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General Category => N Gauge Tutorials => Topic started by: Ricky B on September 30, 2018, 04:11:11 PM

Title: Soldering advice
Post by: Ricky B on September 30, 2018, 04:11:11 PM
I didn't intend my first post to be a cry for help! (Hello all- superb forum.) Just joined a short while back. But today, having organised a Sunday afternoon to myself to try, as a beginner, to cross the bridge (a bridge I've been sizing up for months!) that is soldering wires to Seep PM1 motors as part of wiring my electrofrog points and laying my track. As well as being a soldering novice it's the first time I've done any point motors and certainly first time I've tried to wire them with polarity switching..

I've have a few semi successful practice sessions but today, I cannot for any money, get past first base, to manage to tin the iron tip! The solder will not flow onto the tip at all, instead, it balls up and falls away. As Eric and Ernie used to say, "This didn't happen in rehearsals".

My iron was bought new from Gaugemaster (45W) and I've only used it for practicing. Have I not maintained the tip? The salesman at Arundel (Engine Shed) recommended non Flux soldering and sold me the correct solder. Can anyone advise and try to help rescue my Sunday? Much obliged guys.
Title: Re: Soldering advice
Post by: Philipp on September 30, 2018, 04:58:36 PM
The only time it happened to me was when the iron was too hot, I just turned the temp down and it was fine. No knowledge of the iron you have so don't know if you can contol the temperature, but that was my solution anyway.
Title: Re: Soldering advice
Post by: Stevie DC on September 30, 2018, 05:00:31 PM
It sounds like your tip isn't clean. I use a metal scourer to clean my soldering iron's tip, using a stabbing motion, but have also found that Loctite's Soldering Tinner/Cleaner is really good and use this when the tip won't become clean just using the scourer. The tip should be shiny when hot and if it is dull or is dark, it isn't clean and will form a barrier that will prevent the solder clinging to the tip.
Title: Re: Soldering advice
Post by: Ricky B on September 30, 2018, 05:14:34 PM
The iron is temperature adjustable and maybe it's a temperature thing but I tried turning it down a bit without cracking it.
The chap who demonstrated it and sold it me at Arundel had the temp dial at about "2o'clock" so that's where I try to stick.
The tip maybe has becom oxidised but to my untrained eye, looks like a sharpened pencil nib with the pointy end similar to a pencil's lead.

I've checked the usual online help sources and many mention a dedicated "tip cleaner" substance.
Title: Re: Soldering advice
Post by: Newportnobby on September 30, 2018, 05:27:42 PM
Welcome to the forum, Ricky :wave:
As someone who is crarubbish at soldering (mainly down to shaky hand syndrome) I got a mate to do all my PM1s for me but the symptoms you describe are the same as I suffered when trying to tin droppers. I turned the temperature on my Weller adjustable iron down and it did improve things.
Title: Re: Soldering advice
Post by: themadhippy on September 30, 2018, 05:36:23 PM
get  yer iron to temp.scrape the tip over a damp sponge(or spit on yer jeans and wipe iron tip on wet bit of jeans) , bit of solder on the iron,wipe  over  the  damp sponge/jeans.go solder,wiping the tip after every joint
Title: Re: Soldering advice
Post by: Ricky B on September 30, 2018, 05:38:30 PM
Cheers Nobby!

I'll try to clean the tip (though it doesn't look mucky) and try again on lower temp. Honestly I'm a modeller with more passion and enthusiasm than time so frustratingly, I'll retire from the task today and have to fight again another day.. but when I do 'cross that bridge' and get my track laid with working pointwork and locos crossing them at slow speed without stalling, I'll enjoy the more 'creative' side of layout building and look forward to sharing with the forum.
Title: Re: Soldering advice
Post by: Ricky B on September 30, 2018, 05:41:14 PM
get  yer iron to temp.scrape the tip over a damp sponge(or spit on yer jeans and wipe iron tip on wet bit of jeans) , bit of solder on the iron,wipe  over  the  damp sponge/jeans.go solder,wiping the tip after every joint

Thanks Hippy but the iron has a sponge pad (which I wet) and have always wiped the tip during use. For some reason the warmed iron (perhaps too warm as some have opined) was just eliminating the solder which fell southwards in silver balls- none would stay to 'tin' the tip.
Title: Re: Soldering advice
Post by: jthjth on September 30, 2018, 06:16:07 PM
You need some multi core solder, ie stuff designed for electronics assembly. Eg https://cpc.farnell.com/multicore-solder/3096122-m/solder-60-40-hi-act-1-2mm-250g/dp/SD00961?st=solder

Muticore means it has the flux embedded into the solder wire. The flux in this type of solder is non corrosive, so you donít need to do anything to remove it after soldering the joint.

Set the iron temperature control to something reasonably high. With the iron cold, plug it in and hold the solder wire on the bit. Once the bit gets to the melting point of the solder feed plenty of solder onto the bit as fast as it will take it. What this process does is to put an excess of flux onto your new bit. You should get a lot of smoke from the burning flux - try not to inhale!

