LumberJocks

would this work as a dust seperator?

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by Holbs posted 08-29-2013 01:10 AM 655 views 0 times favorited 10 replies Add to Favorites Watch
View Holbs's profile

Holbs

598 posts in 782 days


08-29-2013 01:10 AM

i’ll be doing my 3HP dual cloth bag Grizzly dust collection setup before snow falls (pvc or metal ducting, thein separator, 18wheeler filter casings), after I get my multiple-fliptop-pivoting-4’outfeedtable bench all situated.

something came to mind while working on an issue with my ‘88 vw cabrio air induction system and venturi’s.

what if.. using 4” pvc feed into a 55gallon barrel from the top center, with an cylindrical cone shaped object of same width (4” wide 8” tall) being sucked by another 4” pvc pipe directly underneath was used to separate dust particles. i’m unsure of the aerodynamics (it’s a science beyond me). to help visualize, i fired up sketchup.

the entering top shavings, particles should be deflected out of the airstream going around the cylindrical conical shape object from the bottom suction. or maybe the middle cone has to be larger width than the incoming/outgoing air stream tubes.

thoughts?

and yes… i could build something like this and see what happens. but i wanted to see if any aerodynamic folk would say ‘foolish’ right off the bat.


10 replies so far

View 47phord's profile

47phord

175 posts in 990 days


#1 posted 08-29-2013 01:22 AM

Where, exactly, would the outlet be? The way I’m visualizing this, the dust would spin around and get sucked right into the outlet. Just trying to get on the same page.

View Holbs's profile

Holbs

598 posts in 782 days


#2 posted 08-29-2013 01:26 AM

the incoming (from jointer, for example) stream would be coming from the top. then be forced around the middle cone. this may have enough force to deflect particles out of the air stream suction from under the cone going down.

View Loren's profile

Loren

7826 posts in 2400 days


#3 posted 08-29-2013 01:32 AM

Probably will clog up with planer shavings.

-- http://lawoodworking.com

View Holbs's profile

Holbs

598 posts in 782 days


#4 posted 08-29-2013 01:39 AM

clog up even with the use of a 4” pvc inlet / outlet?

View Shawn Masterson's profile

Shawn Masterson

1262 posts in 701 days


#5 posted 08-29-2013 01:39 AM

I like the KISS approach. The top hat is easy and time tested/proven.

View Holbs's profile

Holbs

598 posts in 782 days


#6 posted 08-29-2013 01:49 AM

your right, phord. crap :) i figured the suction would only be flowing around the cone from top inlet to bottom outlet. but there still will be suction created in the barrel to suck dust anywhere in barrel.
ok… thein seperator it is :)

View crank49's profile

crank49

3524 posts in 1723 days


#7 posted 08-29-2013 06:14 AM

Some of the heavier particles would be deflected out of the air stream.
But, the finer, lighter particles would follow the cone’s surface and be sucked right into the outlet.
Unfortunately, the finer, lighter particles are what you want to capture.

A cyclone uses a tapered cone but introduces the air tangentially to the larger top end of the cone and as the air stream spins toward the smaller bottom of the tapered cone it increases speed. At the bottom of the cone the air stream creates a vortex that spins inside the outer flow an at an even higher speed. This vortex continues to get smaller and faster as the air flow spirals upward toward the outlet which is in the top center of the cyclone.The taller and more gradual the taper, the faster the air spins. The faster the air spins the more finer particles get thrown out of the flow. It is possible to build a cyclone that will even capture smoke particles, under .1 micron, but the pressure drop required to get this velocity is in the neighborhood of 30 inches.

I’m afraid your concept would have the flow take too short of a path to get much separation at all.

Just a drum with air entering along the outer edge and at a tangent angle and with an outlet in the center of the lid will get a good portion of the dust out; maybe 60% to 70%. The problem with a drum is it lacks the tapered sides and a hole at the bottom that opens up into a larger dust container. When the drum gets to be about half full of dust, the spinning air flow begins to lift dust up from the pile collecting in the bottom and re-entrain it back into the air flow. Without the tapered sides to force the flow into a very tight high speed vortex the dust just spirals its way up and out the outlet.

The top hat, or Thein baffle, is a way to keep the dust in a drum and not let it get sucked back up into the air stream.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View Loren's profile

Loren

7826 posts in 2400 days


#8 posted 08-29-2013 06:27 AM

Reno is like my climate in LA enough that you can probably
vent outside in some way or at least escape the
need to filter all your air. In warmer climates it’s
a lot about collecting chips and volume, not scrubbing
the air for health reasons.

Anyway – with “dust collection” in woodworking there
are really two categories to deal with and this is what
makes it such a pain to solve well in cold climates where
shops are enclosed by necessity. There are “chips” and
there is “dust” and the chips make a mess on the floor
and the dust makes a mess in the air. With 3 HP
you should be able to get a lot of it flowing through
your collector, but if you want it to work best put the
thing outside and if you want to avoid fussing with
the bags a lot (dusty bags are nasty) add a pre-seperator.
The thein is a good design but at 3hp with one operator,
a regular trash can separator lid will work great.

-- http://lawoodworking.com

View Holbs's profile

Holbs

598 posts in 782 days


#9 posted 08-29-2013 02:04 PM

loren… my grizzly has 3 4”inlets at the impeller. i am unsure if capping 2 and using 1 inlet would put a strain on the motor so i leave 1 inlet uncapped. i did try to put it out the rear door of my 2car garage, but already had complaint from neighbor that it sounds like a jet engine (which i found odd because it sounds super quiet when i have ear protection on :) for now, it sits inside and i leave front rollup door and rear door open. tho i know i have to do some dust collecting project before winter comes. i already picked up a 55plastic drum for free with the idea of doing thein baffle when i start the little project. i am strongly considering keeping the dust collection system indoors with an exhaust straight to the outside when it’s warm out and maybe a 3way Y valve for winter to 18wheeler truck filters.

crank.. i was hoping the bottom vacuum would only concentrate on air flow from the upper inlet in a sealed 55gallon drum, and the cone would bounce/deflect out particles from the stream. maybe i should stick to working on telephone systems and voicemails, not aerodynamic engineering :)

View crank49's profile

crank49

3524 posts in 1723 days


#10 posted 08-29-2013 02:54 PM

Holbs, don’t worry about blocking inlets causing a motor overload.

The work load on the fan is directly proportional to the volume of air being moved. So, if you block 2/3rds of the flow, you reduce the motor load by 66%.

A fan motor sounds like it is working harder when you restrict the flow because it increases in speed, but the increase is due to a lower load, not a higher load.

One exception is in the case of some vacuum cleaners. Some of these machines use the air flow from the suction hose, after it passes through the filter bag, to cool the motor. If you block this flow the motor will over heat.

Most shop vacs, especially the wet/dry type, have a separate motor cooling air flow fan and are not prone to the over heating from blocked suction flow.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase