Conventional toaster ovens have large variations in temperature due to their large thermal mass and inability to remove heat. This often causes large overshoot which is not ideal for non-food applications like reflow soldering. This project adds an exhaust fan to better control the temperature.
There is a lot of debate if a DIY reflow oven even needs a PID controller. The argument goes, either spend the money and buy a professional machine for a few thousand or build your own and just eyeball the temperature with a manual on/off switch. Anything in between isn’t worth it because of the large temperature variations due to the nature of the heating elements, etc, etc. There is probably some truth to this, but who doesn’t love over engineering workshop tools?
Side note: This post isn’t meant to be a guide (read: I am not responsible if you burn your house down). I suggest purchasing a kit from whizoo or someone similar because this probably isn’t worth the time investment.