Dust collection system vs. Shop Vac

[Navycraig]

My mistake for posting this. I should have used the search feature first and found what was already out there.


What are the advantages to a DC system rather than a good ole shop vac? I know that with a DC System you can link it to more than one tool at a time and that's a big advantage, but if that's not an important issue for me, are there other advantages to the DC over the shop vac?
I'm not real familiar with the whole "micron" issue so maybe that's it. If so, some advice as to a good level of micron collection would be appreciated.
Another thread in "bargin alerts" talked of a Delta system at Lowes for about $100.00, but I can't find that part number anywhere on the Lowe's site or on the Delta site either.
Thanks,
Craig

[dbhost]

Craig,

Microns, are teeny tiny particles. The lower the number of micron filtration, the smaller the particles will be filtered out. In specific terms, a micron is a synonymn for micrometer, or one millionth of a meter. Web Definition of Micron or Micrometer. This unit of measure is commonly used in describing microtechnology, or microfiltration. Since the materials floating in the air that are dangerous to human health are typically larger than about 5 microns, filtration of 5 microns or less is best.

HEPA, is a filtration technology term used in vacums, such as shop vacs, that filters to .3 microns to eliminate airborne contaminants.

Aside from filtration, there are two things that should be considered, vacum measured in static pressure, and air flow volume measured in CFM. Good Article on the plusses and minuses of DCs and Shop Vacs.

A shop vac will pull more static pressure (vacum) and thus pull harder from a smaller orifice, a dust collector will move larger amounts of air meaning they will be more effective at working with compound miter saws, jointers, and planers.

I use a shop vac (Actually Ridgid 12 gallon wet dry vac) with a HEPA filter, AND the Shop Vac brand Sawdust Collection system. I have no problems with my system clearing shavings from my planer at the end of the circuit through a 20' hose. I do however have a problem with it even pretending to be effective with my CMS. MANY DC users complain the compound miter saw is the one tool they cannot seem to get dust collection working well with.

I think if you are going to use more than one tool at one time, say you are going to run the table saw, and your buddy is going to run the jointer, you will probably want a dust collector. But if you are a single woodworker you will want a good shop vac, with a HEPA filter. I specifically bought the Ridgid vac I did because as far as vacs go, it moves the most CFM I could find ratings on, and it offered an optional HEPA filter. The Shop Vac Sawdust Collection system is listed, and when I bought, on sale at the shop vac web site...

A big drawback of the shop vac setup is the NOISE level. They are noisier than a DC by a long shot...

Shop vac, or dust collector, you will want an air cleaner as well. Something that filters LARGE volumes of air. I am using a home brewed 20" box fan with a 20x20 Filtrete HEPA filter duct taped on as an air cleaner...

Your shop tools may end up making the decision for you though. Many tools come with a 4" dust collection port, and generally speaking, necking down to the 2.5" shop vac hose size doesn't seem to bode well for removing shavings and such...

PM me if you want more detail on the what, where, how, and why of setting up the shop vac based system though... It is pretty easy, but there are some gotchas along the way...

[dkerfoot]

I made a mistake in jumping into buying a dust collector before realizing they don't work that great with 2 1/2" ports. I use it because I have it, but if all your equipment has 2 1/2" ports or smaller, you might want to go with a high powered shop vac instead.

Lots of good info in past threads.

It is the one purchase I wish I could take a mulligan on.

[Navycraig]

Great comments and I really appreciate the replies. My Craftsman shopvac seems to work really well for most of my tools and hooks right up to them with ease. Maybe if I can find a Hepa filter for that I'll be all set. I don't do a great deal of WW, but enough to make a bunch of dust if I don't have something to collect it.
I'm very interested in the box fan air cleaner if you would be willing to provide more details.
Craig

[ksum]

I'll take the other side and suggest a dust collector if you have the room. Even for a 1 person shop. I had a shop vac that I would move to each tool. It was good, but I got tired of emptying it, especially when using a jointer and/or a thickness planer. I get much more sawdust with the DC that I ever did with a shop vac. My wife has some allergies to some woods. When I was getting my band saw, Wilke had a great deal on a blemished DC unit. The wife said get it, so who was I to argue. With a shop vac, I had to do additional vacuuming before I left the shop. (1 car garage) With the DC unit, I don’t.

For me, it was an instance of not knowing what you were missing until you tried something different. I empty it less, have my router table, table saw, and band saw permanently hooked up, and hose that I connect to the jointer and planer when needed. I also hook this up to a compound miter sometimes and get a good bit of the dust. Sometimes I use a shop vac. That just depends on the nature of what I am doing. Once I build a permanent home for the compound miter saw, I'll get as much off that as I do the table saw. I came up with a design of a downdraft and connection to the saw's so-called dust port that has worked well in tests.

On the table saw, I was able to install a Shark Guard and collect from both. This gets just about everything off the table saw. What is left could probably be counted in under a minute.

The really nice thing is that I am not taking time to connect to different machines. I just slide a gate closed and another open. The way my shop is set up, all the gates are next to each other. I COULD set up so the gates open and DC comes on automatically when the tool is turned on, but have not gone that far.

So for me, the advantages are that the DC unit gets more and also saves me time going from one tool to another as well as clean-up time. The downside for many is that a good DC unit may need to run on 220, which may not be available. Mine will run on either, but I set it up for 220 since I have the freedom of easily adding circuits.

Where in MD are you, NavyCraig? I am in Bel Air. If you want to experience the DC in use, you are welcome to visit some time.

Karl

[dbhost]

Real simple. Just take a 20" box fan. (Just about any hardware store or Wally World for about $20.00), add a filtrete or similar 20x20 HEPA filter, and duct tape the filter to the intake side of the fan, sealing any gaps so that air HAS to go through the filter to get to the fan blades. Also tape up any gaps in the box itself... Place the fan as close as feasable to where you are working, and use the fan to pull the dusty air AWAY from you, pulling any dust missed by the shop vac into the fan and filter.

Depending on the model of Craftsman vac you have. The Emmerson built vacs *should* (no guarantee, but should...) accept the Ridgid HEPA filter from Home Depot. Check the application guide for specifics.

Yeah, port size was a contributing factor in my choice. ALL of my tools use 2.5" or smaller ports. I do not presently have a jointer though...

I don't have to do any follow up clean up except on the CMS... And with the Sawdust Collection System, I have my router table, and band saw hooked up permanently. The TS folds up so the hose comes out, but stays in the blast gate. As soon as I get the stands for the planer and Ridgid sander, they will be hooked up permanently... So aside from sanders and table saw, everything will be a matter of moving from one tool to another and closing / opening blast gates...

DC's DO have a HUGE advantage with CFM, no doubt at all there. High CFM shop vacs can work well too.. Low flow vacs can be a real PITA, and ineffective though, which is where I think a lot of folks got a bad taste for the shop vac solution.

DCs such as the Harbor Freight, or Delta with a 20 micron bag, are WORSE than nothing at all. Filtration that large merely uses the high CFM for distributing the dust further instead of truly collecting it...

[LarryG]

Most people want, and need, both. A shop vac is good to start with because it's less costly and can be made to do a pretty good job of helping you keep a clean shop. If you want serious dust collection with the aim of protecting your health, however, you need a dust collector.

Basically, shop vacs move a small quantity of air at high velocity. Dust collectors move a larger quantity of air at a lower velocity. Those differences are key.

Shop vacs are great when you can direct the dust right into the end of the hose, as when connecting to a hand-held power tool like a random orbit sander or plate joiner. They can also do okay with bigger tools that do a good job of directing most of their debris into a built-in, on-board chute -- jointers, planers, etc. (It helps that these two particular tools produce large chips and shavings, and not much actual dust. Some of them throw off so much debris that they can overwhelm a shop vac, though.)

For tools that spray dust everywhere, a vac cannot do an adequate job because it it not capable of moving enough air. Tools in this class include miter saws, band saws, table saws, drill presses, drum sanders, etc. To get truly effective dust collection with tools like these, you must have the higher volume of air that can only be moved by a dust collector. Only by moving LOTS of air can the finest dust be collected right at the source, before it has a chance to drift away on the air in the shop.

A filter is good as a back-up, but keep in mind that by the time the shop's air has been exchanged through a filter enough time to capture the finest dust, a lot of that finest dust has already been filtered by your lungs. The ideal solution is a powerful dust collector that sucks in as much of the dust as possible before it has a chance to get airborne, with a filter to get what little the DC misses. The best time to run the filter is after you've left the shop for the day ... the fine dust can hang in the air for hours, and if the filter runs long enough it will eventually do enough air changes to capture most of it before it settles onto every surface in the shop. This is important because the next time you walk in, the air your body displaces will stir up the dust and put it back into suspension, where it can again be breathed in.

Karl makes several excellent points. A dust collector won't have to be emptied nearly as ofter as a vac; and however much dust you can make a shop vac catch, a dust collector will always catch more. It really is the better solution, for all woodworkers.

