Which soldering iron?

Discussion in 'Open Forum' started by MG, Jan 10, 2020.

  1. MG

    MG United Kingdom Subscriber

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    I'm thinking of buying a soldering iron kit but i'm just wondering how powerful it needs to be? among other jobs that may turn up i've got a few lamps with old solder repairs that could do with tidying up a little and rather than use a blow torch i would like to have a go using said soldering iron,
    Thanks.
     
  2. phaedrus42

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    You will likely not have good results with a soldering iron alone. A gas flame with good adjustment is a must-have for sheet metal work.
    I use a torch to pre-heat the metal and a plumbers copper iron to guide the flow of the solder.
     
  3. MG

    MG United Kingdom Subscriber

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    Thanks Phil, although i haven't used them properly yet as i haven't built up the confidence/made the time, i do have a half decent blow torch and a chefs style blow torch, i just wanted something powerful enough to tidy/smooth the surface of a couple of rough repairs that could do with flattening etc, is 60w hot enough or would i need 100w and over do you think?
     
  4. phaedrus42

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    A temperature of 250-300 (350?) degrees Celsius is good for lead soldering but most electric soldering irons have a smallish tip and therefore not enough heat mass to sustain temperature when transferring heat to the job. That's why gas works so well. Even a small gas torch puts out more watts of heat than a multi-hundred watt electric soldering iron.
    A good compromise is to use a gas torch in conjunction with a very heavy tip electric iron. or a copper non-electric plumber's iron.
    Bright, clean, grease free metal is essential for a good solder joint.
    Use a good rosin flux paste to get the solder to wet the metal and keep the solder shiny and get it to flow where it is needed. Try not to burn it off with the flame ;)
    After the job is pre-heated, play the flame mostly on the iron to keep it hot.
    Solder follows heat so will flow to the hottest area.
    Solder is not like glue or epoxy. A little goes a long way. Wipe off excess with a natural bristle brush or damp rag.
    Mask off area around the intended joint with a felt tipped permanent marker to stop the solder wetting / sticking in that area.
    The solder on the completed joint should have a smooth, even, concave appearance. Convex or blobby means you have too much solder there. It does not make it stronger.
    After completion and when there is no flame anywhere in the vicinity, you can wash away the flux with meths and a toothbrush or with carb cleaner spray.
    If you need to re-do or touch up the joint, make very sure you have cleaned up and removed any alcohol or other solvents from the job and the work area. This includes the rag you used to clean up with and the solvent containers.

    It takes some practice with flame position&control but will produce very neat and strong results.
     
    Last edited: Jan 11, 2020
  5. WimVe

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    I have good results with a gas creme brulee burner. They have a small sharp flame.
    Just buy the cheap ones at the action or similair shop. The are as good as the special soldering ones.
    But don't cook your solder.
     
  6. Thomas

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    We use these at work, and they work great. We plug them into a variac to control the temperature.
    Screenshot_20200111-193421_Amazon Shopping.jpg
     
  7. MG

    MG United Kingdom Subscriber

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    @phaedrus42

    Thank you for the in depth answer, i do tend to stay away from the rarer lamps in case they may need solder repairs, i have been saying it for ages that i need learn how to solder i just never seem to get round to it!

    @WimVe

    I have got one and tried to use it to repair the joint around a Tilley table lamps fuel filler neck but didn't manage it and haven't tried since,

    @Thomas

    I nearly bought a Weller 120w soldering iron with a similar tip but it had sold by the time i asked the seller about it, good idea using a controller too.
     
  8. MYN

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    @MG,
    Yes, you can use an electric soldering iron for some of the touch up jpbs for lamp repairs. Not the electronics soldering variety. They need to be powerful for the intended task.
    At least 200W or higher.
    Together with a zinc chloride-based flux.
    While I've done most of my soldering with the blowtorch and electronics rosin-cored solder, I've also used a 200-300W electric soldering iron on fount repairs.
    I used the sheet metal type of solder for the job. They are available in rods or bars. The zinc/ammonium chloride flux made a lot of difference. I'd say, I could do it a lot neater than using a blowtorch, without overheating the workpiece.
    Apply the flux solution with a small brush on the surface of the part which you want to solder. The solder would melt and follow the tip of the iron and could actually be neatly 'drawn' on the workpiece.
    The difference is, you need not preheat the piece(surprise) as is usually needed with the blowtorch. The solder could easily wet the workpiece(near instant) as the tip of the iron goes over it. The heating is highly locallized and I could touch adjacent areas almost immediately.
    I've tested it on a large piece of brass sheet, which tend to quickly conduct away the heat. To my disbelief, it actually worked, and the solder securely wetted the piece with ease.
     
