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Thread: 5in Flex or 4in DWV pipe?
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14th June 2013, 05:07 PM #1New Member
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5in Flex or 4in DWV pipe?
Hi fellow woodworkers, Im just about to connect my DC3 to my machines and I had everything figured out till I read all the info on here and Bill Pentz website. I was going to run all 4in Pipe to the machines but after what i read it probably wont cut the mustard. So i was thinking what if i take the wye of the DC and run 1 5in flexy straight to the machine it would have a run of about 4m or 5m max and just have a quick connect so i can move it between the machines which at the moment are a bandsaw, tablesaw and a jointer. I will eventualy change my machine ports to either 5in ones or put in another 4in so there will be 2. Just wondering if the 5in flex pipe will cause too much turbulence and would it be more efficient using solid 4in but having a obviously longer run due to it being plumbed to all machines?
Thanks
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14th June 2013, 07:05 PM #2.
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Sorry but 5" ducting won't meet the BP specs either.
Have you read my thread on the generic 2HP DC and how I modified it?.
In principle 5" smooth walled flex will be better than 4" PVC duct but then the choke point on the DC3 will be the 4.5" entry to the impeller.
The maximum flow using a 4.5" entry is 567 cfm - remember this is with no ducting or flex added, any 5" and especially 4" ducting you add from here onwards will send the CFM backwards.
If the 4.5" is opened up as per my thread to 6" then the choke point becomes the 5" flexy but you will then at least get about 700 cfm and adding more 6" ducting wont send the CFM backwards so quickly.
Ideally the 5" flexy between the impeller and the bag housing should be removed on these 2HP DCs and 6" ducting used all around. This will get around 840 cfm with a needle felt bag.
This all assumes you have 6" outlets or multiple 4" outlets on all you machines.
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14th June 2013, 10:57 PM #3... and this too shall pass away ...
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Jonno,
Bob is our resident dust extraction expert. His advice is solid.
As Bob said, you really need 6" pipe everywhere to get satisfactory air volume and velocity. I recently upgraded my machine ports to 6", or to take three 4" ports. Doing this makes a huge difference to dust collection effectiveness, but to many fail to do this, so they choke the airflow at the machine. My upgrades can be seen at https://www.woodworkforums.com/f200/m...66/index6.html
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15th June 2013, 01:06 PM #4New Member
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Thanks for the replies, Im gonna give the DC mod a go similar to yours Bob but it'll be out of timber because thats what i know. Also is there a limit to how much 6in duct you can use before the CFM dropping considerably?
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16th June 2013, 10:25 PM #5New Member
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So I started modifying my DC heres a few pics on my progress
photo(1).JPGphoto(2).JPGimage(10).jpegimage(5).jpegimage(6).jpegimage(9).jpegimage(8).jpegimage(7).jpeg
Because the motor stuck out over the DC base I had to fix the motor to either the wall or make a stand, so I made a stand as I was worried about vibration. Also with the stand I can still roll out the collection part if I wanted to
So all thts left to do is enlarge the intake to six inch which will be easy compared to the rest and block of the other port : )
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16th June 2013, 11:23 PM #6.
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Looks good, real good.
One question - did you leave the steel flap like this?
The reason I ask is that the air flow in that rectangle is not uniform and guess where it is fastest?
Yep - right where that flap is so the flap would cause some restriction is.
I reckon a corner is an ideal place for the DC.
Cheers
Bob
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16th June 2013, 11:30 PM #7New Member
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Definitely not, that would blow right in and block it completely, I used self tappers to pull it in flush with the side and its smooth as.
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16th June 2013, 11:34 PM #8... and this too shall pass away ...
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Looking good, Jonno. I'm sure you will do as good a job with hoods/ports etc, and it will be a nice system.
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19th June 2013, 10:55 PM #9New Member
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Just built the 6in inlet using a DWV joiner and some mdf and bolted it on, turned the DC on and WOW what an improvement I know theres no ducting yet but you can definitely see and feel the difference compared to the original, theres a mini tornado in the bottom bag and it aint going slow. Im really impressed by these simple mods, so thanks Bob for the research and testing so people like me can get a bit more efficiency out of our extractor and in turn reducing that nasty dust
image(12).jpegimage(11).jpeg
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19th June 2013, 11:05 PM #10.
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20th June 2013, 08:43 AM #11... and this too shall pass away ...
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Great work Jonno.
You and me both have reason to be grateful for all the help we get from this board.
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31st December 2020, 10:20 AM #12New Member
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Hi All, This is my first post here so be gentle with me. I bought a Hafco DC3 dust collector, a long 6 inch DWV pipe and elbows. I'm about to do the modification but I already stuck on the first and seemingly hardest step. I'm trying to translate the curve from the side of the bag holder to a 18mm plywood cut and I continuously fail no matter what method I use and I tried quite a few by now. What is the best/easiest method to make this piece? In other words, what's the best method to copy the curve from the side of a cylinder to a timber structure?
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