Once youíve got an excess of solder on the bit wipe it on a damp sponge. With luck you will now have a tinned bit.

The solder Iíve referenced is tin/lead. Contrary to popular myth, leaded solder is still freely available. What you canít use it for is for products destined to the commercial market. It is still used in military and aerospace markets, and produces more reliable joints. Itís also much more forgiving for the amateur user. In terms of health and safety, unless you intend to eat it, by far the biggest risk is from the flux fumes rather than the lead content.

If you donít manage to tin the bit on the first attempt try again.

The solder going into balls as you describe is due to it not finding a clean surface to ďadhereĒ to. The flux reacts with oxide layers and burns them off, leaving a clean metallic surface for the solder to bind to.

As a novice, my first advice is to get hold of some stranded hook up wire. Strip an inch of insulation off and twist the strands together. Clamp the wire in something so you donít end up chasing it round the bench. Then with a hot iron hold the bit on the exposed twisted wire. After a few seconds feed in the solder at the interface between the bit and the wire. The solder should melt and flow onto the strands. A common mistake is to feed the solder onto the bit, rather than the interface. If you do that the flux will burn off before it gets to the wire. You need the flux to clean the wire not the bit. As the hook up wire is cheap, just keep practicing until you get the hang of it. At first you will probably melt the insulation further down the wire. Once you get better, you will be able to quickly tin the exposed end before the rest of the wire gets hot enough to melt the insulation.

For anything electrical you donít want to be using the non flux cored soldiers designed for assembling brass or etched kits.

Hope that helps

Julian Thornhill
Title: Re: Soldering advice
Post by: DCCDave on September 30, 2018, 06:44:27 PM
you donít want to be using the non flux cored soldiers designed for assembling bras

No, one slip with that can be quite painful!
Title: Re: Soldering advice
Post by: Ricky B on September 30, 2018, 07:05:49 PM
Thanks very much Julian for the kind and detailed reply. Yes, I'll practice this more when I've a bit of time. I was under the impression I had multi-core solder i.e., the one with built-in flux. I'll try to get hold of some from the link you included.
To be clear, are you saying that the solder wouldn't adhere to my 'bit' (i.e. the iron's tip) because it was unclean/oxidised or, because I wasn't using multi core flux?
I'm quite sure I'll enjoy soldering when the various pennies drop.
Thanks so far.
Richard.
Title: Re: Soldering advice
Post by: jthjth on September 30, 2018, 07:13:10 PM
I was unsure of the type of solder you were using. A brand new bit will be oxidised and does need tinning. Iíve always found the technique of doing it as the iron heats up to be the most successful. A properly tinned bit will look nice and silvery. As you use the iron you will get a build up of black deposits, ie burnt flux. Simply wipe this off on the damp sponge. Soldering is a bit like learning to ride a bike. It seems impossible to start with, and once you can do it you wonder what all the fuss is about.
Title: Re: Soldering advice
Post by: Mr Sprue on September 30, 2018, 09:26:22 PM
The best way to tin a soldering iron tip is to first clean it up so its shiny with no dark pits before heating ( I use a wire wheel or use a stainless wire brush) next dip the tip in flux then peel off a strand of solder (low melt is the best to use) coil it around the tip covering about a third of the whole tip.

Next turn on the heat but don't have the heat setting too high 10 or so degrees above the melt point of the solder you are using to wrap round the tip should do. Watch over as the iron heats up and the solder begins to melt. When the solder melts on the tip just flick the iron (if your a novice its best directing the excess to fall onto somewhere like a garage concrete floor or somewhere safe (with experience you will be able to aim the stuff onto a 10 pence coin!)

Gently wipe the tip on a damp sponge then its tinned and ready to go.

For what its worth it doesn't matter if its flux cored solder or not, but the temperature of the melt point is the most important if the tip reaches a too high temperature too often then you will be re-tinning on a regular basis! 
Title: Re: Soldering advice
Post by: jthjth on September 30, 2018, 09:45:27 PM
Depending on the iron manufacturer and the construction of the bit, cleaning up the bit with an abrasive can be a bad idea. At work my colleagues professionally hand solder some extremely intricate boards. Iron bits are never cleaned by anything other than a damp sponge. Badly tarnished pcb pads, or solder terminals can be helped by some additional liquid flux. However, Iíve never found the need at home with anything to do with model railways.
Title: Re: Soldering advice
Post by: Malc on September 30, 2018, 10:16:11 PM
As jthjth says, never use abrasive on an iron bit. Copper can be filed. One other thing I never use is a needle point bit, always a small spade bit. There is room for the solder to sit on it. If you are unsure of the type of solder, pull a short length off the reel and burn about 1Ē from the end with a match. If you look at one of the burnt ends you can count the flux cores.
Title: Re: Soldering advice
Post by: Bealman on September 30, 2018, 11:33:19 PM
G'day from Australia, Ricky, and welcome to the NGF!  :thumbsup:

