Dust Collection for 15 Lathes! On a 3Hp DC - Is this even possible?

[Darcy Williams]

First, you are trying to do a good thing with difficult circumstances.

The rated cfm of 2200 cfm for the cyclone is very optimistic based upon what I have read and studied. The cyclone looks a lot like the Laguna and several other brands. These are nice machines but I would worry that the short cone will be an issue when collecting sanding dust from the lathes.

With that cyclone, trying to collect from 3 lathes at once and even if you got the 2200 cfm, your velocity in the 8" ducts will be too low to keep everything moving.

I wish there was some easy answer and I hope others can help you.

Hmm... Thanks. If i drop down to 7" on the main trunk that helps a bit... but there are scenarios where only one lathe will be collected from at a time. Which just complicates everything further!

[Chris Parks]

First, you are trying to do a good thing with difficult circumstances.

The rated cfm of 2200 cfm for the cyclone is very optimistic based upon what I have read and studied. The cyclone looks a lot like the Laguna and several other brands. These are nice machines but I would worry that the short cone will be an issue when collecting sanding dust from the lathes.

With that cyclone, trying to collect from 3 lathes at once and even if you got the 2200 cfm, your velocity in the 8" ducts will be too low to keep everything moving.

I wish there was some easy answer and I hope others can help you.

The problem with the CFM rating is multiplied by the fact that it will be the figure at 60hz and not 50hz which knocks off a considerable amount of impeller speed, about 600 RPM in fact.

[Fitzhugh Freeman]

I've been going down a similar road for our community shop, trying to get something that works with the many limitations in place. I'm glad (in a limited sense!) we don't have that many tools to collect from.

I might have missed it, but I didn't see mention of the air velocity required to keep ducts clear. 3500-4000 fpm is what I have seen most often, both in articles and codes.
In our community shop running a 2hp Delta our ducts do collect stuff, and we've had them get totally impacted in the past (we removed that branch in the end. My best estimate is we were moving only about 1300fpm in the 6" mains, and less on the most troubled one.

Size ends up being a matter of finding the sweet (or least sour) spot between keeping velocity up (smaller duct) and not choking of the flow (larger duct).

Bill Pentz's static calc spreadsheet was really helpful ( even though it didn't give the answer I really wanted!)
There are for sources, like https://www.airhand.com/designing/#size

You may well have already read up on all this.

[John Spitters]

The estimated cfm of 2200 is totally unrealistic, I have a 3hp cyclone with a 15 1/2" impeller and its stated specs are much closer to the real numbers, the real cfm #s are always lower once your filter medium becomes impregnated with the dust fines. A good cyclone design will reduce this effect, however it is still the reality.
The following are the stated numbers of my 3 hp DC.

SPECIFICATIONS:

Motor: TEFC Class "F", 3 HP, 220V, single-phase, 22A
Switch: Remote controlled magnetic
Intake hole size: 8"
Bag material: Plastic
Impeller size: 15-1/2" steel, riveted
Air suction capacity: 1654 CFM @ 2.0" SP
Maximum static pressure (inches of water): 14.2"
Filter: 99.9% efficiency captures 0.2-2 micron dust particles
Filter surface area: 113 sq. ft.
Collection Drum: 55 gallons, steel