Build your own temperature controlled soldering station

Its an interesting project.  However, if you want a good soldering station, it should meet commercial specifications, maintain heat variation ~ + /- 1F for the station and maintain tip heat ~ +/- 10F.  Heaters and tips in quality stations are often made of proprietary materials and add to the advantages of the more expensive irons.  Its not simply a close loop feedback controller on any ordinary heating element and all tips are made the same.  The economies of scale for manufacturing make it cheaper to buy a true temp controlled station than to buy their spare parts and build your own around it.

Its an interesting project.  However, if you want a good soldering station, it should meet commercial specifications, maintain heat variation ~ + /- 1F for the station and maintain tip heat ~ +/- 10F.  Heaters and tips in quality stations are often made of proprietary materials and add to the advantages of the more expensive irons.  Its not simply a close loop feedback controller on any ordinary heating element and all tips are made the same.  The economies of scale for manufacturing make it cheaper to buy a true temp controlled station than to buy their spare parts and build your own around it.

Saturation,

Post some links to the stations you suggest. (In a new post perhaps?)

Cabe

Happy to help, Cabe.  I'm not sure if people are interested so please feel free to suggest the right subforum.

For home or developer use, that is not in a factory production setting, a basic commercial standard IPC conforming station, bolded ones are a best buy.

$100 [ requires occasional user calibration of the analog dial, provides basic solder station temp control and good thermal recovery even for production use]

Hakko FX 888

Weller WES51

$200 [ at this pricing and up, all are calibration free, and have better thermal recovery]

Oki PS 900

Pace  ST 25 + PS 90

$400+ [ high end many options, fastest thermal recovery]

JBC BD-1BA

Metcal 5000

Conforming to IPC will also meet US military, NASA, and ESA and many agency specifications, and the station itself is not high tech.  A reason for buying such a station over a nonregulated or non-feedback iron is that these standards have already proven that such stations maximize tip life and reduces thermal damage to parts, over the long haul.  They are ergonomic to use, and likely in a single user setting, will last the user a lifetime.  Small components, if soldered with a soldering iron, do not have much thermal mass, and can easily be heated into damage not necessarily visible due to a malfunction during post-assembly testing.  Subtle damage usually shows itself as reduced part lifespan over its expected lifespan.

Of particular importance in reducing temperature is that lead free solder increases tip wear over 3X above 350C.  In leaded solder, tip temp did not produce such stark wear rates.  To know where 350C on your tip, you may have to calibrate it.  A simple way to spot check a tip without fancy equipment is to use eutectic solder; with a sharp melting point and no intermediate phase, it will clearly measure tip temp to set your knobs to the right area.  At 300C, the wear rates converge so even a 50C error, fairly unlikely with eutectic solder, will not be a practical problem for individuals who don't need IPC or ISO certification.

Soldering stations worldwide are dominated by at least, Hakko, Oki/Metcal, Pace, and Weller. JBC and Ersa are good brands, but are priced high for individual users,  and are more common in factories, but deserves mentioning.  There are many regional brands and many variants in products in different countries, what you end up with depends on what they make available or is priced competitively; many EU countries add a lot of tax for importation; in the USA the prices are often lowest.   Since the basic electronic technology is fairly low tech, copies and clones can be made by many, but these makers do not OEM for other brands, AFAIK.  Makers like Aoyue or Atten [ Hakko clones to outright counterfeit, too many makers to count], to house brands like Radio Shack, Velleman, or Duratools etc., may have unknown or unreliable specs and performance, and should be avoided.  Avoid unknown for 4 reasons: the name brands are already well known for quality, the cost difference may be small, original replacement parts are easily stocked and made,  many are used by commercial factories and thus, conform for IPC-J-STD-001 standard.

Xytronic is a strange fellow, its a Taiwanese maker with a reputation of its own, been around over 30 years, but it dilutes itself by making OEM and reports of its own quality can be  mixed, but it has stations as good as low end Hakko with similar specs, for half price. If made available as a choice when Weller or Hakko are not, its worth consideration over a brand without a clear reputation.

Soldering stations wear out tips and heating elements, so spare parts are crucial to the station you buy, a buyer will buy as much into the company as the station to get supplies of parts.  Tip and heater technology is key as while electronics can be easily  copied, mettalurgy is more difficult; tips and heaters can look the  same, but originals have special alloys that give them the properties  you paid for in a brand name, fast thermal recovery and durability.  Many clone or counterfeit Hakkos for example, claim compatibility with original Hakko tips and heaters to suggest you can buy their station and benefit from original Hakko metallurgy.

Lastly on thermal recovery.   While there is no standard test one can use to compare soldering irons across all makes, a simple index is to simply turn your iron on, making sure the tip is truly at room temperature; preferably cool the iron overnight otherwise it will shorten the time artificially.  Since the heating LED or indicator remains ON until the final temperature is reached then blinks instead as it cycles off/on, time how long it takes to reach 350C with a stop watch.  For comparison:

JBC AD2950: 6 seconds

Metcal 5000: 12 seconds

Hakko 936: 43 seconds

Sample JBC versus Metcal

Turn On to stable temp graph

How turn-on time translates to thermal recovery from soldering a typical PCB tab:

Hakko's thermal graph of a 936 versus the new FX888 to show how it compares in thermal recovery against JBC and Metcal.  Note the time scale is very different, but the temp cyles 50C, between 250C-300C, similar to JBC spread.