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  1. #16
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    Quote Originally Posted by QC Inspector View Post
    Would you let us know what they decide to do? I'm curious to know if the follow all or some of your recommendations or just leave their sheds as is.

    Pete
    I've consulted in person to about two dozen different mens' shed in the last few years but I only go back to see what they have implemented if I am asked to sort out follow up problems. Most sheds have smart enough members to make good use of just a single visit by yours truly and even though I have not always been back I believe by and large they implement the majority of recommendations.

    Rockingham Mens Shed is a case where I revisited to sort out a VFD problem and saw they fully implement my recommendations and did a great job - very neat and tidy and well thought through.

    Not all sheds are after a complete (re)design - one shed already had 100mm ducting everywhere and large roller doors under verandas so they could keep them open even when it rained They also did all their sanding under these verandas with operators wearing masks. All they wanted advice on was where to locate large ventilation fans inside the shed.

    In contrast there was one small shed I visited 4 times! over about a year (and each time repeated the same recommendations) and I believe they have still to do anything.

    It also depends on who does the work. In one instance the shed sent the ducting job out for quotes and all the duct installation companies talked the shed into downsizing to 100 mm ducting (its cheaper and the the shed doesn't need to modify machinery!). Interestingly this shed has asked me back because they still have problems.

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  3. #17
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    Revisited another mens shed this morning to advise on a lingering fine dust problem.
    A thin layer of fFine dust settling out over everything.

    Smallish shed surrounded by inner suburban housing - about 15 members present.
    I visited this shed mid last last year and made the following recommendations.

    Clearvue Max DC with VFD.
    DC outside in an acoustic damping enclosure
    Rocker Gates with pull cord actions
    9" trunk lines with 6" drop downs.
    Machines opened up to 6"

    The first 3 recommendations were carried out really well - great job - one of the best I've seem.
    The fourth recommendation was only carried out for a couple of machines, the rest were still connected to 100 mm ports and it was obviously the main source of the problem.
    They also had no OH dust collection on their Sawstop.

    This all happened because the bloke I spoke to initially was not the bloke who ended up doing most of work who was away at the time.

    Speaking directly to the bloke who is going to do the machine upgrades indicated he's very competent and I'm confident he will do a good.

    No dust measurements unfortunately - my USB battery for my Particle counter was flat and I did not have the charge cable with me.

  4. #18
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    Today I while shopping a bought some pork belly. Haven't had it for ages and SWMBO Decides to try the crispy skin version of the recipe which involves 40 minutes at around 250C and then its turned right down for a long slow cook.

    20 minutes or so into the Hi Temp stage I hear from my study that SWMBO has cranked up the kitchen exhaust fan and I can smell a sort of faint burning smell. A few minutes later the smoke alarm goes off and I look up to see the particle counters in the study are registering PM2.5 in the high 100s µg/m^3 (above 50 is not good). I head off for the kitchen with a particle counter and can see a blue haze as I walk down the passage. There was nothing on fire in the kitchen, just a torrent of smoke pouring out of the open oven and SWMBO standing there, gasping for air. The PM2.5 is >2000 µg/m^3 ! I cranked the exhaust fan into HI and opened the doors a windows and that cleared the visible smoke away quickly but the PM2.5 was still around 1200 µg/m^3

    Now some 20 minutes later the air in the kitchen is 750 µg/m^3 while in the study (4 rooms way) its 545 µg/m^3

    BTW the pork belly skin now looks really good!

  5. #19
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    The sacrifices one has to suffer through to eat a good meal.
    Hint. Do the first part of the cooking on the barbecue. Then take it into the kitchen for the second part of the cook.

    How did it taste?

    Pete

  6. #20
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    Quote Originally Posted by QC Inspector View Post
    The sacrifices one has to suffer through to eat a good meal.
    Hint. Do the first part of the cooking on the barbecue. Then take it into the kitchen for the second part of the cook.
    Good idea - although that will mean I will need to fix the BBQ.

    How did it taste?
    DELICIOUS!

  7. #21
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    I'm gaining more confidence in using my particle counters in more dusty situations. The manufacturers advice is that using them continuously in dusty environments will permanently damage them. Insertion directly for even a few seconds into a stream of visible saw dust will do likewise so I have learned how far away I can locate the counters to be safe from this problem. I now have a counter running all the time on one of my benches and keep an eye on it when doing a dusty activity.

    Yesterday I decided to clean up my 150mm x 2m belt sander. This sander stupidly has the motor's fan sucking in cooling air right next to the end of the belt such that it competes for air/dust with the nearby main BMH and so some sawdust escapes collection. There is a second DC collection duct directly above the motor but it doesn't not collect all the escaped dust and what I really meed to to is fully enclose the motor with an outlet direct into the second duct.

    The result is sawdust eventually builds up in corners around the base of the motor and belt sander. Cleaning usually involves vacuuming up this dust but yesterday I decided to use the Compressor to see what levels the dust reached and then run the ventilation fans to see what happened. The particle counter was located about 2m away from the belt sander during this exercise and was reading 7µg/m^3, outside the shed was 5µg/m^3

    So with the DC collecting from the belt sander (~800 CFM), ~3 x 3s blasts of compressed air successfully dislodged the dust and sent the dust flying so there was a visible fog inside the whole shed. The dust levels as measured by the nearby particle counter quickly rose to ~50 µg/m^3 (long term this considered unhealthy for seniors and kids or persons with health conditions).

