DC Piping

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rjwolfe3

rjwolfe3

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I have a small portable dust collector that I am currently using. I would like to add permanent piping and am wondering what would best to use.:confused: I know that there is metal and pvc available but I don't know which is better. I also don't know how much I need to worry about a grounding wire. Right now I am using a ductwork kit from Harbor Freight and I don't believe it has a grounding wire with it. Any advice would be greatly appreciated. :smile:

(And no, I have no plans to upgrade the dust collector itself at this time. It has a 1 micron bag and it work really well.:biggrin:)
 
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Rob, I can't answer your questions but was wondering what portable DC are you using and does the 1 micron bag come with it or did you have to buy it separately?

Thanks,
 
rjwolfe3 said:
I also don't know how much I need to worry about a grounding wire. Right now I am using a ductwork kit from Harbor Freight and I don't believe it has a grounding wire with it. Any advice would be greatly appreciated. :smile:
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If the hose doesn't have the wire in it, don't worry about it. If the hose has a wire in it, the wire picks up a lot of charge and can give you a nasty jolt of static electricity. I hope the DC and your machines are grounded. I have mine on Ground Fault Circuit Interruptors. Attach the wire to the machine ground.
 
I use 6" sewer pipe (Green PVC) for my duct work. lowest cost per foot for that size.
If you have 4" ducting you can use ABS (the black PVC) from Home Depot.
plastics will pick up a static charge but i have never had a problem with mine and don't use a wire. If you are worried about it simply get some bare copper wire and run it inside the pipe.
 
I have never gotten shocked yet so if it is not that big of a deal then I will just leave it out. I figured the plastic pipe would be cheapest. Is it necessary to glue the joints?
 
rjwolfe3 said:
I have never gotten shocked yet so if it is not that big of a deal then I will just leave it out. I figured the plastic pipe would be cheapest. Is it necessary to glue the joints?
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I probably wouldn't glue the joints, becuase if you have a clog, you won't be able to get in there, without cutting it.

I would use silicone caulk just to seal them up and make the joints airtight. This will also act as a slight adhesive...at least give it a little more strength from possibly falling apart.

Then if you ever have a problem, you can just peel away the silicon caulk to unassemble.
 
Rob,

You said small dust collector, how small is small? Smaller dust collectors usually do not have enough CFM to use much duct work. DC ducting is a little complicated to get adequate results. You can not just hook up a bunch of pipe and expect good results. Each foot of pipe has a certain amount of static pressure loss and your machine has to be big enough to overcome that SP loss. If not, you will lose significant suction and not have enough CFM though the pipe which will not keep material suspended in the airstream. Then you end up with clogs you have to deal with.

I had a 2 hp Shop Fox with 4" piping to most of my machines with a 6" main line. It did fair but not great. I then switched to a 1,500 CFM cyclone with 6" pipe everywhere and now my system works as it should.

As for pipe, I use PVC and do not worry about wire or grounding. You will not get shocked and it WILL NOT cause a dust explosion. That myth has been debunked many times. If you go ahead with the piping, DO NOT glue it together. If you do, it is permanent and if you decide to rearrange the shop or add a new tool, most of your piping will be wasted. Just fit it together and put a sheet metal screw though the joints to keep it from separating. The fitting is tight enough that it will not leak. The easiest and cheapest pipe to use is thinwall sewer pipe from Lowes.

There is a good static pressure calculator available on Bill Pentz's website here: http://billpentz.com/woodworking/cyclone/index.cfm It is the 3rd link under Tests and FAQs. There is also a lot of good info there that will answer most of your questions.

I don't mean to discourage or overwhelm you but if you are going to go to the trouble of piping your system, I would hate for you to end up with less that satisfactory results and be disappointed.
 
I don't know what is considered small. I have a portable one from psi that I use to use on a grizzly 24 inch sander and it worked just fine. These portable units are 1 1/2 hp and are designed to work as well as the regular 2 stage units. I ran mine out the door instead of using the bag. I have since then upgraded to a monster and run the whole shop on it. I went with metal pipe for the most part on my piping. Not that much more and you have your conductor to keep the static down.

