JPG wrote:The ground wire needs to be wrapped around the pipe with a short 'pitch' so as to drain off any static charge at the points the wire contacts the pipe.
By having a 'short' pitch, the voltage build up is reduced to a safe value.
4" is not recommended for the DC3300. 3" is pretty much a limit.
At least according to Nick.
By contacting the plastic pipe, the drain wire establishes a zero volt potential at that point. Placing another will zero out that point also.
By placing those points close, the potential at a point between them is minimized.
Static voltage will not develop on a conductive surface except when the entire surface is charged the same. The wire merely eliminates the possibility of a large voltage buildup over a long pipe.
All in theory. In practice maybe, maybe not. Does anyone have a documented source where static build up on plastic dust collection pipe created a fire in a wood shop? I don't think so.
JPG, please show us some data that proves this theory. Why go to all this for something that makes no difference at the end of the day?
John & Mary Burger
Eagle's Lair Woodshop
Hooper, UT
A couple questions. Could mechanics wire be used inside PVC piping rather than trying to fit and connect adhesive backed aluminum tape or does the conductor need to stay in constant contact with the PVC?
Regarding the capacity of the DC3300, would it be possible to change out the 1/2 HP motor to one that had a higher rpm and possibly greater HP to increase CFM? Or would an increase in rpm be negligible? If the RPM could be increased, at what speed would cost / benefit be found?
I've mounted my DC3300 on a wall to free up floor space, then have sections of house to get where I need it. Though I haven't had a chance to make any sawdust this summer, in the past I have also hung from the rafters, a square box fan with a good filter bungee corded to it and a use half face mask, and there is still dust on the mask filters. Not certain what can be done to increase dust "trapping", but personally feel I am doing I can do without breaking the piggy bank.
videobear wrote:Many would say the DC3300 is not at all adequate. At least one authority on dust collection recommends a minimum capacity of 1100 cfm.
The other components of your dust collection system have a huge impact on how well it works. Ducting should be 4" diameter wherever possible. Ducting should be smooth wall (not corrugated) where possible. I disagree with the need for metal ducting, but if you use plastic, you should run a ground wire along the ducts, and be sure it is attached to every piece of the ducting and to an earth ground.
Blast gates should be used to close off runs of the ducting that are not in use.
Having said all that, when I looked at how much a really effective dust collector/filter system would cost, I went a different route. In my small (24x24) two car garage-cum-workshop, I use an inexpensive Grizzly two bag system with a 5 micron upper filter bag, and a 3M full-face shield/respirator. The Grizzly connects to only one tool at a time with a flexible hose. The two together cost less than half of what companies like Laguna, et. al., are charging for even their least expensive 1 micron cyclone systems.
Please explain how this does anything. Plastic is an insulator. You can't ground plastic. I don't know who started this myth but it has been around for a long long time.
It is NOT a myth, John. Please don't tell me that you have used a large dust collection system that utilizes PVC ducting and never drawn a static arch off the tubing. In fact, I occasionally draw a static arch just working with the simple dusting system that I have with the DC3300.
You worked on and around air frames so I know you know the importance of using static lines.
I will tell you it is a myth in my opinion. I have a ClearVue cyclone. 5 HP Leeson 220V motor and an 18" impeller. The design is from Bill Pentz. It is the largest one ClearVue makes at almost 2000CFM with an 8" input. It is made out of PLASTIC (actually Lexan I think). It has been used for over 6 years with no problem.
I have never had a shock from it. Yes I have had shocks before but I can't tell you from what DC. There have been only one or two.
The picture is when I first installed the ClearVue.
BTW, see the clean out below the filter of the ClearVue? I have never cleaned it and after 5+ years there is less than 1/8" of dust in the bottom. Very efficient in my opinion.
So yes it is a myth that you can ground plastic or even attempt to or need to.
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John & Mary Burger
Eagle's Lair Woodshop
Hooper, UT
benush26 wrote:A couple questions. Could mechanics wire be used inside PVC piping rather than trying to fit and connect adhesive backed aluminum tape or does the conductor need to stay in constant contact with the PVC?
Regarding the capacity of the DC3300, would it be possible to change out the 1/2 HP motor to one that had a higher rpm and possibly greater HP to increase CFM? Or would an increase in rpm be negligible? If the RPM could be increased, at what speed would cost / benefit be found?