  9. phaedrus42

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    Just be sure to remove the zinc chloride flux afterwards. It is highly corrosive to brass.
     
  10. MYN

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    Yes, zinc chloride is very effective but corrosive. Its acidic. It needs thorough removal by water rinse and preferably some neutralization after the job is done.
    On the plus side, its way more efficient than the usual rosin flux for electronics soldering.
     
  11. MG

    MG United Kingdom Subscriber

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    @MYN

    That is very interesting, thank you, i have just had a quick look on ebay, Weller irons of that wattage are quite expensive and its probably not a good idea buying a £15 cheap Chinese version i guess but there were a few at around £45 that looked ok,
    I have already got some Bakers soldering fluid no 3 which is apparently zinc chloride based,

    @phaedrus42

    Thanks Phil, that is handy to know!
     
  12. MYN

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    Weller is a reputable brand. So naturally you'd get what you paid for.
    I suggest that you test it on a larger piece of brass and note the difference. You won't get burning resin or charring as you could with a blowtorch with electronics solder.
     
  13. MG

    MG United Kingdom Subscriber

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    I think Henley Solon is also another decent brand, i have found a secondhand one that i am tempted to buy but it is rather large, i also came across three part rolls of old solder which is quite thick and may be of use too, all the labels have been removed though,
    I've got a few scrap tanks that i can use so it wouldn't matter if i messed it up.
     
  14. phaedrus42

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    Beware solder on a green reel, it is likely acid core solder. Rosin core solder is traditionally on a red or a white reel. If you cut through the solder with a craft knife and it has three or more fine holes it should be rosin core. One hole only is usually acid core.
     
  15. MG

    MG United Kingdom Subscriber

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    @phaedrus42

    Again thanks for imparting your knowledge Phil, i think they are all blue rolls but i will cut them open to check, are they useless if they are acid core?
     
  16. phaedrus42

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    The scid is corrosive so not the best choice for lamp work.
     
  17. MG

    MG United Kingdom Subscriber

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    Hopefully they are Rosin core as they would last me years.
     
  18. MYN

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    If you could get the job done without acidic-fluxed solder, that'll be the most ideal.
    Acidic fluxes are highly reactive and usually meant for difficult surfaces or where pre-cleaning work on the oxides could not be conveniently done. They'll remove the surface oxidation upon contact, even without heating. On the downside, you'll need to meticulously remove all traces of acid once done.
     
  19. MG

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    @MYN

    I will get some Rosin core solder if the ones i have are acid cored,

    I managed to get hold of a used 200w Weller soldering iron earlier at a decent price so hopefully that will do the job,

    Thanks MYN.
     
  20. JonD

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    A green reel has lately meant lead free solder in electronics work. Some brands are almost neat tin with flux core. Some add copper or silver in small %.
    Melting point is high and not good for lamp work. It is reluctant to flow and the joint always appears grainy.
     
  21. MG

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    I haven't cut them open yet but the melted ones label says Powerflow solder wire 500 gram 11 gauge contains lead 30.. i can't make out the last two numbers
    IMG_9282.JPG
     
  22. JonD

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    They look a bit old to be for electronics & lead free.
    That said there was also lead free for use by plumbers on drinking water pipework. That is older than the electronics usage I suppose.
     
  23. MG

    MG United Kingdom Subscriber

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    I think they will be worth trying at some point especially as they were free.
     
  24. MYN

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    I'd not be too worried if they're lead-free or not. Afterall, most of the lamps we're dealing with are classics. I'd guess that they were soldered mostly with sheet metal or plumber's grade materials.

    Those in the picture appeared and could likely be un-fluxed. It'll be a good idea to have additional fluxes at hand.
     

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