Dust collection duct system

Should a dust collection system be improved with a more powerful collector or better ductwork?

I have a 2HP dust collector in my shop. My Powermatic table saw is about 25 ft. away. I have a 4-in. flex hose with blast gates to separate each tool, like my band saw, 8-in. jointer, 12-in. planer and a lathe. There is very little suction that reaches the table saw. Should I buy a bigger, more powerful dust collector, or would putting in more rigid piping, such as galvanized, help? – Jim Raines

Chris Marshall: Whole-shop dust collection efficiency has quite a few variables to it that all impact how effectively your dust collector and ducting system will work. My first suggestion, Jim, is to get yourself a good reference book on the topic, such as Sandor Nagyszalanczy's "Wood Shop Dust Control: A Complete Guide to Setting Up Your Own System." It's an excellent primer on the factors you need to consider to improve the system you've got.

Here are a few other thoughts. No, I don't think you need a bigger dust collector. A 2HP machine should offer at least 1,200 CFM of draw — plenty for connecting to your table saw, planer, jointer and lathe. What you need are better "arteries" to your tools. If, for instance, you have a single 4-in. hose coming off of the dust collector that connects to all of your machines with branch fittings and additional hoses, that primary hose is starving all of the machines of air pressure. Add to that the fact that the "accordion" baffles inside the flex hose are also reducing airflow. So, yes, smooth-walled pipe (either metal or PVC) will increase airflow and dust collection efficiency. A larger main "trunk" line than a 4-in. hose would also help a great deal, then branch 4-in. hoses with blast gates off of that larger-diameter trunk line. Those branch lines should be as short as possible. Keep bends in the system to a minimum, too: use wye fittings and gradual bends instead of 90-degree elbows to help keep the air moving. And don't forget to close the blast gates on those tools not being used to direct suction where you need maximum air draw. If you can help it, I also would avoid running your ductwork up to the ceiling — let gravity work for you instead of against you by running it horizontally along walls, at about the height of the tools' dust ports.

These are just a few broad-stroke suggestions, but they all will help you get better performance from your dust collection system.