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Choosing a general-purpose soldering gun

Discussion in 'Electronic Basics' started by wylbur37, Apr 22, 2004.

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  1. wylbur37

    wylbur37 Guest

    When I was a teenager, I purchased a Weller 8200 dual-heat (100/140
    watt) soldering gun. It served me well over the years. Then about ten
    years ago, I went through a period where I didn't need to do any
    soldering and decided to give it away as part of "uncluttering". (I
    later realized that was a mistake).

    Now, I need to do some soldering again and need a soldering gun. I
    could purchase a new Weller 8200 through mail-order, which will cost
    over $40. (I could also get one used via eBay for as low as $8, but I
    don't trust buying used stuff from strangers).

    I could also purchase a new soldering gun at Radio Shack, either a
    dual-heat (150/230 watt) model (Cat. No. 64-2187) for $29.99, or a
    single-heat (100 watt) model (Cat. No. 64-2193) for $12.99.

    If I recall correctly, back when I still had my Weller 8200, the first
    heat setting (100 watts) was usually enough for most wiring jobs. Very
    rarely did I have to click it back to the second position (140 watts)
    except to solder some thicker metal items.

    I'm currently leaning towards getting the Radio Shack 100 watt model,
    not only to save money but because the heavier model (150/230 watt) is
    probably too hot anyway and might burn out some components. Another
    reason I'm leaning towards getting the Radio Shack one is that there
    are numerous Radio Shack retail stores near where I live (in New York
    City) and I could just go and buy one over-the-counter without the
    hassle of waiting for it to be delivered. (As for the Weller 8200,
    it's more expensive and I don't know which stores in New York City
    would sell it anyway).


    I was wondering what your thoughts were on ...

    a. whether 100 watts is sufficient for most soldering jobs
    (involving ordinary stuff like LEDs, resistors, etc.).

    b. whether you've had any experience using the Radio Shack soldering
    guns mentioned above and whether you think they're any good.

    c. whether you know of any retail stores in the New York City area
    that sell a Weller 8200 soldering gun for $30 or less.


    Thanks for your help.
     
  2. A gun or an iron? By "gun" I assume you mean the device, invented by Carl
    Weller, that heats up quickly by driving a huge current through a wire tip.
    (It contains a big transformer, and you can feel it buzzing a little as you
    use it.) By "iron" I mean something with the heating element separate from
    the tip.

    It is way too much. If you are working with small components, the best
    soldering instrument is a temperature-controlled iron (not gun) of maybe 15
    to 25 watts. By temperature-controlled I mean that they contain a
    thermostat or temperature sensor to maintain a uniform 700 degrees F (or
    various others; on printed circuit boards I use a lower temperature).

    Because of the temperature control, an iron of this type heats up rapidly
    (in about 1 minute); it runs at full power until working temperature is
    reached, then automatically cuts back its power.

    A soldering *gun* is for appliance repair, heavy automotive wiring, and the
    like. I know that back in the 1960s, people used to use soldering guns with
    small components (which were bigger back then), but it's not easy.

    Don't know.

    $70 will buy you a temperature-controlled iron from Radio Shack, the
    64-2185, that should be a pleasure to use. (I haven't tried it; I use a
    Weller station that I bought secondhand at a hamfest.)

    Radio Shack also has some irons in the 15- to 30-watt range that are not
    temperature controlled. The 64-2051, at $8, looks good for work with small
    components.

    They do have an iron with a gun-shaped handle, just to confuse you.

    Radio Shack is of course catering to the hobbyist market. For
    industrial-quality soldering irons, look at:
    http://www.mouser.com/catalog/618/1261.pdf
    http://www.mouser.com/catalog/618/1262.pdf
    The Weller WES50 and WESD10 are temperature-controlled, like what I use.
    The WTCPT is also very good (it has a thermostat built into the iron, but no
    adjustments or display). Weller's "economical" soldering station is not
    temperature-controlled, but lets you vary the power (which is not nearly as
    handy).

    For an old-fashioned Weller soldering gun (a tool that certainly has its
    place) I'd try Wal-Mart or K-Mart.
     
  3. CFoley1064

    CFoley1064 Guest

    Subject: Choosing a general-purpose soldering gun
    The right tool for the job. Use a soldering iron for PC boards and small work,
    and a gun for the big jobs. If you need to do the Radio Shack thing, your best
    bet for electronics might be the "Soldering Work Station with Dual-Powered
    Iron", RS p/n 64-2184. It's $21.99, and has a built-in stand and sponge and a
    dual temp setup (diode with switch) to give you 20 or 40 watts.

    Having said that, the Weller is a good gun, and worth the price. Of course,
    you'll have to replace the tips, but they're consumables, anyway. A reliable
    beast. You can also get replacement parts from the manufacturer. A reputable
    eBay seller wouldn't deliberately risk negative feedback over something that
    small.