    Then I started the 1200 CFM ventilation and within 3 minutes the levels were <20µg/m^3 and 10 minutes later it was back to 7µg/m^3.

    I'm awaiting a few parts for my DOP (Dispersed Oil Particle) generator and then I will be able to do some higher concentration dust measurements without damaging the detector. The type of oil used in this machine only generates very fine particles and if any oil does get lodged inside the detector It's volatile enough to eventually evaporate from the detector.
    Last edited by BobL; 19th September 2020 at 03:00 PM.

  8. #22
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    Today I had to sand a both sides of 600 x 900mm veneered piece of chip board and decided to use the Ozito ROS connected to the DC by a 50 mm flex.

    Immediately before I started the shed dust background was around the 1µg/m^3 for PM10 concentration even though I had been using the bandsaw and the belt sander for a total of about 20 minutes earlier that morning - with DC running of course.

    The sanding process took about 3 minutes on each side.
    The highest the PM10 got to was 6 µg/m^3 and 2 minutes after I stopped sanding was as shown here.
    0.0 is the PM1.0, 0.3 is the PM2.5 and 1.3 is the PM10 ie basically back to shed background.

    The most difficult bit is finding suitable adapters to hook the sander to the DC - to achieve this I keep a section of rubber adapters and white PVD screw type fittings available at most large hardware stores.

    ROSsanding.jpg

  9. #23
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    Did another mens shed dust consult recently. It was country shed I visited about 5 years ago and there were only 3 members present at the first visit and none of those were present at this visit. It was also at a different location as a few years back they moved into a new shed.

    On my first visit they were only just getting started in a makeshift shed and I made the usual recommendations, ClearVue MAX, 6" ducting, opening up machine ports etc.
    Apart from the ClearVue CVMAX I was not sure what else they implement in their first shed but the Clearview was the only thing thing they had implemented in their new shed and this had major problems..

    Apart from a ~3m run of 6" ducting from the Clearvue into the shed, all of the other ducting was 4" with lots of flexy (especially lots of 2" flexy for small machines) all tight radius blends and those awful 4" black ABS plastic gates,.
    They had two large pedestal axial fans they were using to try and direct dust towards a large roller door but it just looked like they were doing a good job of distributed the fine dust all over the shed.

    The most concerning thing was the Clearview installation. It was located outside the shed () but the 200L collection drum was not sealed so the cyclone was not separating out the large dust. They were not at all concerned about sealing teh drum because they had gerry rigged a second dust catcher. The impeller exhaust consisted of two 4" diameter 5ft long sections of flexy connected to a 1000L IBC shuttle container on a wooden stand about 4ft off the ground. (These containers are widely used rectangular made of HDPE and reinforced on the outside with a steel frame). The top of the container had 3 holes cut in it (2 for the flexies) and one for a truck air filter mounted on top. There was sawdust everywhere over the ground around this setup.

    I tried to be diplomatic about things and they were surprised when I told them they needed to seal the 200l drum and they could then ditch the other container and teh 2 bits of flex coming out of the outlet. They don't even need a muffler as that side of their shed faces open paddocks of farmland. The chap "in charge" of their dust collection system who had installed the second dust catcher seemed a bit crest fallen but seemed to recognise the problems once I had explained it to him.

    I did a few dust measurements around the shed but the dust levels weren't that high as there were not many members present and only a couple making small amounts of dust. There was one member turning a dry jarrah bowl blank and I showed him the dust levels reaching 70 µg/m^3 in about 30 s of turning 1m from the lathe.

  10. #24
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    Thanks for keeping this thread going, Bob. Some of us do not have dust meters so I cannot do your version of crispy skin pork belly - it sounds delicious. Just wait for Blumenthal to poach your intellectual property. "Put in preheated oven at 250 degrees until particle count reaches 2,000 ...."

    Over ten years ago someone, probably you, suggested wandering into the shed late at night and shining a torch around. The suspended dust particles are then highly visible. These are the nasties that are essentially invisible in daylight. I still do this occasionally to remind myself to be careful. Or I forgot something.

  11. #25
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    Quote Originally Posted by GraemeCook View Post
    Thanks for keeping this thread going, Bob. Some of us do not have dust meters so I cannot do your version of crispy skin pork belly - it sounds delicious. Just wait for Blumenthal to poach your intellectual property. "Put in preheated oven at 250 degrees until particle count reaches 2,000 ...."Over ten years ago someone, probably you, suggested wandering into the shed late at night and shining a torch around. The suspended dust particles are then highly visible. These are the nasties that are essentially invisible in daylight. I still do this occasionally to remind myself to be careful. Or I forgot something.
    It depends when the dust was made - if it was in teh morning chances are that most of it has settled out by then. fine dust (0.3 to 0.5 microns) has a "half residence time" (the time taken for half teh dust to settle out of the air of about 30 minutes.This means after 30 minutes half will be left - after 60 minutes ~25% will be left - after 90 minutes 12.5% will be left etc.By next morning or ~10 hours there will be less than 0.1% leftThis assumes the air i of course dead still during all this time.

  12. #26
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    Thanks, Bob, but I am more an owl than a rooster. I rarely do work in the morning, only.

    It always amazes me as to how little fine dust needs to be in the air for it to be highly visible in the beam of torch light.

    I used to think that dust collection was about house keeping of the course visible dust, until I read Bill Pentz and then your writings.

    Eternal vigilance and occasional reminders assist me.

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