Thread: Idiots guide to extraction - Is there a 90/10 solution (performance Vs effort)

No short cuts with dust collection I'm afraid.
Moving the DC outside is the absolute minimum because at least some dust is being moved outside the shed.

This is one way of quantifying it
If 1000 CFM is considered effective performance, then 90% = 900 CFM
Given that 100 mm ducting simply cannot draw more than about 425 CFM you will end up with 42.5%.

Even if that Jet DC is modified its is never going to draw more than about 800 CFM through 6" ducting anyway so the best you can hope for is an 80% solution.
But you absolutely have to use 150 mm ducting all the way as well as modifying all you machines to utilise the 6" ducting.

Alternatives could be to do what you indicate - although why anyone would install 100 mm ducting to get 42.5% is beyond me - as well as adding 20 room changes per hour of forced ventilation.
What that will get you is hard to say and depends on your dust making pattern. It will be better than 42.5% but probably won't reach 80%.

If you undertook all my recommendations and used ventilation you might get close to 90%?
What are the dimensions of your shed.

I think that BobL is too polite.

If the OP is after a 90% solution for 10% of the effort, perhaps the advice could be

Place the DC outside, run 5m of 100mm flex hose into the shed with a floor sweep on the open end.
Don't bother with connecting any of your machines to the DC, just use it, as a "vacuum cleaner" whenever the accumulated piles of dust get too high.


If, as is generally accepted, 150mm ducting and 3 hp (or modified 2hp?) is the minimum for controlling fine dust at source, anything less will represent 80% of the effort for 20% of the result.

Perfect reverse Pareto

Thanks Ian, Yes I forgot about the OP's requirement of, "for only 10% of the effort".

What the OP is proposing is far more than 10% of the effort and I'd estimate it's getting on for 50% of the effort to get only 42.5% of the required performance.
This is pretty typical of DIY dust control efforts I see around the place.

If we could describe performance v effort as a mathematical function then it usually starts out linear, with a long inverse exponential tail where apply ever increasing effort brings about ever small improvements - ie the red line on the graph.
Screen Shot 2018-05-02 at 3.42.06 am.png
In practice some decisions/actions may act like step functions since they require little extra effort but make dramatic implements.
The effort required to implement these decisions varies depending on your situation

1) DC and vacs located or enclosed and vented outside - if you already have a shed veranda and no neighbours this could be very little effort - OTOH you may need to invest considerable effort to build a noise reducing enclosure if your neighbours are closely.

2) Select DC power/impeller size to suit shed size and dust making capability of machinery
If all you have are small machines in a small shed you can get away with a smaller DC plus some ventilation.

3) Select ducting sizes layout to suit shed size and dust making capability of machinery.
6" versus 4" ducting - there's so little difference in effort required to install 6" that its a no brainer so why bother with 4"

4) opening up machinery to facilitate greater air flow
This is the one which really upsets and stymies many woodies. I understand getting out the angle grinder to a freshly minted cabinet saw is not exactly easy to do but that's what it comes down to. Effort depends on machines. Machinery with built in 2" ports are a PITA - bell mouth hoods can help here.

5) Using low powered forced ventilation
This is an underestimated factor for small sheds. Effort depends on your shed structure, double brick walls versus Colorbond etc

6) using Bell mouth hoods
Now were getting nearer the end with the extra effort for less return but lets not forget that it all adds up.

Some decisions can take you backwards
A common one is installing a half decent DC system but then cleaning up with grubby old vac and fogging the shed with fine dust to finish off.
Another one is wood dust extraction but nothing for metal work.

IKEA have a website, order online get it delivered and they can even put it together for you for only money! Would fit with the requirements. I started my DC journey 14/5/17 and am only now getting it sorted. I don’t think anything I do in the shed requires only 10% effort, part of the joy of having a shed and wanting to DIY I guess.

Originally Posted by Cal

IKEA have a website, order online get it delivered and they can even put it together for you for only money! Would fit with the requirements. I started my DC journey 14/5/17 and am only now getting it sorted. I don’t think anything I do in the shed requires only 10% effort, part of the joy of having a shed and wanting to DIY I guess.

So coming up for a year - I'd say youv'e done well in that time.