    Neither of the two Radio Shack guns you're looking at are the best choice,
    although they'll do in a pinch. The one I used a number of years back got
    rather hot to hold after a bit of use.

    If you're going to use it frequently, you need to pump a lot of heat for a long
    period of time, or if the difference between adequate and good is important to
    you, the Weller is worth it. If you want something cheap, go to

    http://www.harborfreight.com/

    They have two cheapies (150 and 185 watts) for 10 bucks each. No guarantees
    there.

    Good luck
    Chris
     
  4. Phil Hobbs

    Phil Hobbs Guest

    Soldering guns are great for connecting metal shields and heavy wires to
    ground planes, e.g. in a dead-bug RF prototype. They cool down much
    faster than a Godzilla soldering iron, which is the other good method

    Cheers,

    Phil Hobbs
     
  5. mike

    mike Guest

    A GUN is great if you need high temperature with low thermal mass
    infrequently. Like when you want to solder a wire onto a tube socket.
    For current electronic work, they're obsolete.

    Get a Weller (or any one of a zillion similar brands)
    temperature controlled iron and be done with it. Ham radio swap meets
    are good places to get used/refurbished ones. Going price is around
    $40. I can put you in touch with a trusted refurbished one if you like.

    For small stuff, Antex makes a 15W iron that works nicely for normal
    components on a circuit board. Does a credible job on Surface Mount
    with the right tip.

    For heavy electronic soldering you're gonna want
    an Ungar 47W 1050degree iron. Lots of thermal mass, but not huge like
    the one you used in shop class 40 years ago. Put it on a light dimmer
    and it will work over a wide range of applications.
    mike


    --
    Return address is VALID.
    Bunch of stuff For Sale and Wanted at the link below.
    Toshiba & Compaq LiIon Batteries, Test Equipment
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  6. Dave VanHorn

    Dave VanHorn Guest


    I've been spending the last couple days doing fine pitch SMD soldering, and
    soldering shield cans and removing 100W VHF and UHF transistors.. One iron,
    two different tips.

    Go Metcal! :)
     
  7. Guest

    For the stuff you mentioned - LEDs, resistors, etc
    get a cheap soldering iron or pencil from Radio Shack
    like catalog #'s 64-2071, 64-2070 or 62-2067

    Later on, you may want to chose a fancy iron with
    grounded tip and heat control - but the Radio Shack
    stuff is irons are good enough to start with.
     
  8. wylbur37

    wylbur37 Guest

    Most people who responded to my original posting tend to agree that I
    wouldn't need more than a a 100-watt soldering tool for most casual
    soldering of LEDs and resistors. Some have even recommended using
    soldering tools as low as 15 watts.

    Now, I've been reluctant to use a low-wattage soldering device
    because of the following reason ...

    With a high-wattage tool, I only need to hold it against the
    connecting wire for a short time before the spot on the wire that
    touches the heating tip gets hot enough to melt the solder. Once the
    solder melts and flows over the wire, I pull the soldering tool away.
    On the other hand, with a low-wattage tool, it takes longer for the
    connecting wire to heat up, and that extra time may allow heat to
    travel along the wire and "cook" or otherwise damage the component.
    So it's actual "safer" to use a higher-wattage soldering tool than a
    low-wattage one, as long as you know well enough to pull it away in time.

    Is there any flaw in my logic here?
     
  9. Dave VanHorn

    Dave VanHorn Guest

    No. The ideal iron has a tightly controlled temperature, but loads of
    thermal mass, and good heat delivery to the tip.

    The tips should be iron plated, so that they don't leach into the solder
    like copper does, and end up becoming sharp needles to gouge the PCB.

    The 40W weller iron with a 700 degree tip is an excellent starting point.

    I went the small iron route, but because of their tiny thermal mass and poor
    delivery, it was miserably bad. :p

    In this field, your soldering iron, and your meter are pretty much your
    primary tools.
    Don't skimp on them.
     
  10. exray

    exray Guest

    Its not so much the wattage as the physical contact to the connection.
    I don't know that a 100 watt Weller gun gets any hotter than a 25-40w
    soldering pencil.

    I do mostly tube work and use a Weller 40 watt pencil with a 1/4" chisel
    type tip. As far as I'm concerned it works better than my Weller gun
    for normal component terminal connections...because of the wide tip.

    Direct chassis connections are a bit different because the chassis
    will act as a heatsink and the little pencil can't keep up as well as
    the 100 w gun. However, a 40 watt pencil isn't going to bog down on a
    terminal strip or tube socket full of wires.

    This 40w with a big tip is TOO big for PCB work. I have a 25w pencil
    with a pointed tip for that work.

    HTH,
    Bill
     
  11. No, but a well-designed 15-watt iron is enough for modern small components.
    3 watts would not be.

    A temperature-controlled iron is best, because it kicks in extra power as
    soon as you apply it to something that starts drawing heat out of it. It
    handles like a much more powerful iron (because of the power in reserve) but
    does not overheat things.
     
