Definitions:

* A substance that aids, induces, or actively participates in fusing or flowing:

* A substance applied to a surface to be joined by welding, soldering, or brazing to clean the surface and “wet” the surface in order to facilitate the flowing of solder and prevent formation of oxides.

* A mineral added to the metals in a furnace to promote fusing or to prevent the formation of oxides.

* An additive that improves the flow of plastics during fabrication.

* A readily fusible glass or enamel used as a base in ceramic work.

The KEY words for us in all of the above are: Flowing, Wet, Prevention of Oxides.

To put it very simply: Soldering processes require clean surfaces so the base metal is well exposed to the molten solder. During soldering operation, fluxes do the following: (a) Remove the oxide films on the base metal. (b) Momentarily prevent further formation of oxide films. (c) Lower the surface tension of the solder to promote wetting.

The actual range of fluxes available is quite wide as they will vary depending on the materials to be joined AND the circumstances the joined materials will be used in. (Variance is in aggressiveness, toxicity and efficiency under a specific heat ranges or soldering conditions).

The three basic types we use are (1) activated fluxes, which include resin based flux and some organic fluxes, (2) corrosive fluxes which include acid based flux and (3) Reaction flux which will react with the base metal and only have a reaction when heat is applied.

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AVAILABLE FLUXES

DCCconcepts Sapphire Flux:

Our 100% favourite, now used by many professionals who cannot believe how well solder flows when using it!

A non-corrosive flux which performs exceptionally when used when soldering with brass, whitemetal, Nickel silver and steel. It is also effective on some grades of stainless steel, including that used for marklin rail.

It is heat activated . Safe for electrical dropper to rail etc and residue is “water system safe” & residues are easily cleaned up with water or meths and water.

(Please note though - it will not damage surfaces but it will stain if any remaining residues are not cleaned—as above, methylated spirits or alcohol or water and detergents will clean it well - a wipe over is all it usually needs)

This is available as both a liquid or convenient soldering paste.

CLICK HERE to see it or to buy.

The Excellent Carrs range of Fluxes

As we do with Carrs Solder, we also enjoy using and very happily recommend CARRS fluxes which have become a standard for many modellers after years of development and constant improvement.

Carr's Grey Flux.

A powerful but corrosive flux for soldering the “usually impossible” metals! ALUMINIUM, MAZAK, DIECAST….

This powerful, highly corrosive flux will strip aluminium oxide & allow No. 179 Strip Solder to penetrate beneath, and fuse with the aluminium. This flux is also effective on many of its alloys including Mazak (A die casting alloy as used for model cars). Spread the flux over surfaces to be joined then heat the metal with a tinned iron or an indirect flame.

Apply solder by running it on from the tip of the iron and a thick tinning will be formed. Don’t linger too long as flux is rapidly consumed & could cause withdrawal of the solder if exhausted. Any other CARR'S soft solder may be used for subsequent soldering onto this tinning, although flux protection should be maintained on the aluminium to prevent it withdrawing. Immediately all joints are made, clean the job with warm water, wipe dry and seal with Carrs Electrofix.

CLICK HERE to see it or to buy.

Carr's Brown Flux.

For the “Harder to solder” metals including! NICHROME, PIANO WIRE, SYRINGE NEEDLES, STAINLESS STEEL etc….

Caution! This flux is a concentrated corrosive acid.

Please observe special precautions when using. If spilt, wash with copious amounts of water and neutralise with Neutralising Rinse. It is formulated for soldering most stainless steels and other difficult metals such as ni-chrome resistance wires.

Also good for piano wire, syringe needles etc. Residues should be carefully washed away in warm water. NB. Stainless steels should be soldered at the lowest practical temperatures.

When heated, nickel and chromium in the mix create an oxide ‘skin’ which is difficult to remove. The prime purpose of the flux is to reduce this, taking the surface back to base metal.

However, above around 400° C, the metal will oxidise faster than the flux can reduce it, creating a situation whereby soldering is almost impossible.

CLICK HERE to see it or to buy.

Carr's Orange Flux.

For jobs that cannot be cleaned after soldering such as GEARBOX CASINGS, TRACK, ELECTRICAL ETC….

