Choosing a dust collector

[rick spurgeon]

After reading Joe's post regarding Harbor Freight's dust collector and after looking at places like Woodcraft, Rockler, etc. I opted for the HF model. $79 vs. $200+? I thought to myself as long as it worked well - and it does. I've got it hooked up to a similar configuration using PVC Sewer and Drain. It has six ports connected to a miter saw, lathe, router table, table saw, planer and floor sweeper. I have not had any problems with power. For someone who wants to have a decent dust collection system at a great price, this is the way to go.

[Jim Podsedly]

The Harbor Freight 2hp, looks identical to Delta etc and I believe made by the same OEM and others are just branded and price bloated accordingly. HF 2hp on sale and with 20% off coupon was $135. You can replace 30micron 30ft2 bags with a 0.5 micron 300 ft2 pleated filter and clear bag s for $91 from WynnEnvironmental. With that you will have an exceptional DC system. Air flow is exceptional and while I have blast gates to each machine I often leave the table saw and the miter saw gates open at the same time and collection is still great. Contrary to popular opinion I use 4" PVC everywhere (vs 6") and even after 20 ft of PVC and 16" of flex hose the draw is exceptional. The downside, a few tools and untold screws and bolts have been inadvertently sucked up when cleaning the shop with the 4" flex. Dont be looking down the hose for blocks, youll lose an eye. I think Sawstop is working on an invention to prevent that.

Spencer,

I second your opinions on the 2HP harbor Freight dust collector. I changed out the 30 micron bags for the .5 microns and now have one sweet DC for a low price. Having a small shop and just being a hobbiest, this DC is perfect for me.

Jim

[Rob Luter]

May I offer some comments? (not an attempted hijack). I spent a good number of years as an Engineer in the commercial and industrial ventilation industry.

When looking at any ventilation system designed to convey particulate matter, you need to consider about three of variables: Air flow (CFM), resistance to flow (Static Pressure), and capture velocity (Feet per minute). Any air mover (in this case a DC) will be rated to move a given amount of air against a given amount of static pressure with a given amount of horsepower (a Delta 50-760 is rated at 1200 CFM against static pressure of 8" Water Column at 1 1/2 HP). The ductwork needs to be sized for minimum resistance at whatever minimum velocity is required to convey the particulates (sawdust). Going with larger duct will reduce the static resistance but will also reduce the air velocity. 4" duct is 77% larger in cross sectional area than 3" duct. As a result, the resistance to flow at the same air volume will be less, but the velocity will almost be cut in half, perhaps to the point that the sawdust will drop out of the airstream and collect in the duct. Blast gates that are properly applied and used when they should be will keep the velocity where it needs to be to convey the dust. Excess static resistance will lower velocity as well, and depending on the fan type it can cause excess loading of the fan motor (too involved to discuss here).

Rules of thumb:

• Use the duct diameter the DC was intended to use (4" for the Delta) to keep the velocity up.
• Keep the duct as short, smooth, and straight as possible. Flex hose is the most convenient and poorest performing airmoving duct there is. It's also widely used (if it's short enough it won't matter). PVC pipe or metal duct is least convenient but the best for airflow.
• Use blast gates to keep the velocity up or go with one duct that's moved from machine to machine.

[Stephen Clem]

I also have a small (garage) shop and have considered a dust collection for a while now. I can't decide whether to do the HF 2 HP deal and move one duct from tool to tool, or to just get a really good ambient air cleaner. I think the ambient air cleaner would be much more convenient. I don't mind sweeping the chips, it's beathing the dust that worries me. I saw a post on here a couple of days ago where a guy (can't remember the name ) had posted pictures of a shop made system he made with a fan encased in a box that had regular HVAC air filtersinstalled on the four sides. The fan would pull air through the filters. I thought that was a great idea, if one could find a fan powerful enough. Any comments on this sort of shop made ambient air cleaner, especially type of fan to use, or commercially available ones? Just thought this might be a better option for some. Or use both?

