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Dust Extraction and Earthing

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Newbie_Neil

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Hi all

I am about to plumb in my dust extraction and I have a question about earthing the pipework. I will be using soil pipe going into the Camvac flexible hose.

I will have two runs containing pipes. Do I earth just the first pipe on each run? What do I use and how do I attach it?

Finally, does anyone have any photographs that might help?

Sorry about all of the questions but I want to get this right.

Thanks
Neil
 

Waka

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Neil

I could be wrong here and no doubt someone wil let me know, on my system I only have the extractor unit earthed. I have an earthing point in the workshopo, so have just connected onto there.
 

RogerS

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Neil

Someone more knowledgeable than me will be along soon but earthing plastic?

I assume you're trying to remove static buildup...but plastic is a non-conductor to all intents and purposes. If removing static is your intention then I guess running a thin earthed bare wire down the inside of the pipes might work.

Roger
 

devonwoody

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Neil. Ubeaut out at OZ has posted some in depth articles re earthing of dust extracting systems. So a search would not go amiss perhaps.
 

Adam

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Roger Sinden":vhauziil said:
Neil

Someone more knowledgeable than me will be along soon but earthing plastic?

I assume you're trying to remove static buildup...but plastic is a non-conductor to all intents and purposes. If removing static is your intention then I guess running a thin earthed bare wire down the inside of the pipes might work.

Roger
I did this (once), after reading some "stuff" about static build up and creating sparks etc. Only some further research seemed to show this wasn't possible. What I did was to thread a piece of tinned copper wire down each tube, and secure at each end with some gaffer tape. Then I'd fold it over the ends of the tube and use some of those little electrical connecting blocks with two screws, to attach it to the next piece.

I found it caused blockages, and shavings would get stuck under them, so when I rebuilt the system, with the extractor in a different position I acutally pulled the whole lot out. I did a post once, about this, but it got a bit mangled, I'll see if I can dig it out for you.

On my extractor, in the top "bag" which lets the air out, I do have a crocodile clip which earths the fabric.


Adam

Rather than did up an old post, heres "part 2". Unfortunatrely, part 1 got deleted somehow, and that was the bit that had the interesting stuff in it.

A long running Tuit of the extractor system was to add a final section to the crown guard on the tablesaw. I finally got round to it this weekend. As it didn't involve too much lifting or twisting, I decided it'd be OK given the back injury.

I'd managed to pick up a few bits and pieces as they removed the "clean rooms" from work. (I work for an electronics company and we maintain certain rooms at specific levels of comtaminents in the air - e.g dust). Anyway, I found one was a perfect adaptor from the TS crown guard, to 80mm pipe.

click on image for larger view

With this installed, I was able to fit some 80mm pipe to it

click on image for larger view

I made a 80mm - 100mm adaptor by cutting a "wedge" out of some 110mm pipe, heating it on the gas hob, and folding it to size, it looks a bit heath-robinson, but works fine.

click on image for larger view

I then used a "U" clip on the roof, to hold the pipes up out of the way. You can see here a join from 80mm to 100mm using the adaptor above, just where it goes through the clip. You can see I've also added a blast gate, and a "Y" section. I need to couple it into the original installation, and the flexible pipe has already been disconnected.

click on image for larger view

You can see here the "Y" section installed, and the two pipes that split from it.

click on image for larger view

I still have an unterminated end which doesn't have a blast gate - I've taken to plugging it instead of using a blast gate...



Which is nothing more than an piece of tube, with some wood through it to stop it disappearing.... (it's a perfect fit)



From several car-boots, and a couple of clearouts at work, I seem to have aquired a good range of measuring equipment.



I'd never come across these before, it's a quick release vice - does it have a "proper" name does anyone know?




One of the things I got is an engineering square, I decided it's not good in a drawer - I need it where I can grab it quickly.



So I made a little holder. Might not be much, but each little item indicates I'm on the road to recovery :p





Adam
 

Adam

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OK, got a bit more data:

(Basically its a re-write of the bit that got lost.)

I've been cutting slots, heating, and bending the pipe to allow it to fit directly to a 100mm pipe.



Then taping up the slots.



Works with blast gates too



If you want to make a permanent joint, use this stuff, OUTSIDE! Boy it gives off some fumes...



Chamfer all cut pipes.



As it says....





Those little blocks I mentioned - I call them "candy" - each sparky seems to have a different name for them...



You can see two of them here:



Down the inside of the pipe, you can see the wire is loose.



Hope that helps. Would I do it again? No. I found it wasn't practical. Marybe if you could take the full length of the pipe inside, it may work, but you can only put tape down to a maximum of an arm length. And I'd imagine it needs to be exposed to the dust to work - so you can't tape it - so it flaps about and gets bits of shavings stuck in it.

I'd avoid any "T" shapes, use "Y"s.

Provided the dust extractor is running from the same ground as the rest of your equipment I think you'd be fine.

