Hey Max,
Thanks for sharing! Yes, that is clear. From what I learned early on, a dust bag filter is never suitable for filtering out fine wood dust. It is also not only relevant how fine in µm (“micron”) the holes in the filter are, but much more how large the amount of dust per air volume, and in contrast, how large the filter area is.
If you have too much dust per air volume, for which the total area of the holes in the filter is too small, then the indication of microns is not much use to you, the filter must also pass the amount of air and at the same time retain the existing large amount of dust. Of course, this does not work well with a dust bag filter which has a small area, when there is a large amount of dust per air volume, because in no time, it is clogged, and if the motor is strong enough, it will push the air through the holes anyway, thereby enlarging the holes of the canvas.
Dust classes
Here where I live the dust bag filters are always classified as dust class “L” (I’m attaching a table below that lists the dust classes).
A cartridge with pleated filter has a much larger filtering area and that’s why it clogs up much later. They usually have dust class “M” not only because of the finer filter material structure, but also because of the larger surface area that can filter out larger amounts of dust per air volume before they are clogged. Also they often provide a manual mechanism to clean the filter when it’s clogged (that works like shown here).
When one plans to mill wood (and especially MDF), I would never say you’re fine with a dust bag filter, at least not for longer time.
Is this your dust collector? Does it allow for a pleated cartridge (canister) filter? I didn’t see that model with one attached, just on some other models, would they fit? You said it’s expensive, which is true. But I think if you stand regularly where your dust collector is working and you mill wood with its large amount of fine wood dust, I think it’s necessary in matters of health (and to prevent the shop to be covered with dust everywhere). You can also see in the table below, wood dust requires always class “M”, even if dust collectors are sold with dust bag filters with just class “L”.
Interesting how you managed to reduce the amount of fine dust to be catched! Does it work well? Would you mind to show the entire frame/enclosure you made?
What dust classes are there?
Type approval Degree of separation filter system Suitability Dust class L1)
> 99% Dusts that are hazardous to health with limit values3) > 1 mg/m³ For simple and harmless dusts, e.g. B. House dust, soil and lime. Dust class M1)
> 99.9% Harmful dusts with limit values3) > 0.1 mg/m³ For all wood dust and dust originating from repair compound, filler and clear coats, plaster, cement, concrete, tile cement and paints such as latex and oil-based paints or quartziferous materials such as sand and pebbles. . Dust class H1)
> 99.995% Harmful dusts with limit values3) ≤ 0.1 mg/m³ For carcinogenic and pathogenic dusts, e.g. asbestos and mould. Vacuum cleaner type B222) depending on the dust class Flammable dusts of explosion class ST1, ST2 and ST3 in zone 22
For non-hazardous and dry, flammable dust, such as aluminium or carbon fibre.1) Source: EN 60335-2-69 and IEC 60335-2-69 Annex AA
2) Source: EN 60335-2-69 and IEC 60335-2-69 Annex CC
3) The relevant national regulations must be observed for limit values, eg in Germany the TRGS 900.
Since the beginning of 2012, the AGW have replaced the MAK and TRK values.
– Source: