Laguna 2hp dc cfm discrepancy...

[Derek Arita]

When I purchased my Laguna 2hp DC from Rockler, their tech info said that the machine was rated at 1600cfm. Compared with the JDS at 1700cfm, there was little difference. At a lower cost and added features, I went with the Laguna. After the DC was assembled and tested, I took a look at the machine on the Laguna site and found that they had it listed at 1450cfm. I then checked the manual and it said the machine was rated at 1600cfm. I called Laguna to informed them of the discrepancy and find out which was correct. They said they'd call me back after investigating the issue...they never did call back. I called again, got the same answer, but no call back.
If, in fact, the Laguna is rated at 1450cfm and had I know that from the start, I might have gone with the JDS unit, even at the higher cost. If you're trying to make the same decision that I was faced with, beware that the 1600cfm rating on the Rockler site and in the manual, may not be correct. By the way, Woodcraft has it rated at 1450cfm. Sure wish i knew the correct number...just for info sake.

[Wade Lippman]

CFM is understood to be plus or minus 60% at best. (well, never plus, always minus).
But seriously, one could be with filters and the other without, or 8" versus 6", or a variety of other things.
There is no "correct number"; saying it is "rated at 1600cfm" doesn't mean anything.

[J.R. Rutter]

A 2 HP blower is going to struggle to give real world performance above 1000-1100 CFM regardless of manufacturer. They must test them to destruction.

The fan curves that I have seen for straight radial impellers are not much different.

Courtesy of the small shop DC guru, Bill Pentz:

http://billpentz.com/woodworking/cyclone/images/BlowerFanTable.gif

[Ole Anderson]

Fan curves can be quite accurate if you know the conditions under which they are tested and the accuracy of the equipment and the experience of the operator. But then that is the way it is for pretty much everything. There is way more to performance of a cyclone than just maximum air flow. You really need to have a full range fan curve that you can trust. My 2 hp Oneida Super Dust gorilla has two different fan curves on the same web site so don't get too upset. What type of machine are you trying to collect sawdust from? Most machines, including table saws with top and bottom collection as well as drum sanders don't require much more than 800-1000 cfm. It is often your ductwork and machine dust hoods that limit your airflow. Look for a machine that delivers 800 cfm at 6-8" of static suction and you will be good for most small homeowner shops as long as you plan on running only one blast gate at a time. Now with 800-1000 cfm, you can get by with most 2 hp cyclones as long as you stay with short runs of 6" pipe, or go with a 7" main if you have longer runs. If you want to go with 6" PVC on your collection system and have a somewhat elaborate piping system, then you ought to go with more horsepower.

[Wade Lippman]

He says that a 15.5" impeller will burn out anything smaller than 7.5hp. The Grizzly 3hp has a 15.5" impeller. While a cyclone has some resistance, it must be less than a thick cake on a filter. Can you explain this?

[David Kumm]

He says that a 15.5" impeller will burn out anything smaller than 7.5hp. The Grizzly 3hp has a 15.5" impeller. While a cyclone has some resistance, it must be less than a thick cake on a filter. Can you explain this?

Wade, a system with duct, cyclone. and filters is going to have resistance in at least the 6-8" SP range so you have to start there and work towards higher SP to see the working range of the impeller. A cyclone will add 2-5" sp and the filters aanother 2-5" so you can quickly get into the 10-14" range depending on your ducting, bends, etc.

Straight radial blades will differ quite a bit at higher SP. They will definately burn out a motor if not sized correctly but will provide more cfm at higher pressure. I run a straight on a vfd to regulate speed as my ducts are long and the blower and filters are some distance from the cyclone. Generally a BI or BC impleller will not overamp a motor unless run without anything in front or behind it. The blower and motor are matched so as not to allow a buyer to burn things up. Dave