[glenn bradley]

I use a 1HP Delta with a trashcan seperator. This connects to a manifold which allows me to use it on one machine at a time as opposed to moving the collector around the shop.

When I use it for the RT and fence it does OK. When I use it for the TS and overarm guard it is a bit weak. The eventual plan is to go to a cyclone and re-deploy this machine for smaller tools across the shop.

[Jim Podsedly]

I also have a small (garage) shop and have considered a dust collection for a while now. I can't decide whether to do the HF 2 HP deal and move one duct from tool to tool, or to just get a really good ambient air cleaner. I think the ambient air cleaner would be much more convenient. I don't mind sweeping the chips, it's beathing the dust that worries me. I saw a post on here a couple of days ago where a guy (can't remember the name ) had posted pictures of a shop made system he made with a fan encased in a box that had regular HVAC air filtersinstalled on the four sides. The fan would pull air through the filters. I thought that was a great idea, if one could find a fan powerful enough. Any comments on this sort of shop made ambient air cleaner, especially type of fan to use, or commercially available ones? Just thought this might be a better option for some. Or use both?

Stephen,

Most people i would say use both. The DC collects the dust at the source and then then smaller particles that make it to the air are collected by the air cleaner.

I have both and would not have a shop without them.

Jim

[Jimmy Newman]

I think the air filtration systems are a very good idea (and I'm planning on buying one of the JET models soon), but they're not a replacement for good dust collection - the idea behind good dust collection is that it captures most of the dust the moment it's created, not giving most of it a chance to get into your lungs. With an air filtration system, the dust floats around until it happens to move through the filter. This means that there is more potentially harmful dust in the air while you are working and for some time afterwards as compared to a dust collection system.

Unfortunately, the product information for the air filtration units can be deceiving. The product information for the air filtration units say things like (for the specific unit I'm looking at):

"The AFS-1000B can filter the air in a 20' x 20' x 8' shop in under five minutes, and filter the air in that size shop a dozen times an hour."

Unfortunately, that's complete BS . Sure, a 20' x 20' x 8' shop has 3200 cubic feet of air, which would only take a few minutes to cycle through the air filter at the rated 1000 cubic feet per minute - but the problem is, after passing through the filter, the clean air exiting the filter immediately mixes with the dirty air left in the shop. This is a classic exponential decay problem, which means that once dust production stops and assuming perfect air mixing and a 100% effective filter (both of which make the model work faster than reality), you only eliminate 63% of the remaining dust per "full cycle". You need 3 cycles for 95% and 4 for 98%. Add in the inefficiencies of a not 100% effective filter, odd flow patterns, and incomplete mixing, and it might take 5 or 6 or more "full cycles" to get to "good enough." Depending on the shop size, that could be 15 minutes to half an hour (or more if you have a larger shop than the unit is rated for) that you are breathing dust after you stop cutting.

That's certainly a lot better than nothing but I wouldn't use one in place of a good DC system.

I don't know a whole lot about the hardware in the air filtration systems, but I would also worry that without picking up dust at the source and dumping into the DC bag, you would clog your air filters very quickly and would have to clean them quite often.

[Wilbur Pan]

Any air mover (in this case a DC) will be rated to move a given amount of air against a given amount of static pressure with a given amount of horsepower (a Delta 50-760 is rated at 1200 CFM against static pressure of 8" Water Column at 1 1/2 HP).

The Delta 50-760 specs do read:

• Maximum CFM: 1200
• Max. Static Pressure (in water): 8

But I think those ratings are derived separately. The Delta 50-760 can generate 1200 CFM against no pressure, and can move a little bit of air against 8" of static pressure.

I'm not singling out Delta. All the dust collector manufacturers do this.

[Steven Wilson]

Jimmy, an air filtration system will do nothing to protect your lungs while your working. I use one in my shop and it's fine for cleaning up the air after the fact but while I'm making dust it's rather useless - you need to use a respirator while making dust. Remember your lungs are breathing the same air that the filter is filtering !

