Another Dust Collection Tip

[Jeffrey Makiel]

I'm on a roll with dust collection regarding this forum. My previous thread "Tablesaw with a mustache" got me going!

A while back, I made some modifications to a standard 2hp single stage dust collector that has worked very well. These modifications are really nothing new, but I believe are understated. They apply to basically all 2hp dust collector clones.

I made 3 significant performance enhancing boosts:

1. In addition to using felt bags versus the original woven bags, I also purchased a 46" tall upper bag from Penn State Industries which increased the square footage of filter;

2. I increased the inlet opening from 5" dia to 6" dia. Some single stage collectors already have 6" dia. With radial blade wheels, the more air moving, the more amps the motor draws (opposite of vacuum cleaners). Therefore, with no duct restriction, the motor is working the hardest. I believe the smaller diameter was to prevent motor overload if the unit is running with little or no duct attached. But this design reduced efficiency when connected to a ducted system that sported 6" diameter duct;

3. The fan was re-mounted vertically. This eliminated two 90 degree elbows; one right before the fan, and one right after the fan. Elbows in these locations have a profound effect on the fan's performance more so than just the pressure loss of the elbows themselves. When I use to be an HVAC engineer, we called this "system effect" because the air flow is not given a chance to properly developed, or become uniform, upon entering the fan. This condition results in a unevenly loaded fan wheel and an overall redution in system performance. Rule one was to always avoid this condition if possible by adding straight duct before and after the fan equivalent to 5 diameters or more.

With the above modifications, my inexpensive dust collector runs like a champ, and is more quiet. Here is a CAD rendered pic of the mods I'm talking about.

cheers, Jeff :)

http://i3.photobucket.com/albums/y84/Beff2/DustCollector.jpg

[Jerry Clark]

Thanks for the info Jeffrey-- I am planning on making some modifications to my collector and may use some of the ideas. :rolleyes:

[Bob Dodge]

Hi Jeffrey,

Way to go on the mods. Well done. That looks very similar to a recommendation I've been making for years now, especially for the Delta 850, but also for the 2hp dc's with 6" inlets and 5" outlets.

My recommendation also involved getting rid of the blower's outlet transition flange, which transitions the blower housing's rectangular outlet, to a 5" round outlet. By doing that, you're left with a nicely open rectangular port, with bolt holes. Using those original holes, you can bolt the blower directly to the side of a shop-built plenum that sits on top of a waste container(s). With twin drums, you can mount the filters side-by-side on top of the plenum. No need for the blower transfer hose.

This design virtually eliminates all the outlet resistance, especially if used with a good set of needle-felt filter-bags. That transfers all the pressure to the intake side, where it does the most good. As long as you provide the proper amount of air resistance in your ducting, the motor should be fine.

For that Delta 850, it already has all 6" porting at the outlet. No need for the plenum.

Bob

[George Grubaugh]

Jeff,

Do yourself a favor & get rid of the bags altogether.

The small particles that they let through can be really bad for

you.

Check out Bill Pentz' cyclone pages if you haven't already.

(can I say that?)

Good luck,

George

[Jeffrey Makiel]

The bags appear to work really well. I've heard of clogging problems with cannister filters which makes sense since these type of filters are commonly used used in industry with pre-separation and continous pulse air jet cleaning. As far as having a cyclone, I have no room vertically to install one. Plus I don't like the sound levels these devices make while doing my favorite hobby. On the flip side, what I don't like about bags is that they are difficult to clean.

I've visited Bill's site. It is very informative. But I also believe that it instills a higher level of fear than need be for the hobbiest. If you are worried about overexposure to dust in your home shop, the only solution is to wear personal protective equipment such as a well fitting particulate respirator, or a positive air face mask. Even if you exhaust all the air to the outside for 100% particle efficiency, this does not mean that you captured all the dust at its source. Proper hood design is paramount, and nearly impossible for the hobbyist that uses his tools for a multitude of tasks, (for example, the tablesaw: rip, crosscut, dados, tenons, vertical panel raising, crown molding, etc.).

Also, let's not forget about power tool usage, especially sanders. Even though you can hook a vacuum hose to a sander, try sanding a board that is narrower than the sander's pad, or simply sand off the edge of a panel and watch the dust fly. ...And then there is hand sanding with no vaccum!

If I had a pre-existing repiratory problem (asbestosis, smokers cough, asthma, etc.), I would probably find another hobby because there is no perfect, or even near perfect, dust collection solution for the home hobbiest. On the other hand, I think woodworking dust exposure at the occassional hobby level for me is a very small risk relative to my lousy weight problem and cholesterol level. Oh, and let's not forget about driving on US Route #1 in New Jersey to work. :)

cheers, Jeff

[Bill Pentz]

Hobbyists are at much higher risk of exposure to the finest unhealthiest dust particles because we trap the air inside instead of blowing it away like large commercial facilities. Even good quality fine dust collector bag and cartridge filters may pass the finest unhealthiest dust. This stuff does not settle as long as we are working and gets blown back into the air with almost any air movement. It also lingers for months before dissipating. As a hobbyist who had done almost no woodworking for more than three months while recovering from dust triggered pneumonia I had my shop tested. The particulate counts for the finest unhealthiest dust were over 12,000 times higher than found in commercial shops or considered medically safe. Worse, when we took the particle counter indoors into my home separated by a closed garage door, my home also was far out of range. If you are not comfortable with the dangers of the 2.5-micron dust often called PM 2.5 do a simple Google search on PM 2.5 health risks (http://www.google.com/search?hl=en&q=pm+2.5+health+risks&btnG=Google+Search) and read over what EPA and some 2.7 million other references say about this risk.

Dust collectors push almost all the fine dust and chips into the filters. As the filters plug the air pressure increases enough to start pushing the finest particles right through. This tears open the filter pores as does cleaning and getting our filters hit by chips. As a result, even fine filters soon pass too much of the finest unhealthiest dust. If we let this dust build up in our closed shops the dust level become very unhealthy. That’s why I recommend using a cyclone to separate off the heavy stuff and then blow the cleaned air outside instead of filters. If your budget cannot afford a cyclone, at least put your dust collector outside. Likewise, all need to regularly blow out our shops because we are not going to get all the dust with any system.

bill pentz