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Dust Collector Plumbing through Wall. Using 4" ABS pipe. How to adapt to Rockler 4" Dust Right ?

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Forum topic by David Grimes posted 04-20-2011 09:50 AM 5188 views 0 times favorited 20 replies Add to Favorites Watch
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David Grimes

2078 posts in 2100 days


04-20-2011 09:50 AM

I don’t have much “plumbing” to do for the DC system in my small shop. It is very minimal by design.

I have three connections to make:

1) To connect 4” flexible hose from the separator feed to 4” ABS pipe on the “dust closet” side.

The ABS goes through the wall (sheetrock on closet side / T-111 rough sawn on the shop side), then 90’s into one leg of an ABS wye.

2) One remaining branch of the ABS wye needs to attach (same as before) to 4” flexible hose. That will go a couple of feet to the Rockler Dust right blast gate that has the hose and handle already attached below it on the wall mount.

3) The other (last) remaining branch of the ABS 4” wye also need to attach to 4” flexible hose. That hose will feed to the table saw already set up for the 4” flexible hose.

All three are really the same fitting issue: How to connect 4” ABS pipe (4 7/16” OD… 3 7/8” ID) to the 4” flexible hose ( 3 15/16” ID). Basically the Inside diameters are the same, but the ABS OD is much greater because of the greater wall thickness. So they kind butt together. Neither will go inside the other.

If the OD’s were the same I could use a flexible rubber adapter sleeve and two clamps… but they aren’t the same OD. Is there a 3 7/8” male : male adapter in ABS or PVC ? That would work.

Surely someone has crossed this bridge and has the answer. Thanks on advance for any help.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia


20 replies so far

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Cwj212

8 posts in 2100 days


#1 posted 04-20-2011 11:57 AM

David,

I don’t know if this helps but I just got a Grizzly mini cyclone DC and use a 5” flex. I ordered a 5 to 4” reducer but it was the same size as the tool Ports. I then ordered a dust right handle, 1’ piece of 4” flex to connect to the 5” hose from the DC to the handle. I also ordered two dust right tool ports. They have a rubber fitting and clamp. They work good. I will need a couple more. I need to switch the hose from machine to machine.

-- Craig

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David Grimes

2078 posts in 2100 days


#2 posted 04-20-2011 07:54 PM

Eureka !

I spent a few minutes at the HVAC supply house looking at everything that is available. When I picked up a 4” to 3” ABS reducer, I was praying that the 3” side OD would measure anywhere between 3.75” and 4”. It did !
The ABS black matching 4” to 3” reducer of course fits over the 4” black ABS pipe on the one side… then the 3” sides OD fits perfectly into the Rockler fittings that I have.

Got three. Problem solved and back in business.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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pjones46

986 posts in 2103 days


#3 posted 04-20-2011 08:09 PM

How are you grounding the system?

The reason I ask, I am in the process of laying out a system and I can buy ABS at resonable prices and would have less loss due to leakage as compared tp metal piping. Not to mention lighter.

-- Respectfully, Paul

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David Grimes

2078 posts in 2100 days


#4 posted 04-21-2011 06:41 AM

I was hoping nobody would ask about grounding. There is so much talk and conflicting data on this subject. I am not an expert, but here are my thoughts (and consequently my plans):

The static buildup that can cause a spark is on the inside. If grounding to prevent the possibility of explosion is the goal, then the bare conductor should be on the inside.

The conductor on the inside should be continuous. Point to point schemes from the outside into the wall with rivets, studs, etc. will not remove the possibility of static sparking. It will negate external user shocks, and thus give the impression that the “problem” has been eliminated, but false comfort nonetheless.

The actuality of explosion requires a perfect blend of physical circumstances that include media, media size, media concentration, humidity, air speed, cfm movement, duct size, duct material(s) used, temperature, etc.

Now, my application, my logic, and my plans:

My entire system will include only a total of 3 1/2 feet of black ABS 4” pipe and fittings (continuous) just to make a manifold that has one port on one side of a wall (to the separator intake), then two ports on the other side of the wall (one blast-gated port to a table saw permanently and the other to the top of the blast gate and swivel and Dust Right 4” expandable hose that I will move between two locations as needed… plus sweep the floor or sweep the benches.

I chose black ABS over white or gray PVC because all other things being the same, it looks good as hell. It looks marvelous. I’m just sayin’... lol

The remainder of my system is the Rockler expandable 4” hose. I will have a total of 35 feet (when expanded… only 5 feet total when collapsed). There is no practical way to ground this with a continuous internal conductor. Period.

One of the best ways to suppress spark(s) that are becoming a heated “ember” (for want of a better word) is to purposefully change the air velocity within the line. It separates the spark ember from the surrounding supportive air/fuel sea that helped create it. When that is disturbed, it quickly dissipates. My manifold will accomplish this, then quickly followed by the top section of the separator.

