Whats the rule of thumb for determining the size of fan for circulating air inside your oven for better temperature control. My oven is approximately 15 cubic feet and it doesn’t have a fan. I thought about just adding on of the high temp blowers that Grainger sells but it seems to be overkill to me. I hate to spend a hundred bucks on a squirel cage blower that will need a bunch of ducting built. I was hoping to buy a small motor on ebay and putting a fan blade on it. I was thinking all I have to do is mount the motor on top of the oven, drill a hole thru the top for the fan shaft with a shaft extender, put the blade on and put a wire guard around it. Am I simplifing this too much? Sorry if these are stupid questions. I’m a mechanical designer but all my experience is with precision gauging. I’m an idiot when it comes to oven design. I bought an old industrial oven from a scrap dealer and now I’m trying to retro-fit it and get it up and running so I can do some hard gun coatings and maybe a little powder coating.