Dust Collection

[Jim Guy]

I currently am using a Delta 1.5HP dust collection system. Not long ago in a trade I managed to get a 37'' duel drum sander. I love it but my Delta (which is only about 10 ft from my sander) is just not doing the job.
To compound the problem I only have a sealing height of about 78".
I think because of that a cyclone is out. I'm in the basement and there is no chance of setting something outside.

Question: If I purchased a 3 hp dual bag system will this be enough? My sander would still be about 10 feet from the unit, but my longest run would be about 55 ft (not counting the drop) to a miter saw. There would be several drops between but there would be a shutoff on each of course.

I'm guessing I would be running 4" plastic pipe.

Can anyone point me in the right direction?

Thanks -

[Darrin Davis]

You need to go to www.airhand.com and read all of their information. They have info on how to calculate all the factors that go into putting together a dust collection system. This is one of many website that I studied before designing a dust collection system for our high school woodshop. You really decrease your flow when using 4" plastic spiral pipe. You should only use 4" plastic spiral pipe at the end of each run to do the final connection to each machine. Airflow is really effected by friction and when the inside of your pipe is riged (like inside of 4" plastic spiral pipe) you really decrease your efficiency. I will look for another website that really explains dust collection "for dummies" like me that really helped me out. It's been 3 years since I used their site but if I find it I will post it here.

[Julio Navarro]

A 78" ceiling height may not mean that a cyclone is out of the question.

I have seen the blower and motor placed beside the cyclone and below the top of the unit. The blower and motor do not have to be on top of the cyclone.

By running an 8" duct up into the top of the cyclone you gain a few feet of head room.

Check out Stu in Tokyo. http://www.ablett.jp/workshop/cyclone3.htm I dont think anyone hes less head room than he does.

[Bill Pentz]

Jim,

I had to run 6" pipe to my dual drum sander to get enough airflow for good collection and had to also upgrade from my 1.5 hp dust collector.

I first tried a 2 hp dust collector, then a 3 hp, and then a 3 hp cyclone, but none of these worked out with all leaving my shop covered in fine dust. The problem was then and continues to be now that the advice and ducting design I received from the various small commercial shop dust collection providers was doubly wrong. First, all only recommended "chip collection" solutions which only move enough air, roughly 350 CFM at our larger machines that is needed to collect the same sawdust and chips we would otherwise sweep up with a broom. If I wanted to collect the fine dust, there was over twenty years of professional air engineering that said I needed to really move a real 800 to 1000 CFM at my larger tools depending on what level of fine dust collection I wanted. Second, instead of being advised to build a ducting system that would work for a small dust collector with just one gate open at a time, all the advice I received and read recommended building these complex tree ducting systems that went from a large main trunk that progressively shrank down to as small as a 2.25”down drop. This is exactly what we need in a professional shop where all machines are being used at once, but in a small shop with a small blower, these designs work poorly. The issue is that when we close down our blast gates to collect from just the machine we are working with, we end up with too little total airflow to keep the vertical runs in the main from plugging and from building up internal dust piles in the horizontal runs. I foolishly considered the advice I received as good information based on my working with my shop vacuum. What I did not realize is that a shop vacuum typically moves air with ten times more pressure, so the air gets pulled through small openings, around tight bends, etc. At typical 7” to 10” water column dust collection pressures air behaves more like water and will barely compress at all. Measuring the airflow in the mains showed that with just a single 4” pipe working my blowers that were rated up to 1800 CFM were barely moving 350 CFM because that small pipe size defined how much air would be moved. Collecting from my tools with the smaller 2.25” shop vacuum sized ports was far worse with the airflow dropping as low as 50 CFM. Airspeed measured in feet per minute (FPM) is related to total air volume by the formula FPM=CFM/Area where area is measured in square feet. My 8” mains at 350 CFM were not moving even 1800 CFM, yet we need at least 3500 FPM to 4000 FPM to keep our mains clear. The 2.25” ports were not even moving 700 FPM which explained why my little vertical run in my main kept plugging when using my tools with smaller ports. This and the CFM requirements tables published by air engineering firms whose customers get cited, fined, and even closed down if they do not stay in compliance with government air quality regulations show why you are going to need both a bigger blower and that 6” ducting to effectively collect the fine dust from your big sander.