Seems a bit strange to me that this so called expert at Arundel was telling you not to use flux.
Title: Re: Soldering advice
Post by: Lazy-Ferret on September 30, 2018, 11:46:58 PM
Just to add to @jthjth (http://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=1299) excellent reply, when you do get your iron working, get into the habit of only wiping the bit as you take it out of the holder and are about to start to solder, then when you finish soldering the joint, put the iron back into the holder without wiping. This does two things, it helps to stop the flux attacking the iron bit while in the holder, as there is a larger amount of solder still there, and secondly, the act of wiping on the cool sponge as you take it out, cools the bit a small amount, which means that the iron starts re-heating as you start to solder, reducing the temperature allowing the flux just a little bit more time to clean the bit as you start your solder joint.

Never use anything abrasive on a modern soldering iron bit, especially is it is a temperature controlled one, as it will ruin it. What I was taught to do, was to take a sheet of kitchen roll/paper towel, fan fold it up until it is a strip about 1" wide, then fold it length ways a couple of times, until it is very thick, but you can still fold it in half one more time. Put this down on the bench like a pillow, and holding the soldering iron just above it, melt a load of solder onto the bit, using the paper to keep it on the end, then fold the paper round the bit, and rotate the iron a few times, to rub the bit clean in the molten solder. Don't hold it for too long, as it will get hot and burn your fingers. If it is bad, you might have to do this a couple of times.
Title: Re: Soldering advice
Post by: Mr Sprue on October 01, 2018, 07:50:23 AM
Good old Google will provide you some videos if your still uncertain!  ;)
Title: Re: Soldering advice
Post by: Ricky B on October 01, 2018, 03:32:25 PM
G'day from Australia, Ricky, and welcome to the NGF!  :thumbsup:

Seems a bit strange to me that this so called expert at Arundel was telling you not to use flux.
Hello there Bealman! Thanks for the warm welcome. The chap at Arundel was apparently an ex telecomms man to whom soldering as part of his job, had been second nature. He demonstrated the iron and solder in the shop but he was one of the significant minority who say 'don't bother with flux' and I believe sold me a solder that contained flux.

In the practice sessions I've had attaching wire to spare bits of track, I don't seem to have had too much trouble tinning the iron tip but yesterday, when I sat down to make some proper progress, I couldn't get any solder to linger on the iron. I'm going to order some of the solder recommended by JTHJTH and give it a try.
Title: Re: Soldering advice
Post by: Malc on October 01, 2018, 04:29:53 PM
I must admit, the only time I have used flux in the last 40 years of working as an electronics engineer is when I am soldering 15mm water pipe. As long as you clean the work pieces and in the case of track, give it a rub with a file to abrade the surface, Cored solder works fine.
Title: Re: Soldering advice
Post by: Ricky B on October 01, 2018, 04:42:44 PM
Thanks for your angle on it Malc- as I've researched it it does feel like trying to forge on without flux has put me in a tiny minority so good to here your experiences. It'll be a few days before I can do another test but when I do, no doubt I'll be reporting back on here..
Title: Re: Soldering advice
Post by: Yet_Another on October 01, 2018, 11:25:42 PM
Just to chuck in my 2d: turn it off if you're not going to use it for a little while. Leaving it hot and unused does cause the tip to oxidise (which I then found difficult, but not impossible, to tin).
Title: Re: Soldering advice
Post by: Platy767 on October 06, 2018, 01:45:13 PM
jthjth has given you the good advice - use a 60/40 Tin / Lead Rosin cored solder for connecting wires to wires, droppers to track and wires to point motors and other electrical connections. Don't waste your time with Lead Free solders.

When you have it properly tinned and have it working well, I suggest you smother the tip in rosin cored solder before you turn your iron off at the end of a session. I mean, wipe clean, then smother in solder before you turn it off. Let it cool with a covering of solder. When you next power up, let it heat up, wipe clean, touch the tip with solder wire to tin the tip, then tin your wire or track connection, then hold the joint together and apply the iron. Soldering is easy if you have cleanliness and heat transfer.

Mark
Title: Re: Soldering advice
Post by: Ricky B on October 15, 2018, 11:49:20 PM
Hi again all,
An update on my soldering efforts- partly to get a few more guiding pointers to help me further along the road, partly as others might find help in my experiences.

Following JTHJTH's advice,  I sent away for some tin/lead solder with 'rosin core'. The one I bought (via eBay) was actually 63/37 and Chinese made. I now believe I had previously been using "lead free" and maybe rosin free?

In order to try to get my iron tinned I tried a gentle rub-up of the cold tip with a fibre glass pen. I bet some of you have spotted two mistakes already!..

However, with the cleaner tip the solder began to tin the tip rather than sliding off. More like it!

I also found that my iron (40w) had maybe not been hot enough previously.