The humidity in Southwest Georgia is ALWAYS high. If I made a simple rule for my shop that I never use the DC when humidity is less than 30%, then I would never have the conditions required for a static electrical explosion. Funny thing is that around here there are few days annually with humidity that low, so not much of a constraint. Southwest Georgia is almost never a dry cold climate.

Bottom line: I will not “ground” the only 3.5 feet of “groundable” ABS that represents less than 10% of my total DC system length (when expanded). It would be foolish. I would feel stupid doing it. What about the 35 feet of expandable hose? Hmmm… I wonder if i could get Hasbro to make me a 3 7/8” diameter slinky ? See what I mean ?

With all the thousands of Lumber Jocks (present and past), why is there a total lack of DC explosion stories ? I don’t mean stories where you got shocked by static discharge. I don’t mean stories from the commercial lumber mill or truss factory. I don’t mean the retired lumber Jock that used to work at a flour mill and experienced some big fireworks.

Will all Lumber Jocks that have DC systems of 5 hp or less PLEASE step forward and share your DC explosion stories with us so that we may learn at least how common this type of event occurs ?

Selected Reading:
http://sacramentoareawoodworkers.com/Articles/DustCollectionandPVCPipeDangersDebunked.pdf
http://www.waterfront-woods.com/Articles/Electricity/static.htm
http://billpentz.com/woodworking/cyclone/ducting.cfm#StaticElectricity

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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David Grimes

2078 posts in 2100 days


#5 posted 04-21-2011 07:26 AM

Addendum:

I WILL be mounting an AC wired smoke detector with battery backup in the “DC closet”.

And I may put one of these in or below my separator baffle:

http://www.stovetopfirestop.com/index.php?page=Venthood

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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bubinga

861 posts in 2128 days


#6 posted 04-21-2011 09:14 AM

Okay so if static electricity is contained inside, why would I get a shock grabbing the outside of the shop vacuum hose ???
I have heard of PVC pipes exploding producing shrapnel, caused by static electricity, or should I say read articles in wood mags

-- E J ------- Always Keep a Firm Grip on Your Tool

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pjones46

986 posts in 2103 days


#7 posted 04-21-2011 09:23 AM

Ok, why do you get a shock after you walk accross a carpet and touch someone in the winter. Same reason, I think.

-- Respectfully, Paul

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David Grimes

2078 posts in 2100 days


#8 posted 04-21-2011 09:23 AM

Bubinga, you are correct. So am I.

I said “The static buildup that can cause a spark is on the inside. If grounding to prevent the possibility of explosion is the goal, then the bare conductor should be on the inside.

The conductor on the inside should be continuous. Point to point schemes from the outside into the wall with rivets, studs, etc. will not remove the possibility of static sparking. It will negate external user shocks, and thus give the impression that the “problem” has been eliminated, but false comfort nonetheless.”

So sure, grounding the outside will make it not shock you, but will not prevent a spark where the air/fuel mixture is… the inside. Bomb = Oxidizer + fuel + ignition.

I did not mean to be argumentative in any way. Only fully explaining myself.

Regards.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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David Grimes

2078 posts in 2100 days


#9 posted 04-21-2011 09:35 AM

pjones46,

Yes. Two non-conductors / insulators (your shoes or socks and the carpet) rubbing together in winter (low temperature and low humidity) will build up static on YOU because the charge produced by the friction is not carried away by the carpet or the shoes or socks (they are not conductors). You become the conductor.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

View bubinga's profile

bubinga

861 posts in 2128 days


#10 posted 04-21-2011 10:20 AM

According to all the information I have collected, putting the ground wire on the outside will prevent a spark where the air/fuel mixture is… the inside. Bomb = Oxidizer + fuel + ignition.
According to all the information I have collected, it is not necessary to put the wire inside
My entire system has the wire on the outside, for 15 years never a hint of any static build up anywhere

-- E J ------- Always Keep a Firm Grip on Your Tool

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David Grimes

2078 posts in 2100 days


#11 posted 04-22-2011 01:45 AM

Bubinga,

I began by stating that I am no expert. I have been led to believe that there are two “problems”. Static buildup and discharge on the outside that you can attest to because you have felt it yourself before. I would expect that your outside grounding would eliminate that common problem. I said as much in the original post.

The other is the static discharge inside the pipe where the friction of shavings/dust rubbing against the non-conducting walls of the PVC or ABS creates the static electricity. Inside is where the combustion could take place under ideal conditions.

