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iFixit wants to fix the soldering iron
(www.engadget.com)
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How precise are you talking? Usually, cheaper soldering stations get that way by not having a lot of thermal mass, which is particularly needed for desoldering. Otherwise, the PID control tends to keep things good enough. Tuning the PID parameters can make a difference, but once you have a heater and a heat sensor, the software is more or less the same for everyone.