Dust collection help/ideas wanted please

[AES]

G'morning all,

I have quite a dust collection problem in my cellar/workshop, as it’s (obviously!) part of the house and most important, it’s shared with “ ‘er upstairs”.

A recent post in the Scroll Sawing section here drifted quite a bit off topic (“Guilty as charged m' Lud”), showing what I thought was a good idea by using a rainwater hopper-type collector as a dust collector hood (pages 4 & 5 of the link below refers).

my-new-hegner-workshop-tidy-up-t87357.html

I couldn’t find a hopper in my local DIY emporium, but did find a big plastic funnel, which after some bodging around with bits & pieces of plastic pipes & fittings and self tappers plus bathroom silicon sealant has morphed into this:

If it’s important, the OD of the funnel is approx 9.5 inches, height of the conical section approx 6 inches, and overall height is about 18 inches.

I’ve paid careful attention to making the internal connection joints as smooth as possible, and the internal pipe diameters reduce quite gently from 75 mm at the top of the conical section to 50 mm at the top end shown (which couples nicely onto the shop vac flexible hose, with the help of the hose clamp shown). As seen, there is only one bend of about 45 degrees.

The shop vac is a Karcher wet/dry model A2654 rated at 1800 watts. In “normal use” it sucks like a good ‘un and was superb at sucking up water when we had a cellar flood last year – through it’s normal 50 mm flex hose I stress.

As the first experiment I used a piece of thick obechi scrap, shaping it against a 60 grit disc on the small (5 inch) disc/belt sander shown below.

While I sanded the scrap my wife held the funnel close to the disc at the area where some/most of the dust was appearing, with the vac running of course. We could see that some of the obechi dust was definitely being sucked into the funnel but at a guess it was less than 50% of the total dust produced – my wife remarked “that’s not exactly the full yoke of the egg dear”! And in the pic you can see quite a lot of dust residue still adhering to the sander.

I should also add that before this test the vac filter was cleaned and a new (empty) paper bag fitted. (When I can get this set up to work OK I’m going to make a Thein or cyclone separator, plus add a quieter vac).

So what now please?

Is it “just” a question of a more powerful vacuum? (The Karcher is pretty good at sucking but is VERY loud – I can’t hear the phone in the cellar ring when the vac’s running).

Bigger funnel?

Smaller funnel (the one shown is just about as small as is convenient when trying to work with the sander shown and would definitely be too small to cover the other disc/belt sander I have)?

Bigger diameter pipe work?

Now I’m going to rig up some thin sheet metal “vortex generators” about 1 inch high and a bit curved/angled, then silicon them into the inner part of the cone (to try and induce turbulence, so – hopefully - increasing the suction effect). I’m by no means an aerodynamicist but do understand the very basics. I’ll just set them at about 15 degrees to the flow at the top of the cone, changing to about 30 degrees at the bottom. I’ve no idea if this will help but will report the results (if anyone's interested).

Any other ideas or comments on any of the above gratefully received in the meantime.

Thanks in advance

AES

 

[AES]

Ladies & gents,

I must confess to being a little disappointed that no one has any ideas in response to my 1st post - Youtube, etc, has lots of stuff about dust collection but nothing I've found has been of much help in my particular situation. Perhaps I really am barking up the wrong tree?

Anyway, here's an update. The pic below shows my first idea about adding sheet ali vortex generators inside the cone of the funnel. Testing the same way as before (1st post) does show some improvement in suction but not as much as I'd hoped - hardly worth making a proper job of sticking the tabs into the cone (so far, just temporary self tappers used). I'm far from sure that fiddling with this idea any further is worth while.

So again I ask:

1. Do I "just" need a bigger/more powerful shop vac? (Apart from the not inconsiderable extra cost involved, there's the noise too - as per my 1st post the present Karcher vac is too loud for comfort now, and I can't "see" that even a Henry will be all that much quieter - AND they're B.....dy expensive here).

