J. Phil Thien's Projects

Quote from: D Romano on January 15, 2008, 08:38:50 AM
The separation could be alot better for the fine dust.

BTW, if you perform that test with a large cyclone, you're still going to fill your shop with fine dust.

In fact, there was a guy that posted in one of the WW forums in the last few weeks saying that his shop was filling with dust and he tracked it down to a small 1/8" hole in a weld on his cyclone (I think it was an Oneida).  The hole was in the plenum that feeds the filter stack.  So this was separated air, as clean as the cyclone could get it.  And a 1/8" hole was filling his shop with dust.  Dust that would have normally been caught in the filters.

I guess what I'm saying is, don't believe everything you read about the separation rate of large cyclones.  They still shoot plenty of fines to their filter stacks.

Quote from: D Romano on January 15, 2008, 08:38:50 AM
Since the dust does not naturally want to come up straight through the big donut hole, I think I will install an outlet pipe in it, making it more like phil's original garbage can separator. Making this outlet pipe smaller in diamter and/or lonnger will help the separation but increase static pressure.

Keep us apprised!  Post some pics of your work if you get a chance.

Quote from: D Romano on January 11, 2008, 08:12:52 AM
Phil,
It sounds like your shop is alot cleaner than I was thinking, but is the whole whole filter doing the brunt of the work? I thought the only ambient air cleaner was the small Shop Fox one. Is the Honeywell getting clogged up when you use the shop? If you don't mind me asking, how clean is your tissue?

You are correct about BP's findings. He seems to be saying that it is impossible, in a hobbyist environment, to control the dust to the degree he claims is necessary.

David

I've only done limited testing, so I'm not going to go out entirely on the branch and insist the electronic air cleaner is the key to my success.  After all, I only cut 12 linear feet of MDF.  I have to do more testing.

If I don't wear a mask and work in the shop for a couple hours and use MDF and hardboard, well, my tissue says as much (if you know what I mean).  If I am working with hardwoods and wear the mask when I'm performing operations that create lots of fines (hand sanding, for example), then I'm fine.

More testing is really required.  It looks like some other WWers are going to order the meters and it will be interesting to read not only their results, but I'm sure countless ways they'll figure out how to improve (lower) their #'s, too.

David,

I'm kinda going in a different direction with this.  First, the purpose of my test was to determine whether there was a real, lingering health hazard of having a woodworking shop in the basement.  I have satisfied myself that just a few minutes after machining, airborne dust levels return to levels that I won't say are "safe," but which aren't too different than you'd find outside or in your office (1/6th of what you'd fine in downtown L.A., for example).  That is taking into account particles down to approx. .8 or .9-microns.

The purpose of the .3-micron filter is to track longer-term generation of sub 1-micron particles.  That is, what happens when I run it for two weeks in my shop basement.  What will the filter look like.  How much will the CFM drop (it gets 195-CFM according to my measurements when fan is on high).  Now what happens when I take it to work and repeat the experiment?  How much different will the filter look?  How much less (or more?) will CFM drop?

I'm still in the quantifying stages and I'm going to resist making any changes until I know where I actually need them and can determine how much they will contribute to improving any problems I identify.

Keep in mind that BP's own testing of shops (even those w/ his cyclones) found that they all failed.  Within minutes of machining MDF I believe every single shop that was filtering indoors (and not exhausting shop air) saw their #'s climb approximately the same as mine.  I believe some of these shops had the same type of high CFM air filter as you have.  And some have found the higher CFM air scrubbers exacerbate the problems unless they filter to under 1-micron.  I have to read his tests more carefully, but I believe only shops that open their doors and blow their air outside were able to stay within the parameters he (BP) was seeking.

In my case, I greatly benefit by the Honeywell electronic air cleaner (it is a hole-house air cleaner attached to the furnace).  I have heard people rave about these, and others disparage them.  In my case, my unit is blowing air in the 20's (meaning 2000 particles .8 or .9 microns and up).  This is extremely clean air.  I have always suspected it works well because even with all my kid's pets, our plush carpeting, and our lifestyle, our house requires less dusting than any other house I've been in.

