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Pushfit soil pipe as dust extraction

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DBT85

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IIRC Mike Jordan once referred to anyone doing it with plastic ducting and home made blast gates as "penny pinching clowns". :rolleyes:
 

Spectric

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Hi

Don't forget that brown underground soil pipe is not UV resistant, it will fade and degrade in sunlight wheras the Black and Grey are designed for exposure to sunlight above ground.
 

Mike Jordan

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My only motive for such abuse is to concentrate the minds of fellow woodworkers. The few pounds saved will be easily offset by the fact that your insurance will be negated by the increased fire risk from static and the total lack of fire resistance.
Using incorrect materials will provide your insurers with a great excuse to point out the elevated risk you created. It's quicker and easier to do it right!
 

Rorschach

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My only motive for such abuse is to concentrate the minds of fellow woodworkers. The few pounds saved will be easily offset by the fact that your insurance will be negated by the increased fire risk from static and the total lack of fire resistance.
Using incorrect materials will provide your insurers with a great excuse to point out the elevated risk you created. It's quicker and easier to do it right!
Maybe just avoid the abuse, in my experience it doesn't concentrate the mind, it makes people more likely to rebel and makes people think less of the person doing the abusing.
 

clogs

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as for MikeK's over expensive metal ducting....it could be a country specific price prob......
I just bought enough guttering for an average 3 bed detached house and it cost over €850 euros....just materials in plastic......
full body showers in a fiber glass screen assy is very cheap in France [about a 1/3 of the UK price]
but nuts n bolts are 5 times more expensive than the UK.....
brass plumbing fittings here are about 30-50%cheaper than the UK dont ask about France.....
it all in the geography I'm afraid.......
I like ur style MikeK more photos of the shop and ur fancy add on's please.....good for ideas.....
 

Spectric

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I would not get too hung up about static electric generation in your extraction systems, lifes to short and it will not shorten it any more unless you waste time thinking about the what if's. If it was carrying natural gas or flour then I would take it seriously but it is going to take some spark to ignite your wood dust in a home workshop, it has not got the power of the Haddron collider. Personally I do my best to minimise dust but always end up having to give the place a good hoover regularly as I prefer to make dust and not worry about controlling it to much.
 

DBT85

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My only motive for such abuse is to concentrate the minds of fellow woodworkers. The few pounds saved will be easily offset by the fact that your insurance will be negated by the increased fire risk from static and the total lack of fire resistance.
Using incorrect materials will provide your insurers with a great excuse to point out the elevated risk you created. It's quicker and easier to do it right!
Any actual evidence of your claims? or just the usual PVC causes explosions myth?
 

MikeK

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as for MikeK's over expensive metal ducting....it could be a country specific price prob......
I just bought enough guttering for an average 3 bed detached house and it cost over €850 euros....just materials in plastic......
full body showers in a fiber glass screen assy is very cheap in France [about a 1/3 of the UK price]
but nuts n bolts are 5 times more expensive than the UK.....
brass plumbing fittings here are about 30-50%cheaper than the UK dont ask about France.....
it all in the geography I'm afraid.......
I like ur style MikeK more photos of the shop and ur fancy add on's please.....good for ideas.....
Had I known about the substantial price difference in metal ducting between Germany and the UK, I would have made a trip across the channel with my truck for a shopping spree. My upcoming dust collection change will replace the existing 120mm metal ducting with 150mm S&D pipe.

I prefer to think of my shop add-ons as functional upgrades that happen to look nice. ;)
 

Doug B

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I would not get too hung up about static electric generation in your extraction systems, lifes to short and it will not shorten it any more unless you waste time thinking about the what if's. If it was carrying natural gas or flour then I would take it seriously but it is going to take some spark to ignite your wood dust in a home workshop, it has not got the power of the Haddron collider. Personally I do my best to minimise dust but always end up having to give the place a good hoover regularly as I prefer to make dust and not worry about controlling it to much.
It’s not the risk of fire, I tend to agree with you on that Roy it’s the bloody big static shocks you can get off it if it isn’t earth that’s the real pipper.
 
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Sandyn

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If you blow dry sawdust, even just air at high velocity along a plastic pipe there is a risk of static build up. The effect is a very real demonstrable physical phenomenon. BUT it may not happen with every set up, it depends on so many things like materials, humidity. Some plastic tubes are made from a conductive material, carbon is added to the plastic to make it conductive enough to stop static build up. Conductive plastics.

Some people may be plagued with it, others may never have problems. All of you must have done the static electricity tests at school? rubbing a balloon then holding it above your head, hair standing on end. Sticking a balloon on your chest, even stoking a cat can generate static charges and sparks ( a source of huge amusement for me).

When the sawdust passes along the tube, it causes charge to move to or from the plastic pipe, so the pipe may end up with a huge positive or negative charge. It depends on the material. The end result can be a static shock and possibly a spark. It's not the same as electricity flowing, it's the build up of charge, so it happens with insulators and of course electricity will not flow in an insulator, which allows it to build up charge, then dissipate that charge to a passing ground point, like your hand.

If I ever had the problem, I would try an experiment with conductive paint, I would have an open end of the pipe vented to the outside, then blow air along the tube, while spraying Conductive paint in where the air is being blowing in. You would then need to bring a connection from the paint out to ground. I would just use copper tape. I have never tried this, but it's a way of getting the inside of a tube conductive and hopefully static free. It might wear off very quickly, but not certain how robust it would be. An alternative is to stick copper tape as far as you can along the inside of the pipe and ground.
 

Keith 66

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I just fitted extraction for a laser cutter, all stuff bought from ductstoreuk.co.uk, 150mm spiral duct was £18.04 a 3m length, 100mm £11.25. Screwfix price for grey pvc 110mm pvc soil pipe is £15.89.
So its actually cheaper to use the proper stuff!
As for static that can be proper fun, i was once trimming a new 18ft GRP boat hull & once i had finished got the shop vac going & started sucking up all the dust, vac was metal cased, after about 5 minutes i went to turn it off & as my index finger approached the switch at a distance of about 3/4" a great fat spark jumped the gap to my finger with a sharp crack!
While polishing moulds static shocks were a regular occurence.
 

Arnold9801

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If I can inject a teeny bit of science in here?

The static comes from the wood chips scraping along the inside of the plastic pipe. Exactly the same effect as stroking a balloon across a woollen jumper and then sticking the balloon to a wall.
NONE of the pipes create static by themselves. The greater the flow speed, the more static produced.

Now, how are the pipes connected to the wall? if they are fixed with pipe clips, and you have left the rubber bumper pads on the clips, then the pipe is insulated.
If you have metal clips touching the pipe and then fixed to the wall in such a way that the metal clip stud is NOT insulated by a plastic wall plug you have earthed the pipe.
If the pipe goes into a metal container with a motor attached, its earthed through the mains lead.
So, most systems are earthed somewhere and will never produce shocks.
But if you have a powerful extraction system, into plastic hoses and plastic pipes and plastic cyclones, and the securing clips arent physically touching brick walls, guess what? you have static!
easy peasy innit?

On large installations I have heard of bare copper wire being threaded through the entire run and earthed through the pipe at each end.

I think as there isn’t doubt both ways regarding static on extraction pipes, there isn’t any harm in playing safe as the consequences if it does go wrong are only to obvious. So... to play safe is it just alright to wrap copper wire around the outside of the plastic ducting or is it a MUST that it has to go on the inside?
 
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