Help me fine tune this DC piping?


bleedinblue

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I'm not sure there is much to be done though...

I just added this hard pipe.  Since I pieced this DC unit together a couple years ago I have just been dragging an expandable Rockler hose from tool to tool and the suction has been sufficient enough to help with the mess. 

The entire run is only about 12 feet.  The blast gates are aluminum. 

The pipes are just friction fit together.  I don't feel any leaks.  My hand test tells me I'm losing maybe 30-50% of my suction compared to the blue hose connected directly to the cyclone. 

Should I tape each pvc joint to make sure there are no leaks?  Is there anything else I can do? 

20181030_163605.jpg

20181030_163552.jpg

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I would  definitely put aluminum tape on all the joints.  Its a good way to go in the event you want to take it apart someday.  You will have leaks at all your joints, if you check with smoke you will see but you won't really be able to feel it with your hands.

I didn't tape mine when I first put it in but went back a month or so later and there was some improvement.  The tape isn't that expensive to not do it in my mind.

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A straight run the last 6 feet or so ahead of your cyclone is supposed to work better.  Given the picture is there any reason you couldn't lower that horizontal to the level of your blast gates and tap right off the wyes?  That would save you a 45 degree bend and some captive air weight.

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15 minutes ago, gee-dub said:

Given the picture is there any reason you couldn't lower that horizontal to the level of your blast gates and tap right off the wyes?

This was my first thought.  And, if you could keep it directly at level of the inlet to the cyclone, you could then rotate the conical part of the cyclone slightly so it would go directly to the pipes - eliminating at least a single 45.

 

 

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I tape the joints on our ducts with clean release painters duct tape.  It will come off a couple of years later with no problem.  I first taped everything up with real metal duct tape, but it was a pain to cut everything loose the next time we moved.  It says clean release 14 days outside, but it's several years inside.  Home Depot used to sell it, but quit a couple of years ago.  I always keep some on hand for various things.  Any time you want to use duct tape, and get it off later.

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/Scotch-Tough-Duct-Tape-Outdoor-Painter-s-Clean-Removal-Tough-Duct-Tape/?N=5002385+3293369434&rt=rud

Looks like it may have been replaced with this stuff:  https://www.homedepot.com/p/3M-Scotch-1-88-in-x-25-yds-Tough-No-Residue-Painter-s-Duct-Tape-2425-HD/100653893

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I had originally planned on keeping the main run the level of the cyclone inlet.  I changed my mind last minute because I thought it may feel too cluttered.  If this design doesn't work out, it shouldn't be too difficult to go back to the original plan. 

I'll look for that tape the next time I'm at Home Depot Tom, thanks. 

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What diameter is you main line?  The intake to my SDD is 5", when I first ran my duct work I bought a short piece of 6" and 5" and compared the CFM between the two.   The 5" was better than the 6", so I ran a 5" main.  Of course that is with my HF unit, so it might not make that much difference with a larger DC.  I did my testing with a hand held anemometer and it wasn't very scientific, but it did convince me.

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1 hour ago, Chestnut said:

I'd consider bringing your solid pipe closer to the tool and try and use less flex. 12" of flex vs 36" of flex is a big difference. Or i guess in your case 5' vs 10' :P

Yeah, I dropped the flex from each blast gate just because I was less than confident on the fit between the pvc and blast gate.  I had to wrap the blast gates with black tape to get a friction fit.  Because that connection would be difficult or impossible to tape to get a good seal, I wanted to minimize those connection points.  I may still add in sections of solid pipe if I need to squeeze out a few extra CFMs though, just to check for improvements.

1 hour ago, Just Bob said:

What diameter is you main line?  The intake to my SDD is 5", when I first ran my duct work I bought a short piece of 6" and 5" and compared the CFM between the two.   The 5" was better than the 6", so I ran a 5" main.  Of course that is with my HF unit, so it might not make that much difference with a larger DC.  I did my testing with a hand held anemometer and it wasn't very scientific, but it did convince me.

It's all just 4".  The inlet of my cyclone is 4" and my unit is a (stock) HF unit, so I didn't see a reason to go bigger.  If I was smarter and gone with the dust deputy XL instead of this steel cyclone, I would have tried to go bigger.

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I think you will gain significantly if you lower the main.  I have mine about 36" above the floor - saved all the length of going up and then back down.  Important with smaller DC units.  That will also decrease the length of the flex duct (big source of drag) at each station.  I hang my various sleds and jigs on the wall above the main.

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Another tip.  My DC has some cross bars in the inlet pipe. Presumeable to stop larger pieces to prevent damge.  Occassionally the inlet will plug up there.  So I have a short (12") section of flex right at the inlet so that I can easily remove it to unplug the inlet.

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  • 1 month later...
17 hours ago, bleedinblue said:

I tweaked it, ya'll were right.  It wasn't nearly as difficult as I thought it would be, either.  I bet suction has increased 50% at least.

Good to hear.  Now you make me want to uncoil that rat's nest that I have way too close to the blower intake ;-)

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