[Jimmy Newman]

Jimmy, an air filtration system will do nothing to protect your lungs while your working. I use one in my shop and it's fine for cleaning up the air after the fact but while I'm making dust it's rather useless - you need to use a respirator while making dust. Remember your lungs are breathing the same air that the filter is filtering !

That's what I was trying to say .

[Wilbur Pan]

I think the air filtration systems are a very good idea (and I'm planning on buying one of the JET models soon), but they're not a replacement for good dust collection....

Everything you say is true. But keep in mind that even the best dust collection systems will not capture all the dust at the source, so that you'll need air cleaners, or some sort of backup plan to deal with that dust.

One of the things you can do to make things better is to increase the CFM so that you are filtering the air more frequently. The usual advice is to have enough air cleaner capacity to filter your room volume about 6-10 times an hour. I aimed for 25 air exchanges per hour in my shop, which is equal to circulating the room volume in a little under 2 1/2 minutes. The nice thing is that this is easy to do: just install more air cleaners.

I really do think that the conventional wisdom of "6-10 times an hour" is really underpowered. On the other hand, bandsaws used to be sold with 1/3 HP motors, too.

[Jeff Raymond]

I use metal stove pipe (grounded) on my DC system. Then I wrap each joint with (GASP!) duct tape to insure a good seal. That, with blast gates close to the DC, allows maximum suction, especially for the jointer and planer. Got a 2-Bag Delta (220V).

[Rick Hubbard]

Since there is already a discussion going on about DC’s, maybe I can piggyback my own questions about DC selections.

I have a relatively small (24x26) shop that through pure “dumb-luck” I have managed to lay out in such a way that dust-generating machines are arranged in clusters. One “cluster” (in one quadrant of the shop) has two bench-top sanders and jointer. The adjacent quadrant has a cabinet hybrid TS, a large router table, bandsaw, planer and drill press.

Up until now I have been using a shop vacuum as a DC (with predictable efficiency) but have decided to purchase a Jet DC1100. My plan is to construct a 5’x6’ outside “lean-to” on the outside of my shop and to install the DC and my air compressor in that structure. This arrangement will isolate the noise of these two machines and further isolate the dust that infiltrates through the filter bag. I’ll use 2x6 wall studs and pack them with insulation to mitigate the loss of warm air from the shop (important here in Maine in the winter).Does anyone see a problem with this scheme?

Here are a couple more questions: The Jet DC has 2 four-inch connections. My plan is to use both of them, with one running just a couple of feet through, the wall (with a blast gate) so I can use a single flex hose to connect to either the bench-top sanders or the jointer. The second connection I would like to hook into a piece of straight 4 inch diameter spiral pipe, about 15 feet long and drop it down to the quadrant of the shop where the TS, router table, BS etc are located. From this drop I plan to use a single 4 inch x 10 foot hose to connect (through another blast gate) to one machine at a time (since I never have more than one running at a time). When I make my connections at each end of the spiral pipe, something tells me I should use two 45 degree elbows at each end (rather than a single 90). Is this correct, or given the light demands on the system is it OK to use a single 90 at each end? Related to this, is the quality of blast-gates a consideration? I will only have two, so if it is worth the money to buy one type versus another, I’ll spend the extra money if it is warranted.

Thanks for the advice.

Rick

[Dick Davis]

I recently replaced my 1hp Delta DC with the 50-76, which I outfitted with the Wynn Engineering pleated filter as described in the FWW article. I am thrilled with its performance in my basement shop. When I researched which DC to buy, my first choice was the Oneida cyclone. It's only drawback (for me) was the price as I'm only a hobbiest woodworker. My new Delta DC connects to about 20' of 4" PVC with a wye and blast gate to each tool. I use only 1 tool at a time and open only its blast gate.

Good luck with your decision.

[Steven Wilson]

The Jet 1100 is a bit underpowered to support much duct work, step up to the 1200 instead. As for the 2 4" duct ports, just remove them and you are left with one 6" duct port which is what you want to hook up to your duct work.