A non-corrosive resin type flux, which should be used for jobs that cannot be washed, such as gearbox casings, track laying, and electrical wiring. This flux is compatible with speedy solder. It is ideal for wiring repairs where adequate solder is already present.

The residues should be cleaned off with Cleaner Degreaser if it is intended to paint over the joint. This flux burns at a higher temperature than natural resins so that charring is less likely to inhibit the solder flow.

CLICK HERE to see it or to buy.

Carr's Yellow Flux.

A new “Easy clean” flux (clean up with Water or Meths and Water). Excellent for WHITEMETAL, BRASS, NICKEL SILVER or most OTHER COPPER BASED ALLOYS including BRONZE & PEWTER

NB. The formula of this flux has been changed. It is now supplied in a PVC jar, whereas, the previous formulation was supplied in a glass bottle.

This is an ideal flux to use when soldering whitemetal, brass, nickel silver and other copper based alloys. It is extremely easy to remove any residue after soldering, with Neutralizing Rinse or water.

CLICK HERE to see it or to buy.

Carr's Green Flux: Active flux for steel & non-ferrous metals. (Alkaline neutralizing needed) BRASS, COPPER, STEEL, NICKEL SILVER ETC

Carrs biggest seller and for most modeler's the flux they instinctively turn to. It is suitable for use with steel, (but not stainless steel), Copper, Brass, nickel silver and similar alloys.

It is an active flux and leaves residues that are corrosive. For that reason, care should be taken to remove these. An initial wash in Neutralising Rinse followed by several washes with water should remove all traces.

CLICK HERE to see it or to buy.

Carr's Black Flux: A POWERFUL Active Flux (Alkaline Neutralizing Needed) STEEL, GALVANISED METALS, HARDENED STEEL

This is a very powerful general-purpose flux for steel and galvanised metals. The residues should neutralised with Neutralising Rinse and then washed off with warm water.

This flux is an equivalent to Bakers Fluid for steel.

CLICK HERE to see it or to buy.

Carr's Red Flux 250ml: Active at low temp. Easy clean up with warm water Generally used for... WHITEMETAL & NON-FERROUS METALS.

This is an organic flux compound, very active at low temperature, which makes it ideal for use with whitemetal. Also very suitable for other nonferrous metals.

Breaks down at around 240° C to leave non-corrosive residues. However, this shouldn’t be assumed * the joint should be rinsed or wiped with warm water.

CLICK HERE to see it or to buy.

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Part 2B

Cleanliness, fluxing, tinning and post solder cleanup

We have already spent a lot of time covering the tools, materials and resources that can make or break a soldering job; however there are a few simple rules that must be followed if you are to enjoy soldering and get a consistent result. Nothing hard, nothing complex… Read on.

Let’s start with the basics:

Clear the work area… If it’s a work-bench put other things to one side and give yourself a clear area to work in... If it’s on the layout, clear away stock and tools and clean up the area around where you will be soldering. If it is under the layout move stuff away to give yourself a clean space and somewhere for tools to sit – plus adequate space for a work-light.

This may sound a bit pedantic but to solder well you have to have the Iron at the correct angle to the work – and you also have to sometimes hold things at strange angles so your fingers don’t get burned. This takes clear space, and if you do NOT make a clear area to work in you DO risk knocking things over, spilling the flux, burning or damaging things or becoming frustrated.

Clean up the work surfaces…. And the material you will solder.

If it’s the parts of a loco or wagon kit, or even bits of wire and tube/sheet for a scratch-built model, file the edges square to remove the cusp that’s left from the etching process. Clean the surfaces to be soldered with fiberglass pencil OR a DCCconcepts cleaning block. Wire is best cleaned with a strip of wet and dry emery paper (between 600 & 1200 grit is OK).

If it’s RAIL - clean it with a fiberglass pencil or a strip of wet and dry paper… Or a needle file if you can get under the rail web. Clean rail should shine.

Clean the Soldering iron tip and get it ready to use…

Clean the soldering Iron tip (A DCCconcepts brass wool tip cleaner works really well. Do NOT be tempted to file or sand the soldering Iron tip. If you do that you will shorten its life considerably – the plating that helps tip life and heat transfer is VERY thin.