[LCHIEN]

the argument missing in all the discussion above, is that the DC has probably 10 or 20 times the air flow (volume of air per minute) of a shop vac.
This is important (no one has mentioned) because such a volume of air being removed near the cutting location will pull all the fines (e.g. nearly invisible particles down to around 1 micron in size) spit out from the tool. They go whizzing off in all directions (because they are light) and only the huge volume of air sucked in by the DC will keep them from becomeing dissipated all over your shop. An air cleaner takes many minutes to clean the air, its really to clean up the few percent that the DC doesn't catch.

Now to really make this happen everything has to be right... The DC has to have enough suction head to overcome the hose restriction (hard piping is better than flex hose) and the tool opening has to be big enough not to choke flow and the tool has to have effective hoods to direct the air flow to carry the dust into the DC opening. And you need fine pore filtering to trap the dust.
When its done right, no shop vac can come close to competing with a DC because of the volume. But its hard to get it right.

If your sole purpose is to keep the cuttings and chips off the floor, then a shop vac or casually plumbed DC will do. The other half - the micron sized particles, needs a carefully tuned DC to do the job, these are for the most part invisible (you will see a fine dust covering over everything in the shop) and easy to ignore, but they are probably worst for you healthwise, if that's the reason you want to collect dust.

[cgallery]

the argument missing in all the discussion above, is that the DC has probably 10 or 20 times the air flow (volume of air per minute) of a shop vac.

I get what you're saying but I think the #'s are closer to between 2x and 2.5x, assuming that the DC is working through a 4" hose to a 4" port in your tool.

If you're hooking a 4" DC hose up to a 2.5" tool port, you can expect that advantage to all but disappear.

[LarryG]

I think the 2x to 2.5 ratio is probably closer to correct, too, but I also understand the point Loring is making.

But, more important, I forgot to comment on the port size issue. You do have to match the port size to the pipe size. Bill Pentz goes so far as to advocate replacing the 4" ports that come standard on most stationary machines to 6". His reasoning is that it does little good to have the 6" mains most moderate- to largish-size amateur shops will need and then neck it down to 4" at the machine. That's why I plumbed my system with 4" pipe. I figured that size was a better match for my HF 2HP DC, and it matches the ports on most of my tools. The system may not ultimately move as much air as I'd like it to, but at least everything is fairly well matched throughout, so that the various parts of the system aren't fighting against each other.

As Loring suggests, it's a lot easier to talk about how to do this stuff right than to actually do it right.

[dbhost]

Which gets us back into the discussion about static pressure...

Probably the BEST solution, would be a DC that would provide high CFM AND high static pressure. Most do not. The problem with a dedicated DC is necking the hose size down to fit things like quarter sheet sanders, or even the BT3100's 2.5" port. The restriction can cause a DCs impreller to simply cavitate like a boat propeller spinning in the air, moving no air at all, or very little. Simply put, a DC is NOT a vacum by any means, and a vacum isn't exactly the best solution for dust collection / control. A combination of BOTH systems, sized appropriately for the tools in use and in question would be best.

If your tools are port sized for 2.5" fittings, they they are designed by the engineers, many with Bachelor's degrees, but likely some with PHd's that SHOULD know what they are doing, that thought up those tools, for shop vac fittment for a reason...

If however, your ports are 4", or even 6", then your tools ought to be connected to a DC... None of mine are yet. I have a feeling that will be coming with the advent of a jointer, and lathe...

I am NOT advocating staying away from a proper sized DC setup used for the right purpose. But I also hope you don't steer away from a shop vac solution if that is the right choice for you.

The likelihood is low, but if you have access to environmental factors engineers, ask them. Any idiot can post whatever they want on the internet without knowing what they are talking about, myself included...

A good resource to read might just be the OSHA guidelines on protecting woodworkers from woodworking hazards on page 29 of THIS pdf file. If you want to get picky about the proper way to protect your health from wood dust, you need to move at LEAST 2500 CFM according to OSHA, FAR above and beyond what the DC units most recreational, and many professional woodworkers use.

Best of luck to you in sorting this out. Folks are going to give their opinions based on their experience, preferences, and exposure to various technologies and techniques. It's not always easy to sort out... But rest assured that it is all well intentioned....

[LarryG]

If your tools are port sized for 2.5" fittings, they they are designed by the engineers, many with Bachelor's degrees, but likely some with PHd's that SHOULD know what they are doing, that thought up those tools, for shop vac fittment for a reason...

