Hackaday Prize Entry: A Cheaper Soldering Solution

Everyone goes through a few phases during their exploration of electrons, and nowhere is this more apparent than the choice of soldering iron. The My First Soldering Iron™ is an iron that plugs directly into the wall, and doesn’t have temperature control. They’re cheap, and electronics isn’t for everyone, giving the quitters the opportunity to take up woodburning as a hobby. The next step up is a temperature controlled iron, probably an Aoyue or Hakko. The best soldering iron? You’re looking at a Metcal or Weller, and your wallet will become a few hundred dollars lighter.

Your My First Soldering Iron™ need not be terrible, though. For his project for The Hackaday Prize, [HP] is working on a soldering iron that is cheap, accurate, and uses the very nice Weller RT tips. No, it’s not as good as a Metcal or proper Weller, but it’s good enough for some fine soldering work and will give the Aoyues and Hakkos a run for their money.

If price is a reasonable measure of the quality of a soldering iron, the irons that use these Weller RT tips are the best irons around. The tips, though, are pretty cheap: about $30, which gets you a heater and thermistor and not much else. There have been numerous reverse engineering efforts for this iron ([1] and [2]), and even a few Arduino-based circuits that replicate the functionality of the Weller base unit.

[HP] is going in a different direction to heat these iron tips. Instead of building a big box to hold the electronics, he’s building everything into the handle of the soldering iron. With brains donated from an ATMega168, a few op-amps, MOSFETS, and a single power jack, [HP] can heat up this soldering iron tip in a compact, hand-held unit.

For his Hackaday Prize entry, [HP] did a rundown of soldering pen in a video. You can check that out below.

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32 thoughts on “Hackaday Prize Entry: A Cheaper Soldering Solution

    1. Metcal is the best. As the tips are not running hot in the power save stand they last much longer than Weller so the high tip cost is not too bad. Comparing the soldering performance of a Metcal to a Weller is just wrong though, Weller is just a normal soldering iron.

  1. DIY kits on a cheap with similar quality to weller tip $18:
    http://www.ebay.com/itm/381511728230 Temperature Controller T12 Tip Bracket + Handle Case For HAKKO Soldering Iron
    http://www.ebay.com/itm/381511733009 Digital Soldering Iron Station Temperature Controller Kits for HAKKO T12 Handle
    http://www.ebay.com/itm/171924965310
    can even go hilariously ghetto $7, no tip:
    http://www.ebay.com/itm/171716994488 Soldering Iron Station Temperature Controller T12 Handle Circuit Board + DC Plug

    chinese clones of T12 hakko cartridge tips are REALLY good, heat up in few seconds, solid thermal mass, thermocouple is right at the tip, not to mention ~$6 price for replacements and huge selection of shapes.

    Its a surprisingly solid replacement for genuine $250 FX-951, doesnt needlessly beep when swapping tips and you get a knob to set temperature, not alarm clock two button interface from the eighties Hakko keeps forcing on people. Im really confused when people spend $200 (europe price) on 888 when you could have something from this century.

  2. I don’t do any really small/delicate work so I’ll stick with the gear I already have. A couple of old 70s/80s Weller irons, some old radioshack desoldering irons with a squeeze bulb and an antique 40s Weller soldering gun, all still in perfect working condition. They sure don’t make stuff like they used to

    1. I had two soldering guns that use pieces of bent wires as heating element and transformer with one coil of thick metal bar as a secondary winding. They last forever and can easily be used to do almost anything through-hole. But there are some masochists that use those heavy-duty beasts for SMT work which is just crazy.
      For my line of work I use Zhaoxin 868D, which is a decent clone of Hakko (I think) soldering station. I also have Yhua soldering station that is giant piece of junk. It was sold here as plastics welder when it got the reputation of being crap. Before that I had a simple soldering station that used SCR motor controller for crude temperature adjustment. I dropped hot iron on my thigh and ended up with quite nasty burn…

      1. I have a dumb looking smiley face on my leg after dropping my iron on my knee three times over the years. every time i see my knee i have to see that stupid face.

