Shop-Vac dust collection (pics, big)

[cgallery]

Shop-Vac vs. dust collector seems to be getting a lot of discussion lately. I don't doubt that real dust collectors drastically outperform shop-vacs. However, I just don't have the room.

This doesn't mean I want to forgo the convenience of a dust collection "network," though. I had previously created a drop-box/plenum contraption that I dubbed FrankenVac, which worked very well. When I expanded my shop (still tiny), I outgrew the FrankenVac contraption. So I purchased some 3" plastic flex and wye's and built this network.

I use a 12-gallon Shop-Vac outfitted with the HEPA filter and the paper filter bags. This keeps the filter clean and working at peak efficiency.

Next in line is my proprietary cyclonic separator, built on top of a 7-gallon clear trash pail from Wal-Mart. This cyclonic separator works wonders. The key to its operation is the integration of a ordinary child's toy on the inside. Some day I will reveal to all how this works, as soon as I really get a grasp on it myself. You may remember me asking about patents a few months ago, this was the reason I asked. All my fines stay in in ths 7-gallon pail, nearly nothing makes it to the Shop-Vac, and I can run the separator pretty much to the rim w/o fear of everything getting sucked back to the vac.

If you're going to use the cheap plastic gates, do dog-ear them. This creates small (approx. .125") blow-holes that allow trapped sawdust to escape when you close the gate. Without this, they will start jamming and won't close entirely. The entire system suffers because each gate is a little bit open.

I use this network on my router down-draft box. Almost nothing escapes it, no need for collection at the fence. And it works equally well for working in the middle of a piece, no just at the edge.

This network also handles my Inca 8-5/8" jointer/planer. Has no problem keeping up with .5mm passes of full-width oak/pine boards (although this does fill the 7-gallon separator FAST). Finally it is used on the BT3K and on a 9" Inca bandsaw.

There are two other advantages that I can think of for Shop-Vac based networks: (1) HEPA filter keeps the dust that it DOES grab in the system. I've been in shops w/ big dust collectors that accumulate dust on their shelves and floor faster than I do. (2) I can easily connect tools to the port on my bench for collection into the same system. Works for my RO sander, my biscuit jointer, belt sander, hand-held router, everything! Once system does it all. And I know, I just know, that a big dust collector isn't going to handle a RO sander (okay, I don't KNOW that, but I've read that. .

All the ports on my tools are 2.25" or less. So until I get a larger shop and tools with larger ports, this configuration will have to do.

[Thom2]

I'll share mine too .... I do have a Grizz 2hp DC now, but I did with this setup for probably 2 years and it worked a LOT better than I ever expected it to. It actually did a really respectable job of keeping up with my Ridgid planer. I know a lot of people will find that hard to believe, but Popeye was here to witness it. I never did try it on the jointer because I just felt I was wasting my time, just to big of an open cavity under the jointer bed, so I never bothered.

[thestinker]

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Please post up the secret to your cyclone....I am curoius.

RS

[crokett]

I tried using a 5gal bucket as a separator for my shop vac and it did diddly-squat. Very little got left in the bucket. I think I need a bigger bucket. I'd like details on the inside of your separator also.

[siliconbauhaus]

I look forward to when you can reveal your design secrets mate. I'm looking to go th shop vac route as well.

[footprintsinconc]

I'll be waiting aswell because i have to get back to woodworking, but cant afford a dc yet. and i need to do something for my shop vac, so the fines dont get into the vac (i go thru bags, like you wont believe).

[niki]

I made it "All in one", on wheels and just drag it to each machine/tool.

The design and construction is based on "maximum efficiency and minimum duct losses".

I removed the original inlet and used the full diameter of the shop-vac (usually, the inlet dia is smaller than the hose dia and is restricting the flow).

Another factor is the duct length, the longer the more loss of momentum (boundary layer).

Every change of direction (ie, elbows or bendings of the hose) is creating turbulances or drag that also causes "loss of momentum" and reduces the efficiency of the system.

Because of the above reasons, Im using short hose (3 feet) and straight, as I can, connections.

Below, is a pic of the unit. You can see all the post here

http://bt3central.com/showthread.php?t=24930&highlight=R2D2

Hi from Japan
niki

[Veramacor]

Here's the FrankenVac,

Its attached to a Delta DC not shown. I hate the look of hose so I went internal as much as I could with the BT mobile base cabinet.

