Homemade bator vent hole size

[Grampa with chickens]

?????

I'm making a rather big (18x36") bator. I've been hunting all afternoon to find out what size and how many vent holes i need.

Any insight or opinions??

 

[shelleyd2008]

You need probably about 6-8 (?) around the bottom and the same around the top, about the size of a screwdriver point, for air flow. You will also need a coouple (mine has 4) on the top about the size of a quarter or so, that you can open/close at will. These will be necessary for when the chicks hatch, to allow more oxygen to enter the incubator. Honestly though, I only ever have one of my big vents open. Good luck. Does your incubator have a fan? Just make sure that the 'sucker' part of the fan is not in front of the vent holes to pull cool air in.