Dust Collector Pipe Reduction

[TDKPE]

Just so you know, I opened the inlet on my HFDC to 9”, and sat it on top of my 18” día. Pentz cyclone.  Moves a lot more air with some of the restriction removed, but it’s still below the 16A I think that motor is rated for.  Though without a nameplate, it’s kind of hard to tell what it’s actually designed for.  

[jteneyck]

Here's a photo of what I did.  DC fan connected directly to the cyclone with the opening enlarged to be equal with the cyclone outlet.  



The 6" outlet hose goes to a plywood box with a vent window inside:  



My cyclone was repurposed from an industrial vacuum cleaner system so it's sub-optimal, but it still captures all but the finest dust:



John

[Mike in kc]

The most important issue when selecting Ducting, is what the velocity of the air will be within the ducts will be.   There is a minimum air velocity, below which the "dust" will not remain suspended in the air flow.   

Basically, with a given number of blower CFM, the velocity becomes faster as the duct diameter is reduced, and vise versa.   I apologize that I can't remember that minimum velocity number, but its been at least fifteen years since I looked at the issue, but hopefully someone here can address that issue.

I built my Cyclone, added a Neutral vane,  welded up the impeller, and built the blower.   The Cyclone plans came from plans in Wood Magazine probably 2002 or so.  

[TDKPE]

Well, since we're showing ours, here's mine.  Cover the kids' eyes.

18" dia. Pentz design, which is what the Clear Vue is based on, I believe.  Center tube is 9" dia, though it looks smaller in the picture, and the "2 hp HFDC" blower inlet was removed and a 9" inlet made to match it. 

   

   

   

   

After building it, I moved it to the other end of the shop and added a really long run of 8" flex to the casement window.  Not ideal, I didn't want to rearrange the shop or tee the duct network to handle the lathe also. 

   

What nobody has ever noticed is that my inlet and outlet are on the same side.  OK for a small blower, but not so good if I upgrade to a larger one, as the spiral air flow inside the cyclone separator has to reverse rotation direction when it hits the blower wheel.  

[SpiderDave]

Thanks fredhargis, I wanted to make sure that by the time my pipe reaches the tool it wasn't a disappointment after all this.  I'm learning a lot about my choice of words here.  By DC unit, I meant the entire set up rather than just the motor but I see where 'I' went wrong.  Sorry about that, not to brag but I can do some pretty impressive things and I still find difficulty explaining simplest things.  Especially when I'm not standing in front of a person, to show them.

WxMan, yup the more I learn the less I know with this project - bewildered indeed.  I started wanting the same HF blower you have.  But this one was practically free, so I thought at the time I was halfway there. Little did I know, it got complicated. Trying to get it right (and ask questions correctly) has really slowed things down.  Feelin' like I'm close. I bet you're glad you finished yours, ha!

I've been searching for 6" pipe lately of pretty much any kind, and it's like they know people use it for a DC.  PVC or ABS or sewer pipe has a dramatic jump in price between 4' - 6" and not on stock - special order only.  I was thinking of at least making nice swooping bends myself with the smooth plastic type of pipe and use metal duct for the straight aways.  I gotta try, but sometimes I think I may be trying too hard to get it all dialed in optimally.

[R Clark]

It's all good.  And, yes, I am glad the system is in operation.  It may not ever be finished, but it's in operation.

As for ducting, I bought 30 gauge snap-together HVAC duct from Menards.  For the bends, I bought the the duct fittings that adjust from 0-90 degrees of bend.  Most of those bends are two of those fittings at 45 to make a longer, more gradual direction change.

I just couldn't see my way clear to pay for the special-purpose DC piping available.

Like I said, it works.

Good luck on completing your system.

[jteneyck]

It's all good.  And, yes, I am glad the system is in operation.  It may not ever be finished, but it's in operation.

As for ducting, I bought 30 gauge snap-together HVAC duct from Menards.  For the bends, I bought the the duct fittings that adjust from 0-90 degrees of bend.  Most of those bends are two of those fittings at 45 to make a longer, more gradual direction change.

I just couldn't see my way clear to pay for the special-purpose DC piping available.

Like I said, it works.

Good luck on completing your system.

Not throwing stones at what you did, but suggesting others proceed with caution about using 30 gauge metal ducting.  If your DC produces can produce 10" or so of static pressure it will likely collapse straight lengths of 30 gauge, 6" duct.  A 2HP HF unit won't likely do it, but 3HP units are getting there and 5 HP ones will do it for sure.  

John

[SpiderDave]

Not throwing stones at what you did, but suggesting others proceed with caution about using 30 gauge metal ducting.  If your DC produces can produce 10" or so of static pressure it will likely collapse straight lengths of 30 gauge, 6" duct.  A 2HP HF unit won't likely do it, but 3HP units are getting there and 5 HP ones will do it for sure.  

John

Thanks for the warning John, I knew it could happen but honestly hadn't really given that much consideration with my 3HP unit - until now.  I already bought some overstock ducting that was super cheap, so I'm kinda stuck with using that for now.  It would've been disappointing to watch the straight aways go 'boink' when I turned it on.  Thanks for bringing that up!  I may just roll out some flat tapered rib supports to put along the inside of the ducting before I snap it together.  Maybe a smooth rivet at the bottom to hold it in place as well.  I'm thinking 2 (or 1 in middle) on each section should hold up.  Unless someone has a better method?