Quote Originally Posted by John TenEyck View Post
That's the same thought I had.

Bandsaws need a surprising amount of CFM to capture the sawdust when resawing. The solutions above work, to a degree, but the two 4" ports on my Grizzly work fine as long as it have enough air pulling through them. It didn't when I first hooked up the saw and I got dust piling up everywhere, even in the upper wheel housing. That cascaded a whole study of why I didn't have enough flow from my 1200 CFM DC and eventually led to a redesign of my system. I didn't need to buy anything, but I had to reconfigure it to reduce the static pressure losses I was getting between the saw and the exhaust port. Once I did that the saw remains sawdust free even after extensive resawing of 12"+ thick stock. 4" diameter ports will carry about 400 CFM, IIRC, which means 800 CFM for the 2 ports. It doesn't take much static pressure loss to make a 1200 CFM DC drop below 800 CFM. At 500 CFM, and likely less, Jimmy made the right call to try to reduce the airflow required. That works as long as the airflow is properly directed, and the CFM is still high enough to carry away the sawdust. At some point, however, it won't be able to keep up, which may or not be a problem for him, it just depends upon how he uses it.

John
Yeah, I did a bunch of research and pulled a lot of ideas from all of the things you guys had posted over the years. I was considering putting a cover, at least partially, over the lower port like you had done, to increase pressure on the top port. But so far, I haven't needed it. Honestly, reducing the amount of free air available to the lower port with the seals probably was enough to keep sufficient power diverted to the top port. And it doubled as a way to keep the airflow directed.

I will say it probably helps that I have less than 10' of flex hose in the total system, so I'm not getting much loss there. And the collection bag is made of felt and probably doesn't filter much. But, I have it placed just outside the garage when in use, so it can blow all of the fine dust it wants into the outside air. So it passes a lot of air.