Replies

1. 
   Walker1 | Aug 19, 2005 06:41am | #1

       850 cfm. will do just fine.   I have a 1hp. GI. 750cfm. DC. in my shop, hooked up to my cab. saw, and it more than keeps up. I move the hose to whatever machine I'm using. The unit is on casters, so it's easy.  I could have bought a bigger one, but I'm not sorry I didn't.  I even roll it outside, when I feel like working outdoors.

                       Cheers.                                       Walker1  

2. 
   herg | Aug 19, 2005 02:55pm | #2

   I had the Penn State 750 cfm model and it worked great on any single tool.   The 850 will do just fine .

   Roger

1. 
   daryl | Aug 19, 2005 04:53pm | #3

   The 850 will work for a while, but the real issue with good DUST collection is how you get it. When I capitalized dust, it's because those moveable collectors are really chip collectors. The real dust, the sub micron stuff is the dust you need to catch, but rarely do.

   The optimal solution is to first change the source pickup. If you are using a contractor's saw, with an ampty bottom, then pick up the bottom falling dust, using a 6" hose--that's right, 6", 5" is the minimum, 4" is really useless. Keep the flex to a minimum if you can. Also, don't forget to grab the dust from the guard, especially when ripping. That's where most of the dust comes out--you really can't get bigger than a 2 or 3" hose there, but enlarge it to as big as you can after that.

   The collector, rated at 850 CFM, will probably give you 450 after you hook everything up. That's because the ratings are measured with no hoses attached, and an empty filter bag. The problem is an empty filter bag filters nothing; when it gets caked up with gunk it will filter better, but then your real CFM goes down the drain. You add some good rigid pipe, at 6", you get some good movement. You add an elbow, it goes down, you had flex, it goes down by a factor of (literally) nine.

   So pick up everything with large hoses, as rigid as possible, use a cannister filter if possible, the biggest collector you can-a cyclone, especially by Oneida or Woodsucker-and you will see a dramatic difference. I converted from a Penn State with 4" flex to a permanent Woodsucker 2HP cyclone, using 6" metal ducting, and flex hoses at teh connections only. For the temporary connections, I used quick disconnects. All the flex and ducting was from Oneida, which makes great equipment. The Woodsucker configuration suited my shop more, but Oneida clearly has the best service. The Woodsucker does work great however, I now have a very flexible setup, and no dust.

   The ultimate is probably the Felder. It runs something like $3,000, but works like nothing you've ever seen. Sorry to run on so long, but I spent months on this before installing what turned out to be great.

3. 
   PlaneWood | Aug 20, 2005 05:06am | #4

   You didn't mention a planer.  IMHO, you need 1200 cfm for most 12" planers unless your just doing finish planing with a bench top unit.  Bigger planers will require more air.

   I put mine outside in it's own little house.  Punched two holes in the shop wall for blast gates.  MUCH less noise and the residual dust goes outside and not inside!  The down side of that is that it sucks my cold air outside!!!!!

   PlaneWood by Mike_in_Katy (maker of fine sawdust!)
   PlaneWood

4. 
   Dave45 | Aug 20, 2005 05:23am | #5

   The 850 cfm should work fine if you keep your hose runs short and fairly straight.  If your budget can stand the strain, however, I would recommend an 1100 - 1200 cfm unit.  It's almost a sure bet that you'll eventually want to hook up more than one machine and the extra capacity will be there for you.

   I have the Jet 650 cfm unit and have been kicking myself for the last two years for not getting a bigger system.

5. 
   jericho | Aug 20, 2005 12:27pm | #6

   hello tom,

   you've received the best advice in that others are having success with a similar unit in a similar way. just as a matter of reference for future cfm needs you might look at http://www.airhand.com/designing.asp   . this is Air Handling Systems. you get a good feel for what cfm requirements are needed for what size dust port on what type of machine.

   jericho

6. 
   SaltyDawg | Aug 20, 2005 04:42pm | #7

   As to your DC questions: I've had a similar Grizzly DC for over 12 years and have been reasonably happy with it. I don't remember the CFM rating but it has a 1.5 HP motor. One BIG upgrade was a better upper bag. Installing that really made a big difference in its performance. I run 3 lines to different machines and use blast gates at each machine to control suction. Another must is to use plastic pipe for as much of the ducting as possible. Flexible tubing is great but the coils create turbulence inside which tends to reduce the overall performance. Duct Tape also closes small leaks and every little bit helps. No DC will ever be 100% but mine does well over 90% so I'm satisfied. Good Luck.