Dust collector duct drop sizing

[Bill LaPointe]

Finally getting around to installing my 3hp Jet dust collector. Collector will be located in a separate room, adjacent to shop. Several questions:

Should the separator be located just before the collector or closer to the machines?

Multiple small separators at machines or just 1 at collector?

Using 6" pvc for main run about 45' max. For 4" hose, connection should 6" be used all the way to machine port with a 2-3' of 4" flex hose or come off main with 4" pvc to machine port with 2-3' of 4" flex hose. Difference is about 6-8 feet of 6" versus 4" pvc pipe. Easier and less costly to use the 4" but don't know if worth any efficiency loss.

Can't picture more than 1 machine running at a time, but since I am old I'm sure I will forget to close a blast gate or 2 or 3.....

Loss of 6" 90 deg elbow appears to be the same as 2 45's, why do most recommend using the 45's?

Thanks for any help

[Paul Wunder]

Bill,

I can speak to some of your questions:

Flex duct has 2-3X the air flow restriction as smooth pipe. Best practice is run 6" duct as close as possible to the machine port and then attach the 4" flex duct to the existing port. (of course, if you can upgrade the ports to 6" all the better). It should be cheaper this way too.

The usual way that 2 45 degree elbows are used is with a length of straight pipe in between the elbows. This gives a smoother flow of air.

Paul

[Ken Garlock]

Welcome to the Creek, Bill. Do stop by often and wade right in.

I agree with Paul. If you have the room, go with 6" PVC right up to the machine. I used 45 PVC sanitary tees to start a branch off the main main line followed immediately with a regular 45 elbow.
Also, try to keep the length of 4" pipe down to very minimum. Anything less than 6" is going to restrict the airflow.

Have fun with your new toy, I hope it really sucks.

[Eric DeSilva]

...of course, if you can upgrade the ports to 6" all the better...

I agree seeing if you can retrofit machine ports is a good idea. I popped the outlet plate off my Grizzly jointer, and found it was easy to retrofit--I just took a thin sheet of ply, cut it to size, cut a 6" circle in it, and screwed one of the plastic Clearvue 6" blast gates to the ply. I also did my Unisaw, although that was a bit more complicated (see http://www.sawmillcreek.org/showthread.php?t=137928). I couldn't do a number of machines, since they had cast iron 4" ports, but at least one of those had two ports--the cross section of two 4" ports is pretty close to a single 6". I also used a Clearvue 6" > 2x 4" manifold and some stiff 4" piping to supplement DC for my SCMS (http://www.sawmillcreek.org/attachme...5&d=1271126631), but did drop to a single 4" for my DP, since it was at the very end of a loooong 6" run.

So, my general theory has been:

1. Go 6" as far as possible, to the machine itself if you can
2. Use 2x 4" at the machine if you can't
3. Use a minimal run of 4" as a last resort.

BTW, I really liked the construction of the clearvue 6" blast gates.

[Bill LaPointe]

Eric,

I like your idea since I like to use my floor space to pile more stuff on. My saw is identical to yours except that I raised it up on a 4" platform because I am tall and it is more comfortable for me to work at. I'll see what I can do to get 6" duct to adapt as you have.