I was laid up from surgery complications for a few months and used my time to research and build an incubator. While I've been around farming all of my life this is our first flock and first time to incubate eggs. We incubated 4 dozen eggs of mixed breeds (cheap eggs) they started hatching a few hours before day 20. 28 eggs hatched during the 24 eggs before getting to day 21. Presently starting day 22 the other 20 eggs have not done anything. I'm not sure if I have enough posts to post picture of my incubator for reference. Here is a brief description of what I've built: Plywood box insulated with 2" styraoam walls covered with FRP board for easy cleaning. Lower chamber has a heat sink of 6 gallons of water in two tubs, rocks, 3 100 watt halogen bulbs, there is a computer fan to push air into this chamber and finally all of this is covered by an aluminum plate with a 1" air circulation space on the outside. Above this are two double cake pans that have water added in during lockdown to raise the humidity. Finally the egg chamber with egg turner, 2 computer fans on the lid to keep air circulating and temp distribution. When I set it up it ran for a couple of weeks before adding eggs. I put some water balloons in and measured temp with a human mercury thermometer. With my thermostat at 100.3, I got a consistent reading 99.5. Considering hatching was happening before day 20 and seems to have finished right at day 21. Does this mean that my temp was a little to high? Also the only hygrometer is a cheap analog on the end of an outdoor thermometer. When I added water on day 18, I was getting a reading of 50-55.