  12. I should add that for successful soldering, you have to develop a sense of
    timing.

    As soon as you apply the iron to a joint, heat is drawn out of it.

    If you try to solder several joints in succession, and the iron isn't
    temperature-controlled, it will gradually cool down. You'll have to apply
    it to the joints longer and longer, and because this provides time for heat
    conduction, you'll overheat the components.

    With experience, you determine the right pace.
     
  13. Guest

    There is. It includes a hidden assumption that the lower
    wattage tool is too small. When you use a properly sized
    iron for the job, going to a higher wattage provides no
    practical increase in the safety to which you refer.
    But it does include some drawbacks.

    A higher wattage tool is generally physically heavier and
    bulkier than a low wattage tool. A gun is definitely
    harder to control than a small iron or soldering pencil.
    A 100 watt iron or gun is WAY more than you need for what
    you mentioned. Using it may be hiding a problem. If you need
    100 watts to solder an LED, you are doing something wrong.
    If you can't solder an LED with a 25 watt iron, you are doing
    something wrong. A 25 watt iron will not overheat an LED,
    unless you are doing something wrong.
     
  14. wylbur37

    wylbur37 Guest

    I'm not disagreeing with anything you just said.

    However, I wish to point out (just to be a P.I.T.A. :) that there are
    pragmatic reasons for doing things that might not otherwise be done in
    theory. So, despite the fact that someone might not *need* to use more
    than a 25-watter to solder an LED, they might still use a 100-watter
    anyway. Why? Because in the real world, not everyone has the budget to
    afford purchasing more than one soldering tool for different size jobs
    (nor have the physical space to keep more than one). Therefore, they
    would select a "general-purpose" soldering tool and try to use that
    for "everything" to the extent possible. (Doesn't sound very
    "professional", but then not everyone on this group has to be a
    "pro"). :)
     
  15. This raises the interesting question of how to modify the tip of a Weller
    soldering gun to be small enough for circuit-board work. I seem to recall
    having seen some trick with a sharpened piece of #14 wire, or something like
    that.
     
  16. Ken Weitzel

    Ken Weitzel Guest

    In a real pinch, fasten a common pin to your tip by
    tying it on with a couple of pieces of solid hook-up
    wire. Tighten the wire by twisting the ends with your
    pliers.

    Use the pointed end for tiny things, like dip connections,
    the heavy end for regular pcb connections.

    Ken
     
  17. mike

    mike Guest

    Don't confuse thermal mass with watts.
    I categorize irons into three categories, best first.

    1) Metcal makes an iron that's RF driven. It can put a LOT of watts
    into a small tip almost instantly to keep the temperature constant.
    The tip can be just hot enough to melt the solder, small enough to get
    into a tight space and supply enough power to keep the temperature
    stable over a wide range of joint sizes (load thermal mass). Once
    you've tried one, you'll never want to go back. For personal use,
    the fatness of your wallet is a factor in obtaining one.

    2) Weller makes temperature controlled irons of various types.
    The coupling between the tip and the source power is looser than
    with a Metcal. But you still get pretty good soldering at relatively
    low temperatures.

    3) Uncontrolled irons. These rely on power and thermal mass to do the
    job. Big iron with low watts can work over a wide range of load mass
    if it's big enough. Small tipped iron has to get way too hot because
    of low thermal mass. So, it's too hot on tiny parts and too cold on big
    parts. But you can still get there if you size the iron to the job.
    I have a 1050 degree 47 Watt Ungar for the big jobs. Big ole tip, lotsa
    thermal masss and a light dimmer to control the temperature for the job.

    One thing I haven't seen mentioned so far about guns is the BIG ole
    inductive spike you get when you let go of the trigger. Theoretically,
    this could be isolated from the tip. Is it in practice?? Big guns
    were invented long before people tried to solder SMT fets.

    mike

    --
    Return address is VALID.
    Bunch of stuff For Sale and Wanted at the link below.
    Toshiba & Compaq LiIon Batteries, Test Equipment
    Honda CB-125S $800 in PDX
    Yaesu FTV901R Transverter, 30pS pulser
    Tektronix Concept Books, spot welding head...
    http://www.geocities.com/SiliconValley/Monitor/4710/
     
  18. Dave VanHorn

    Dave VanHorn Guest

    Excellent iron, about $200 on ebay, look for the SP-200.
    I reccomend a 1/8" chisel, a narrow chisel, and a curved pinpoint tip, at
    600 or 700 degrees.

    Also, 63/37 solder only!

    Very nice, $120-ish
    Good as a backup iron, I have one at a repeater site, in case I need it.
    Big guns are for soldering shield cans, if I ever find one that the metcal
    can't handle with the fat tip.
     
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