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  1. #1
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    Apr 2001
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    Default Hand vs Power sanding

    I watched an interesting video today, by Peter Parfitt, which was made several years ago. In particular, what was interesting was that hand sanding posses more of a danger than modern power sanders with good dust collection. In his case, he was using a Festool sander-vacuum cleaner combination.

    The other interesting factor was that Peter does not have a dust collector and relies on his Festool CT26E (same as mine) for all his dust collection. I do not recall whether he has a thicknesser or a jointer, and his table saw is a Festool, where the dust collection is part of the circular saw. His measurements demonstrated that it left about 10x less dust in the air as a full tablesaw. Bob (BobL) has written a great deal about dust being re-circulated by vacuum cleaners. The CT26E (and other Festool vacs) have HEPA filters, and these appear to be working in the context of Peter's set up.

    Your comments ... ?



    I have the Mirka hand sanders. After viewing this, I purchased a dedicated Mirka hose for them (the Festool hose is too stiff for these sanders, and I have tended to use them without dust control. No longer!).

    For those unfamiliar with the Mirka hand sanders, they are used with Abranet mesh ...















    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

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  3. #2
    Join Date
    Feb 2006
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    Default

    Some 8 odd years ago when I checked out around 2 dozen DIY sheds and their dust extraction gear the only vacuum cleaners that were not problematic were near new high end machines. Even those, any more than a year or so old, were leaking and themselves contaminated, and hence contaminating their working environments. The leaks ranged from minor (ie the only way to know they were leaking was to use a particle counter) to those that were were "bleedingly obvious" because on close examination we could see the dust stains around the leaks. Minor leaks could be handled using reasonable shed ventilation such as you have in your shed Derek, but for folks working in almost hermetically sealed sheds/spaces especially in winter then dust would build up

    I have made several recommendations in this forum around checking and maintaining vacs but if you are a regular user of vacs then unless you are in the business of regular cleaning and checking with a particle counter then the safest thing to do, like DCs, is not use them inside a shed but located them outside the shed or in an air tight enclosure that is vented outside the shed.

    Overall risk(of individual to timber Y) = exposure x sensitivity(of individual to timber y)
    If someones sensitivity is high then even a low exposure might trigger an allergic response.

    I do have a cheap and cheerful W&D shop vac that I use every couple of months to do something or other in my shed, usually cleaning metal swarf off machinery, and grinding dust and welding slag off the floor.. When I use this vac I connect up and run a vac air outlet hose into one of my DC ducting posts. I also run my ventilation fans (2600 CFM) so any leaks are whisked away in pretty short order. However, there still seems to be a fair bit of "grey goo" dust (metal working related dust) all over the place that I still need to do something about.

    Hand sanding can be safely performed in a shed with adequate ventilation on top of a "down draft" sanding table - a table with a hollow top that is perforated and connected to a venting dust extraction system. The table needs to be large enough so that most of the holes are not covered up by the work itself.

  4. #3
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    Perth
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    Default

    Bob, I am with you ... that's why this video was so provocative. I also emphasised that it seemed to work "in the context of Peter's set up", which includes a HEPA filtered VC.

    I am paranoid about dust, which I blame you for

    It is the dust that remains hanging in the air that really bothers me and, in spite of the good ventilation I have, I am thinking about a ceiling extractor. Do you consider that a waste of time and money?

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  5. #4
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    Feb 2006
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    Perth
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    Default

    Quote Originally Posted by derekcohen View Post
    Bob, I am with you ... that's why this video was so provocative. I also emphasised that it seemed to work "in the context of Peter's set up", which includes a HEPA filtered VC.
    One problem is that HEPA (High efficiency particulate arrestance) is a descriptor/label without a legal definition. A manufacturer can use a piece of flywire as a vac filter and call it a HEPA filter. If HEPA is mentioned, look for the " efficiency at a specific micron size". I consider something a true HEPA if it is better than 99.95% efficient at 0.3 microns or greater.