I sort of started back in 2006 when I bought my first TS and a 1HP DC and within days had a few mm of dust all over my shed and dawned on me that many of the things I did at work in dust research could be applied to wood dust and that it gave me access to the gear needed to DC test manufacturers claims and to work out ways to optimise things. However, I did not really get into it until 2011 when I did my shed extension and installed the bigger DC and 6" ducting. Along the way I've been able to test almost everything I have done plus a whole lot more, not just in my shed but in ~2 dozen other DIY, pro, and mens shed workshops. Since then some of my setups have changed as new results came out of experiments and there are still a couple of things I'd like to tweak and machines t to hook up differently.

As of now I think I finally have my TS, BS, belt sander, lathe, DP, planer/jointer, and extraction for power tools working. On the Metal work side the Welder fume hood works well.

Having a particle counter constantly running in my shed is most instructive as every time I do something I can quickly check what sort of dust levels are involved.

Two things that need sorting are the metal dust catcher on the metal grinders need to be beefed up from 4 to 6" and the router table needs a better enclosure than a plastic box held on by an ocky strap.

I realise this extended "dust collection journey" is not what most woodies are after but hopefully it has helped a few people along the way and saved them a bit of time and.

Originally Posted by BobL

If we could describe performance v effort as a mathematical function then it usually starts out linear, with a long inverse exponential tail where apply ever increasing effort brings about ever small improvements - ie the red line on the graph.
Screen Shot 2018-05-02 at 3.42.06 am.png
In practice some decisions/actions may act like step functions since they require little extra effort but make dramatic implements.
The effort required to implement these decisions varies depending on your situation.

Bob, after reading your numerous dust posts, I tend to think that your graph should have an inflection point.
The first 40% of effort really only collects the really coarse dust -- the stuff that falls to the floor beside or inside a machine.
The next 30% captures up to maybe 95% of the total dust.
To capture the final 5% (which contains almost all of the really fine stuff) consumes the final 40% of the effort.


To describe performance in terms of total dust is perhaps miss leading.

Originally Posted by ian

Bob, after reading your numerous dust posts, I tend to think that your graph should have an inflection point.
The first 40% of effort really only collects the really coarse dust -- the stuff that falls to the floor beside or inside a machine.
The next 30% captures up to maybe 95% of the total dust.
To capture the final 5% (which contains almost all of the really fine stuff) consumes the final 40% of the effort.
To describe performance in terms of total dust is perhaps miss leading.

I agree - in fact the effort/performance curves for coarse and fine dust are quite different.
For coarse dust its much easier to get close to 100% extraction because it can be seen.
With fine dust you can't see it and you cannot see or feel airflow so without a particle counter or working from principles determined using a particle counter its like operating in the dark.

Thanks for the feedback on this post. I respect a great deal of knowledge and commitment to effective dust collection exists on the forum. Clearly my original question was somewhat rhetorical but I think Ian's last post was closest to aligning with my original point. The law of diminishing return makes it almost certain that there will be an inflexion point somewhere in the effort/outcome curve. Spending 40% of effort to capture the last 5% of fine dust is just not what interests me and I say that with acknowledgement of the health risks. My woodworking time is so precious that to chase such an elusive goal would mean spending the next year+ of workshop time fine tuning my extraction gear at the expense of any other skilled craftwork. As an alternative I have to some degree shaped my chosen craft to be more mindful of the health risks. I do very little sanding in my woodwork and when I do I move it outside. My game is really machinery for bulk stock preparation and as such aligning a sensible extraction system in accordance with one's chosen method of work is something that I think makes some sense.
The 6 points in your second post BobL are exactly what I was after. This is really useful guidance to focus in on where the biggest improvement can be made in order of priority. I'll be upgrading my extraction system and moving to 6" ports as a valued investment. While I respect the technical guidance provided here, retaining something like BobL's top 6 as a fixed headline post and providing links to a couple of great detail posts that provide more information on each point would be a great introduction for newcomers to the art of extraction. Just a thought for the mods. Thanks again for accelerating my learning in this area of the craft.