As for glueing the pipes together, I think that depends on where they are at. I ran my pipes along the ceiling and where they drop down I don't want them to fall so I would definately glue them there. On my system I'm using mostly metal pipe and every joint is popriveted. Plus taped to insure no air loss.

If you are just using it for 1 machine, say your lathe, I would use flexible hose to the machine and the shortest run possible. And by the way the cheapest way I have found is the black drain pipe you get in 50 ft rolls. It has ridges in it but I have not had any problems with it and that is what I used with my portable with no problem. I had to attach it to a piece of pipe then to the machines because it is a little bigger but this was no problem.
 
Biggest things that I can remember during my DC system research.

Obviously, the longer the piping run is, less suction power. With that in mind, if you want to hook up several machines, put the blast gates as close to the DC as possible. This way the machine doesn't have to suck on a long line of piping for no reason at all.

Try for relatively straight piping runs. More torturous the path= less suction power.

Turns: The typical 90 degree turns you get with pvc pipe, etc are hard on the machine. Gradual curves make the air flow a lot better.

Main run should be as large as the machine can use. usually 6 inch. I noticed on my machine (1 1/2 standup DC) if I connect the 4 inch hose I get really good suction. When I connect the 2 inch line to my scroll saw, etc I don't feel as much suction at the end.

Designing a DC system for a small (or large) shop can be somewhat of an art form. Many people delve into CFM cacluations, etc. But if you keep the above in mind, you should be able to make a setup that will work for you.

And I think this is the longest post I've done here. My fingers hurt now. :cowboy:

edit.. almost forgot:
I view the ground wire in this way. I saw my DC system collecting stuff on the outside due to the static electricity generated. Basic copper wire, etc is cheap. I would rather install simple wire wrapped around the hose and ground it to be safe. Why take any chances with your safety. If you have metal ducting, it is simpler, just ground the end of each line. If you use plastic gates with metal ducting, simply jumper the wire across the gate to keep the circuit going.

I would rather spend 30 minutes installing all that wire, than the 4-6 hrs a trip to the ER might take.
 
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Thank you all for the responses. I really can't afford a new dc at this time as much as I would love to have a monster sucker. I only plan on having one run of about 20 ft with 4" pipe. The only reason for that long of run is that my radial arm saw which is being used as a sander is on the other side of the shop. I will be putting a gate in so that I'm not losing much suction. Right now I have 20' of flexible hose and haven't noticed any loss of suction. It will also run to my lathe and a third drop to be shared with my chop saw and drill press. I plan on mounting the dc on the wall like the one in the Rockler catalog once I can figure out how to attach it (on wheels right now).
 
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Unless you have an industrial system a ground wire is not necessary. There's simply not enough static generated in a home system to go KABLOOIE! A ground wire MIGHT help a LITTLE in preventing shocks to YOU whenever you touch the system but you can always add it later if you need it.
I have the Oneida 2HP Dust Gorilla and granted, I have metal ductwork, but I never get any kind of a shock. Look in the Photos section-Shop Shots- if you want to take a look at it.
 
DC is one of those things that can be argued about forever. I have read posts that people use 1-1/2" hoses are are happy with the results. Most of the equipment you can buy has only 4" inlets on the DC and 4" hook up on the machines. The sad thing about this is that it leaves most woodworkers thinking that 4" is the standard so must be correct or good enough. the truth is it is not. the reason for 4" hook ups is economics.
If I set a DC with a 4" inlet and one with a 6" inlet next to each other. I could offer the one with the 6" inlet for less money and still sell more of the 4" model. 4" pipe is not only cheaper by far. It is much easier to find. That is the reason manufacturers stay with the 4" inlets and hook ups. machines with 6" simply will not sell.
Anyway the issue about 4" pipe is this. People are going to use it no matter what. But it is physically impossible to move the amount of air needed through a 4" pipe. It simply will not fit. Adequate DC is a balance between not only how much air you are moving but how fast you are moving it.
put sand in a glass of water. and try to stir the water fast enough to keep the sand from staying on the bottom. it takes a lot of stirring. if you put just plain old dirt in the water you would not have to hardly stir at all. with DC you are trying to move the air fast enough to keep all the dust stirred off the bottom so to speak. technically this is called keeping the dust entrained in the air stream. you also have to move enough air in to the stream to gather the dust you are creating out of the room.