2. Have I got to use bigger hoses & pipes? (I see lots of 4, 5, and 6 inch diameters mentioned on the various Youtube items I've watched). How does one go about hooking such big pipes up to any shop vac, which all seem to have roughly 2 inch inlets?

P.S. I don't really have the space to have a "proper" dust collector to power dust extraction in the cellar, and installing it outside isn't a realistic option either.

As before, I'm missing something here, so any help/advice will be gratefully received.

TIA
AES

 

[CHJ]

I think you would be better off placing your machines in an open fronted enclosure so that you control where the dust entraining air is coming from, unfortunately for the 'frontal' area that will present I think you will need to have a High Volume Low Pressure extractor to move sufficient air to be effective.

This crude shield around my chop saw works reasonably well with a Lidl vac fitted with a 63mm hose but works much better with a 100mm hose connected to a cheap high volume (and much quieter induction motor) extractor.

 

[AES]

Thanks for that CHJ. A good steer. Yup, it would be quite easy to rig up a "hood" as you show.

Interesting point about pipe dia too, thanks.

Any chance of hearing what your "cheap HVLP" extractor cost, what brand, the power rating, where you bought it, plus rough LxWxH dims, and even a piccie please? And when running can you hear the radio (or phone ringing) over it?

TIA
AES

 

[CHJ]

...

Any chance of hearing what your "cheap HVLP" extractor cost, what brand, the power rating, where you bought it, plus rough LxWxH dims, and even a piccie please? And when running can you hear the radio (or phone ringing) over it?

TIA
AES

This Pattern but a different (cheaper) brand:-
.... Linky Pic.

But the supplied bags are normally only Chip proof so you would need to fit finer mesh bags or a cyclone if you can't vent the dust outside.

Noise wise not quite as loud as my Lidl extractor and a deeper lower tone sound. (one linked to says 70dB(A))

 

[AES]

Thanks for that CHJ. The link you provided had all the info I need for now - I must have a look for what's available here - and at what prices!

I've also found some stuff by Mathias Wandell ("Woodgears") where he makes a pretty similar-looking unit, but with built-in separator (Thein-type if I remember correctly).

Anyone on here had any experience of building their own please?

Krgds
AES

 

[sploo]

In answer to one of your earlier questions: air movement. Lots and lots and lots of air movement. To get decent suction (and move enough air to really capture fine particles) with a funnel that large you'd need a monster impeller and motor.

In terms of separation, a good cyclone is great, but I understand the Thien Separator is pretty good too - especially if you're limited for space.

The problem is that those separators rob you of a lot of airflow, so you need an even bigger impeller + motor. Even then, it's probably not a bad idea to vent the "dirty" air outside, as opposed to trying to filter it and return it to your workshop.

The solution I came up with is here http://spikyfish.com/DustExtraction/. It's... ok. I get some dust coming out through the vent if I forget to empty the bin for a while, but it works well enough that I've never had complaints from the neighbours.

I have built small cyclones for use with shop vacs (see pics below). They've been OK, but if I'm doing anything that's going to generate a lot of dust I'll use the main extractor, so the vac is only for the occasional clean up, and only when I'm wearing a Trend Airshield.

 

[AES]

Thanks a lot for that sploo, very helpful - and for the link (lots of useful info there). Clearly I'm going to have to think about a big(ger) motor and impeller (amongst other things)! I'm still considering "just" buying something, not yet decided, we'll see.

Krgds
AES

 

[sploo]

Thanks a lot for that sploo, very helpful - and for the link (lots of useful info there). Clearly I'm going to have to think about a big(ger) motor and impeller (amongst other things)! I'm still considering "just" buying something, not yet decided, we'll see.

Krgds
AES

No worries.

CHJ's suggestion of an open fronted enclosure is probably your best bet, but with a sander the dust is likely to go everywhere.

Pulling dust - especially dust moving away from the extraction - is hard. You could possibly add a fan to help blow the dust back towards an extraction enclosure, but you might just end up blowing dust everywhere. No easy solution I'm afraid.