I've mounted my DC3300 on a wall to free up floor space, then have sections of house to get where I need it. Though I haven't had a chance to make any sawdust this summer, in the past I have also hung from the rafters, a square box fan with a good filter bungee corded to it and a use half face mask, and there is still dust on the mask filters. Not certain what can be done to increase dust "trapping", but personally feel I am doing I can do without breaking the piggy bank.
Be well,
Ben
In my basement shop, 15x15ft I have a Jet 1100 cfm dust collector with a 30 micron bag. 3 20" box fans hung on the ceiling, with 2" pleaded Merf 8 filters on them. After 6 months of work down there, and not much hand work, sawing, planing, jointing and routering on a table set up, fans on accordingly, on horizontal services that where untouched there was minimal dust. I wish I had a pleated 1 micron filter on the DC but after that cant see the expense to upgrade. No major sanding in there though. I suffered in the garage in the cold. Not too bad, had a paper route and remember 15+* below zero temps and wind to deliverer them, and that was B4 they had the wind chill thingy/index!!! Walking paper route, not a drive in the car thing!! AND DONT walk on the grass!!!!!
KNOWLEDGE AND EXPERIENCE EQUALS WISDOM. Albert Einstein
The Greatness officially starts
Greenie, Grayling, SS stand alone BS and BS SPT, jointer and belt sander, 3 Ers with Speed Changers. I think those 3 cover my ER needs, and space for them.
I do have an understanding of static charge on a surface(non-conductive).
I too consider all this concern re starting a fire with a discharge a lot of activity over a highly unlikely event. I do not think there is the potential for sufficient energy to do so.
However the likelihood of a person getting 'zapped' is pretty good.
The problem with the plastic piping is the triboelectric charge created when the wood particles travel through the pipe.
Now any charge built up on a non conductive surface will not dissipate by conduction over the surface to a grounded point, but the grounded point will have a potential equal to ground. The charge will remain on the rest of the surface. There will however be a potential gradient across the surface with increasing potential the further from the grounded point one gets. Hence the closely spaced grounded 'points'. And yes the charge can flow across the insulated surface. Not like 'regular' dc current however. More a case of redistribution.
╔═══╗
╟JPG ╢
╚═══╝
Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
The other point is that static electricity does not build up on conductive surfaces, only on insulators. For those who have worked on sensitive electronics will have fond memories of the wrist straps and all of that iso training.......
Ed
{Knight of the Shopsmith} [Hero's don't wear capes, they wear dog tags]
I used to get shocked pretty good from my 4" pvc duct in my system until I wrapped some bare copper wire around it down the full length and attached the end to a copper water pipe.
jsburger wrote:
Please explain how this does anything. Plastic is an insulator. You can't ground plastic. I don't know who started this myth but it has been around for a long long time.
It is NOT a myth, John. Please don't tell me that you have used a large dust collection system that utilizes PVC ducting and never drawn a static arch off the tubing. In fact, I occasionally draw a static arch just working with the simple dusting system that I have with the DC3300.
You worked on and around air frames so I know you know the importance of using static lines.
I will tell you it is a myth in my opinion. I have a ClearVue cyclone. 5 HP Leeson 220V motor and an 18" impeller. The design is from Bill Pentz. It is the largest one ClearVue makes at almost 2000CFM with an 8" input. It is made out of PLASTIC (actually Lexan I think). It has been used for over 6 years with no problem.
I have never had a shock from it. Yes I have had shocks before but I can't tell you from what DC. There have been only one or two.
The picture is when I first installed the ClearVue.
BTW, see the clean out below the filter of the ClearVue? I have never cleaned it and after 5+ years there is less than 1/8" of dust in the bottom. Very efficient in my opinion.
So yes it is a myth that you can ground plastic or even attempt to or need to.
I just hope that NOTHING ever occurs to make you change your opinion on this. Please don't use "ungrounded" PVC for your ducting!
Wow, I didn't think my little comment would've raised such controversy!
Yep, static charges build up on INSULATED things. In fact, one of the first particle accelerators, the Van de Graaf generator, works like this. And in fact, the way that a Van de Graaf generator carries charge is very similar to the way in which a static charge can build up in a PVC duct system.
The purpose of the ground wire is, of course, to provide a pathway for the charge to bleed off. The idea is to prevent a spark that could catch a bag full of dust and chips on fire.
(Regarding 4" pipe being too big for the DC3300...I agree. I was speaking of a system with a higher CFM rating.)