So tinning iron seemed to be fine, tinning of wires also began to seem fine and Aafter much trial and error, I'd attached sets of droppers to seven lengths of n gauge code 55 Peco flexitrack. But I still:

Had trouble getting to tin the underside of the track.
Had problems with melting sleepers so long was it taking to get the joint to 'fuse'.
Though I achieved some soldered joints, the quality of the solder I question- all joints are matt not glossy and as the solder cools it becomes pasty and lumpen rather than flowing through the joint like model soldering does.

I reckon the Chinese solder might be dodgy and still wonder if I should invest in some flux. Admittedly I bough a cheaper version than JTHJTH said. But steps forward! Thoughts?
Title: Re: Soldering advice
Post by: Malc on October 15, 2018, 11:57:15 PM
To stop the sleepers melting, cut the longitudinal bits under the rail and slide the sleepers away from where you are soldering. The grey nature of the solder is called a dry joint. You need to get the iron hot enough. Rough up the underside of the rail with a fine file, flux might help you here. Place the tinned iron tip onto the rail with the wire trapped between the iron and the rail. Push the solder into the gap where the iron meets the rail until it melts. Do not move the wire once the solder has flowed into place, just lift the iron up. Ideally you need 3 hands.
Title: Re: Soldering advice
Post by: Ricky B on October 16, 2018, 12:27:35 AM
Thanks Malc.
I already had been cutting the the web away allowing the sleeper to slide to and fro so giving a good area to work on. Cleaned area with fibre pen first. When applying (tinned) iron, trapping (tinned) wire against rail underside I didn't hold solder to intersection of joint though relying on tinned surfaces. The solder looks shiny when tinning but rapidly fades to, well, lead colour.
Title: Re: Soldering advice
Post by: jthjth on October 16, 2018, 06:51:52 AM
There are two possible reasons for a dull joint, the dry joint as mentioned, or your tin lead solder is actually lead free solder. An annoying feature of many lead free formulations is that you appear to produce a series of dry joints, which actually arenít. A common cause of dry joints is movement of the joint as the solder solidifies. Admittedly this is hard to achieve with track droppers, but a good rule for soldered wire joints is there ought to be a good mechanical joint before solder is applied. This usually means bending the wire into a hoop, or similar, around the terminal. For your dropper problem Iíd suggest stripping a length of rail out of the plastic sleeper web. You can then practice your technique on the rail without worrying about melting the plastic. A small bottle of flux might be helpful. You need flux intended for electronic assembly, rather than some of the acid fluxes intended for putting brass kits together. Practice really is the key to soldering. Itís a bit like learning to ride a bike. Seems impossible to start with, and once you can do it you wonder what all the fuss is about.

As an aside, Lidl are currently selling 48W digitally controlled temperature adjustable soldering irons for £17. You even get two reels of solder and some spare bits. Iíd have purchased one save for the fact that I already have three soldering irons.
Title: Re: Soldering advice
Post by: Platy767 on October 16, 2018, 09:13:04 AM
The iron tip you use can also contribute to success. I use an old Weller TCP 48W iron (only because that was what I learned to solder with in the early 70s) with a PTAA 7 tip. I also sometimes struggle with melting sleepers, so will be using the suggestion of moving sleepers in the future. I usually solder to the side of the rail after scrubbing with a fibreglass pencil, a wipe with iso and tinning the rail side using a tin/lead rosin cored solder. I tin the dropper and then bring the dropper wire to the rail and flow the joint. If you have a long or pointy tip, it may not have enough heat reserve to properly flow the joint.

I find I don't need to use additional flux, but using some while practicing on a rail offcut is a good idea. As jthjth says, use a flux used in electronic assembly (rosin based applied with a small paint brush or cotton bud), not the phosphoric acid based fluxes for kit building, and definitely not Bakers Fluid!

This is a link to a paste from an Australian shop, but I'm sure you can find a liquid flux or something similar in the UK.
https://www.jaycar.com.au/solder-flux-paste-56g-tub/p/NS3070 (https://www.jaycar.com.au/solder-flux-paste-56g-tub/p/NS3070)

Keep at it, practice, use the right materials and you will do ok.

Mark
Title: Re: Soldering advice
Post by: Ricky B on October 17, 2018, 09:29:54 AM
I'll report back again when I'm next able to have a session with the iron. Unfortunately I'm only able due to work commitments to get a window now and then. But thanks again jthjth, Platy767, Malc and Yet_Another for showing interest- most kind.

In summary, my iron was bought new at and recommended to me by, the Engine Shed Arundel. It's the pointy, pencil shaped tip sort.

Even though I bought a reel of tin/lead solder (supposedly!), a comment by a guy on YouTube next to a soldering video suggested he'd bought some 63/37 ratio Chinese solder and "it was rubbish etc etc".. I think I've acquired the same brand. Maybe due to my Yorkshire thriftiness I 'saved' a few quid in the brand jthjth linked to but ended up with dodgy solder. Maybe.

