Dust Extraction Ducting

[wobblycogs]

Hi guys,

I'm just starting to fit out my new workshop and I'm thinking of putting in some ducting for dust extraction. At the sucking end I'll have a Record Power DX4000 which has a 100mm connection - it's a bit of a compromise dust extractor as it does reasonable volume (380m^3/hr) but can also achieve a fairly decent vacuum, for now it's fixed as I can't afford to replace it.

What I would like help with is picking the correct duct sizing. The longest run is likely to be about 12m after it's gone up from the floor, snaked around the room and gone back down to floor level. I'm not sure that the dust extractor is up to pulling dust through 100mm pipe over that sort of distance. So, I was thinking of using drainage pipe at 68mm. I could probably just about stretch to metal ducting but I'd rather try and use pvc pipe as it's a fraction of the cost, now much of a problem is static build up though?

Any thoughts gratefully received.

 

[stewart]

I might be wrong but if you step the pipe size down I think you actually lose suction. When I put a smaller bore pipe on my record dx5000 it doesn't have the same power as the 100mm pipe.


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[MattRoberts]

Indeed - HVLP extractors are designed to work with large volumes, and can actually stall if the air flow is restricted too much. It might well be a case of trying the runs you mention, and shortening if it's not working.

As for static build up, the purists recommend running wire around the pipe and grounding it, however by all accounts the conditions that need to be met in order to actually start a fire in the ducting are pretty remote.

 

[Mike Jordan]

A twelve metre run of pipe must mean a decent size workshop! I suggest you need an extractor which can cope with the machinery you are likely to invest in when your hobby takes a hold. I designed my own small workshop system having seen a number of profession and amateur set ups down the years. I chose to use a one and a half horsepower chipping extractor sited in a separate small store rather than the workshop, the machine has a plastic bag at the bottom and a cloth bag at the top to vent the air. The extractor is connected by a 150mm diameter short flexible pipe to a 150mm steel pipe which runs through the roof space over the workshop, 100 mm diameter pipes steel pipes come down to each machine and are connected by short lengths of flexible pipe via blast gates. A five metre length of flexible pipe is connected to one of the down pipes for sweeping up purposes. This must sound like a big investment but works very well. The advantages include - limited friction losses because of limited use of the corrugated flexible pipe, no static problems caused by plastic drainpipes, no losses caused by small diameter pipes, blast gates direct the power to the machine you are using. Above all there is no fine dust in the workshop caused by leakage from the filter bag.
My hand held sanding machine is connected by a short length of 50mm into the 100mm sweeping up hose when required, this isn't really recommended practice but it works very well. If you do the job properly it will only need to be done once. Best of luck with the project.

 

[Monkey Mark]

I can't comment on the size of the ducting but I'll day a little on the static side of things.
Firstly the static itself; Static can produce s very high valtage however, as has already been mentioned, the chances of it being a problem are rare. It seems to be more of an American thing than anything else.
Secondly, the use of wire; The wire is use to keep potential voltage difference to a minimum. Without a difference there is no spark = no issue. Wrapping wire around the outside of the pipework does NOTHING. It may appear that it is because less dust will stick to the outer surface however the issue is with static inside, not outside. The only way to do it is run wire through the inside and have it grounded at either end.

Would i do it? No. The chances are so slim that i simply don't think its worth it.

 

[beech1948]

My shop is long and somewhat narrow ( 59x14 ft) and I use 3xDX4000s. I use 150mm plastic foul drain pipe because of the extra volume of air tranferred and also because the supplier had slow 90 degree bends as well as several slow 45 degree bends which helped get me into position.

I had to drill 150mm holes in the DX4000s and used a 150mm spigot sealed with roofing sealer as the attachment.

Have a look around and see whats available. I think my 150mm stuff came from Screwfix but it may have been Toolstation.

 

[PAC1]

Duct sizing is as much about what is on the other end of the duct and the number of bends. You are starting off with a low volume, if you go up down and snake around there will not be much suck at the point of action whatever size duct you use. Bends create turbulence that seriously reduces the suck. Slow bends are better but no bends are best. By experience with a similar machine is there will be no suck left after that route. You might be more efficient to not bother with ducting and buy a wheel kit for the extractor so you can move it from machine to machine. I made one from some mdf and small casters. Then when you can afford a big chip collector install ducting for the chip creating machines and keep the DX4000 for fine dust such as chop saw, band saw and sanders.

 

[wobblycogs]

As a bit of background I've been woodworking for about 15 years (and used to post here quite a bit), this is just the first time I've had a workshop that would warrant a fixed dust extraction system. The new shop is very roughly 6x6m but it's L shaped and has 3 doors so I've got about 25 to 30m^2 of usable space (photos attached).

I'd like to put the dust extraction system outside but unfortunately that's not an option as there's nowhere suitable. I could make the 12m ducting run shorter by running the duct work down the middle of the ceiling but that would then interfere with the lighting, the run is long because I've got it snaking around the edge of the room. The biggest chip creator I have is the PT which I've run with the DX4000 for a few years. It's got enough suck to cope with that and I can't imagine I'm going to get anything that can create more chips than that any time soon. Having said that I think PAC1 is probably right, after running through half a mile of duct work the DX4000 is not going to be up to the job. On the upside I've already built a wheel base for it so that's a job I don't have to do

Thanks for the help guys, I think I'll put the duct work on hold for the moment and see how I go with wheeling the dust extractor around.

 

[MattRoberts]

What you could do is put some short individual ducting in place hooked up to each machine. You can then wheel the extractor over and using a quick release 100mm clamp (available from axi) just hook up to the ducting rather than fiddling about with each machine's port.

Then if you do upgrade the extractor later, half of the ducting work is already in place

 

[wobblycogs]

Great idea, I hadn't seen those quick release clamps before. I think I lazy morning browsing the Axminster site with a coffee is in my future...

I've just seen Axminister are doing the CT-90H for about £350, the budget might just stretch to that in a few months, would that have enough suck to pull chips over the sort of distance I'd like?

 

[PAC1]

The JET DC1100 is only a tenner more and has much more suck. If you can house it outside so that it vents externally it could work for you. It does well for me
By the way that looks a very nice space.

 

[sunnybob]

Consider re-siting the extractor to the inside of the "L". You have instantly cut the run distance in half. you could even make a star shaped system out to each machine with a blast gate at the start of each run to shut off all unused ducting.
More pipe work admittedly, but you would get away with one size smaller extractor unit, and that much less noise.

 

[wobblycogs]

...that looks a very nice space.

Thanks, it's taken a lot of time and effort to get this far. Once the workshop is up and running one of the first jobs is to make the windows and doors for it. I made a some sash windows last year and really enjoyed it, I've not made a door yet though so that should be fun.

There should be a picture of the shop model I'm working to attached. My planned location for the dust extraction was the bright yellow half circle at the top of the image (that's the DX4000). Thanks to your advice and a bit of frantic reading I can now see I was being more than a little optimistic regarding what that extractor can be expected to do.

The metal lathe and milling machine don't exist yet but I'm hoping they will one day . The router table, drill press and mitre saw are on mobile bases. The big purple box is a CNC machine I'm building (very slowly). The big blue box is the workbench. The sink (bottom corner) is about the only thing that can't be moved.

Looking at the model again, knowing what sort of size the dust extractor will need to be I'm wondering about blocking one of the double doors. I only need those doors for getting really large things in and out the shop and that's fairly rare.

 

[sunnybob]

looking at that, i would site it where the grey square is between the windows . From there, straight up and along the centre of the ceiling to the milling machine, with branches off each side.