Bottom line although many will say there 4" pipe works just fine. for what it really needs to be doing it is actually a physical impossibility.
My final thought on it is some DC is much better than no DC. and people will still opt for the lower, much lower cost option of 4" pipe no matter how it is demonstrated as inadequate.
Now all of you with 4" ducting can jump in and say how well your system works. the difference is on a micron level of collection anyway. and it is the micron size dust that will do the damage to your lungs.
 
I think I agree with Daniel. Depending on what dust collector you have depends on how efficient 4" pipe is. A dust vac and a dust collector work 2 different ways. The vac with 4" inlet would work great with 4" pipe but a dust collector works by moving volumes of air not by sucking. So if you can hook up a 6 inch pipe at the collector and shrink it to the 4 inch at the machine you move more air then you would if you ran just 4 inch pipe. Sounds crazy I know but if you put a 4 and a 6 inch pipe side by side and restricted the 6 inch to 4 at the end you'd be able to tell he difference.
I also agree that using plastic pipe will not create an explosion.
And like wolfcoast said a straight run is best with fewest bends.
 
Bill, and mostly for those that just gotta know how the restricted 6" pipe thing works. Because it is true as long as you do not restrict the opening for very long (inches)
air will compress as well as speed up to get thought the 4" opening and then expand to fill the 6" pipe again. you actually get nearly as much air flow into the 6" pipe as long as the restriction is a very short one. This trick will not work at the collector end though. THis whole issue is getting far into the "Science" of how to move air though and most people will never know that much about it.

If you absolutely have to use 4" pipe. Keep the runs straight and as short as possible. No 90 degree bends (use two 45s with a straight run between them)
and every turn needs to have a straight run after it. at least 2 feet of straight run at the inlet of your DC

The longest run of pipe I have in my shop is about 10 feet. with two 45 degree bends in it and at least 2 feet of straight pipe after each 45. and I use 6" pipe. I have 4 feet or more of straight run into the DC itself. what the straight areas do is allows the air to get the dust entrained in the stream again after the dust was slammed up against the pipe at the bend. the air actually makes a vortex (tornado) that is laying on it's side, at each bend and you want this to get settled down as well. in short bends are a really bad thing avoid them if at all possible.
 
Daniel said:
Bill, and mostly for those that just gotta know how the restricted 6" pipe thing works. Because it is true as long as you do not restrict the opening for very long (inches)
air will compress as well as speed up to get thought the 4" opening and then expand to fill the 6" pipe again. you actually get nearly as much air flow into the 6" pipe as long as the restriction is a very short one. This trick will not work at the collector end though. THis whole issue is getting far into the "Science" of how to move air though and most people will never know that much about it.

If you absolutely have to use 4" pipe. Keep the runs straight and as short as possible. No 90 degree bends (use two 45s with a straight run between them)
and every turn needs to have a straight run after it. at least 2 feet of straight run at the inlet of your DC

The longest run of pipe I have in my shop is about 10 feet. with two 45 degree bends in it and at least 2 feet of straight pipe after each 45. and I use 6" pipe. I have 4 feet or more of straight run into the DC itself. what the straight areas do is allows the air to get the dust entrained in the stream again after the dust was slammed up against the pipe at the bend. the air actually makes a vortex (tornado) that is laying on it's side, at each bend and you want this to get settled down as well. in short bends are a really bad thing avoid them if at all possible.
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I agree with you in theory but when you talk about micron level it all don't mean diddly if your dust collector has 30 micron bags. I have a 1.5 hp delta, I believe it's 1200 cfm but I'm not sure at the moment. My old run was along the outside wall of the shop and was 28 feet (total) with 4 drops and 2 45 degree bends with 5 feet of straight pipe between them. the drops were in the form of wye's and I was not pleased with it from day 1. Truthfully, it sucked because it didn't suck very well. I'm in the midst's if "re-deranging" my shop and the new run will be diagonally across the shop with 3 wye's. total run of pipe will be about 15 feet. I hope it will work better
 
