Dust collector vs. shopvac

[bob buttons (Unregistered Guest)]

I was wondering what everyones experiences with these 2 systems are. i have a 6.5 hp shopvac 18 gallon. it seems pretty powerful but doesnt really get all the dust for us. I see that a lot of people have the dust collectors with the top/bottom bag design. the 2 bag systems have a CFM rating of 600-1200 for 1-2 horsepower models. my shopvac has 6 HP's and from what i have found a CFM rating of around 120 approx. is HP's more important than CFM's??? has anyone used both for a fair assessment? thanks!!!

[sheldon@dingwallguitars.com]

We have a large and small shopvac, 1 hp double bag, 2 hp double bag, 1.5 hp onieda cyclone and are building a 3 hp ambient air collector.

HP is misleading. The four most important factors are cfm, static pressure rating, filter efficiency and filter sizing. If you're producing a lot of chips, a cyclone is helpful, if it's mostly dust, you just need a bag.

The bigger Shopvacs seem to have a pretty decent static pressure, but they clog up fast.

Most of the "name brand" taiwanese dust collectors are pretty similar and better built now than a few years ago. Most suffer from bags that are WAY underdesigned. Even the ones that advertise a 1 micron rating. If you buy a 1 hp, you'll soon wish you had bought a 2 hp. Either way, expect to upgrade the bags with some Onieda units. They'll not only collect the finer particles more efficiently, but they'll also be less restrictive which translates into more cfm.

[stevem]

WOW, Sheldon, you must make a lot of dust to need all those dust collectors.

I am currently researching cyclones. How has the Onieda worked for you?

[evan]

Bob,
I've got a 3hp Onieda, and two Fein Vacs.
the Onieda web site is very informative www.oneida-air.com (http://www.oneida-air.com). I'm glad I spent the money my shop is vertually dust free.
EMC2

[ron brown]

Bob,

Have you ever put an "AmProbe" or watt-meter on your "6.5HP Shopvac"? To produce 6.5 HP at 120 V it takes 40.4 amps before losses. I'd be willing to bet beer for next years Jamboree your "6.5HP Shopvac" pulls closer to 10 amps than 40 amps.

BTW - grab your watt-meter before you brag on the 3 1/4 HP Poter-Cable or those big HP "SkillSaws" too. Vacuum slesmen aren't the only tool salesmen who like to stretch the truth.

Ron

[mrdovey]

Bob...

You can look over my DC setup in detail at http://www.iedu.com/DeSoto/dust_collection.html

I think the more important number is the CFM.

...Morris

[kivimagi]

Help me with my physics here:

Could a reasonably cheap 1/3 hp motor, generate a large CFM number? The motors typically rotate at about 1700 rpm, and it seems like you could increase this with a larger diameter wheel on the blower.

[ron brown]

Ryan - and all,

Here is the reference page I use for dust collection information:
http://cnets.net/~eclectic/woodworking/cyclone/BuildCyclone.cfm
There are many things to consider. If your health is important, you will collect the dust.

Ron

[erik_f]

I think I saw it on here...and I tried it...and it works great...on Amazon, there is a company that makes covers for a 30 gallon steel garbage can...they turn the garbage can into a cyclonic dust collector...all you do is run the garbage can before your dust collector...someone one here said they were using two...and they ended up with almost zero dust going into the bags the actual dust collector...so gave it a shot...and it freakin' works like a charm...even with MDF dust, most of the dust ends up in the first one...with a little in the second and almost zero in my dust collector...My dust collector is a small delta it was around $130 the Woodstock things were $20 each and the garbage cans were $15 each...so I figure for around $200 I got a simple and effective 3 stage dust collector...oh, and emptying those cans is just a matter of popping the lid off and taking out...unlike the bags which are a pain to get off and on.

[kerrazy]

Bob,
I ran with a rigid Shop Vac initially. Worked real well, with the exception of having to dump it regularly. Then I attached it to my 3HP shop dust collector. works just as well. I too have put one of thase cardboard barrels inline with my dist collector and a woodstock cyclone head, I am very pleased. I intially had the hoses reversed so it did not do as suggested. I also found a barrel works better than a garbage can I believe do to height.

Dale

[sheldon@dingwallguitars.com]

SteveM - we make a lot of dust, there's no getting around either a lot of smaller collectors, or one really big one (we don't have the ceiling height). I like the Oneida, but it's one of the older ones with the internal cartidge filter. It's a real pain to disassemble the machine every week to clean the filter - especially for the kid I hire to do it ; ) Shaker bags would have been much better.

Ryan - You're correct, a 1/3 hp fan motor can drive a 16" blade fan and get better than 3000 cfm. A squirrel cage maybe half of that. The problem's happen when you ask those fans to push/pull air through a filter. That's where the static pressure specs become important. A properly sized filter (polyester fabric type used by Oneida and others)will resist air flow by approximately 2-3" WC when loaded. The blade fan or squirrel cage cfm will drop to zero long before the static pressure gets to even 1" WC.

I learned this only after purchasing two 3000 cfm barn fans and 400 sq ft of cloth thinking I'd found a cheap way to collect ambient dust

[kivimagi]

Sheldon,

That makes a lot of sense. I currently have a 3 hp motor, which is 3-phase.

I'd like to find a single phase motor, or a way to use my 3-phase with a remote control. I'm not sure if I can interrupt the connection between the 3-phase ac drive, and the motor, and have it retain the rpm setting.

Thanks

[gerald_d]

Ryan, could you explain what you mean by that last sentence please?

[kivimagi]

Gerald,

I have a 3-phase motor that I'm running on single phase. I have a baldor ac drive that powers it up. I'd like to put a "Long Ranger" type remote controlled switch some where in the line from the utility box, to the motor.

The ac drive typically has an rpm setting, that resets when the power is cycled. I'm not sure if it would reset when the connection to the motor is reset or not. I guess I should just experiment with it.

[gerald_d]

Got it now Ryan. I think that you should read the Baldor book and see if sudden connects/disconnects are allowed on its output - these electronic boxes contain a canister of smoke looking for the slightest excuse to release. (The book may also tell you if you can adjust the default reset speed.)

[beacon14]

Ryan,

I use a rotary syle phase converter for my edgebander (Not sure if this is the same thing as you are referring to, but it's a large, heavy motor with some kind of magic box attached. Single phase current turns the motor, and 3-phase current comes out of the magic box). Once the converter is running, I can turn the bander off and on at will. However, I was told by the guy who made the thing that it's not good for the converter to run it without a load for any extended period of time. So if you are thinking of leaving the converter running, and switching the dust collector motor off and on as needed, that might be a consideration.

[kivimagi]

Morris,

Where did you purchase the 4" dust port on your dust skirt?

[mrdovey]

Ryan...

I bought the port (flange?) at Woodcraft Supply.

...Morris