I am about to make some recommedations to my friend about the design and layout of the piping for his dust collector. Now the stumbling point His position is that a 1200cfm dust collector is more than twice the cfm necessary to handle the dust from a Grizz 1023 saw, a X5 Unisaw would perform about the same. He intends to run 20-30' of 4" flex hose to his cabinet saw and branch off to his 8" jointer. He's only talking about using 1 blast gate as the jointer "can't use as many cfm's as the cabinet saw" and that leaves about 550cfm to handle the jointer even with the cabinet saw connected.
I think he is missreading the Grizz information and relying on it to design the piping. Try as I might to change his mind I am having no luck. I think he is making a grave mistake. To further compound his misinformation he is used to using Craftm-ans wet dry vacs up to this point. While they make work effectively up to a point they are not dedicated dust collection sytems. Nor do they move the same cfm' as a dust collector.
I am suggesting that he use 6" metal pipe and fittings to a terminating point at the cieling. Then making his drops, with independent blast gates, in 4" flex or metal pipe.
Any information you have on the subject would be helpful as I am going to probably blamed for not enforcing my suggestions if they are found to be true. It will end up being my fault if his original system fails. Go figure