I'd like to be able to do reflow on a very occasional basis, but real reflow ovens appear to be either no good or very expensive, and Arduino-controlled toaster oven projects seem to be very elaborate, with hours of work and a good bit of money involved. But recently I found this:
Basically, he leaves the toaster oven alone, and manually controls the reflow process with the aid of a cheap TM902C thermocouple thermometer. It seems to me that this ought to work. Of course there would be the issue of thermocouple placement, but you would also have that with a controller setup.
What I'm having trouble with is the choice of toaster oven. I assume quartz heating elements would be needed because they heat up and cool down rapidly, but I don't know whether two elements or four elements is best. There is also the question of a convection fan.
I assume four elements and a fan would be best for doing more, or larger, boards, but I also see people using a two-element oven with no fan, including Ben Heck - at about 0:44 into this video:
Walmart has a two-element Black+Decker oven for $30 and a Hamilton Beach two-element for $27. Then $5 for the thermocouple and a couple bucks for a kitchen timer, and for under $40, and no work, you would have a working reflow oven. You would need to settle on a brand of solder paste, I assume leaded, and practice a bit with its recommended heating profile, but I don't see why an Arduino would do better at contolling this than I would, assuming the TM902C is reasonably responsive and accurate. I mean, if you can reflow using a hotplate, this ought to work.
I would appreciate any suggestions from those with experience with these toaster oven projects, particularly with respect to the choice of oven. And of course if you've actually tried manual control as described in the first video, I'd like to know how well it works for you.
Thanks very much.