There is a HVAC vent right above the table saw that is constantly on (the fan on my HVAC equipment is always running which is what is recommended when you have an electronic air cleaner).  This is constantly dumping clean air into the shop, which means the recovery after machining MDF (I don't use a lot of this) is pretty quick.

My gut tells me the thing that would improve my #'s most would be the additional of a Shark Guard w/ dust port on top of the saw.  But like I said, I'm going to run the meter and the .3-micron filter for a while and get a good baseline before I make any changes.

Background: My shop is in my basement. I have a Ryobi BT3K, a small Inca (8-5/8" wide but short bed) jointer/planer, Inca 9-1/2" bandsaw, A Ridgid oscillating belt sander, and a router table with downdraft box. I use a Ridgid shop vac with 2-1/2" flex hose network for "dust" collection (along with a separator).

All my tools have 2-1/2" or smaller ports. I have a couple of different dust collectors but I don't use them because I just can't run 4" piping (perhaps some day I will figure out a way to do this--my shop is TINY). My shop vac gets about 150-160 CFM w/o separator. With the separator and network I get about 125-CFM. Absolutely not enough for collection of fine dust.

So the more I read Bill Pentz's site (among others) the more concerned I've gotten that I'm breathing boxcar loads of super-fine dust. That, this dust never settles and every time I enter the shop I breath more of it.

I realize my setup is sub-optimum, but the question is, how much of a price am I paying for it?

Recently I stumbled upon a particle counter that is really geared towards homeowners. It uses a laser to count particles in two sizes.

From the manual:

Quote"Small particles are all particles detected by the DC1100 right down to its detection limit--typically below 1-micron. Large particles are all particles detected above the large particle threshold which is typically around 5 microns."

The meter comes with a table to help interpret the readings:

Quote
0 - 25 Excellent Air Quality
25 - 50 Very Good
50 - 100 Good
100 - 350 Fair
350 - 1000 Poor
1000 + Very Poor

So I got this thing and plugged it in in my basement and let it settle for a half hour or so. I had not used any tools for at least 24-hours.

On returning to the shop, it was reading 53/4. You have to add "00" to the end of the readings, so 53/4 translates to 5300 particles total (per cubic foot), with 400 of them being larger than about 5 microns. So far, so good (looking at the table my reading was considered good).

So I switched on the vac and started to cut some MDF. I basically cut the edge off a 3/4" thick piece of 24" long MDF, taking about six swipes. This type of cut (where the blade isn't buried in the wood but rather the left edge of the blade is exposed) seems to generate the largest amount of visible dust above the saw.

I then switched off the saw and watched the meter spike. Approx. one minute after I was done cutting, the meter hit a max of 1955/515. So 195,500 particles (down to 1-micron) and 51,500 larger than 5.0 microns. Nearly twice the 1000+ reading that garners a "poor" rating from their table.

Subsequent readings:
+3 minutes (from peak): 1001/223
+9 minutes (from peak): 499/91
+46 minutes (from peak): 54/2 (now, it could have been low for a while, I had to go upstairs and wasn't paying super-close attention to the meter).

I'm taking for granted that the meter does, in fact, measure down to under 1-micron. However, I will say that the meter is extremely sensitive. Just moving around in the area (within six feet of the meter) causes readings to climb.

Some interesting factors: Above the saw is a vent from the furnace. The furnace has a Honeywell electronic air cleaner. When I close this vent, and let the [new] fine dust air cleaner (down to .3-micron) filter run for just fifteen or so minutes, the meter gets down to 18/1. With the vent reopened the meter almost immediately climbs to 50ish/3-4ish. So my take on this is that, with the vent open, the air from the rest of the house dilutes the super dirty air the table saw creates as I cut. So after cutting the #'s peak, but then fairly quickly start to drop again.

It is too early to make any real generalizations. I hope to use the meter to improve dust collection/filtering in my shop, home, and office (where we service PC's that are full of dust--similar issues to home wood shop).

BTW, the black thing is the meter, the big thing sitting on the floor is my new fine air filter.

Quote from: Todd on January 10, 2008, 06:03:10 AM
How about a plastic 55 gallon drums.  It used to hold soap for a carwash

That would work but plastic isn't optimum due to static clinging that occurs.  But I've used it and it does work.