Scott, A DC with a 30 Micro bag is a dust fan. It woudl serve to make every square inch of your shop bad breathing space.
28' is a lot of run when you figure that every inch of that pipe is adding to the static load on the DC. simply put the motor only has so much energy and to much is being lost trying to drag the air through all the pipe. you woudl get better results with the same set up by going to a larger motor and probably a larger impeller. 14" impeller with a 2HP motor is about as small as a good DC can get unless your equipment is pretty much right at the inlet.
keep in mind that with dust collection your are actually more interested in getting the really fine floaty stuff not he stuff that falls to the floor. I know most people like the idea of there shop staying sparkly clean, I can tell by the photos of everyones shop, but that simply is not realistic. keep the air clean and safe to breath is the pourpose of DC. if you cannot feel the air moving around your forearms while working you are not moving enough air. turn on your DC or Vac whatever you have. then take a hand full of baby powder and puff it up into the air a few inches right where you are turning or whatever. if any of that powder comes toward you or reaches your face, starts whifting across the room or goes anywhere but up the pipe. you do not have good enough DC. Don't throw it but think of all the Baby powder size stuff that comes off your work as you turn or saw. most shops end up covered in a fairly thick layer of the stuff. then think about how much you move your hands etc while turning and how those movements would stir up and churn that baby powder. it is sort of just hanging out in the air and you move your arms causing air to move. you turn your body or whatever. If your DC is not moving more air than you are with your movements that dust will follow you not the DC. it does not take much to move that powder several feet from the work by just waving an arm. you want your DC to be able to drag it back again. at least most of it anyway. A vac works because you put the business end right where you want it. a DC has to set still and get all the area around you.
 
Daniel said:
Scott, A DC with a 30 Micro bag is a dust fan. It woudl serve to make every square inch of your shop bad breathing space.
28' is a lot of run when you figure that every inch of that pipe is adding to the static load on the DC. simply put the motor only has so much energy and to much is being lost trying to drag the air through all the pipe. you woudl get better results with the same set up by going to a larger motor and probably a larger impeller. 14" impeller with a 2HP motor is about as small as a good DC can get unless your equipment is pretty much right at the inlet.
keep in mind that with dust collection your are actually more interested in getting the really fine floaty stuff not he stuff that falls to the floor. I know most people like the idea of there shop staying sparkly clean, I can tell by the photos of everyones shop, but that simply is not realistic. keep the air clean and safe to breath is the pourpose of DC. if you cannot feel the air moving around your forearms while working you are not moving enough air. turn on your DC or Vac whatever you have. then take a hand full of baby powder and puff it up into the air a few inches right where you are turning or whatever. if any of that powder comes toward you or reaches your face, starts whifting across the room or goes anywhere but up the pipe. you do not have good enough DC. Don't throw it but think of all the Baby powder size stuff that comes off your work as you turn or saw. most shops end up covered in a fairly thick layer of the stuff. then think about how much you move your hands etc while turning and how those movements would stir up and churn that baby powder. it is sort of just hanging out in the air and you move your arms causing air to move. you turn your body or whatever. If your DC is not moving more air than you are with your movements that dust will follow you not the DC. it does not take much to move that powder several feet from the work by just waving an arm. you want your DC to be able to drag it back again. at least most of it anyway. A vac works because you put the business end right where you want it. a DC has to set still and get all the area around you.
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I agree that 30 micron is excessive but have you looked at any of these on the market today?

http://www.woodcraft.com/product.aspx?ProductID=412085&FamilyID=63647

http://www.woodcraft.com/product.aspx?ProductID=943864&FamilyID=60039

Both come with 30 micron bags.


However, I disagree that the purpose of a dc is to keep the air clean and safe to breathe, it's main purpose it to collect dust. If you want to keep the air clean and safe to breathe you need an air filtration system like this one:

http://www.woodcraft.com/product.aspx?ProductID=815488&FamilyID=4673

I have both and I never run the DC without the filtration system running. Matter of fact I have the filter set up to pull the dust from the DC and send clean air into the shop.
 
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