Thread: Dust Extraction / Control used by woodturners

Originally Posted by mick59wests

I think of a 'scrubber' or air filtration as part of the strategy for removal of fine dust. I hope that I can remove at least 95% of fine dust at source more than 90% of the time. However, I never expect to remove 100% of it 100% of the time so the air filtration (and ventilation) is going to up my fine dust removal from around the 95% mark to closer to 99%. Is this a reasonable expectation or is the 99% more likely 96%?

It would be nice to be that prescriptive but every situation is different and some are quite different.

Using a drill press it appears that a decent DC will capture 99.99% of fine dust - therefore, air scrubber is completely unnecessary

Turning and sanding a small spindle on a lathe using a decent well setup DC will capture 99+% of the dust.
Turning a large bowl on a big lathe is going to spray stuff all over the place - depending on your DC you will be lucky to get 95% or maybe even 75% of the fine dust during the turning operations.

Now, how to get the rest out.
Using a scrubber will clear a bubble of air around the scrubber and that is about it - the size of the bubble will depend on how much dust there is and how long the scrubber is running for.
If the bubble is around the operator that is very useful but what about the rest of the shed.
Just running a scrubber for longer is not a solution if the amount of dust generated is greater than the capture rate, the non-captured dust fils the shed and eventually starts to settle in the corners and shadowed areas on shelving and low to ground etc. This settled dust cannot be picked up by the scrubber so so the next time you walk by or move that surface the fine dust will recontaminate the shed.
To get around this multiple scrubbers would be needed, but even then with only marginal improvement. It's always better to put more effort into capturing at source.

I have been asked about using a compressor to fluff up all the fine dust and run a scrubber overnight. I tried this and it sort of worked but it's very tricky to measure redeposited dust and I gave up on it after I blew some small machine parts onto the floor and lost some of them.

Running the DC after the last dust making activity has the benefit of replacing wood dust ladened internal air with cleaner external air. However, if there is only one opening from one side of a shed to the DC inlet then like the scrubber all that will be cleared is a tunnel of air between the opening and the DC inlet. To clear the air in the shed you can of course open all windows and doors on one side and all DC inlets on all machines which increases the size and numbers of tunnels. Better still would be to install vents on the walls near the dead areas so that air can be pulled from all areas of the shed during and after dust making activities.

Thanks Bob again for the help. I don't know how to get a paragraph break happening, so I can't make the read a little easier for you.

1. I won't sell the old cyclone. I reckon I can make it do for the saws in the main part of the shed. It's more the turning end that I'm worried about, particularly now that I have the s750 Stubby and have started turning larger platters.

And 2., you are right, the crap just does go everywhere. No way to capture it at source effectively.

Even worse when arrives here, it's everywhere.

So I'm thinking a Clearvu in the turning end of the shed, aided by two Microcleans above the VL 175 and the 300, with a down draft gate on the tail stock end of the Stubby permanently left open to scrub the air. (The Stubby is bolted to the floor under it's own power pendant. ) Plus another shroud behind the Stubby lathe to capture sanding dust, same for the other two lathes. That leaves four gates open at one time.

Or do I need blast gates?

Also, the Jet scrubber I'll leave high in the ceiling (which is useful in winter in bringing the heat down from the ceiling).

I assume I can vent the Clearvu inside the shed?

If not, I'll have to put up with the cold but that's got to be better than the dust.

As I said, I have one circuit left on the power board, including an existing 15amp one for the old cyclone and a new one as well. But no more.

And no, I don't want to build another shed outside the big one to house a cyclone. So I will have some noise issues to deal with as well.

The turning area is 9m by a little more than 6m, which should house all my turning gear but the cyclone. Oops, forgot the bandsaw, so gates will be needed.

Also forgot the floor sweep, lots of chips to get rid of.

Any other options to a ClearVu? Most of the stuff on the net seems heavy industrial.

I hope some of the other ClearVu owners can chip in with their thoughts. Or maybe I post over on the Dust Extraction forum>?

Thanks again.

