Shop vac. vs. Dust Collector question (newbie)

[Harley Reasons]

A temporary solution to aid in using your Ridgid Vac may be in constructing a cyclone collector. I'm sure there are several great sites with instructions on how to build your own. I did a quick google and here is an example Jerrjens Mini-Cyclone.
The obvious advantage to using the cyclone is having to empty the shop vac less frequent. Another trick with using a shop vac I've read about is adding a disposable paper filter over the top of the pleated filter.
Also a heads up: Check your local HD BORG for a special on filters. I know at ours we have a box of four that has been put on clearance for $22.50. These are the same filters that normally sell for $14.95 each.

[Mark Kosmowski]

If you need to use the shop vac for dust collection, consider upgrading to a HEPA filter.

In addition to the primary dust collection system, also consider an ambient air cleaner.

[Russell Tribby]

I use a shop vac and a dc in my little shop. I have a Ridgid 3650 that I removed the legs off of and put on a cabinet. See this thread, http://www.sawmillcreek.org/showthread.php?t=70358. My shop vac is then hooked up to that and the dust collection is excellent. I ripped and resawed 150 bd.ft. of poplar yesterday and I had to empty the vac twice. There were very little shavings on the ground. The only problem came when I was resawing and couldn't use my Shark guard so there was quite a bit of dust on top of the table. I also use the vac with my router tables and it captures 95% of the dust I produce from there. I just recently got a Delta 50-760 dc from Amazon and it has been a great addition to the shop. I had to plane and joint the same bunch of poplar a few days ago and probably filled up the dc 6 times. Had I been using my shop vac, which was what I did in the past, I would've had to empty it at least 15-20 times. Not only was it extremely messy but it was such a waste of time having to stop every 15 minutes, shut everything down, empty the vac, clean the filter and then hook everything back up again. I got along doing this for about 5 years but now that I have a dc I see how much time I was wasting. It has certainly been a good investment for me.

[David Freed]

Not necessarily. I see your point. But when I wear a dust mask, I probably breath in less sawdust without a DC then I would with a DC and no dust mask. But that's another topic.

Not true. I don't think you understand what a good dust collection system can do. In a commercial setting, OSHA requires that the dust collection system must keep the air clean enough to breathe for extended periods of time with no ill effects. Some of the hobbyist dust collectors on the market today (the cheap ones) actually do more harm than good because they stir up more dust in the air than they capture. Shop vacs do the same thing. They do not clean the harmful dust out of the air; they just stir it up.

Bills breathing problems were so bad that his doctor told him to stop woodworking because breathing the dust was going to cause him severe trouble. Bill wouldn't accept that, and started experimenting with dust collection to find a way to be able to keep working in his woodshop. He ended up designing a hobbyist cyclone that has the air in his shop as clean as than the air in his house. The plans to build the cyclone that he designed are free on his website.

Ed Morgano uses Bills design to make the ClearVue cyclone, which he advertises on Bills site.

Go to Bill's site and do some reading about dust and its harmful effects.

[Peter Quadarella]

Shop vacs do the same thing. They do not clean the harmful dust out of the air; they just stir it up.

If someone is using a 1 micron HEPA filter in their shopvac, why would that be true? Also, how does that apply to someone using a mini cyclone with their shopvac?

I'm truly curious, because I've been debating getting a dust collector, but still use the two solutions I just mentioned.

[Ryan Sparreboom]

Seems this is a bit of a hot topic.
My shop is half of a 2 car garage. Well actually, the whole garage when I'm working in it. Anyway, most times when I'm in there I have the double overhead door open (18' wide?) and when I'm doing the real dusty stuff like cutting on the table saw or sanding, I wear a dust mask. So I think I'll be O.K for now.

Mark mentioned an ambient air cleaner. How do they work and are they worth it?

[David Freed]

If someone is using a 1 micron HEPA filter in their shopvac, why would that be true? Also, how does that apply to someone using a mini cyclone with their shopvac?

I'm truly curious, because I've been debating getting a dust collector, but still use the two solutions I just mentioned.

The air that actually goes through the shopvac does get filtered. The problem is that a shopvac is a high suction, low volume "dust collector". A lot of the dust does not get pulled into the shopvac, and just gets stirred around in your shop. A "good" dust collector has a good filtering system, plus high volume to pull the dust in from the machine that is making the dust. A crude example would be a handheld hair dryer compared to a fan. Which one would you put in a window to clear the dust out of a room? I hope I explained this so you can understand. I'm not to good at explaining sometimes.

[Phil Thien]

Shop vacs do the same thing. They do not clean the harmful dust out of the air; they just stir it up.

My Dylos meters call bull on that.

[Phil Thien]

The air that actually goes through the shopvac does get filtered. The problem is that a shopvac is a high suction, low volume "dust collector". A lot of the dust does not get pulled into the shopvac, and just gets stirred around in your shop. A "good" dust collector has a good filtering system, plus high volume to pull the dust in from the machine that is making the dust. A crude example would be a handheld hair dryer compared to a fan. Which one would you put in a window to clear the dust out of a room? I hope I explained this so you can understand. I'm not to good at explaining sometimes.

The problem is, a lot of the dust doesn't get pulled into the big DC, either, and gets stirred around the shop, too.

The biggest reductions in airborne dust seemed to come from improvements in hood design. For example, those with blade guard based DC on their table saws had substantially less airborne dust than those w/o.

[David Freed]

My Dylos meters call bull on that.

The problem is, a lot of the dust doesn't get pulled into the big DC, either, and gets stirred around the shop, too.

The biggest reductions in airborne dust seemed to come from improvements in hood design. For example, those with blade guard based DC on their table saws had substantially less airborne dust than those w/o.

I am trying to follow your posts. In the first it appears you are saying that the shopvac is keeping the shop air as clean as a dust collector, and in the second it appears you are saying that neither will clean the air. Were you checking the shop air or the shopvac exhaust air with your meter? If you are checking the shop air, which shopvac and which dust collector are you comparing?

I do agree that you have to have a good hood design. A good dust collector will only work as well as you let it. If you are using a restrictive hood with a good dust collector, you are choking it down to a shopvacs volume capability and you would get about the same amount of filtering, but that is not a fair test. The speed and effectiveness of getting and keeping your shop air clean is directly related to how much air is getting filtered (volume).

Maybe I didn't state clearly what I meant earlier. I said that a shopvac doesn't clean the harmful dust out of the air. The reason it doesn't is because most machines are making a cloud of very fine, harmful to breathe dust all around them even though you can't see it. A low volume dust collector, whether it is a shopvac or a good collector being restricted by a bad hood design, is not pulling much of that dust in. The more air you can pull away from any machine through your dust collector, the more of that dust cloud you will pull in also.

I have modified the hoods on some of my machines by adding extra ports because they were designed so poorly, it was throwing chips onto the floor. Now you can watch the chips get thrown out by the machine, and then, while still in mid air, get sucked right back in because of the air flow being pulled through by my dust collector. With that kind of airflow I know I am pulling in a good portion of that invisible dust cloud.

[Wilbur Pan]

Mark mentioned an ambient air cleaner. How do they work and are they worth it?

In its simplest form, an air cleaner is a big fan that pulls air through a filter that traps the dust that is floating around in the air. I think that they are an underappreciated component of dust control.

Here's my take on dust collection strategy.

1. The best thing to do is to trap the dust at the source, before it gets into the air. As has been mentioned, due to crappy collection hood designs at the tool end or other factors, this is nearly impossible to do with tools out of the box. So everyone needs a back up plan to take care of the dust that escapes.

2. The best back up plan is to vent the air (and dust) outside. Since you have a garage, opening the doors and placing a fan in another window/vent to draw fresh air in and vent the bad air out is a viable idea. But this isn't always a viable solution, especially if you live in Edmonton and it's wintertime.

