Dust Collector Modifications

[jteneyck]

I've had a Grizzly 2 HP dust collector for at least 15 years.  It's similar to this one:




I piped it to 6" ductwork running across my shop under the ceiling, and dropped 5" hose to each machine.  Soon after I got it I came by a small cyclone from an industrial vacuum cleaner and I installed it in front of the dust collector to collect the big stuff.  About 10 years ago I "upgraded" the stock 30 micron bags to 2 micron ones, top and bottom.  I noticed that the flow was reduced, but it still pulled everything from my various pieces of equipment so I was fine with it.  Then I bought the big bandsaw last Summer.  I ran 6" duct from the main 6" trunk to the bandsaw, installed a 6 to 4 x 4 wye connection and ran two short lengths of 4" hose to the bandsaw.  At that point, the poor performance of the DC showed itself in spades.  Sawdust would quickly build up in the bottom of the saw and some would get carried up to the top wheel as well.  Worse, sawdust would get trapped between the blade and lower wheel.  

I needed to do something and I considered several options, including just buying a new, larger DC with a canister filter.  But before I spent money I wanted to see if I could improve the performance of what I had.  I started by making a simple water manometer from a length of clear plastic tubing, and set about measuring the pressure drop at various locations.  I've forgotten all the numbers but I do remember that I only had a couple of inches of pressure drop at the bandsaw, and that wasn't going to do it.  I disconnected the DC from the cyclone and bags and ran a hose out a window.  I had 11" of water, exactly what Grizzly claims.  Note, however, that was with no bags.  When I added the bags back I only had 7"; not good.  I added the cyclone back and I was down to only 3 or 4". 

With some council by TDPKE (many thanks for the help) I took the DC apart and coupled it directly to the top of the cyclone.  I sized the opening to match the outlet of the cyclone, which was around 8" diameter.   I increased the outlet hose size from 5" to 6" and ran a hose to a nearby window.  What I have now looks like this. 



I built a manifold for the hose at the window, with an access port, so I can open/close the window as desired. 



On the outside I removed the fine window screen and replaced it with 1/4" hardware cloth.  The dust you see on the window and ground is after running the drum sander for a couple of hours; not bad and OK with me. 



Of course if I'm now blowing air out of my shop I need makeup air, so I knocked out a couple of glass blocks in the window across my shop and built a barometric damper.  It works great, and the boiler and hot water heater are unaffected by the DC.    



Now that the weather has warmed up, I'll knock out one more block and install a window like at the outlet end, and then build a larger barometric damper on the inside. 

The cyclone is short and stubby, but is actually pretty efficient at capturing even fine sanding dust:



So how does it all work?  Well, I now have about 4" of pressure drop at the bandsaw and I can resaw and cut veneer for hours w/o dust building up inside:



Performance at all my other machines is greatly improved as well.  You have to tug at the blast gates now to open them.  The motor amps. are well within the max. listed on the motor plate so there's no danger of overloading it. 

I've saved myself about $2K and that makes me happy.  The penalty is that I'm sucking cold air into my shop in the Winter and hot/humid air in in the Summer.  But I have heat and a dehumidifier in my shop so it should remain comfortable.  Time will tell but so far so good. 

John

[TDKPE]

[Jack01]

Great