Very basic question about soldering problems.....

[Zerogee]

To all those of you who are experts with a soldering iron, please bear with me a moment.... my soldering skills and experience are very limited, I can usually manage to get a half-decent joint (if not often a pretty one), but I've often had an annoyingly random problem that there must be a VERY simple answer to: sometimes the iron tins up beautifully with just the slightest touch to the solder wire, but other times (within the same work session) the solder is repelled from the iron tip - it melts, but just "retreats" to form a round blob on the end of the solder wire, rather than melting onto the iron tip as it should do..... what is happening here? Does the tip of the iron need cleaning, and if so with what? I've tried wiping it on the cleaning sponge of the iron stand, but that doesn't seem to clear the problem.....
A brief Google of "common soldering problems" brought up masses of info but I haven't yet found a specific answer, so I wondered if anyone here could save me a lot of wading through pages of stuff online....?

Thanks!
Jon.

 

[Zerogee]

Thanks for the "like", Keith - do I take it that you've encountered the same problem, and would also like to know the answer?

Jon.

 

[idlemarvel]

I have the same problem but I don't have an answer. As you say it seems random. I tin the tip when it's new and I wipe the tip every time but at some point it just stops working as you describe and I can't see a pattern to the behaviour. Very frustrating.

 

[G-force1]

Usually it is an indication that the tip needs cleaning. If the iron isn't thermo controlled it can over-heat and the flux and other stuff burns on. Usually a wipe on the damp sponge will clear it but if not then it needs to be scraped a bit harder. You can use a fine file though of course that is reducing the tip. Even scratching it with the edge of a model knife will do it, but make sure that you tin it straight away.

It comes down to the old saying "Cleanliness is next to Godliness" it applies with all parts of soldering, the metal to be soldered, and the iron.

 

[mike]

I can only say how I do mine. I turn the iron on low. Let it get got. Ie the old dirty soidler turns bright..and I use a old craft knife to scrape the old soidler off.. I freshly tin the iron after I have cleaned it.. cleaning everything you intend to soidler.. old wire ends need trimming back or cleaning..

 

[Zerogee]

Thanks for the answers, G-force and Mike - I did find several comments online warning about NOT using anything abrasive when cleaning the iron tip, but if the sponge is just not getting it all off then I guess it's worth a try anyway!
So I may well be running the iron too hot in the first place?

Jon.

 

[G-force1]

It depends HOW abrasive. Scraping with a model knife is hardly heavy. Unfortunately Scotch-brite pads which would seem ideal, are plastic and melt.

The better you get the more confident, the more confident, the better you get.

 

[mike]

Possibly.. over heating will not help at all...you burn away the flux in the soidler. And makes it impossible to make a joint..a iron can get too hot when doing lots of soldering..

 

[Zerogee]

With a typical standard lead-free solder, what temperature range should the iron be running at?
I do have a temp-controlled iron, but not a digital one - it has a simple turn knob marked in coloured zones, labelled at 300, 350 and 450 C.

Jon.

 

[G-force1]

That's a tricky one. It depends very much on the combination of metals in the solder, this will affect the grade. Plumber's solder melts a lot lower than electrical solder, and stays molten over a wider range, to allow wiped joints etc. Lead free isn't as easy to use as the old stuff, but the E.U. decreed that we mustn't use lead, likewise they decreed we mustn't have Cadmium in Silver Solder and that's a right pain to use now.

Try setting the iron as low as will allow you to melt the solder, the problem may occur when it then doesn't provide enough heat to heat the job as well.

 

[Zerogee]

In this case, Rapid's standard lead-free, which is 99.3% tin, 0.7% copper.... they quote its melting point as 227 C, but I don't know what that translates to in terms of recommended working temp....?

Jon.

 

[PhilP]

Right..
1. sponge needs to be damp.. Wipe iron tip, quickly, 2-3 times. Turn iron slightly between each wipe. - Idea is to get a clean tip all round.
2. Immediately apply some cored solder, to tin the iron..

Personally, I find the cheap 'coppery/brassy' metal curly scourer from a 'pound shop' a LOT better for cleaning the iron.
NOTE: Many iron tips are plated.. If you file the end, you cut through the plating.. The iron tip will then burn-away more quickly, and you get a ragged edge to solder with.

For normal 'train electronics' I use my soldering iron set to 400C. - But I get in and out quickly! - Three seconds maximum.. If you have not got a joint in that time, then pause to see what is wrong. let the work (if electronics) cool before attacking it again. - Normally with a freshly tinned iron, as most problems a dirt / oxidation of one or more of the surfaces..

Hope that helps?

PhilP.

 

[James Day]

Guys,

Many years ago I bought a tin of Soldering Iron Tip Cleaner from Squires the tool people.

Similar things can be found in eBay today.

When the tip gets dirty as you described, you just rub it on the surface of the contents of the tin, which is a hard grey dry paste.

As if by magic your tip is born again!

Given how long ago I bought it, and how much had been used, I think I need to mention the passing on of this wonderful little tin in my will!

My Dad taught me to solder - he was trained to use those massive copper irons that you heat up in a fire or on a blow lamp. He swore by flux and gave me two little tins of flux paste that I still use.

I realise that even mentioning this is likely to get me chucked off the group, but I don't tend to suffer from dry joints if I use flux first - Yes I know this is multi core heresy!

James

 

[Zerogee]

Thanks Phil and James - especially for the advice about the tin of tip cleaner.....

I think another pop in to Rapid on the way back from the Post Office today is called for!

Jon.

 

[G-force1]

There's little wrong with that James as long as it's a non-corrosive flux when used for electrical stuff. Personally, you cant really beat a bit of Baker's Fluid for all the rest.

 

[Zerogee]

........ I don't tend to suffer from dry joints if I use flux first......

Isn't this a medical problem rather than a soldering one....?

Jon.

 

[G-force1]

I'm always in a state of flux!

 

[dutchelm]

Despite warnings of non abraisive cleaners there comes a time when you need to be drastic. Get a file & reprofile the tip, get it back to bare metal, cover it in flux, switch it on & apply new solder when hot.

 

[Zerogee]

Thanks to all, chaps - as several folks seem to have had the same troubles that I have had, I'm glad I stuck my head over the parapet and asked the question, I hope the answers will be as useful to others as they have been to me!

Jon.

 

[James Day]

Despite warnings of non abraisive cleaners there comes a time when you need to be drastic. Get a file & reprofile the tip, get it back to bare metal, cover it in flux, switch it on & apply new solder when hot.

Completely agree either the tip or the 'pad' part of the tip will erode hollow with use. I have done this a number of times.

Ultimately after several re-profilings, there is nothing else for it - put your hand in your pocket and buy a new bit!