It does a great job so far on the router and vacuum hose, but I have to seal up the BT some more to get better suction at the blade.

[thestinker]

So is "Frankenvac" powderd by a shop vac or a DC?

[BigguyZ]

cgallery-
I too would definitely be interested to see how you made your separator. I'm looking at making a home made minivac cyclone one, but am too lazy to get to actually building it. If yours is cheap and easy to do, that'd solve most of my DC woes!

[footprintsinconc]

Veramacor:
that is a nice table and dust collecting out fit! one question though. the individual gates are on the back side of the horizontal piece with all the hoses, so how do you access those gates? secondly, on the other side of this horzontal piece, that chamber needs to be sealed tight so that no suction is lost when the top is down, so how did you seal it when the top seem to be removable (because you took a picture. lastly, if the top is removable, is it hinged or do you undo some screws to lift it out ....?

niki:
your ideas are always creative! when you drop the vacuum thru the top, wont it just keep getting sucked in the blue bucket below? is the hole in top of that blue bucket the exact same diameter as the vacuum body?

general question:
there has been talk about using a bigger diameter pipe to get more air flow. from what i remember, and thats not much, Q (flow) = V (velocity) x A (area).
the motor is the same no mater what, therefore, the suction force will be the same. so at the juction of the vacuum and the hose, Q1=Q2, the two things that change are V and A to maintain the same Q.

therefore, using an example, if a dc is rated at 1200cfm. then Q1=Q2=1200cfm. If a 4" dia. hose is used, to maintain 1200cfm, the velocity will increase, but if the pipe dia was chandge to 6", then the velocity of the air will slow down, thus the airflow will remain the same.

all the post are contrary to this, they all say that 6" pipe gets more air flow vs a 4" pipe wiht the same motor. can someone point out where i am going wrong?

[LCHIEN]

...
general question:
there has been talk about using a bigger diameter pipe to get more air flow. from what i remember, and thats not much, Q (flow) = V (velocity) x A (area).
the motor is the same no mater what, therefore, the suction force will be the same. so at the juction of the vacuum and the hose, Q1=Q2, the two things that change are V and A to maintain the same Q.

therefore, using an example, if a dc is rated at 1200cfm. then Q1=Q2=1200cfm. If a 4" dia. hose is used, to maintain 1200cfm, the velocity will increase, but if the pipe dia was chandge to 6", then the velocity of the air will slow down, thus the airflow will remain the same.

all the post are contrary to this, they all say that 6" pipe gets more air flow vs a 4" pipe wiht the same motor. can someone point out where i am going wrong?

There's a basic tradeoff in dust machinery.

1) If you use a bigger diameter pipe/hose ten there is less overall restriction. Kind of like trying to suck a milkshake thru a small straw or a big straw. With a given machine you will get more flow thru a larger pipe

2) Air velocity and flow are different things. As you noted, you get more velocity with a given flow if you use a SMALLER pipe. You need a certain velocity (IIRC about 3000 feet per minute) to suspend all the particles in the pipe or risk having clogs or failing to suck in the fines.

But the tradeoff with a given machine is, smaller piping to get the velocity up leads to lower flow which actually reduces velocity. So increase the pipe diameter and the flow increases but the velocity falls too low. Your alternative is to shorten the pipe, this also decreases resistance and increases the flow, but its not practical at some points.

So given a diameter, length run of piping, its loses from turns and wall friction, and a desired velocity, there is only one other variable you can control and that is the impellor and HP of the motor. If you can increase the motor size and impellor size then you can overcome the resistance of the pipe by applying more static pressure and achieve the desired airflow which given the pipe size chosen dictates the velocity which was the original objective.

That's why they have 3, 4, 5 HP dust collectors and bigger.

To address your orignial issue, maybe where you go wrong is that a DC rated at 1200 CFM does not do 1200 CFM at all times. Its "rated" CFM is with absolutely no restriction - no inlet hose and not output filters.
Slap on hoses and filters and the CFMs will fall drastically as the suction pressure rises. I noted in a recent magazine review most 1200 CFM-type DCs will only do 500-800 CFM when plumbed to a short pipe and 2-bag filters. Load up the filters and increase the plumbing, use lossy flex hoses and you will get even less.