I don't know that I'd give the engineers too much credit for that one. It's probably more a result of marketing than anything else. The tool manufacturers know that most DIYers and weekend woodworkers own shop vacs, whereas comparatively few own dust collectors.

There's also the physical limitations. A hand-held power tool with a 4" hose attached would be unwieldy to say the least.

[ksum]

I am plumbed with 6" pvc, and go down to 4" flex as close to the machine as possible. The shorter the smaller pipe runs, the better. Going to a 2.5" opening with a 4" or even 6" pipe is better than running to it with a 2.5" pipe. In my cases, the band saw has 2 4" ports, and the table saw has a 4" for under and a 2.5" for the Shark Guard above. Likewise, the router table has a 4" below and 2.5" on the fence. There are secondary gates on all the 4" and 2.5" lines, so they can be closed when they will not get dust. The idea, however is the total cross sectional area.

I read thru Bill's site and agree with the information on using larger pipe sizes. Remember that when you go to 2 pipes, drop the pipe size AND do it as close to the machine as possible. There is flow loss when going thru a smaller opening, but if it is just at the port, the loss is not as much as it is thru even a foot of pipe. With that in mind, the advantage is still there hooking a 4" pipe up to a 2.5" opening if a reducer is used right at the port. especially if it is a connical reduction. Opening size and friction are the culprits there. A larger pipe means less friction on the air stream. The air will also compress some thru a very short section, but does not want to stay compressed. Also note that going from one 4" main pipe to two will work against you. Always go fom 2 smaller ones to a single larger one on the main.

For sanders, I use the shop vac, along with a unit that turns it on/off with the tool. There would be too much strain on my DC with those smaller hook-ups and I would burn up the motor. Plus the hose is just way to big to make manageable.

Regarding larger tools with small connections, I honestly believe these smaller connections are sales tools as opposed to efficiency decisions. For many of the portable saws, a contractor is not going to lug around a DC and a shop vac. But they WILL have a shop vac. So if you are making a saw to sell to them, sell them one with a connection they can use. My first saw was a borrowed Dewalt. It had a 2.5" connection. If I were using it today, knowing what I do now, I would rig a bigger connection and use DC, as I only use it in the shop.

Additionally, for the saws with 2.5" connections, I would still consider a blade guard with dust collection hook-up. With that also at 2.5", your total cross-sectional area is 0.0682 sq ft. While smaller than 4", you are not going to cavitate a DC. A 4" pipe gives you 0.0873 sq ft, and a 6" comes in at 0.1963 sq ft. I would modify the saw to a 4” connection, and put 2.5” on a guard. That gets you 0.1214 sq ft. If you want to optimize the main pipe based on this, you would use a 5" pipe (0.1364 sq ft) but since that was too expensive, I went with 6".

As an example of not using DC for everything: Last night I tried my DC with a circular saw. That "sucker" had, I think, a 1.5" hookup. I only used it for 1 cut, and it still got more than the shop vac would have, but I won't try it again. While it didn't cavitate (at least not noticably) there was a definite strain on the DC's motor.

So like dbhost is saying, match the tool to the method, but as LarryG is suggesting, do not limit the method to the port size if the tool should really have a larger port. If you can put a larger port on the tool, do it.

[dbhost]

Just a thought to chew on a bit here...
MINIMUM OSHA recommended dust collector.

3HP 220V Single Phase powered, would require 4" ducting. Most likely best to plumb to blast gates as close to the tool as possible, neck down to your 2.5" stuff, and go with the smaller diameter hose, or start cutting up tool enclosures for 4" dust collection flanges, and using 4" hose runs. (Best solution, but not always feasable...)

Regarding larger tools with small connections, I honestly believe these smaller connections are sales tools as opposed to efficiency decisions. For many of the portable saws, a contractor is not going to lug around a DC and a shop vac. But they WILL have a shop vac. So if you are making a saw to sell to them, sell them one with a connection they can use. My first saw was a borrowed Dewalt. It had a 2.5" connection. If I were using it today, knowing what I do now, I would rig a bigger connection and use DC, as I only use it in the shop.

There is a pretty good possibility that you are right there. HOWEVER... Many of the "Contractor" and Hybrid saws I have been looking at, such as the Hitachi C10FL, Ridgid TS3660 etc... have 2.5" DC ports on them... I don't think anyone in their right mind would even consider a full on cast iron top / cast iron wing contractor saw to be anything vaguely portable. The main advantage to those saws is smaller space and the ability to be rolled around a workshop...

[cgallery]

Just a thought to chew on a bit here...
MINIMUM OSHA recommended dust collector.

That thing is bigger than my shop!