Earthing Dust Extraction Pipes

[RogerS]

Hi,
With all due respect, if your knowledge of electricty is really that low (meant in the kindest possible manner, none of us can know everything about everything), I would strongly recommend you getting someone around who knows what they are doing.
.....
All the best,
Daniel

Bang on, Daniel...you've sussed out Rorschach very quickly. =D>

 

[Bigbadmarky]

I appreciate all your replies and the concern raised on my behalf.
Contrary to popular opinion (my wife's included), I'm not a silly person. I wasn't planning on bodging an earth via the extension. I was merely trying to be polite to the chap and grateful for his suggestion. My primary rule in DIY is I'll have a crack at anything but won't touch electrics or gas. Following said rule has seen me through 38 years and will hopefully keep me going for a bit longer.

I found a couple of videos on Youtube which were useful and informative. This one my John McGrath was particularly useful https://youtu.be/812Ez9OT0As.

My shop vac is in a fixed location so it would make much more sense for me to have a fixed earth point somewhere in its vicinity. I think I might try and run a copper wire through the pipe and aluminium foil tape round the outside and earth it to the garage wall as suggested. Hopefully that will discharge static from the inside and out of the pipes and save my sanity.

Thanks for all the replies.
Peace out,
BBM

 

[sunnybob]

Foil tape can be hit and miss as far as electrical conductivity is concerned. Bear in mind the the foil is fixed to the pipe with a layer of goo. If the goo is thick, its an insulator. If its old and dry, then it most likely will conduct.
You would normally get a circuit, but I wouldnt guarantee a circuit using just that. Bare copper wire is foolproof, just make sure your connection to a ground is also foolproof.
If you have any concerns about using the mains earth, Its quite acceptable to just beat a length of iron rebar into the ground near your installation (at least a foot deep, deeper is better), and then connect your earthing strap to that.

 

[Rorschach]

Foil tape can be hit and miss as far as electrical conductivity is concerned. Bear in mind the the foil is fixed to the pipe with a layer of goo. If the goo is thick, its an insulator. If its old and dry, then it most likely will conduct.
You would normally get a circuit, but I wouldnt guarantee a circuit using just that. Bare copper wire is foolproof, just make sure your connection to a ground is also foolproof.
If you have any concerns about using the mains earth, Its quite acceptable to just beat a length of iron rebar into the ground near your installation (at least a foot deep, deeper is better), and then connect your earthing strap to that.

Insulation from the adhesive is negligible and with foil tape you have the benefit of surface area as opposed to a thin bare copper wire. We are not talking about conducting a current in the say way as wiring up some lights for example, we are providing a path for the static to leak away, after all it is building up in PVC pipe, PVC itself used as an electrical insulator.

Edit: Forgot to add, if the OP is getting a shock from a certain location, say the top of the pipe next to his sander, then if that area is covered in the earthed foil tape it would be literally impossible to get a shock there again, even if the adhesive was providing insulation.

 

[Bigbadmarky]

Thanks for the advice chaps. Much appreciated.
I might use foil tape to stick down some bare copper wire on the outside of the pipe. Belt and braces approach!
Thanks again,
BBM

 

[Lons]

I appreciate all your replies and the concern raised on my behalf.
Contrary to popular opinion (my wife's included), I'm not a silly person. I wasn't planning on bodging an earth via the extension. I was merely trying to be polite to the chap and grateful for his suggestion.
BBM

Absolutely the right decision BBM you're clearly very sensible but there's no need to be polite to someone who suggests a practice that's unsafe. While you have the sense to ignore it unfortunately none of us know how many others who lack that common sense and basic knowledge are browsing the forum and think it might be a good idea.

We all have a responsibility to not post potentially dangerous practice, better to post nothing at all than suggest someone wraps copper wire around the earth pin on a plug. There are people out there who don't even know which pin is which for heavens sake.

Bob's suggestion you wack a length of metal earthing rod into the ground is sound advice.
Stay safe.

 

[gregmcateer]

Good people,
If I may jump in with a diameter question that's indirectly related.
I'm planning to get a DE and pipe it. Just a bandsaw and lathe next to each other. Should get 125 or 150mm, or will 100mm be enough?
TIA
Greg

 

[sunnybob]

Depends entirely on your motor. No point having an oversized pipe and an undersized motor, nothing will move.
Every extractor unit will come with the recommended pipe for that size.As a general rule, bigger is better.

