Well my new diy bator seemed to be keeping everything perfect so I got 15 BCM eggs to add to the dozen or so RIR eggs I collected from my own flock. Everything worked flawlessly until day 8. I had every single egg with good veining and nice development when I candled on day 7. I went to work on day 8 and when I got home the thermometers were all maxed. The indicator light on the thermostat was off, but the heating lights in the bator were still on. I picked up the thermostat to unplug it and "click" the relay went off. I opened the bator and it was at least 140 degrees in there This was my trusty thermostat that I have hatched 3-4 batches with and never had it fluxuate more than +/- .5 degrees. The eggs were all hot to the touch. I cracked a few open to verify what I already knew... Each and every one of them had a perfect little chicken embryo that was dead as a doornail. The veins weren't even red anymore - they were brown. Let my mistake be a lesson to all of you - make sure and use 2 thermostats because when one fails with no backup it is NOT a pleasant feeling.