Yes, having decided to solder droppers to the bottom of my Peco flexible track,  I cut webbing away to slide sleepers hither and thither to make room. But in some cases, I'd obviously had iron in contact so long I'd distorted some sleepers. Not to worry, I am making progress but there are so many slight variables which, until I suddenly "pedal that bike without stabilisers", make it hard to know the actual reason for teething troubles.

At the end of the day, I did attach droppers to six or seven lengths of track- but as noted, I don't 'fancy' the look of the joints though they feel strong enough.
Title: Re: Soldering advice
Post by: Old Crow on November 13, 2018, 11:01:28 PM
I had the same problem with new bits not tinning. Flux is the answer; you can buy it little tins. Sure there is supposed to be flux in the multicores but coating the whole bit in flux and then tinning it works for me. Also I never use lead-free solder, horrible stuff that doesn;t run. Lead/Tin for me.  For all joints to rails etc, I clean the area and then put on a drop of fllux and the solder flows nicely even when the rail might be dissipating some of the heat.
Title: Re: Soldering advice
Post by: Ricky B on November 18, 2018, 02:15:30 PM
Cheers for that Old Crow.. that sounds to make sense and contributing to the body of opinion that says even though my practice sessions using multi core tin/lead solder have been partially successful, it would do no harm to get some flux. Talking of which, I'm still not certain where to buy it (other than online sources).
I failed to get any after a visit to Tolworth Showtrain. Is liquid flux normally carried by the Wickeses and B&Qs of the world or is it an electronics shop I need?

 
Title: Re: Soldering advice
Post by: jthjth on November 18, 2018, 02:20:12 PM
Flux from the DIY sheds is likely to be for plumbing purposes, and is likely to be corrosive. There are quite a lot of suppliers on Amazon for not much money. If it states rosin it should be fine.
Title: Re: Soldering advice
Post by: Ricky B on November 18, 2018, 03:17:37 PM
Thanks for that jthjth. Avoiding the corrosive variety seems key. Are fluxes  usually pastes or is there a genuinely liquid one- and any advantage either way?
Title: Re: Soldering advice
Post by: jthjth on November 18, 2018, 03:26:59 PM
I doubt really matters, paste or liquid. Either way, you need very little of it - flux is just a surface treatment. Try not to inhale the fumes.
Title: Re: Soldering advice
Post by: Ricky B on November 18, 2018, 04:15:07 PM
Many thanks jth.
Title: Re: Soldering advice
Post by: ntpntpntp on November 18, 2018, 04:32:30 PM
Generally I use Fry Powerflow paste which is actually for lead-free, though I avoid lead-free solder as it's not friendly to use.   I have a small 50g pot which has lasted for several years. It seems difficult to find the 50g pots at the moment, but the 100g pots are readily available.

I also have a flux pen which dispenses liquid flux and can by handy for pcb work.
Title: Re: Soldering advice
Post by: Papyrus on November 18, 2018, 04:51:40 PM
I've just read this from beginning to end and found it extremely useful - I've certainly learned a few things where I have been going wrong. Mods - may I suggest this is moved into Tutorials? It deserves to be easily available.

Cheers,

Chris
Title: Re: Soldering advice
Post by: daveg on December 12, 2018, 06:12:13 PM
I was recommended Bakers No 3 flux by @Malc (https://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=497) of this parish and it has been a real godsend.

Not cheap but it will last forever - unless you knock the bottle over  :-[

Dave G
Title: Re: Soldering advice
Post by: jthjth on December 12, 2018, 06:36:55 PM
Bakers no 3 flux is corrosive. It has to be cleaned off after the joint has been made. It has its specialised uses, but for electronics/electrical connections use a rosin based flux. There is plenty of choice on the likes of Amazon for little money.

Regards

Julian Thornhill
Title: Re: Soldering advice
Post by: JanW on December 12, 2018, 08:14:15 PM
Flux for soldering droppers to track?
No need for that IMHO.
I have soldered lots of dropper wire to track and have never used flux for that.
There is one important thing that has not been mentioned here: don't heat the solder too long, especially when tinning. The rosin flux burns when it is heated and if it is gone the solder won't flow well.
Here is what I do:
- Clean the bottom of the rail with a small file or scrape it wit the tip of a sharp screwdriver
- Apply the iron and the solder at the same time and immediately remove the iron as soon as the solder flows. Try to leave a shining rather thick spot of solder.
- strip the wire, twist the end together and tin it exactly the same as the rail foot. Tin it relatively thick and shining.
- put the tinned parts together and touch it with the iron. Since there will be rosin flux left it will flow nicely. Immediately remove the iron. No melting of sleepers...

If you don't get a nice joint, start again and make sure you have 'fresh' solder with some rosin flux in it on both parts.
I find that if the joint is not good I usually didn't use enough solder.

During my years of professional pcb repairs (I don't want to know how many I repaired...) I have learnt that the optimal temperature for a long life bit is approx. 350 degrees.
Hot enough to apply enough heat but not too hot to burn the bit.
We had our Wellers on for eight hours a day.