If after cleaning it AND wiping it on the damp sponge held by your Soldering Iron stand, it isn’t evenly “bright silver” all over, then it may need re-tinning.

Use the tip re-conditioner to re-coat the tip with clean solder.

TECHNIQUE:

Turn the Iron off, and let it cool about 60%. Turn it on and gently roll the tip on the surface of the Tip re-conditioner. As the Iron heats it will melt the re-conditioner material and sink slightly into it.

As the Iron reaches full temperature, the flux will start to smoke a little. Remove the Iron and wipe it on the sponge. It will be perfectly tinned. Now, turn the Iron down to a low temp setting (or turn it off) until you are ready to solder.

OK, now the workbench, job and Iron are ready to go, lets look at FLUX:

At the top of the page we reviewed fluxes in depth, so we will presume you’ve chosen the flux needed and have it ready.

TIP:

Flux gets knocked over often if you aren’t careful… and apart from being expensive, its not good for many materials if spilt everywhere, so DO think about sticking the flux bottle to a bit of wood or some other form of wide base. You WILL be glad you did, believe me!

If we are doing electronic or electrical work you should not really need flux at all as the solder such as DCCconcepts “Sapphire 179” already contains enough for most electronics tasks… but if a solder IS needed we will want a “No Clean” or “Easy clean” flux that is NOT acidic. Acid fluxes will destroy PCBs and copper quite quickly.

Same for rail – use a “no clean” or easy clean type as it’s a pain to remove from rail joints, especially if the track is already laid. For other materials please refer to the flux information provided last time.

The flux can be applied in several ways:

For PCBs – brush or flux pen (excellent for crowded PCBs that need a no clean flux)

For rail joints – with a brush or cotton bud

For wires to be tinned – Flux with a brush OR dip them into a small pot of flux if you are doing many at one time.

For seams or brass details – with a brush

For making track – we suggest that a flux paste applied with a syringe OR a cocktail stick is best for bullhead rail (Goes only where you put it) however for flat-bottom rail use a liquid flux as it’ll flow under the rail and pull solder into the joint beautifully.

For Whitemetal – a generous amount to really wet the area

For Aluminium – be generous here too – the joint MUST be complete on alloys before the flux is burned off.

When to TIN the items to be joined:

For most construction work in Brass and Nickel silver tinning isn’t necessary as long as we are talking about a simple seam or spot joint. It only needs to be clean and well fluxed. TIN on kit assembly where speed is important as where there are other adjacent parts that may become unsoldered if heat is applied too long, where there is a fine bead to be sweated to the edge of a sheet, where two parts are to be “laminated” as in inner and outer halves of a coupling rod or perhaps where an overlay has to be allied to a tender side. It is also sometimes VERY helpful to pre-tin tiny parts such as lamp Irons – Then, if the footplate is tinned as well, all that is required is a little flux and a quick application of the Iron and the job is done!

ALSO Pre-TIN:

* All rail joints at the rail, and the wires before soldering to the rail.

* Any Steel, brass or Nickel Silver if whitemetal solder is to be used (Low Temp solder will stick really well to solder, but it will NOT stick to Steel, brass or whitemetal.

* Any item that will be damaged by excess heat. Its better to pre-tin copper pads on PCB’s, to pre-tin the pads on surface mount LED’s and anything near to something else that will melt of too much heat is applied to the joint area – like RAIL when soldering droppers.

When soldering the two pre-tinned items together, add flux again, and the final joint will be made in a VERY short time. As a guide, we estimate that a standard dropper should take no more than ½ second to solder.

Don’t linger longer than necessary with the Iron.

With Brass and NS sheet or larger items you DO need to make sure the joint flows well but this will be quite obvious from the actions of the flux and solder itself. Once it has flowed remove the Iron, examine, and if needed re-flux and re-heat any area needing improvement. A good joint is a quick joint… too much time and too much solder will both make for a bad result – and can damage parts too... If it takes longer, or if there is a lot of solder on your joints, you need to practice to get that right

(or perhaps we need to discuss and refine your techniques—feel free to email or call use if you would like some “one on one” advice or help)

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Part 2B

STEP BY STEP

preparing parts & soldering metal kits

Building a brass locomotive kit is often made to seem hard by those who do it, and in fact a badly designed or less than perfectly etched kit can certainly try the patience of even the best builder of models...