Of the 6 things listed above,

1) DC and vacs located or enclosed and vented outside.
This is the single best simple thing anyone can do. It does mean installing ducting (ie 3) OR be able to move you machines up to a machine, which is a daft idea especially if you want to save time for the next couple of decades

Steps 2), 3) and 4) are not options but they go "hand in hand" - if you do one you must do the other two to be effective otherwise you may as well do none.
2) Select DC power/impeller size to suit shed size and dust making capability of machinery
3) Install ducting sizes (pref 6") layout to suit shed size and dust making capability of machinery.
4) opening up machinery to facilitate greater air flow to utilise 6" ducting

This is a choice but it is a wise one and is underestimated especially in a DIY situation.
5) Using low powered forced ventilation

This is now getting towards or past the inflection point
6) using Bell mouth hoods
Now were getting nearer the end with the extra effort for less return but lets not forget that it all adds up.

Originally Posted by Sunnycoaster

Thanks for the feedback on this post. I respect a great deal of knowledge and commitment to effective dust collection exists on the forum. Clearly my original question was somewhat rhetorical but I think Ian's last post was closest to aligning with my original point. The law of diminishing return makes it almost certain that there will be an inflexion point somewhere in the effort/outcome curve. Spending 40% of effort to capture the last 5% of fine dust is just not what interests me and I say that with acknowledgement of the health risks. My woodworking time is so precious that to chase such an elusive goal would mean spending the next year+ of workshop time fine tuning my extraction gear at the expense of any other skilled craftwork. As an alternative I have to some degree shaped my chosen craft to be more mindful of the health risks. I do very little sanding in my woodwork and when I do I move it outside. My game is really machinery for bulk stock preparation and as such aligning a sensible extraction system in accordance with one's chosen method of work is something that I think makes some sense.
The 6 points in your second post BobL are exactly what I was after. This is really useful guidance to focus in on where the biggest improvement can be made in order of priority. I'll be upgrading my extraction system and moving to 6" ports as a valued investment. While I respect the technical guidance provided here, retaining something like BobL's top 6 as a fixed headline post and providing links to a couple of great detail posts that provide more information on each point would be a great introduction for newcomers to the art of extraction. Just a thought for the mods. Thanks again for accelerating my learning in this area of the craft.

Good morning Sunnycoaster

My "last post" (post #7) needs to be read in the conjunction with what I wrote in Post #3.

With woodworking machines (and to a lessor extent sanding by hand) you are dealing with two types of dust -- coarse and fine.

While somewhat tongue-in-cheek, Post #3 describes the Pareto principle in relation to coarse dust. The particles are sufficiently large (heavy) that they readily fall out of the air, so can be vacuumed up when the quantity of dust lying around becomes "excessive". Alternatively, a relatively low effort DC installation will collect most of the coarse dust at source.

Unfortunately, when discussing total dust, collecting enough of the fine dust to make a meaningful difference in terms of a user's health is too often seen as icing the cake. (Hence you question around "Where is the value in spending as much, if not more, time and dollars collecting the last 5% as was spent to collect the first 95%".)
The answer of course is that the first 95% is really only nuisance dust and the last 5% is the really fine dust which will get deep into your lungs and cause you serious grief.

While I don't have access to the measurement tools that BobL has developed, I think -- and I must stress the '"think" bit -- that a room air filter would be an essential part of a low effort / lower cost dust solution.
Picking up BobL's points,
1) locate the DC outside or in an enclosure that vents to the outside -- being aware that if the prevailing winds will blow the DC's exhaust back into the shed going outside is a waste of time and effort.
2) try and match the DC's hp and impeller to the size of your shed and the dust making capability of your machines. AND install 6" ducting and adequate air flow through each machine. And avoid sharp bends in the ducting.

If (2) lies outside a user's comfort level, or is not possible, then I suggest that either a room air filter AND/OR forced ventilation is essential.

Originally Posted by ian

While I don't have access to the measurement tools that BobL has developed, I think -- and I must stress the '"think" bit -- that a room air filter would be an essential part of a low effort / lower cost dust solution.

In terms of cost, ventilation usually trumps room air filtration (RAF).

The Gotcha is in very cold or hot environs when it may not not be possible to always vent so RAF may be the only way to go. However as our audience is primarily aussie then ventilation is a real option for most locations.

