My Toaster Reflow Oven Project - Part 2

This is a continuation of my toaster reflow oven project.

I disassembled my toaster oven project and moved the controller away from the oven to test the theory that it was overheating.  I monitored the temperature at the controller and at various surfaces on the oven with an IR temperature sensor.  Running for over a half hour with the heating elements on full the controller never locked up.  The temperature of the controller in this setup never got much above 80 F (approximately a 15 F rise over ambient).  The external surfaces of the oven (without the plastic cover around the outside) were around 250 - 300 F.  The oven was able to reach a maximum temperature of 503 F.  From about 490 F on up it was not increasing very fast at all.  I think the maximum temperature of the oven with the factory installed heating elements is probably not much more than 500 F (260 C).  This is high enough to melt most solders (even lead free).  I was hoping for a higher range, but it makes sense that the oven tops out at 500 F given that this is the maximum setting on the temperature dial for the oven, and there are probably safety regulations about building an oven with heating elements that could significantly exceed their maximum rated temperature.  One thing to note is that it may be necessary to use both top and bottom heating elements to achieve the maximum temperature and for reflow soldering you probably only want to use the top heating elements to avoid reflowing the bottom side at the same time and thus having compenents that were previously soldered on fall off due to gravity.  Maybe shielding the bottom with a tray is sufficient.  Another test to run is to see what the maximum temperature in the oven is with just the top elements on.