And it is very well possible that your solder doesn't work well.
At work I recently threw away a new reel of solder because it was impossible to produce a neat joint with it.

Good luck and keep trying.
It is not difficult at all but you need some practice to get the hang of it.

Jan
Title: Re: Soldering advice
Post by: themadhippy on December 12, 2018, 09:27:03 PM
Quote
Flux for soldering droppers to track?
No need for that IMHO.
I have soldered lots of dropper wire to track and have never used flux for that.
so you use a raw mix of tin and lead? how do you get over the oxidisation?
Title: Re: Soldering advice
Post by: JanW on December 12, 2018, 09:52:39 PM
 :D
Title: Re: Soldering advice
Post by: daveg on December 12, 2018, 10:10:23 PM
Bakers no 3 flux is corrosive. It has to be cleaned off after the joint has been made. It has its specialised uses, but for electronics/electrical connections use a rosin based flux. There is plenty of choice on the likes of Amazon for little money.

Regards

Julian Thornhill

Interesting Julian. What are these specialised uses?

I shall keep an eye on the dozen or so switches where I used the flux for problems.

Dave G
Title: Re: Soldering advice
Post by: jthjth on December 12, 2018, 10:50:38 PM
Iím no expert on soldering outside of the electronics industry, so I canít give any accurate advice on why corrosive fluxes are used. From observation it seems to be for things like plumbing or perhaps brass model construction where you have very large areas of corroded surface that needs to be soldered. In the electronics world rosin flux is king, though there are moves towards other exotic substances because inhaling large amounts of rosin fumes is ďa bad thingĒ. We have to have fume extraction installed where large amounts of hand soldering is done. For occasional hobby use itís not an issue. (Apparently you can become suddenly sensitised to it, and can then never go near flux fumes again.)

Anyway, for your average electronics joint, rosin cored tin lead solder is what you want. Rarely have I had the need to add extra flux. Perhaps for a heavily corroded joint, but there you are often better cleaning it up with a fine abrasive first.

If you notice a joint, over time, going grey, white or green then you generally have a corrosion problem.

Where I work we hand solder thousands of joints per year, on pcbs, on connectors, large and small (done under a microscope) and the whole outfit has one tiny bottle of flux that has been in use for the last 5 years or so and is still half full. So itís not needed very often.

As another poster has pointed out, you need to feed the solder into the joint, not into the iron bit and then the joint. If you do that, the flux gets burnt off before it gets anywhere near the surface it needs to treat. Place the bit on the joint, and then feed the solder into the interface between the bit and the joint. The first little bit of solder that melts helps to make a good thermal contact and gets heat from the bit into the joint. So I generally feed a tiny bit of solder in, pause momentarily whilst the joint heats up properly and then feed in more solder to make the joint.

Regards

Julian Thornhill
Title: Re: Soldering advice
Post by: Ricky B on January 18, 2019, 05:22:20 PM
I'm just approaching the soldering subject again (having begun this thread a while back) and was about to buy some rosin flux - though those who don't believe in the need for flux make their case very well.

If I was to buy some, which to buy? A glance around eBay shows many (rosin based fluxes)  which are pastes. Any opinions (amongst those who think using rosin content flux when I'm already supposedly using rosin core solder) which? A recurring brand is 'Kalfonia resin based NO CLEAN' in a flat can like a shoe polish container.
The word TERMOPASTY is also there but that sounds like a warning on a Cornish savoury snack that it might burn your mouth...

What resonated with me was an earlier comment (sorry can't just say just here who it was) that the solder "can be in contact with the iron too early" and "the flux can then burn off before the joining is done". That feels like a mini Eureka moment and tomorrow we test solder again with this in mind!
Title: Re: Soldering advice
Post by: jthjth on January 18, 2019, 05:57:42 PM
Try this
https://www.amazon.co.uk/WEL-LF25-rosin-based-F-SW21-WELLER/dp/B01MQ1MS8R/ref=sr_1_6 (https://www.amazon.co.uk/WEL-LF25-rosin-based-F-SW21-WELLER/dp/B01MQ1MS8R/ref=sr_1_6)

Iíve no direct experience of this particular product, but Weller are one of the leading producers of professional soldering equipment for the electronics industry. Itís cheap enough, and although itís only 20g it ought to last you a lifetime.
Title: Re: Soldering advice
Post by: Ricky B on January 18, 2019, 06:15:50 PM
Thanks jthjth. And of course it was your reference to the technique of not overheating the solder prior to joining that I noticed- and you were too modest to highlight that! Thanks so much for taking time to impart your wisdom thus far👍
Title: Re: Soldering advice
Post by: jthjth on January 18, 2019, 06:29:34 PM
Soldering is like learning to ride a bike, impossible to start with and then trivially easy once you get the hang of it. Iíd strongly suggest getting hold,of some stranded copper hook up wire. Strip off half an inch or so of insulation and trust the strands to stop them fraying. Then practice tinning the exposed strands. By tinning I mean putting enough solder on such that you canít see the individual strands anymore. Keep doing this until you can quickly tin the exposed wire without significantly damaging the insulation further up the wire. Much better to practice on some cheap wire before you attack your track. Also worth practicing on some scrap track as lesson two.
Title: Re: Soldering advice
Post by: ntpntpntp on January 18, 2019, 07:15:04 PM
I use Fry Powerflow flux these days.  The small jar will last for years with the tiny amount you need to use - when you need it (which I agree isn't always, if you're using cored solder).  I don't use it for wiring joints, but I do use it for things like soldering rail to screws at board joints etc.