But, the gist of my post is that I only have 3.5 feet of groundable ABS (whether inside or outside or both), and that 3.5 feet is the manifold. So I am not going to ground at this time. (not until the first time I get shocked) lol

I can guarantee you one thing, though: If I had PVC or ABS ductwork coursing around my shop, then I would probably do both outside and inside just to make it a non-issue.

Regards, DG

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

View GeorgeShaw's profile

GeorgeShaw

4 posts in 2034 days


#12 posted 05-10-2011 06:28 PM

David,
A wire on the outside of the ABS will help a lot, as will grounding the spiral wire in the expandable hose. I’m an electrical engineer, so let me explain:

Static (a non-moving electrical charge) can’t build up readily on a conductor (metal) because the electrons can easily flow from one place to another and will find a path to ground. Static can build up on an insulator (like plastic) because the electrons don’t flow easily—there is a lot of resistance to the flow, but the resistance is not infinite. The greater the length of the plastic, the more the resistance. So we want to keep the length of plastic until a conductor small.

Grounding the spiral steel wire in the expandable hose works great because the length of plastic to a conductor is at most half the spacing of the spiral. This will significantly limit the static charge that can build up and will drain it away when the DC is turned off. Spiral wrapping an ABS pipe will have a similar effect, just keep the spacing to at most a few inches. I’d bet you could find conductive paint that would work, too.

Last year I grounded the spiral steel wire in the flex hose connected to my Delta 50-850 DC. Static (as felt by me) was completely gone. Since the wire is in the middle of the plastic wall of the hose, I can assume that the static on the inside is similarly reduced. The static is not actually gone, but reduced enough that I can’t feel a spark. No spark, no fire. I have not done any electrical tests on it to see just how good it actually works, only that I never feel even a static charge on the spiral hose now.

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David Grimes

2078 posts in 2100 days


#13 posted 05-11-2011 05:17 AM

George,

I had wondered if grounding that wire (that is already integral to the hose) would be beneficial. I can do that with ease by tying both 4” branches together and through the manifold and to ground with 4 entire feet of bare copper !!! lol Yes, this is by design a low drag, high efficiency “sport model” of DC systems. :=)

I will do this at the first hint of static electricity. Thanks for the suggestion.

Welcome to Lumber Jocks, too.

Regards,

DG

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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Grandpa

3256 posts in 2136 days


#14 posted 05-11-2011 09:34 PM

http://home.comcast.net/~rodec/woodworking/articles/DC_myths.html

This is the link to a site that someone recommended last week. It has more information than I have seen collected on the subject. I have a question for George if he comes back to this link. When I use my miter saw there is no problem. when I use my shop vac there is no problem. When I connect the shop vac to the saw the dust stands up on the vac hose like hair on a bad dog. Do the 2 tools need to be bonded? I think we are dealing with a bonding issue here too. I think most people don’t know the difference in bonding and grounding. My saw is grounded through the electrical system but the shop vac is all plastic. I can’t remember if it has a ground wire to the electric system and right now it is raining so I plan to allow all that to go onto the ground and soak in. There is no wire in the vac hose. I would suggest that everyone go to the site listed above and study this in depth. I think this man knows his business.

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GeorgeShaw

4 posts in 2034 days


#15 posted 05-12-2011 01:03 AM

Excellent link. Unfortunately, as an electrical geek, I do understand all the stuff on the page :-). Without checking all his information in detail, his arguments appear correct. If static-caused dust explosions were a significant issue in the home-sized shop there would have been lawsuits that would result in disclaimers and warnings all over their dust collection equipment manuals, and my Delta manual does not even mention it. I’d been debating metal v. plastic duct as a permanent feature in my shop, and it is nice to understand why I can go with plastic.

The reason for my grounding the spiral wire in the flex hose was to eliminate the nasty shock I received every time I got near it. As Mr. Cole mentions, the benefit of grounding the spiral conductor or adding a spiral (or other) conductor are to create leakage currents that drain away the static charge quickly. The static shock is not only potentially dangerous for the person, but might also be for electronics he might be operating. A sharp, unplanned move around operating machinery is not a good idea, if nothing else.

Grandpa, as to your question, I assume that when you are operating the shop vac you are holding the hose? The human body, being mostly salty water, is a good conductor and absorbs static charge any place you touch the hose, or the hose touches various items as you move the vac around that drain off some charge. When you connect the shop vac to the miter saw, the hose (an insulator) touches little and the charge builds up over time. The current leakage path is the length of the hose—very long. Try wrapping a wire around the hose (bare or insulated) and connect it to the metal of the miter saw (grounded). There should be less static build up—it is not a bonding issue.

Mr. Cole’s article also explained why could I get really nasty shocks from the dust collector hose and an old hose on my shop vac. The hoses have a metal spiral that, as a conductor, allows static charge from all along the hose the discharge at once. No metal spiral, and only the static charge in the local area can flow to cause a shock.

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