Here are a few comparisons (using manufacturers air flow specs - they are all too high but probably by about the same factor)

Bunnings 200mm Arlec exhaust fan : 10c/CFM.
Probably the fan most unlikely to have its claimed CFM but replacing the grille with some chicken wire will improve performance dramatically but may also shorten its life somewhat. I have never obtained more than ~5 tears out of these fans. Nevertheless a fair short term solution for budget minded DIY operators. Noise claim is 48 dB but will be louder if grille is removed.

Vent fans from "Gro your own" companies - these are really nice quiet fans design to run continuously for long periods
Good quality Ebay versions range from 30c/CFM for small (4") fans to 21c/CFM for large (12") fans.
Noise levels range from 47db to 56db for the larger ones
Almost silent German Gro fans are available but cost/CFM approach those of RAFs.

Looking at maximum flow rates, the Carbatech room air filter costs around 53c/CFM, a similar Hare and Forbes unit costs 42c/CFM. Noise level for the B&F unit is high (69dB)

RAFs have the advantage that they eventually remove all dust from the air which is useful for applying some finishes but also have disadvantages. For a start they do not remove all fine dust during every pass so for the same flow take ~15% longer to remove the wood dust from a room. They also will not maintain their specified air flow unless they are regularly cleaned.

Overall, for general WW in Australia I'd say ventilation is the way to go even if you do have high volume extraction installed. The noise of high volume extraction can be significant and very annoying - the port I sometimes vent with is the BMH on the lathe and that generates 71dB at 1m. For me the dB level is less of an issue than the high frequency "hissing" involved.

I have a very fancy RAF but only use it when I have the AC on and am doing lighter duties, ie hand tools, assemble and no machinery. That thing sucks every single 0.3 and larger micro dust out of the air - the air even tastes "fresher" under that filter. Under that filter even the pro particle counter from work reads 0 particles per cubic meter and I use it as a way to clean out the particle detectors and to check that they have not become contaminated

Folks should really keep their eyes open for cheap ventilation fans in eg salvage yard and kerbside pickups. In my shed have 2 squirrel cage fans that both came out of skips and generate up to 2800 CFM of extraction. One fan is a 1/3rd HP squirrel cage fan and cost me half a can of spray paint to cover the rust, and the other one is 3 phase so it cost me $70 to install a used small VFD on it, so cost to me s a whopping 2.7 c/CFM

I had a 1HP 600 mm Evap AC fan for months going for free on Gumtree and these forums and just a couple of weeks ago while consulting to a regional Mens shed and explained the benefits of ventilation (ie hard sell) was I able to give it away.

Good Morning Sunnycoaster

I think you are being a little optimistic in expecting a 90/10 return to effort by application of the Pareto Principle. Vilfredo Pareto actually calculated an 80/20 ratio in the 1890's and innumerous studies since have verified his presience.

The Pareto Principal is often depicted graphically as below:

WWF.pdf

From this you can read:

• 10% of effort yields 64% of output,
• 20% of effort yields 80% of output,
• 36% of effort yields 90% of output,

The rewards for effort certainly are diminishing, and it is up to you to decide where on that chart you prefer to be.

However, as BobL has said, the courser dust is quite easily removed and it is quite benign. The finer dust is the one that is most dangerous to your health, and that is in the last 10%.

Bill Pentz has written extensively on this and it is worth reading his stuff. Continental safety rules are significantly more advanced than those of Australia and USA and may also be relevant.
billpentz.com

But the views of BobL, Ian and all offer the best path towards optimising your return to effort. If the pipes are too narrow, the impellor is too weak, the motor is too small, then you shoot yourself in your foot!


Cheers

Graeme

Originally Posted by BobL

Good quality Ebay versions range from 30c/CFM for small (4") fans to 21c/CFM for large (12") fans.

I've just fitted two 400mm fans to back window in my workshop. Perhaps it's overkill, but they fit the window space perfectly. But they're not very quiet - probably cos I didn't spend a fortune on them.

Originally Posted by Colin62

I've just fitted two 400mm fans to back window in my workshop. Perhaps it's overkill, but they fit the window space perfectly. But they're not very quiet - probably cos I didn't spend a fortune on them.

You shouldn't need to have both on all the time or ( if you can fit a light dimmer onto them) run full speed all the time.
What sort are they?