  3. I’m a huge fan of the OKI/ Metcal RF irons. They use RF, the skin effect and a thin layer of ferromagnetic steel than changes properties at the curie point.

    Although there’s at least one poorly documented open source driver for these, I’m aware of one clone available (“Micron” http://www.altronics.com.au/p/t2080-micron-curie-temperature-controlled-soldering-station-100w/) but can’t vouch for the latter’ quality.

    Driving that in a handpiece would be awesome, and you don’t need to sense temperature, only current/resistance.

    1. it took me a long time to catch on, but I’m now a metcal person, too. got mine used on the bay, just have to hunt around for a while. tips are easy to find, not expensive (on ebay, again) and the curly-q tip style is more useful than I had imagined.

      I do have to admit that as a kid I did get a wood burning set (this was back in the 70’s) and I did use that as My First Soldering Iron(tm) since I did not have anything else. once I got tired of misusing tools (lol) I finally did step up to something closer to a real one, but still not temp controlled. I had to build an scr/triac light dimmer to have something that would not run at full temp all the time.

      nearly 40 yrs of soldering; and I still remember those woodburning iron times. so glad I’m not a kid anymore and can buy my own tools when I want to ;)

  4. Well I’m a huge fan of jovy isolder 40s, they have similar performance to the metcal and cost only $110, the low price is achieved by using a high power but low mass tip and some very clever firmware. The iron heats up from cold in 2 seconds and is capable of dumping a lot of energy when required e.g soldering ground planes and terminals.

  5. Designing a good soldering isn’t black magic. There’s mainly one thing that’s important: You want to keep the contact surface of the tip at the temperature set by the user at all times. For this to work, the heat transferred to your components, wires, PCBs etc. has to be replenished by the heater, so you’ll want a high heater power. However, higher heater powers require tighter feedback cycles as to not overheat the components, which is not easy to accomplish. The second component of a soldering iron is the temperature sensor that provides feedback for the heater control. Quite obviously, it should track the temperature of the tip as closely and quickly as possible. This necessitates having as little heat capacity (“thermal mass”) and thermal resistance between the contact surface of the tip and the sensor. The third component is the metal connecting the heater, the sensor and the contact surface of the tip. This leads to a certain thermal resistance between heater and contact surface, sensor and contact surface. It also has a heat capacity.
    If we look at some designs, we can quickly figure out what kind of iron is probably going to perform rather well.
    The plug-in-the-wall type has a very large heat capacity, so it stores lots of energy that can be released when heat is drawn away from the tip. There is no feedback, but the heater power and thermal design of the iron barell lead to an equilibrium temperature where the heater can just keep up with the losses through thermal radiation and air convection. It’s no fun soldering with these things.
    The standard mid-cost soldering station has a heater that sits around or inside (doesn’t really matter) some section of metal that’s connected to the tip with the contact surface, with the sensor near the heater. It’s a design that works rather well, but heater power is limited by the lack of adequately quick feedback wrt the tip temperature. The temperature of the sensor starts dropping when a lot of heat has been drawn out of the tip, but then the tip temperature is already lower than one would like. Thermal resistance between heater and tip is also a bit of an issue, and tips for these kinds of irons tend to be rather large to allow them to be fixed to the barrel, increasing their heat capacity. What can you say about these irons? Industry standard, they work quite well, the tips are just small pieces of metal, so they’re quite inexpensive. If you want to solder quickly, you increase the temperature, leading to more stored energy in the tip and fewer issues when the heater-sensor feedback cycle is not able to keep up the temperature of the contact surface very quickly. Main advantage: Easy construction, cheap tips.
    All of the high-end soldering stations known to me use some kind of integrated tip. There, the heater, sensor and contact surface of the tip are all integrated into one cartridge. They are not serviceable and exchanging one of the components does not have to be taken into consideration. This means that the three internal components of the cartridge can be placed perfectly. The sensor can sit right next to the contact surface, the heater can sit somewhere where it can provide lots of heat that can get to the tip quickly. The only downside to this is that the tips are rather expensive, since you’re not replacing the tip, but practically your soldering station handpiece, sans the components that allow you to hold it. Prices of around 30 to 40 Euros aren’t uncommon for these cartridges, and since they’re consumables, you should expect to replace them regularly. The Weller mentioned in this article uses this system, as well as the JBC soldering irons. Soldering with these kinds of irons is obviously better. However, given the substantial cost of these tips, I’m not sure if it’s worth it for hobbyists.

    1. I never understood the Metcal worship that seems to be expected. I worked in a shop that used Metcals exclusively, and I remember a) the supervisor would get really pissed if somebody left one on for a long period, and b) it seemed to work about the same as my low-end Weller. So somebody please enlighten me. What’s so special about a Metcal iron?

        1. mike did a clip showing off his metcal desoldering huge metal can from multilayer board, cant find it now
          you need to try soldering 12 layer board with heavy copper pour to see difference, of course if you dont need this capability then $200 weller is just fine, even $30 Gweilo 936 will do

  6. Just as my introduction for the project states: Everybody have their own favorite soldering iron. I know that the weller Rt tips can be used for a lot of good things so enabling more people to use them (i.e. making them cheaper) will hopefully spark someone to get started on SMD soldering.

    The project is not a ‘This-is-the-one-and-only-soldering-rion-you’ll-ever-need’-type. It’s just a new take on the traditional soldering station. Keeping essentially all functions in the handle and allowing the whole instrument to be cheaper is a fine goal for my project

  7. As a regular user of the Weller RT tips, i see one little problem with this project. The thing i really like about the new tips is that they are very small and light, compared to most other soldering irons that i’ve used before. Especially when soldering at the limits of my possibilities (0402 is common, 01005 happens some times), i like to have a small, lightweight handpiece. So, adding all the circuits to the back of the tip would be quite a step back from the original that has only the connector and a wire to the station.

  8. Never saw any practical advantage whatsoever in a multi-hundred bucks iron over any cheap direct-mains-powered one. If the tip is adequate and it melts the solder, then it will do the job just as well as anything else there is. It’s a basic tool, not an exquisitely refined piece of art. Get over it.

    1. Clive is just a nice guy, too nice
      all three are garbage if solder is your daily life. Especially the usb one – its like buying a car because you were pleasantly surprised it was actually able to roll forward.

  9. my cheap soldering solution is a hakko 907 knockoff handle, first thing you do is replace the heating element with a genuine one (the original ones burn out easily). I power it with one of those ebay 150 watt boost converters, and an ebay panel meter to see how much current I’m pushing. I put it all in a nice box and it works really well for small smd jobs and large copper wires. Nice thing about it is i can power it from a 12 volt wall adapter or a 12 volt lead acid battery for jobs on the go.

  10. Never understood the worship for Metcal. Yes, they make excellent tips that get hot quickly and are controlled by the Curie point of the material. But they simply cannot match the precision of JBC tools for extremely fine rework.
    Sure the JBCs only heat up 90% as fast, but the tip selection is much better, and they seem to last longer than the Metcal.
    When you have to rework 01005 components all the time, nothing comes close to the capability of JBC tools.

    1. not sure that matters, for extreme rework nothing beats a hot air station really, it’s a joke to think you’re going to use a soldering iron for that, only for very basic repair or attaching bodges maybe, that sort of work is nice; I do agree, the JBC tips tend to be of higher quality metallurgically, but the Metcal tips and not very far behind and in the real world the difference won’t matter, I have done it; the stations themselves are of comparable quality, maybe JBC running a bit behind actually

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