It's sold as suitable for lead-free solder, though I avoid that stuff!

(https://images-na.ssl-images-amazon.com/images/I/4103VACC6ML._SX425_.jpg)

https://www.amazon.co.uk/Frys-Metals-Powerflow-Flux-Small/dp/B0001P07MA/ref=sr_1_7?ie=UTF8&qid=1547838590&sr=8-7&keywords=fry+powerflow+flux (https://www.amazon.co.uk/Frys-Metals-Powerflow-Flux-Small/dp/B0001P07MA/ref=sr_1_7?ie=UTF8&qid=1547838590&sr=8-7&keywords=fry+powerflow+flux)
Title: Re: Soldering advice
Post by: Platy767 on January 18, 2019, 10:52:54 PM
Hi Ricky B.

Have a look at the first 15 seconds of this video tutorial.
www.youtube.com/watch?v=Zu3TYBs65FM (http://www.youtube.com/watch?v=Zu3TYBs65FM)

The chap heats the joint and feeds the solder wire into the joint. I use a different profile soldering iron and tip and have it tinned with solder, but the solder wire feed is the same. This is a big joint of twisted wires, so when you solder droppers to your track, tin the dropper (I actually use a single strand tinned copper wire) (not much heat or solder required), use a brass or fibre brush to clean the track, then tin the track (a bit of thermal mass required in the tip, but not too long or the sleepers will melt!). After each part is tinned bring them into contact and apply the tinned iron tip. You may not even need any additional solder wire as the nice clean parts may solder without additional, but if it is required, feed the solder wire straight into the joint. A good joint is always shiny.

In N gauge, clean tinned copper wire and clean tinned nickel silver track solder very well with only the rosin flux in a rosin cored solder wire. The extra external rosin flux should only be required in larger, dirty joints or very application specific situations like hand soldering multi leg surface mount components.

Mark
Title: Re: Soldering advice
Post by: Old Crow on January 19, 2019, 12:27:37 AM
Hi Ricky. I've used a few of those paste fluxes and in my opinion flux is very necessary when you are soldering to something like a rail that will absorb a lot of heat. I've also built old-style valve guitar amplifiers and flux is essential when soldering to metal parts there. Thing is first to clean the items and to tin the wire; that doesn't need flux, just put the wire in a small vice with the end free and apply resin-cored solder plus the iron and it should deposit some on the end of the wire. Now I have no time for Lead-free solder; it just doeesn't seem to flow well but of course it's a matter of judgement whether you think lead, or lead fumes are present enough to be a health hazard but I always use a 60/40 lead-based resin cored solder.

Clean the rail, even very fine sanding and apply flux paste to the area to be joined. You can try applying a little solder to the rail too - tinning it. Then comes the part where you need five hands because you have to hold the parts in position whilst applying the solder and the iron. I'll use all sorts of aids to hold parts in position from masking tape to crocodile clips on flexible wire.If you get it right, the solder should flow and make a clean joint. I even solder rails together sometimes. If making a long long curve with flex-track, the only way to get fair curve including a join is to solder the sections first.
Title: Re: Soldering advice
Post by: Ricky B on January 19, 2019, 01:19:57 PM
Hi Ricky B.

Have a look at the first 15 seconds of this video tutorial.
[url=http://www.youtube.com/watch?v=Zu3TYBs65FM]www.youtube.com/watch?v=Zu3TYBs65FM[/url] ([url]http://www.youtube.com/watch?v=Zu3TYBs65FM[/url])

The chap heats the joint and feeds the solder wire into the joint. I use a different profile soldering iron and tip and have it tinned with solder, but the solder wire feed is the same. This is a big joint of twisted wires, so when you solder droppers to your track, tin the dropper (I actually use a single strand tinned copper wire) (not much heat or solder required), use a brass or fibre brush to clean the track, then tin the track (a bit of thermal mass required in the tip, but not too long or the sleepers will melt!). After each part is tinned bring them into contact and apply the tinned iron tip. You may not even need any additional solder wire as the nice clean parts may solder without additional, but if it is required, feed the solder wire straight into the joint. A good joint is always shiny.

In N gauge, clean tinned copper wire and clean tinned nickel silver track solder very well with only the rosin flux in a rosin cored solder wire. The extra external rosin flux should only be required in larger, dirty joints or very application specific situations like hand soldering multi leg surface mount components.