 

[gregmcateer]

Thanks, Bob
I am thinking 2 or 3hp. Was wondering if 3 hp is overkill for say 4 metres ducting, or is it still worth it to shift dust quickly? Filter obviously still required, and planned

 

[sunnybob]

If money is not too much of an issue, then your next question is "am I going to get more machines"?
A smallish bandsaw and lathe will work on 100 mm and maybe 1 hp fine, but if you are planning on adding a planer or thicknesser, then you need a much bigger motor and pipe.
Its a "piece of string" question to be honest. Do you want operating room clean? or are you happy with some dust escaping the system?
But if you are of a technical nature then you can study the BILL PENTZ web site and scientifically work out every aspect of your system. Be warned, its a very technical work. :shock:

 

[gregmcateer]

Cheers, Bob.
I think that probably answers it.
No plans, likelihood or space for any other 'big' machines. I've been on the Pentz site and it's mostly way over my head - big picture clear, detail not at all.
I guess I need to price up 100mm and a 1 - 2 HP extractor with a proper fine filter on top. If it's not too big a number, look at larger duct for efficiency.
Thanks again.
Greg

 

[sunnybob]

I'm hands on technical, and can follow any diagram, but that site just has too much info :roll: :lol:

But think long about upgrades and additions. I've been doing this woodworking lark for only 6 years and I've completely re arranged my single car garage at least three times to make room for more equipment. 8)
I could have saved myself many hundreds if I'd known then what I know now. :shock:

 

[gregmcateer]

That's a good shout!
I will think long and hard and I'll buy the best I can reasonably afford (And get past SWMBO!!)
Cheers
Greg

 

[Lons]

I've been doing this woodworking lark for only 6 years and I've completely re arranged my single car garage at least three times to make room for more equipment. 8)
I could have saved myself many hundreds if I'd known then what I know now. :shock:

What!!! Only 3 times in 6 years :roll: what are you doing Bob mine is constantly evolving. #-o

 

[sunnybob]

Lons, the active ingredient there was "COMPLETELY" rearranged.
Minor weekly shuffles dont count :roll: :lol: :lol: :lol:

 

[gregmcateer]

I'm loving all this- and I hope learning, too! Trouble is, it is clear a little knowledge is a dangerous thing!

If I went with a 2 or 3 HP extractor with a 125mm duct, is this worth it as the bandsaw only has 100mm port? (Lathe can have 125 from source).

And second question, blast gates near source, or near extractor?

Thanks again

Greg

 

[Inspector]

Most 3hp DC's have the same impeller and housing as a 2hp DC. Usually about 300mm. The reason they flow more air is the extra filter allows more flow. Better 3hp DC's will have a 330mm or so impeller. If you get a 3hp use 150mm duct. When you get to the bandsaw you split the 150mm into three 100mm pipes. One to the lower blade guide area under the table, one to the bottom of the cabinet and the third just behind the upper blade guides above the table. Three 100mm pipes flow approximately the same air as a 150mm duct.

Blast gates are best located at the main trunk where the branches come to join. If the extractor has a 2 or 3 way splitter at the inlet get rid of it. It creates a lot of turbulence at the impeller. Better is a large pipe straight to it for several feet with wyes to branch off to other machines.

Lathe benefits from as much air as it can get. so use a 150mm duct all the way to it. A bellmouth hood provides the best flow into the duct so will capture fine dust further than from a pipe without.

Pete

 

[gregmcateer]

Inspector Pete,
That's really clear advice, thankyou.
Am I correct thinking a circular bell mouth good is better than a rectangular one?
TIA
Greg

 

[Inspector]

Round bell mouth to a hose/pipe is as good as you can get.
If by rectangular you mean a square duct with the four sides flared with the same radii it will be pretty good too.
If by rectangular you mean the flared cone shapes like a Big Gulp type the bell mouth is better.

I've linked this before but the gent is using a 6" duct on a 3 ph DC. https://www.youtube.com/watch?v=xjtHCmR-N3M

Pete

 

[gregmcateer]

Wow! That's some suck power!

I'll keep searching, but haven't found anywhere here that seems to sell the round bell mouth. Maybe worth trying a local fabricator, as I live in the original Black Country :lol:

Thanks again - much appreciated