    Another less specific filtration descriptor called MERV (Minimum efficiency reporting Value) is sometimes used. This is a number between 1 (least efficient) and 20 (most efficient) applied to specific contaminants (eg smoke and bacteria) but a specific micron size rating is not always included in the descriptor. MERV17 are supposedly 99.97% efficient at particle size >0.3 microns.

    I am thinking about a ceiling extractor. Do you consider that a waste of time and money?
    I reckon most DIY WW fine (invisible) dust problems (not visible sawdust) can be addressed or at least significantly reduced by using forced ventilation and have written about this a number of times. I have on many occasions been recommending the use of impeller type extraction fans favoured by the "grow your own community" as they are quiet, efficient, use low power, and due to high volumes of sales very competitively priced. Beware, there are cheaper less efficient types use a propellor style fan blade and are nothing more than a bathroom type exhaust fan. The more efficient type use a centrifugal impeller like a dust extractor but they do cost more. You should try to install sufficient capacity that targets/aims for 20 room air changes per hour but any number of rom changes is better than none.

  6. #5
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    I would be very interested in a test on a Festool vacuum that has seen some years service, can Bob and Derek arrange that? We hear so many stories of how good they are so does the hype stack up after some years of service?
    CHRIS

  7. #6
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    I was waiting to put this up until I had collected more data on more vacs but seeing as how that is unlikely I will show this now. I'm sorry I did not collect more data about the age and condition of the vacs but my primary aim was to collect efficiency data on Dust collectors and Vacs were tested as a sort of afterthought.

    Here is a summary of the vacs I tested back in 2011/2012. The Vac number tested is shown on the horizontal axis. The vertical axis shows the "efficiency" of the vac at filtering fine dust it takes in across the following micron size ranges.
    0.3-0.5 0.5-0.7 0.7 - 1.0 1-2 2-5 >5
    NB> The >5 micron range does not extend much beyond about 10 microns.

    The test just measures the filtration efficiency for a range or dust particles sizes of what goes in compared that to what comes out the back of the vac. It does not test the ability of the vac to grab the dust at source in the first place. This depends on flow rates and teh actual setup

    Please bear in mind these are SPOT efficiency tests consisting of between 2 and about 10 repeated measurements usually in their "as is" state. In some cases the vacs were subsequently cleaned and serviced and the results are in indicated as such - eg vac #3 is vac #2 (Festool 2Y old) after it has been serviced cleaned and seals replaced.

    Dust efficiency test tests depends on many factors such as humidity, bag cleanliness, how regularly they are services, type of machine being used, type of wood, and the machine operator. The results can vary

    The vacs tested were as follows.
    Screen Shot 2019-02-13 at 5.39.27 am.png
    Screen Shot 2019-02-13 at 5.23.21 am.png
    All the vacs with zero efficiencies made more fine dust than they sucked up. Can you see now why I dislike vacs?

    I draw your attention the vacs 2 & 3 and 4 & 5. 2 & 4 were "as is" 2 and 5 year old Festools. They had leaking seals and leaking bags and filters. The owner was horrified. He then serviced the machine which included replace meant of the filters, and seals. Note how #2 improved significantly but #3 did not improve anywhere near as much as #2. I'm not sure why, slightly twisted body that did not seal is my guess.

    Vac #6 is a Festool straight out of the box - they are indeed fantastic, but like any gear they need to be looked after on a regular basis. #20 is a 6 month old Festool - I know the owner personally and she is a meticulous maintainer of equipment.
    Attached Images Attached Images

  8. #7
    Join Date
    Feb 2016
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    Perth WA Australia
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    Default

    This thread reminds me of a tradie that came to do some flooring at my place. Before he started he setup his festool vac and table saw.

    I thought to myself ahh excellent time to see how efficient festool vacs are at collecting dust as I had been considering getting one for some time. The moment the vac kicked in even before the flooring hit the blade a plume of visible dust came streaming out of it.

    I suspect he hasn't replaced his filters in some time...

    He did an excellent job on the flooring by was definitely glad he was in my driveway and not inside.

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