3. Lacking a fresh air vent system, an air cleaner is the next best thing. Where air cleaners come up short is that the conventional wisdom is to get an air cleaner with enough CFM to exchange the air in your shop 6-10 times an hour. I went for 25-30 air exchanges per hour. You can bring down the dust concentration in the air much more quickly by increasing the number of times the air gets circulated through the air cleaner. This is cost effective and easy to do -- all you have to do is install another air cleaner. This is especially easier and cheaper than to trying to upgrade your dust collector to a cyclone system.

4. Dust masks, if yours is like this, are pretty much useless, for two reasons. They don't provide a tight fit to your face, so dust can get around the mask, and they don't filter out the tiniest particles which cause the most damage to your lungs. Unless, of course, your dust mask is something like this.

[Phil Thien]

I am trying to follow your posts. In the first it appears you are saying that the shopvac is keeping the shop air as clean as a dust collector, and in the second it appears you are saying that neither will clean the air. Were you checking the shop air or the shopvac exhaust air with your meter? If you are checking the shop air, which shopvac and which dust collector are you comparing?

I do agree that you have to have a good hood design. A good dust collector will only work as well as you let it. If you are using a restrictive hood with a good dust collector, you are choking it down to a shopvacs volume capability and you would get about the same amount of filtering, but that is not a fair test. The speed and effectiveness of getting and keeping your shop air clean is directly related to how much air is getting filtered (volume).

Maybe I didn't state clearly what I meant earlier. I said that a shopvac doesn't clean the harmful dust out of the air. The reason it doesn't is because most machines are making a cloud of very fine, harmful to breathe dust all around them even though you can't see it. A low volume dust collector, whether it is a shopvac or a good collector being restricted by a bad hood design, is not pulling much of that dust in. The more air you can pull away from any machine through your dust collector, the more of that dust cloud you will pull in also.

I have modified the hoods on some of my machines by adding extra ports because they were designed so poorly, it was throwing chips onto the floor. Now you can watch the chips get thrown out by the machine, and then, while still in mid air, get sucked right back in because of the air flow being pulled through by my dust collector. With that kind of airflow I know I am pulling in a good portion of that invisible dust cloud.

My comments were based entirely on anecdotal evidence resulting from the Dylos group buy. If you search sawmillcreek.org for "Dylos results" I think you'll find plenty of evidence that even those users with BIG DC's (cyclones included) were surprised that firing up their equipment and cutting some MDF resulted in quite a bit of airborne dust. The exception seemed to be those augmenting their cabinet collection w/ blade-guard based DC.

A large DC that is pulling 800 cubic feet at the tool is able to evacuate a sphere of approx. 2.95 feet (diameter) every second. So as long as the dust produced by the machine stays within that diameter of a sphere, the DC should collect it (of course, the tool and shroud interfere, but I'm talking theoretically).

But my 150-CFM shop vac can evacuate a sphere of approx. 1.68 feet every second. So the fact that my little table saw (BT3K w/ 2.25" port) has a blade shroud whereas my friend's Unisaw does not, probably accounts for the fact that his cyclone doesn't keep up w/ his saw any better than my shop vac keeps up with mine.

FWIW, the blade of a table saw is shooting dust towards the operator at approx. 100-MPH (which is faster than the air moving in most any DC duct I'm familiar with). Without blade-guard based DC, your chances of getting that dust are pretty much nil. You may see dust leaving your tool and turning around and going towards the DC. But there is plenty of dust that is leaving the tool and escaping, too.

[David Freed]

Phil,

I will go along with everything in your last post. I rarely use a tablesaw, but what you say about it does make sense.

Changing the subject a little, what is with the mixed up posts here? A recent post will be back with some from two days ago.

[Phil Thien]

Phil,

Changing the subject a little, what is with the mixed up posts here? A recent post will be back with some from two days ago.

I think you have to change your "Display Mode" (up above) to "Linear."

[David Freed]

Yep. That fixed it.