Dust collection system.

Messages
266
Location
Victoria, TX
After blowing out the shop twice today and with diminishing results I decided it was time to set up the dust collection system and use the dang thing.

I am in a bit of a quandary about running the ground wires. It appears that my dad had ground wire running inside the ductwork of the system. In the other examples I've seen online it is not done like that. The ground wires are attached to the outside of the ductwork and then grounded to tools and the blower and/or motor. ONe had a ground going to an outlet with the wire only connected to the ground prong.

Is there a reason he ran them inside? Unfortunately, he cannot answer this and many other more important questions I have.

Alan
 
There are many thoughts around the subject. I personally don't have ground wires, never had issues with static or getting shocked on the pvc lines

I assume it's pvc or flex lines that you've got, but if it's metal, you really only need wires from the machine ground to the duct and jump a ground from metal to metal where there isn't conductivity.
 
Well.. you can't really ground PVC because it's an insulator... There are a lot of theories about how you can reduce static buildup, which seem to have wildly varying reports of success (which makes me think there might be a lot more success in peoples heads than there is in the pipe).

I think I'd vote somewhat against putting a wire inside the pipe simply because it's something for shavings to hang up on, and that seems like a bigger pain in the neck than an occasional static zap which is annoying but mostly harmless.
 
I've run my DC system with 15cm (6") PVC pipe for 16 years (has it been THAT LONG...? :oops:) and I've never, ever had any static problems.
Like Darren said there are many views on this subject and maybe on a HUGE industrial setup with all-steel piping there is an argument for it, but in my 16 years of experience there is no need for ground wires.
Match your duct size to your blower, this is a DC NOT a vacuum cleaner. With a vacuum cleaner you a concerned with suction which is measure by how many inches of water it will lift or something like that, a DC is different it is all about how many Cubic Feet of air it flows. Large heavy chips that you can sweep up are not the main concern for a DC, (but a good DC will get most of them too) it's all about the super small particles that are made when highspeed steel cuts the wood, this talc-like powder is what you want to be your main objective, these are the particles that get into your lungs and never leave. You want CFM (Cubic Feet per Minute).
The 4" ducts matched to the right blower can do an adequate job but really you want a 6" system for at least your main runs if not right to the machine to really work well.
I put a lot of time into my DC system and it works well, I do not regret doing a good job on it.
Good luck!
 
Skip the ground wire, it's just going to be a PITA in the future when you change something (and you will make changes). MY stuff has always been PVC. The first system I had was grounded, with wire wrapped wrapped around the exterior of the ducting. That was when I learned the truth in in my first statement.
 
The success of a pvc duct system without a static drain line may be dependent on the typical humidity in a given area. I can see how a static charge could build more in a dry area than in a humid area. Regardless of what others might say, from personal experience I have gotten a mild shock from plastic flex duct so I can only imagine what a full plastic system could do. That's one, among many, reasons I ran all steel duct for my system and any flex going to machines has a wire in it.
 
all pvc no ground wire and use the largest pipe then drop to tools. i go directly outside, no bag system works well for me and there are many on here who have seen it.. but i will say yu have to turn it on for it to work and in my experience you still get dust from some machines. but anything you get rid of is good
 
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My system is PVC and not grounded. The only place I get s static shock from is when I touch the cyclone. Always a small shock, nothing large, ever. My DC is in a closet where I store paints which my wife accesses from time to time. Grounding the system would rob me of the joy I get when she goes to get a can of paint and I hear that "CRACK" of static followed by a few not so nice words. :rofl:
 
I think the black flex and some of the Super Dust deputies are abs plastic, which may be more prone to static. And it could very well be as Bill mentions the humidity. :dunno:
 
I live in a dry windy area. I run the wire around the outside of the pipe as I did have annoying static issues. This will be environmental. The question is, did dad run the wire because he read about it in a magazine or do you really have static problems in your area? An easy test is to run the shop vac and suck up a bunch of sawdust. The air and spoil moving through the isolated plastic hose is what creates a charge. Does the spoil cling to the hose? Do you get a shock when you touch things? If not, don't bother. It's an easy add later if required.
 