 

[CHJ]

The only real answer is large volumes of air movement into the extraction system, this comes with a penalty of air movement noise of course, I know my system in the lathe shed which exhausts outside the shop generates enough air movement noise to drown the lathe motor and personal protection mask motor noise. (it is quite happy to transport a 80mm diameter buffing mop or similar sized oddment of wood into the inner workings of the extractor though)

Unfortunately the OP is in a cellar with little prospect of a high volume low pressure air exhaust system.

 

[AES]

Thanks to both sploo and CHJ. Not easy stuff is it????

The biggest problem I have, apart from needing not to spend too much, is the fact that apart from 2 small windows at just above outside ground level (plus a door), is that the whole cellar is made out of thick reinforced concrete - including a nuclear fall out shelter (really!), the door to which for example is a steel frame and concrete in-fill well over a foot thick. (The Swiss take Civil Defence VERY seriously) :roll:

Krgds
AES

 

[Jamesc]

Just to add to what others have said capturing airborne dust is very difficult.

The actual key is air velocity (speed) you need fast moving air to capture it. You could try mounting a second cone inside your first but say 10mm smaller so that the air is only extracted around the rim. This is how commercial cooker hoods work. The problem with the funnel is it actually slows the the air down. What you want is the same air speed from capture to the extractor. This can be done by careful design, basically what you want is the same cross sectional area throughout - hence the inner cone.

I once used to do this type of design for a living but haven't run this kind of calculation for over 30 years so I am a bit rusty.

James

 

[sploo]

Thanks to both sploo and CHJ. Not easy stuff is it????

The biggest problem I have, apart from needing not to spend too much, is the fact that apart from 2 small windows at just above outside ground level (plus a door), is that the whole cellar is made out of thick reinforced concrete - including a nuclear fall out shelter (really!), the door to which for example is a steel frame and concrete in-fill well over a foot thick. (The Swiss take Civil Defence VERY seriously) :roll:

Krgds
AES

Yea, that's not easy.

If the sander is your main problem, and you have the space, then you could rig up a set of "walls" made of polythene sheet (or similar) around that tool, to try to trap the dust in that area. You'd have to always use a really good mask or respirator in that "room", but it might keep the worst of it from the rest of the cellar.

What you really want to avoid is dragging dust through into the house - a big worry with a workshop that's connected to a living area. Making an airlock (well, just a small area where you change), with doors on either side, would help reduce dust being pulled through.

 

[AES]

Yup, thanks sploo.

I'm still thinking about it all, but you're dead right, I MUST not let dust creep into the house!

Presently I do just about everything (especially sanding) outside the cellar door (with the door closed :lol: ) with tools & workpiece/s balanced on the Workmate, but not only is that not ideal when it's raining or cold, now I'm getting on in years and doing less & less "work work" I want to spend more time in the shop "playing".

We'll see, I'll have to do more thinking and more reading and Youtubing - I'll get something sorted in the end, but meantime thanks to you (and to all the other posters), I've bookmarked your info and will be back to it again on and off.

Cheers
AES

 

[sploo]

Yup, thanks sploo.

I'm still thinking about it all, but you're dead right, I MUST not let dust creep into the house!

Presently I do just about everything (especially sanding) outside the cellar door (with the door closed :lol: ) with tools & workpiece/s balanced on the Workmate, but not only is that not ideal when it's raining or cold, now I'm getting on in years and doing less & less "work work" I want to spend more time in the shop "playing".

We'll see, I'll have to do more thinking and more reading and Youtubing - I'll get something sorted in the end, but meantime thanks to you (and to all the other posters), I've bookmarked your info and will be back to it again on and off.

Cheers
AES

Yea, I generally just have to accept that big sanding and planing jobs have to wait until a dry day. Otherwise the garage just gets covered.

With a big enough workshop you could rig up a "dirty" room; where the worst dusty jobs are done, but that's not practical for us mere mortals.