Unique dust collection question

[Michael Koons]

I have upgraded a few tools in my shop lately and it's put me in a bit of a dust collection conundrum. My old 1 HP canister is obviously inadequate for some of my tools. Right now I'm wheeling it around my shop and it's becoming a pain in the neck.

I installed 4" PVC pipes for dust collection 10 years ago to my tool stations. I now know this was wrong and my current setup is not how I'd do it today. I will be moving from this house and shop in a few years and I don't want to change this set up since it will be temporary.

My question is... Can I upgrade my DC to a 3HP canister, attach it to my current system and have it work well enough? I know if I were to do it all over, I'd buy a cyclone and put a duct system in that was ideal, but I can't do that at this point. My 4" runs to the big tools (jointer, TS, planer) are all very short. The longer runs are to the router table, band saw and other small machines.

Basically, I want to throw HP at the problem to overcome my bad duct design. I'm not in a position to buy a cyclone today or in the near future due to time, space and budgetary restrictions.

PS - This group helped me with my TS decision recently and I went with the MM SC4 Elite. It arrives on Friday and I will post pictures, my decision making process and my experiences when it arrives.

[Jamie Buxton]

The trouble with 4" ducting is that there is a limit to how much air you can suck through it, no matter how hard you try. It's the soda straw effect: the small diameter makes so much friction inside the tube that not much air flows. The upshot is that a 3 hp sucker won't pull much more air through a long 4" duct than a 1 hp sucker.

If you can afford the 3 hp sucker you're considering, you might get one for wheel-around duty now, and bolt it down when you get a 6" duct system. For instance, Oneida makes wheel-around 2 and 3 hp cyclones that are only six feet tall. Their footprint is 33"x48", which is likely a bit bigger than your 1 hp canister system, but that's what you'll get in a bigger sucker. Or JDS makes wheel-around 2 and 3 hp systems that I think of as half-cyclones. They're a little over five feet tall, with a 28x40 footprint. I call them half-cyclones because they have rather short cones on the cyclones. The short cone removes less dust from the input stream, so the system depends more on the canister filter (kinda like the all-canister system you have now). To help keep the filter clean, they include an automatic flapper on the inside of the canister.

[David Kumm]

It depends on the impeller type you use. Traditional DCs are low pressure blowers while vacuums are high pressure low cfm blowers. Higher HP and larger diameter blowers will pull more cfm through a given size pipe. A straight blade will pull more than a backward inclined one. I tested a 5 hp blower and got up to 9000 fpm through 4" pipe but the run is short. If you could upgrade even a section of the main to 6" it would help your flow. If not you need to look for the blower that delivers cfm at high SP. 15+" or more. Dave

[Michael W. Clark]

You can certainly pull more air through the 4" with a bigger motor/fan, but it will take a much bigger motor/fan than you think. If you don't change the system, the required power is the cube of the flow increase. Theoretically, you could increase your flow 45% by going from a 1 hp to a 3hp motor. A 300% increase in power for a 45% increase in flow. Note that you cannot just put a larger motor on the same fan, this will have little/no effect unless you turn the fan faster. You will need a correspondingly larger fan.