Would you mind elaborating on what this means to you? I.e. what does "fully grounded" mean to you?
Static electricity in dust systems
- Thread starter lwhughes149
- Start date
-
- Tags
- dust electricity static systems
- Status
Would you mind elaborating on what this means to you? I.e. what does "fully grounded" mean to you?
First of all congratulations on the DC upgrade. :icon_thum As has been said the chances of a dust explosion are remote in a home shop but the surprise of a static discharge can be a hazard when you have your hands near spinning blades and bits. IMHO all machines should be bonded to the DC system to cut down on static charge potential differences. I use a metal trash can as my separation barrel because it takes up a little less floor space, causes a little less static build up, and I do not have to worry about it collapsing if I lean on it while negotiating around my crowded shop. In answer to your question, bare stranded copper wire is available from Radio Shack without having to buy a DC "grounding kit". :wsmile:
I have read before where people have used aluminum ducting tape with good results. They just ran a line of it down the inside and one line on the outside of the pipe, connected the two, and grounded the tool and dust collector to the duct work. I have not attempted this but when I do eventually setup my system, this is probably the route that I will take.
I am currently waiting for the man to come and wire the dust machine and then I will press on. BTW, my plastic trash can has holes in it where I tried my hand at composting so it is out. I will probably opt for a metal can from ACE. Do I understand that the trash bag inside the can needs something to make it rigid so it will not cave in?
I have never used a trash bag but it is my understanding that you need something to keep the trash bag against the inside of the can since the DC does not discriminate and will attempt to digest the bag as readily as it does shavings. :gar-La; The problem with putting something inside the bag such as wire mesh is that you then end up with the mesh trapped in a bag full of shavings which sounds like a pretty messy proposition when you go to empty it.:confused_
Last edited:
This is what I have:
It's essentially a can inside a can. When you need to empty it, you simply lift out the inner piece, then lift the bag out of the container. It's not cheap - this one is from Grizzly and costs $70.
Maybe you could do something with one of those tomato cages:
What part does the incert play? Do I need the liner in order to use a trash bag? I like the size and the wheels on yours.
Thanks Glenn now I understand.
I think Chris (Merril77) is probably picking a nit; "ground" implies a complete circuit, which you don't generally have with static electricity. So what you actually do is sink the charge into a really big capacitor (the Earth). 
I am serious about my question though. I wonder if purposefully introducing small sparks inside the tube to avoid larger ones outside the tube is really a good idea or not.
My completely not scientific Google, read articles and scratch chin research indicates that explosions are far more likely to happen at large commercial operations where they use metal tubes. I haven't found a reported incident of plastic tubes in a DC ever being involved in a sawdust explosion.
I am serious about my question though. I wonder if purposefully introducing small sparks inside the tube to avoid larger ones outside the tube is really a good idea or not.My completely not scientific Google, read articles and scratch chin research indicates that explosions are far more likely to happen at large commercial operations where they use metal tubes. I haven't found a reported incident of plastic tubes in a DC ever being involved in a sawdust explosion.
Radio shack no longer stocks antenna wire:gar-Cr. Google copper antenna wire and you will find several sources:icon_cheers.
:gar-Cr Is nothing sacred any more ? One of my favorite memories was making a crystal radio with my Dad ( a WWII Army Air Force Radioman/Navigator).:wsmile:
Ok, well I hate to break it to you, but since PVC is an insulator, you can't ground it. The only part of the pipe that is grounded is the part touching the wire. They call it "static" electricity because it doesn't tend to move, since it exists on an insulator. So a wire running down the inside of a PVC pipe might reduce the charge in <1% of the surface area. The rest will still have a charge, and that charge can't move to the wire because it is on an insulator. Ok, it'll move a little, because no insulator is perfect. But for all intents, the charge on the other side of the pipe will be completely unaffected by that wire.
If you really want to get into the details I suggest reading: http://home.comcast.net/~rodec/woodworking/articles/DC_myths.html I admit it is tough reading. I'm an electrical engineer and I had to work hard to understand it - as it's been a long time since I worked that side of my EE skills.
The only way to prevent buildup of a static charge inside the dust pipe is to use a metal pipe. Well, I suppose you could cover the entire inside of a PVC pipe with aluminum foil tape. That would work, but as the author points out, this could result in a different type of discharge that has a higher energy. That part is way past my theoretical understanding, so I won't even go there.
But none of this really matters, because you'll never get enough of an electrical differential inside the tiny DC pipes we're using to induce a discharge. Not even close.
Chris
Uhhh...why would you want to do that??? The (theoretical) danger of explosion is INSIDE the pipe, not outside it! The dust density outside the pipe (in your shop) is nowhere near dense enough for combustion. If it was, you couldn't breathe.
I don't. That is my point. If you don't run wire in there, it may get really highly charged, but with nowhere to discharge there will be no spark. So why run the wire in there?
Anyway, you were headed down a different, but possibly even more correct line of reasoning against "grounding" plastic pipe. I said it can't be grounded because the ground for a static charge is not "the ground" per se. You are saying you can't ground an insulator, which is even simpler to understand and practically impossible to argue against. But somebody will... :gar-La;
Ok, we're on the same page! :>
Update on the dust system. I purchased a metal can from ACE yesterday for $21.00. It sits in the shop this morning waiting for the electrician to come today and wire the system in. It will be a play it by ear today. I don't have a linner for the can but I am still thinking. Maybe an old plastic can cut to be inserted. I just love working in the shop.
I am ahead of you, I have the plastic can ready to be cut down. The system is up and running along with the separator and it is really nice. I am going from 1hp to 2hp. One additional question. I understand the concept behind the separator but I was wondering what other benefits came from having the separator. I have approximately 20' of pvc duct work throughout my system and had considered adding another few feet for my tablesaw. I can make a few changes if I need too and I can use my 1hp to attach just to my tablesaw thus preventing the need for additional duct work. I haven't tested it throughly just yet, it went in yesterday. Any thoughts guys?
M
McRabbet
There is only one rule you must follow with dust collection: Capture it at the source! AO go ahead and add your old 1HP unit at the table saw and you will be fine. The separator does the "heavy" work when it is installed in line with big chip producers like a planer or a jointer, but is not needed for a table or bandsaw since they only produce finer sawdust and no chips per se. The other primary benefit is that you do not need to empty the bin at your dust collector anywhere near as often (my old technology separator still gets 90% of the mixed dust/chip stream and that means I do not empty my bin very often)!
- Status