BTW, plastic garbage cans tend not to work, they collapse too easily.  The drums are much stiffer.

Quote from: KC7CN on January 09, 2008, 04:13:03 PM

Quote from: memilanuk on January 09, 2008, 03:34:46 PM

ROTFLMAO!!!

Me too!

I can't believe I missed that the first time I read it.   :D

I tend to think you may have been feeding too fast.  I would try again and this time slow down the feed rate of the debris.

I think the postition of your elbow is fine as-is.

Another thought occurred to me.  If there is insufficient CFM, or if the separator is "stuffed" (fed too quickly), you won't get optimum separation.  I have tested my units by pretty much burying the hose in a can of sawdust and find that separation efficiency is greatly reduced.  However, when running with a machine (table saw, jointer, planer, etc.) the makeup of air to particles makes the separators job much easier.

I guess I would suggest double-checking all the obvious things, like that the baffle larger dimension is all the way against the edge of the can (no gaps), and that if you seal-off the input tube that your DC starts free-spinning (unable to get any air from a leak in the can or top).  But, your implementation look correct.

Quote from: Dennis Paish on January 07, 2008, 08:43:56 PM
Thanks Phil.
I can not find a 30 gal steel garbage can anywhere in Calgary, Alberta, Canada.  Would a 16.5 gal (Height: 25"; Diameter: 17") steel garbage can work?

Dennis

That would be too small for 4" in/out.

How about a steel drum?  They are used for shipping liquids and are commonly available in 50-gallon sizes, but you can also find 30-gallon and smaller.  Maybe even able to find a deal on used ones by calling a recycling facility.

Metal works better than plastic (which has a tendancy to collapse or at least pucker under suction).  For 4" in/out I'd use a 30-gallon can.  I think my 30-gallon cans are approx. 20.5" diameter at the top.

Quote from: D Romano on January 07, 2008, 02:13:53 PM
I use 6" ducting, but after the impeller, there is a 4" duct leading to the separator ring. That step down in size must really increase the velocity. Seems like it would be better to increase the diameter after the impeller, not decrease it.

I can't disagree with that!  Perhaps they (original designers) did it as a way to prevent the blower motor from overworking (the more air the impeller moves, the more current the motor draws)?  I donno.

Quote from: D Romano on January 07, 2008, 09:22:49 AM
Had another thought- In a DC, the separator ring is a doughnut with about an 8" hole in the center. Anyone have any thoughts on making that smaller? I'd guess that smaller gives better separation but at the cost of reduced airflow.

Yep.  You may be able to choke it down a little w/o impacting the overall CFM (especially if you're using 4" ducting).  But I'd try leaving it as-is for now.  8" should still leave a 5" or so ledge at the edges, which should be plenty.

Quote from: D Romano on January 07, 2008, 06:56:06 AM
Also, while looking at the assembly, I began to rethink the use of the neutral vane. The neutral vane is said to increase airflow, presumably by reducing turbulence and therefore SP when the air enters the separator ring. But, does anyone know if it helps separation?

It appears to me the the dust would circle around the outside of the ring, hit the back of the neutral vane (4" pipe) where it would be deflected into the center of the ring and drawn up through the large hole towards the filter. What force would be driving it down to the collection bag? It would take the path of least resistance. I had tried to address this by putting a ramp on the back of the vane, but especially with the baffle in there now, it seems like it would hurt the separation.

By the time the air makes a single revolution the chips that are going to settle will have done so.  Gravity is foolproof in this regard.   ;D

So as the airstream circles once and then hits the neutral vane it will hopefully be pretty clean.  However, if there is one thing I've learned with baffle use, it is that turbulence is your enemy.  My concern is that the turbulence will cause problems for new air entering the chamber, and any particles that do get picked-up again from the bag.

My advice would be to try with and without the neutral vane, but I suspect that removing the neutral vane will improve overall performance.

In terms of the roundness of the ring, yeah, these aren't perfect.  It can take some trial and error when fitting them.  Getting the larger diameter as close to the side of the can (or ring) is important to prevent turbulence in the bin (or bag).

Looking forward to your report (and pics).