Unfortunately, moving enough air is not enough as most of our tools needed upgraded with bigger dust ports and much better dust hoods, plus we also need to get rid of that fine dust once it is captured. Most tool makers provide tools that either come with no dust collection built in or at best “chip collection”. To get good fine dust collection with these tools, you must ensure that their hoods block the dust streams, control the dust, and then direct that dust for collection. Likewise, your ports and hoods need to have enough opening to support the needed airflow without so much opening that the FPM needed to control the fine dust drops too low. Assuming you fix up your tool ports and hoods, get a big enough blower and ample sized ducting, then there is still the issue of how to get rid of the fine dust. I have long recommended using a cyclone and blowing the discharge directly outside with no filtering. That is what most commercial firms do and they find that if they use radiant heating they do not have a problem with keeping their shops heated except in the most extreme weather. Those who live in extreme climates where it is necessary to heavily heat or cool their shops, plus those like me who live in areas where it is illegal to vent outdoors, need to filter. Filtering is another nightmare mess because most hobbyist filters are advertised with maximum potential filtering instead of working. Anyhow, as you can see, making repair is going to take you some time to do your homework and then is going to cost some time and money to work out a viable solution for your shop.

bill

[Jim Guy]

Thanks everyone for your input.
Guess I have some homework to do.

[John Grossi]

I am concerned about dust in my small basement shop. It is 12X30. I use a Delta 1.5 chip collector, which in my opinion is just a glorified shop vac. Being it is on wheels, with a 6' long hose, I just roll it to my table saw and my planer. I was considering one of the air filters that you mount on your ceiling, the one with the electrostatic filter, such as the 50-860k by Delta. The Delta rep. tells me what a terrific job it will do picking up the fine dust that is so worrisome. Would this be a waste of money? I am not a production shop, just building bookcases, some cabinetry, and small projects for the home. I realize there is no perfect system. I just would like to keep the fine dust from going thru the house and keep my lungs clean. Any help would appreciated. Paul

[Al Willits]

DC and the Sawstop seem to me to have a lot in common, the sawstop being state of the art in keeping the human body in one piece and DC like what Bill suggests is the ultimate dust collection for the wood worker.

With unlimited income, either are a piece of cake, just order the sawstop instead of that Delta/Powermatic/whatever saw and and if all goes well, years from now you still have all your fingers.
Looking into what Bill and a few others suggest for duct collection it gets fairly easy also, with a bit of reading you can design a DC system that makes a hospital room look dusty and all is well.

Problem lies with those who have not a unlimited budget and have to make concessions, a 4 or 5K saw is a safer saw, but may be more than what's affordable, tack on a 2 or 3k (?) DC system and we have gotten past weekend warrior status for many.

So it would seem to me, when asking for something like a DC/saw/whatever system for a persons garage/shop, that maybe a price range might make the decision much easier.
Just a thought.

Al ...who's been drooling over the Sawstop at Woodcraft, but can't afford the divorce right now....

[Jim Becker]

Paul, the air filter/cleaner will certainly help get rid of the fines in the air...but too late to help you relative to your health. Efficient collection at the source is the key...
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Jim, with some creativity, you'll find a way to accomodate your dust collection needs. There are some "shorter" commercial cyclones available...JDS has a product, although I don't know the specs in detail. You can also do something like Julio suggests, either building a system to suit or using a commercial "add on cyclone" (Oneida has them as do others) with an appropriate blower as well as leveraging the space between the joist above the unit. And, yes...4" duct isn't going to cut it. You can't fit enough air in it to reach the CFM you likely need to properly and efficiently collect chips and more importantly, fines, from your drum sander and other tools.