Dust Collector branch questions.

[paul cottingham]

Sorry to belabor this, but i can't seem to wrap my head around this. I currently have 4 in. pipe going to all my machines but the router table and an auxiliary port, both of which are 2.5." Where I am confused lies here. If I move my trunk to 6", and use wyes to step down to 4 in. for the tablesaw, jointer and planer, am I any farther ahead? Or should I move to 6 in drops for those three machine to see any benefit at all?

I have read and reread Bill Pentz' site, and have read everything i can, but can't seem to grasp this.

I am using a 1200 (on paper) CFM 1.5 HP steel city DC. I have a cyclone in series with my planer only, to preserve airspeed in the system. All my ducting is 4" pvc, with very short spiral pipe to each machine.

Thanks again.

[Logan William]

I don't have any of the tables in front of me but one thing to be careful of is that as your main trunk gets larger, your airspeed decreases. You need to keep in that 4500 to 5k fpm to ensure particles don't drop out, your trunk diameter and airflow through it need to be somewhat matched up. If you're planning on upgrading to a larger collector in the near future this might be a good move, if thats the collector you will have for the near future you might have more problems with the 6" line than the 4"

[paul cottingham]

Thanks for the thoughtful reply.
So, if I'm to understand, a 4" trunk may be better for me? I am concerned about CFM, and keeping dust entrained in the airstream. Bill's spreadsheet would seem to indicate that 6" would be better, but I am an historian, and a computer networking guy, not an engineer. :-)

If 6 inches is better, I am back to my previous questions.....