Dust collector system design

[Arlin Eastman]

It's always a guess to say whether something like this will work, but that seems to be enough collector for what you want. With a 12" impeller and a 2HP motor, it should draw adequate air. One thing about your design that might bite you in the butt is the 4" drops feeding the 6" trunk line. There needs to be enough air in the 6" to carry the chips/dust, especially across 36'. What i'm queasy about is whether the 4" drops will allow enough air for that to happen.

I am with Fred with this.  36' line is a very long like for 2hp.

[fredhargis]

I'm still learning about all this ... I kept seeing mention of cyclones, and thought they were an alternative to a filtered separator.  Now I realize a cyclone is a pre-separator that is upstream from the separator. Correct?  Contrary to what I said before, if I add an $890 Oneida cyclone to the system, I could probably vent the exhaust out of the building, and I'll have a much better performing system.  The additional expense would be less than a new 3 hp separator. But does the cyclone incur an additional static pressure loss that outweighs the improvements of a cleaner filter and open venting to the outside?

Correct, most of us do not consider the filter a separator so our language is getting in the way. A separator will allow you to vent out without concern of a huge pile of chips next to your building. It also increase the SP loss considerably whether that outweighs the direct vent gain is purely a guess. You don't have to add an Oneida $890 cyclone, there are a lot of other (cheaper) options from a trash cover (not my first choice) to a Thein to an e bay cyclone to a shop built unit.

[Ken Vick]

I'm designing a dust collection system for a new wood shop my son is building in a new makerspace.  He has a 2 hp Delta 50-761.  The plan right now has two 6" horizontal lines - one is a 36' line going to the table saw and chop saw, and the other is a 15' line going to the jointer and planer.  Then there will be 4" drops to the tools.  It will all be with 26 gauge galvanized steel.  I'm making the lines as straight as possible, and using 45 degree bends (not 90) wherever possible. The lines will be 11-12' above the floor (the building is 15' high). Does anyone know this machine enough to tell me if this design sounds adequate?

Ted, another thing to consider if you are thinking about venting the fines outside and especially with the 3HP cyclone you are considering is that in addition to the fines, you will be venting a lot of noise.  If you have neighbors within a hundred yards you are likely to get complaints.  DAMHIKT.  My 5 HP Clearvue was due for new filters (after many years of use) and I decided to try venting outside..  I cut a hole in the block/brick wall and ran the ducting to the outside.  When I cranked up the cyclone I was astounded how loud it was outside even with hearing protection.  At my property line about 130' away it was still very loud.  So I knew if I kept it this way I would need to restrict use to when people were away at work.  This was a nuisance since I like to work on weekends and evenings but i am retired and so using the cyclone during weekdays was doable for a while at least.  The neighbor who complained said she could hear it in her house about a hundred yards away with the windows closed.  I don't doubt her.  Yesterday I ordered 2 new filters ($400+, ouch).  I have lived here almost 5 years using filters with no complaints so for me the "venting outside" failed.  I loved the performance of the cyclone without filters, noticeable improvement but keeping on good terms with your neighbors is more important than a little better efficiency out of the cyclone.  BTW, there was only the tiniest bit of wood dust on the ground at the vent even after hours of sanding shop sawn veneers with my dual drum sander.  So if you don't have neighbors, vent outside.  You'll be happy you did.  Ken

[jteneyck]

I've been down this same path with my 2 hp DC.  It was only rated at 1200 cfm but was OK (likely 700 - 800 cfm where I needed it) with the bag filters until they would start to load up.  My longest run is about 30 ft through a 6" smooth metal duct to a 5" drop to my RAS.  But the bags would load up very quickly with fines, flow would go down substantially, and then chips would jamb up from the planer.  So I added a cyclone and all was better for a while even though the static losses went up by about 4".  Then I tried adding a large BS with 2, 4" drops.  It wouldn't keep sawdust from building up in the lower wheel housing so I had to do something and didn't want to buy a new DC system.  I ended up doing pretty much what TDKPE did.  I go rid of the bags, mounted the DC fan assembly straight onto the top of the cyclone after enlarging the opening to match the inlet of the cyclone, around 8" dia. IIRC.  I upsized the outlet from the fan from 5" to 6" and vented it with a short length of flex hose outside.  As Ken said, it's noticeably noisy, but I have no neighbors behind me so it's fine.  

My opinion is you will get the best performance w/o a cyclone, increase the size of the bags, and keep them clean.  Basically, keep to your current design but increase the size of the bags.  If you add a cyclone the bags will stay clean a lot longer but your static losses will increase substantially unless you mount the fan housing directly to the cyclone and upsize the fan inlet. So I would start with basically what you propose.  I would measure the static pressure at each machine and put an ammeter on the motor, and see how the numbers change as you open/close gates and with run time between bag cleanings.  Plug ups in the ducting and dust build up in the machines will tell you when the static pressure and amps are two low, meaning you need to clean the bags before you reach either threshold value.   

John

[tedrussell]

Thanks to Arlin, Fred, Ken, John, and of course TDKPE, for the great info. Didn't realize you had all replied because I'm new to the forum and didn't see we're now on page 2.

As you can see from a second post I made, I've found a 3 hp Oneida cyclone, and once I replace the bearings and rewire to 3-phase (or get a single phase 3 hp motor for it), I should be all set.

The building is in an industrial area, but there are houses across the RR tracks that might hear the noise. We'll probably just go with collecting the fines in the filter bag for now.