Hi Jeff,
It certainly does sound like you need to do some work to your dust collection, it might also be worth posting in the dust collection forum, it was only the headline that caught my eye as I don't normally visit the turning section.

As Bob has already said if you are looking at having multiple machines operating at once and still want to achieve acceptable airflow at each machine then a larger DE system is required, 5hp or more, really depends on total flow needed and total pressure losses within the system, things like pipe size, pipe length, cyclone, number of fittings, (gates,bends,etc) total length of hose, all effect pressure losses and you can be a bit smart with the control of it with a variable speed drive (VSD) you will be able to control the speed (airflow) for times when you want maximum flow (more than one machine operating) and turn it down for times when only one machine is in use thus saving power, this can be setup to be an automatic or manual change.

Other options to a CV are the Felder DE units the RL 200 has numbers that are right at were we want, (for one machine) although can't see at what pressure tho? also claims to emit lessthan 0.1mg/m3, I think Bob has posted before re what was allowable, seem to recall 25mg/m3 but not sure, Bob might confirm this, upshot of this is you may get away with not needing to vent outside in winter and quiet 70dB.

Floor sweep, I made this one up for Roy at his workshop
https://www.woodworkforums.com/f200/d...rkshop-172717/


Other operational things to consider, the jaws on a chuck act like a fan sucking in air/dust towards the centre and spraying it outwards in every direction, so preventing the dust from going over the back of the plate towards the chuck , for this to work you will need a close fitting dust shroud/hood located on the rear side of the plate, also, when sanding a plate if you sand in the top quandrant you will be directing the dust away from you and into a dust shroud if positioned at the rear of the machine.




Pete

Originally Posted by pjt

. . . .and you can be a bit smart with the control of it with a variable speed drive (VSD) you will be able to control the speed (airflow) for times when you want maximum flow (more than one machine operating) and turn it down for times when only one machine is in use thus saving power, . . . .

And noise.

Other options to a CV are the Felder DE units the RL 200 has numbers that are right at were we want, (for one machine) although can't see at what pressure tho? also claims to emit lessthan 0.1mg/m3, I think Bob has posted before re what was allowable, seem to recall 25mg/m3 but not sure, Bob might confirm this, upshot of this is you may get away with not needing to vent outside in winter and quiet 70dB.

The current OHS limit for OZ is the same as the US, 5 mg/m³ for softwoods and 1mg/m³ for hardwoods.
The Felder unit meets the European standard but none of these makes any allowance for real health culprit which is not the concentration of dust but the numbers of fine dust particles per cubic m.
If the 0.1mg/m³ was all in small particles that could still represent a millions of small particles per cubic metre
OR
If it could be one 0.1 mg particle of sawdust in a cubic meter of air i.e. harmless.

A more sensible standard mentions the particle size range e.g. the European medical standard is "0.1 mg/m³ (PM₁₀) "
The means 0.1 mg/m³ for particles of 10 microns or smaller. Still not brilliant but better than nothing

Originally Posted by BobL

For your size shed you really needs a DC with a ~5HP motor and a 17" impeller and 8" ducting.

We went to 5HP when we upgraded the DE at the local men's shed earlier in the year. Your workshop might even be larger, Jeff...

They already had a cyclone built to Bill Pentz' specs, so getting there step by step.

Originally Posted by BobL

And noise.



The current OHS limit for OZ is the same as the US, 5 mg/m³ for softwoods and 1mg/m³ for hardwoods.
The Felder unit meets the European standard but none of these makes any allowance for real health culprit which is not the concentration of dust but the numbers of fine dust particles per cubic m.
If the 0.1mg/m³ was all in small particles that could still represent a millions of small particles per cubic metre
OR
If it could be one 0.1 mg particle of sawdust in a cubic meter of air i.e. harmless.

A more sensible standard mentions the particle size range e.g. the European medical standard is "0.1 mg/m³ (PM₁₀) "
The means 0.1 mg/m³ for particles of 10 microns or smaller. Still not brilliant but better than nothing

As they say "the devil is in the detail" so if Jeff wanted some peace of mind, moreso if he chose to not vent to outside for winter, some more details from Felder re the particle size/s of that 0.1mg/m3 is what he would be needeing.