However, it isn’t often like that, and you CAN have an easy and pleasant task ahead if you follow these tips:

GENERAL TIPS

Choose a brand of kit that has a good reputation. If you need advice on this, feel free to email us and we can point you in the right direction.

* Read the instructions carefully and simultaneously examine the parts, so you can relate “words and kit-bits” & mentally strategise & practice the assembly sequence

* Have a clean and well lit work area with plenty of room to lay out parts

* Follow instructions carefully and prepare parts / pre-test fit before you even turn the soldering iron on.

* This includes a thorough cleaning of the part immediately before the Iron is picked up – you can NOT clean the items hours before as oxides & atmospheric contamination happen fast and they WILL affect soldering quality.

* Take it one step at a time. Double check each step before and after for neatness and accuracy of placement.

* Take frequent breaks from assembly. Have a cup of tea or coffee and a break, then re-examine the work so far before recommencing – it’s surprising how errors that you would miss during a long work session simply will leap out at you as you come back to the bench after a break.

* Be honest with yourself - is it right or not—is it as good as it could be!

Don’t be afraid to unsolder a joint, clean the parts and re-do the job. Perfection pays off, and being fussy at each step is MUCH easier than trying to correct errors or remove excess solder at the end of the job.

* Keep the whole job clean. Each time you take a longish break from it, make the last task that session a gentle scrubbing with “Jif” and an old toothbrush. It’s surprising how much more pleasurable it is working on a clean sub-assembly.

STEP AT A TIME PROCESS:

Carefully examine both the instructions and the fret, and pre-identify the parts. This is important as:

(a) sometimes an “identifiable” part is created from two parts that may be of uncertain purpose and

(b) (b) there may be similar but not identical parts for other areas of the model and confusing these may lead to an error not obvious until it’s too late.

Cut the parts ONLY for the current work session from the kit. We recommend DCCconcepts shears or DCCconcepts Sprue cutters for this purpose – they are by far the BEST, CEANEST and most DISTORTION FREE way to cleanly cut brass or NS parts from an etched fret bar none! To look or buy, please CLICK HERE

Clean up the “CUSP” for the edge of the parts. This cusp is created on the edge of EVERY etched part by the acid etch process. Use a sharp fine-cut file OR appx 500 grit wet and dry mounted on a balsa, styrene or shim brass strip.

By cleaning off this “cusp” a neater edge will result, and finely tolerance parts will fit better.

Clean the surfaces to be soldered.

I use a fiberglass brush OR for large areas some 600~1200 grit wet and dry paper. Cleaning time is also good “thinking” time, to plan the assembly sequence that comes next.

Turn on the Iron and check that the tip is clean and well tinned.

Flux the surfaces of the parts and TIN areas to be soldered if necessary. CARRS 188 or DCCconcepts 179 are the best tinning solders.

“Less is more” here—add too little rather than too much. A very fine tinning is all that’s needed. – run out any excess with the Iron OR remove with solder wick if there is too much applied.

Hold the pre-fluxed parts together and re-flux.

Put a small amount of solder on a clean Iron tip and apply if possible to the Back of the joint. Run the Iron along the joint as the solder melts (it will be obvious). Do this in a steady process and remove the Iron as you get to the end of the seam.

Do NOT allow the joint to move for several seconds – I routinely countdown 5 seconds for every joint… this is long enough for all solders we recommend to harden after removal of heat.

LOOK over the joint. 99% will be perfect. For the odd 1%:

Re-heat and adjust angle or positioning

Or….Add more solder and re-flow (don’t forget the flux)

Or….Remove excess with the solder wick dipped in flux.

Relax repeat instruction above for the next part….and the next….

SMILE – It will be easier than you dared hope, and you are doing something special that very few modellers will EVER achieve. You are developing a new skill and with it will come a level of pleasure & pride in the hobby that far too few people really ever manage, simply because they didn’t try….

Best of all, you can now have the added pleasure of being able to create something special, truly unique, truly yours!

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Do you still have questions about soldering? No problem – just click here to email us and ask, we’ll be happy to help!

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