Static electricity is a bit different in behavior than the electric power that is running through wires and machinery. It is comprised of electrons that are in the outer orbits of the atoms that make up the non conducting materials. They aren't held to the atoms very tightly, so with little external force, they can be made to jump from one atom to another that is deficient in it's free electrons. This jumping back and forth between atoms is not a problem until they all begin jumping in the same direction due to the external force. They get carried on your sawdust in your dust collection system and can build up to high levels much like charging a battery, when the dust particles passing through your system collect electrons from the source or path surfaces, even though these surfaces may be considered to be non conductive. When the difference in quantity of electrons builds sufficiently between different non conducting areas, they try to go back to the area that is deficient in free electrons. They try harder and harder as this difference increases and they will take the shortest easiest path that they can find for this. If it happens to be through you, then so be it, and you get the shock as they pass through you on their way back to the area that is deficient in free electrons.

The best way to avoid this problem is to use all metal in your system, and ground it through your electric power system, or some other grounding point, ie water pipe, stake in ground outside, etc.

Another effective way is to provide many easy paths near or on the non conducting surface that will continue to give areas of your non conducting surface many points at which these electrons can get back to where they came from, before their balance in quantity gets significantly high and make a spark. In times of elevated humidity, the electrons usually find their way back through the moisture in the air, but when the humidity is low they cannot, and build up to the point that they will seek out another way to get back and be balanced again.

For non conducting portions of a dust collector system, a spiral wrapping of light gauge uninsulated wire with the ends, or at least one end, connected to a metal blower, etc. with that metal blower or other tool then connected to a ground source like the green ground wire in the power system. This will provide this path within a few inches of every non conducting surface and give these electrons an easy way to get back to where they came from before they can build up significantly. A high unbalance is what causes the shock, since it finds this return path through you. The metal spring wire in a flexible pipe or hose will work fine for this, if the ends of this spring are connected to the metal machine. Where this wire doesn't exist, wrapping the plastic pipe with wire will do the same. You won't need many wraps. A spiral of wire with a spacing of 4-6 inches per wrap should do the trick on 4-6" PVC, if it is connected to a metal ground point at one or both ends.

This information isn't a true scientific explanation, but it is in a form that most can easily understand. I'm a retired Automation Engineer (EE) and once designed control systems for high speed automated manufacturing lines. I have solved many problems that were caused by static electricity in manufacturing. An electronic component that is designed to operate at 5 volts can be easily destroyed if 1,000 volts of static electricity goes through it. This same 1,000 volts of static electricity going through you would hardly be felt. Static electricity is just a charge difference (unbalance of free electrons) between two points and there is little to almost no power (amps) to it.

Charley
 
I don't have ground wires in my system either... I use the flex hose from the machine to the out let tube... I used the aluminum dryer hose under the work bench and through the wall to the impeller and DC .... don't know that I've ever had a static problem.
 
Wow! These are some great and very informative responses. I appreciate you guys taking the time to relate all of this.

Here are some pictures of the system I've got.
IMG_1110.jpg

IMG_1114.jpg

I haven't decided on a permanent home for it inside the shop and it can still stand a bit of cleanup. I may put it against the wall to the right of where it is now. Still close to the door for clean out. I'll move the planer and jointer in front of it to shorten the distance that dust has to travel. Then run 4" PVC the length of the shop with two or maybe three (probably only two) drop downs for smaller tools (sanders).

I saw a home vacuum system once where the hose retracted inside of a larger diameter pipe for its full length.

When I turned the unit on it appeared to have plenty of pull and the dryer vent I put on it to try picked up anything it got near. It's got that three way splitter and I suppose I could use one for the planer and jointer, another for the table saw and routers and the third one for the overhead. All my dad's ductwork was brittle and cracked. Look out Home Depot, make some room in your piggy bank...

From reading the responses I think I'll forego grounding the whole system and possibly just ground the main unit to the shop supports or the electrical system ground rod just outside that door.

My dad lived in Kerrville, TX which is relatively dry. I live in Victoria, TX which has relatively high humidity. I little static ping doesn't bother me, a "Dust Explosion" does although I did not find any reference to home wood shop dust explosions or fires while using properly maintained equipment.

I'm not sure how much dust my dad was collecting because there was a significant layer of woo bdust on the walls and ceiling. The floor was covered. He had no issues, but he did have it grounded.

Again, I thank you all for the responses. That's one of the things I like about this place. Everyone is eager to help out.

Alan
 
I little static ping doesn't bother me, a "Dust Explosion" does although I did not find any reference to home wood shop dust explosions or fires while using properly maintained equipment.

Alan
When I built my system I dove deep into this subject, as my shop is literally a hole in the ground, a fire would be a HUGE problem.
I have never found any actual reported case of a fire in a DC system caused by static discharge, in a home workshop, the few fires that did originate in DC systems were almost always caused by a hot piece of metal being carried into the DC system, and even these were not 100% confirmed.

In the end, it's your workshop so you have to decide, but I'd also check your home owner's insurance to make sure that there is no stipulation that the ducting must be grounded, grounding the actual blower is a no brainer ;) :)

When you first set everything up try to make it sort of temporary because you WILL alter the system as time goes on, none of my PVC joints are glued, a few I ran some screws through to hold better because there is 8' of six-inch flex hose hanging off a 45 or such. That should also be mentioned, if you don't already know it, don't use any 90 elbows if you can avoid it, use two 45 elbows instead, and never you a "T" joint, use a "Y" joint (I'm talking about PVC pipe here).

Best of luck.

Stu
 
I had a DC fire once, but it was because the run capacitor blew on the motor, leaked some oily goo that caught fire.
The scary thing was I couldn't get it shut off and had to unplug it to get it to stop.
Hit it with a fire extinguisher and all was fine.
 
Looks like a nice DC.

Many of us here are using PVC, the S&D (Sewer & Drain thin walled stuff), which you can get larger diameters of, but most home stores carry the 4" variety. For corners you'll want them to be a sweep, which most of us use two 45* elbows with a 6" straight piece between to simulate, try to avoid any sharp 90* corners as you'll loose more CFM than the sweep. Most of the commercial blast gates plastic or metal, can be adapted to the pvc with a few layers of duct or masking tape to shim it to size.

Some pics of my latest install here: https://familywoodworking.org/forums/index.php?threads/darrens-shop.19814/post-506466

You'd be better off as Larry mentioned using larger 5" - 6" pvc for the main trunk, with your size of DC, then reducing at the tool/drop to the size the tool needs.
 
That rig should pull a fair bit of air alright (y)

You might consider removing the splitter and running a somewhat bigger mainline from it. The trick with a DC like that is balancing airflow and air speed (these are high flow low pressure fans as opposed to a shop vac which has a low flow high pressure hence the reason the shop vac works with smaller hoses).

You want the most airflow you can get while keeping the airspeed high enough to pull all the gunk through and not let it build up in the pipe. Larger piping == more airflow, but less airspeed, smaller piping vice-versa (curves and junctions rob both flow & speed so try to layout to minimize those, ditto flex pipe). On my system (which is quite under powered compared to yours) I had a two way splitter I removed and replaced with 5" piping, I tried a section of 6" but it was leaving a lot of trash in the pipe. The 5" pipe is a bit harder to find but may still be a decent choice if you can get it as it will definitely keep the flow higher than 4" and the speed higher than 6" (you may well have enough oomph for 6".. but I don't think there's a huge advantage in that regard and some risk the speed could be to low.. in which case you have a bunch of pipe you've bought...).

A roll of the aluminum "actual" duct tape (tape for ducts.. not duck tape haha) works wonders for sealing up small leaks in the DC system and connectors. All the little leaks add up to a lot more loss than you might think,
 
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