Pete

Originally Posted by pjt

As they say "the devil is in the detail" so if Jeff wanted some peace of mind, moreso if he chose to not vent to outside for winter, some more details from Felder re the particle size/s of that 0.1mg/m3 is what he would be needing.

Sort of - what is needed is the efficiency of the filter for various particle sizes, like the graphs I post in the dust forum, but doubt Felder have measured this because all they worry about is the dust concentrations in mg/m³. There are several ways of measuring these dust loads and one is using particle size distributions which is what I do, but there are easier ways of doing this using external pumps and filters which is probably what they do.

I do have some data for a Felder filter but because it is only one filter I would prefer not to put this up in the forums and have folks make judgements based on one measurement. If people want to know the results off line they can PM me for details.

Originally Posted by BobL

Sort of - what is needed is the efficiency of the filter for various particle sizes, like the graphs I post in the dust forum, but doubt Felder have measured this because all they worry about is the dust concentrations in mg/m³. There are several ways of measuring these dust loads and one is using particle size distributions which is what I do, but there are easier ways of doing this using external pumps and filters which is probably what they do.

I do have some data for a Felder filter but because it is only one filter I would prefer not to put this up in the forums and have folks make judgements based on one measurement. If people want to know the results off line they can PM me for details.

I do seem to have a recollection of a thread/post on this subject, apologies for going back over old ground, so what we want to know is how good the filter is at stopping a range of particle sizes, viz. for every 100 particles of say 1um size if only one escaped the filter then is 99% eff. for that size, similliarly for 100 particles of say 5um if 2 escaped then the filter would be 98% eff. for that size, and so on.
Then all the escaped particles would add upto xmg/m3, in the Felder case they state less than 1mg/m3.
Then we want to know if any of the escaped particles sizes are harmful in those % concentrations.
Jeff can't quite breathe easy yet



Pete

Originally Posted by pjt

I do seem to have a recollection of a thread/post on this subject, apologies for going back over old ground, so what we want to know is how good the filter is at stopping a range of particle sizes, viz. for every 100 particles of say 1um size if only one escaped the filter then is 99% eff. for that size, similliarly for 100 particles of say 5um if 2 escaped then the filter would be 98% eff. for that size, and so on.
Then all the escaped particles would add upto xmg/m3, in the Felder case they state less than 1mg/m3.
Then we want to know if any of the escaped particles sizes are harmful in those % concentrations.

Correct.

Particles bigger than about 10 microns don't float all that well and settle quite quickly and only get inside airways if folks stick their nose or mouth in the sawdust stream. Those smaller than 10 microns and in particular those less than 5 microns tend to float around for a while allowing them to be scooped up. This is why dust particle size analysis focusses on particles of 5 microns or smaller.
Like this


The 5 - 10 micron size are the ones that get as far as the inside of the nose - these cause nasal allergies and maybe worse. Those between 5 microns and 0.3 microns get into the lungs and cause breathing issues.
The reason that we don't worry so much about those smaller than 0.3 microns is because these are not trapped inside us and are usually breathed back out again

I've bitten the bullet and have decided to order a ClearVue Maxi cyclone for the turning end of the shed. And I will have to vent outside, which doesn't matter much on 9 acres. Cold in the winter though.

Some of the guys on the Dust Extraction forum have been providing some good advice. I think I may have to get a sheet metal worker to make up some hoods. The one for the Stubby with its 750mm swing is going to give me problems. Any ideas on design? Maximum bell diameter?

I don't think positioning the hood with some adjustment will be easy either. I'll have to mount something to the floor probably.

Jeff, just stand near the fire

Originally Posted by jefferson

. I think I may have to get a sheet metal worker to make up some hoods.

Suggest you begin by making some out of thick corrugated cardboard and testing out different designs and configurations as prototypes before having the hoods you finally settle on made up in metal. It is so easy to reconfigure cardboard prototypes with just a box cutting knife and a reel of tape.

Some of my cardboard prototypes lasted for years.

Good ideas Neil. I'll keep that in mind when I get down to the business end of things.