Mark



Hi Mark,

I watched the video- it happens a bit quickly.. what are his wires attached to? Is that metallic thing his soldering iron?
I'm actually sat here at kitchen table with hot iron, Rosin core solder wire etc and some track lengths to have another practise.
I'm starting to understand the theory but the actual timing of each action is still trial and error. What Jthjth has said above, heat the joint then feed the solder wire into it otherwise the flux within will burn off. A case of timing. So the question arises, if I tin the soldering iron tip, doesn't the heat of an iron that remains hot, burn away all the flux core before it has chance to do its job, i.e., before I try introducing it to the junction of tinned dropper and underside of rail?
Many thanks for your comments.
Title: Re: Soldering advice
Post by: Malc on January 19, 2019, 02:16:06 PM
The tinning of the iron is to get better contact with the thing you are soldering. If you have tinned both parts, the flux has done itís job. Itís function is to make the surface suitable for soldering. Then when you bring the parts together, you donít need the flux.
Title: Re: Soldering advice
Post by: Ricky B on January 19, 2019, 02:55:50 PM
Hi Malc,
I've been stripping the wire back and tinning it ok- am sat here at it as we speak. I've been tinning the underside of the rail and before introducing the wire to rail, adding a bit of extra solder to the iron tip. Note, I've held off using my mythical fourth hand to hold extra solder in the intersection of the joint- even with a 'helping hand' with its crocodile clips I've not worked out a method of applying a hot iron to the wire trapped against the track underside AS WELL
 AS offering solder into the joint! But my so called joints today have again been rubbish. Sometimes I hold the iron a bit too long on the joint so the wire, unattached itself after maybe being attached properly. The joints I have made that have held are hideously lumpy and bulbous - you would laugh!
When the joint doesn't 'take' my method is to add more solder (from the tinned iron) but the process is maybe too long with any flux burning off.
I keep watching examples of other modellers' work on YouTube and the pleasing hiss of flowing solder as they hold the iron against wire and rail is frustratingly elusive still😕. I do believe my iron is hot enough by the way. And I have ordered some rosin flux paste though with rosin core solder, can well see why other experienced solderman like yourself and jthjth say 'shouldn't be necessary'. But I shall persevere!

Title: Re: Soldering advice
Post by: Malc on January 19, 2019, 05:34:14 PM
Hi Ricky,
All I can say is you shouldnít need to add much solder if your tinning is up to spec. I hold the track in a small vice to give me a hand to hold the wire and one to hold the iron. Place the wire on top of the solder on the track and using an iron with a small spade bit, press it onto the joint. Hold it onto the joint until the solder melts and then lift the iron off. I use a temperature controlled iron set at 400deg. The only way to solder successfully is to practice lots. A good joint should be silvery and smooth. Get a spare bit of rail, settle down and keep on at it.
If you feel the need for flux, go for it. However, flux is acidic and should be washed off after you fix the joint.
Title: Re: Soldering advice
Post by: Ricky B on February 25, 2019, 10:28:06 PM
Just a quick update in view of the excellent advice I've had from you lads.
My moments to practice soldering are spasmodic but- now armed with some flux paste - a good couple of sessions in last few days have moved me on to the stage where I'm fairly confidently attaching wires to the side of n gauge code 55 rail. On spare rail used for practice that is.. I'm almost at the point when I'm going for a 'take' and attaching droppers to the actual rails to be used in my layout. :claphappy:

As a slight diversion from my actual technique, I've gone away from soldering to the underside of the rail which involves too much displacement of sleepers for my liking, in favour of soldering to the side of the rail. There's less 'to aim at' but less beggaring about cutting/moving/ replacing sleepers.

My method as such that has evolved is:

(By the way, I believe I am using rosin core solder by the way but have chosen to try flux as well.)

Clean/burnish area of rail where dropper is to be attached with fibre pen.
Apply flux to this area on rail side.

Strip about 10-15mm of insulation off the dropper wire to expose its multi strand wire. Twist the end together, apply a smear of flux then tin it using solder from tip of iron.

Wipe iron tip on wet pad then apply more solder to iron tip.

With length of rail held in crocodile clip of 'helping hand", hold tinned wire end against prepared area of rail and then apply tip of iron. If I've held wire in right spot and have decent amount of solder on both wire and iron's tip, a pleasing hiss of burning flux occurs. Then one of two outcomes ensue: I remember not to hold iron in place too long, remove it and a fairly solid connection between wire and rail is the result; or, the the solder doesn't flow (probably too little solder/inadequate tinning) and the wire fails to attach.

In conclusion, I'm getting the hand of it BUT! .. none of my joints retain that professional 'mercury gloss'. Instead, as they are flat and dull like lead.

But I'm getting closer and won't be long before power can flow through the lines of 'Wheldon Bywater' (my project has a name!) and I have no further excuse for not doing scenics, building etc..