Thats my thoughts.

Adam
 

Newbie_Neil

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Hi all

Thanks for sharing your thoughts.

DW. I'll have a look on ubeaut.

Adam. I had found your part one post, but all the relevant images were not being displayed. Thank you for taking the time to do the update. Much appreciated.

Cheers
Neil
 

Scrit

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Probably the best site on dust extraction is Bill Pentz's http://billpentz.com//woodworking/cyclone/index.cfm. He has a section on how to bend and form PVC pipe at http://billpentz.com/woodworking/pvc.html, info about dust hoods and also as some interesting information on grounding PVC pipe with a link to Dr. Rod Cole's research on this very subject at http://mywebpages.comcast.net/rodec/woodworking/articles/DC_myths.html which may cause you to question the need to earth PVC/soil pipe ductwork at all.

Hope that helps

Scrit
 

Adam

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Scrit":z1li4axl said:
http://mywebpages.comcast.net/rodec/woodworking/articles/DC_myths.html which may cause you to question the need to earth PVC/soil pipe ductwork at all.
Hope that helps Scrit
I read that at some point before, and it makes good reading.

As it said, I'm more concerned about smouldering occuring in the dust bag due to a spark from a blade hitting something abrasive, and then nestling in the bag for a few hours before starting a fire.

Adam
 

Scrit

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Adam

You're probably right to be more concerned more about that - we have one DX in the shop which went up when extracting a pad sander (at its previous owner's I might add). PVC bags don't offer much protection against fire! As a point of interest commercial/industrial users are routinely ordered by their insurers to remove all waste sacks/materials form extractors and place them outside of the premises at the end of each day/shift (or at any time when the premises are to be left unattended for a period) - mine certainly does. The HSE give similar advice.

Scrit
 

ProShop

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Neil,

Why not use Spirolux it's cheaper than soil pipe, much lighter and your building in your static earthing :D

Just a thought :)
 

Newbie_Neil

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Hi John

devonwoody":4bhob0dm said:
What is spirolux?
The Camvac flexible hose that I already have/use has thin metal strips. Is this what you are referring to?

I was going to use the soil pipe for strength and longevity. Is there a better way of achieving this?

Cheers
Neil
 

Adam

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Newbie_Neil":25m1lypw said:
Hi John

devonwoody":25m1lypw said:
What is spirolux?
The Camvac flexible hose that I already have/use has thin metal strips. Is this what you are referring to?

I was going to use the soil pipe for strength and longevity. Is there a better way of achieving this?

Cheers
Neil
I thought spirolux was the metal tubing made from winding a long strip of metal into a tube. If I did my system again, I may be tempted to make it from 100mm metal tube. Saves faffing with adaptors.

Adam
 

Adam

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I think this picture from their site says it all...



Adam
 

DaveL

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Scrit":1b0gf7u0 said:
some interesting information on grounding PVC pipe with a link to Dr. Rod Cole's research on this very subject at http://mywebpages.comcast.net/rodec/woodworking/articles/DC_myths.html which may cause you to question the need to earth PVC/soil pipe ductwork at all.
Well I have PVC soil pipe and not even tried to earth it, shop hasn't exploded yet.

I use a metal dust bin with the cyclone that the dust drops into. The dust could still burn but it would take much longer to get out of the bin compared to a plastic or cloth bag, so I hope it would be spotted before disaster strikes.
 

Woodythepecker

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Neil, my son is due back from the US soon (mind you he has told us this 3 times already in the last year) and i have been refitting his workshop as a surprise.

When i got around to the extraction system John recommended that i fit Spriolux, and i have to say that it is money well spent. If anyone wants to fit this sort of system let me know and i will go through my paperwork because although the piping itself is a good deal cheaper, some of the joints e.g. elbow's and Y junctions etc are cheaper elsewhere.

As for earthing plastic soil pipes, this is one of the reasons i went for metal ones because no one could tell me how to do it successfully, but after reading the links it now appears that these do not need earthing anyway.

That said i do not regret fitting the system i did, because metal piping is far better, and i have earthed it by running it to a 3/4x30 inch solid copper ground spike, which i have hammered into the earth outside his workshop.

Most extractors come with a flexible pipe and the metal strip that runs through this pipe can be earthed to the machine you have it connected to. in fact Scheppach supply a earth lead with their extractors to do this very thing.

Good luck with your system.

Regards

Woody
 

Losos

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Neil - As others have pointed out Dr. Rod Cole of MIT has done some research and you don't need to earth your system if it is 100mm or LESS, I think it's important to emphasize the fact that his findings negated the need for earthing on sub 100mm piping. If you're planning on using a dust extactor system with plus 100mm pipe then do NOT use plastic. BTW Dr. Cole works for MIT (Massachusetts Institute of Technology) and IMHO there ain't no higher authority on electrical / electronic technology anywhere on this planet. (They invented the transistor & many many other things)
 

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