Dust Collector pipe question

[Splinter]

This is like my DC.. http://www.cpojettools.com/products/710700ck.html

It is a 2HP 1200 CFM at 4" DC machine. Now for the questions.....

I can remove the y (for 2 4" ports) at the machine and it has a 6" port. If I was to run 6" S&D pipe out to my tools and then reduce the pipe down at each tool to 4" to connect to the tool's port would I get better dust collection than leaving it at 4" and running all 4" pipe?

I will probably have a short piece of 4" flex at each machine to get the pipe to the DC port.

I have 4" blast gates at all machines and only run one machine at a time with all other blast gates closed (If I don't forget to close one).

[GeorgeL]

Dolan,

Absolutely. A 6" main would be much more efficient than a 4". Some say to run 6" all the way to the machine and increase the port size to 6". I have a similar Dc from Penn State and went your route with 6" S&D mains with 6" drops to the planer and miter saw, 5" drop to the jointer and 4" drops to the lathe, table saw, band saw and router table. The biggest bottleneck you will find in your system is the 5" outlet from the blower to the filter. I increased mine to 6" and it made a world of difference. Also look for good flex hose that is nearly smooth on the inside to eliminate friction. I went with Wynn Environmental and am very satisfied.

George

[Bas]

What George said. I used 4" PVC all the way, but that's because (a) 4" is cheap and 6" is expensive and (b) my DC isn't powerful enough for 6" (velocity would drop too much). But if I ever upgrade to a better unit, I'd redo the pipes.

[Alan in Little Washington]

Run 6" all the way. Look at the inlet, and if there is a screen or something similar blocking the inlet, remove it (unless you have plastic impeller). Enlarge your outlet. Enlarge your blast gates and machine ports to 6." See my comments about stepping down duct size your DC Pipe Layout Tool thread.

Other notes- that blower has only a 12" impeller and that CFM rating is given for 4" pipe (likely measured with no reasonable resistance) so is likely much less than stated when in operation as part of a system. It should do fine in a small (to medium?) hobby woodshop, but won't do it for a larger shop (or with long/convoluted duct runs.) You would be better off discharging directly outside (if you live in the sticks), outside to a bag system, or adding a separate cyclone and a cartridge filter. Despite claims to the contrary, cartridges in a system like the Jet will become impacted with dust and quickly lose efficiency. That is why most of them have some sort of beater bar rig. The whole purpose of a cyclone is to separate out the dust and chips so they do not clog the filter (of whatever type).

Remember, flow is affected by inlet resistance (machine ports, blast gates, ductwork design, etc.) but is affect just as much or more by stuff on the other side of the blower (clogged dust bags, clogged cartridge filters, ductwork, etc.)

You can upgrade your system to a cyclone at any time using your existing DC blower. It can be added to either the inlet or outlet side of the blower and does not need to be the typical motor/blower-over-cyclone stacked system as sold by Oneida, Grizz, Clearvue, etc. (most also sell just the cyclone unit w/o blower). My cyclone is configured in a push-through mode- I added it downstream from a motor/blower unit from an old, bag style, Griz DC.

For those who haven't visited my shop, here is a pic of my DC and cyclone. I finally found my DC and cyclone construction pics on my old computer so will upload them later and start a separate post for those who might want to bend some metal and build one someday. (yes it is tall! This version of the Pentz design cyclone has a cone length 3X the diameter of the cylinder. Clearvue and others based on the Pentz design are typically 1.64X. 3X is purportedly better at separating the fines?)