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  1. #1
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    Default Space for Hafco DC 7

    Hi guys,
    As mentioned on another thread I am looking to buy a Hafco DC7 this week.
    I will then have to get a new power line run out to the shed to actually use it.

    I have a single car garage shed with a carport at the front. We hope to be able to move somewhere else within a few short years. The sooner the better in fact. It is already workshop tetris every time I want to do work.
    I roll the assembly table out into the car port to work unless it is just a quick session.
    I also roll the air compressor out into the car port when I use it.
    I roll the jointer half way out. This is because the carport floor is not flat so I can't really have the jointer out there.
    The SCMS is also on wheels but I'm yet to roll that outside even though it makes plenty of dust.
    The thicknesser and router will be in a table which also gets rolled outside most of the time.

    This is mostly to reduce dust risk but it is also more pleasant working outside under the carport anyway.

    I could buy a 2hp dusty like others have but it seems to me that the biggest cost will be in the ducting and housing it, so the extra cost of a 3hp dusty is not so much.
    Also BobL advises that the 2hp dusty can be made to work but is not ideal. Hence I figure I'll go with the DC 7.

    The drawback is that the dusty is going to be in the way. To be honest it is going to be a struggle to get the shed door closed if I add this DC7 into the floor space.

    I believe he shed is clad in asbestos, so modifying it to have the dusty outside is not so simple. I think I might be able to do it through the eves. Maybe. Or more likely through the back window. Then I need to build a lean to which has all kinds of set back issues. Plus we don't want to spend a lot because we would prefer to move. I'm trying to devise a plan for some sort of housing for it. Might have to 'bend' a few bylaws. (More like savagely deform a few bylaws to be honest).

    So while I'll grapple with those issues, initially I'll have the dusty in the carport. So I'll roll it out of the shed into the carport every time I want to do anything. This is far from ideal because although it will be out of the shed, it will not be far enough away from the entrance. I can move it so that it is not right in front of the shed door but basically it's too close to the door to be a long term solution. Some of the dust is going to waft back. Plus there is the issue of the dusty needing to move just so I can get into the shed. That is going to be a major annoyance.

    Anyway for me, it's all about incremental improvements. So a dusty in the carport is better than no dusty at all.

    I suppose I could view this machine being in the way, as an incentive to make sure I develop a better solution rather than have it rolling out to the carport for too long.

    My question is, should I go for a smaller dusty than the DC 7 to save some real estate until I have more space?

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  3. #2
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    Default

    Hi Dave,

    Yes you're correct that having a dusty is better than no dusty. However a moving dusty is also not a very good dusty, as the more you move it the most chances it'll develop a leak. However going back to the initial point of having a dusty is better than having no dusty.

    Before i ran my dust extractor ducting i was in a similar situation to yourself, every time I needed to do something required me spending atleast 30 minutes to shuffle the shed around before i could get to what I wanted to do, the end result was me cutting corners and doing things in a not very safe manner. So even though I had a dusty i hardly used it.

    My point is if you don't have the space for a large dusty don't get a large dusty, a modified 2hp unit is adequate for a small setup. I'm assuming since you don't have a dusty you havent bothered opening up your dust ports on your machinery. I'd probably be inclined to devote time to that before being concerned about how big your dusty is.

  4. #3
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    Have you got a "personal door" or window opposite the main opening to the garage?

    If so then, given its only a 1 car garage, that you can operate most of your big machines outside, that your'e in Brissy, that you're moving in a few years, and the large effort and expense needed to install 6" ducting etc, I would just upgrade shed ventilation rather the DC.
    Leave the main car entry open and place a large fan in a doorway or window would do more for fine dust than any medium size DC.

  5. #4
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    Quote Originally Posted by BobL View Post
    Have you got a "personal door" or window opposite the main opening to the garage?

    If so then, given its only a 1 car garage, that you can operate most of your big machines outside, that your'e in Brissy, that you're moving in a few years, and the large effort and expense needed to install 6" ducting etc, I would just upgrade shed ventilation rather the DC.
    Leave the main car entry open and place a large fan in a doorway or window would do more for fine dust than any medium size DC.
    Thanks.
    Each wall has a window including the wall with the big door. Some parts of the windows are permanently open. It's never sealed in there. I'm not inclined to fix those windows because it's more pleasant with its permanent ventilation.
    With a bit of creative thinking I could open up the window structure on the wall opposite the door to ensure a better flow.

    I always open the door way. Partly this is because I have to open it up to work in the space. Partly because of your education on dust issues and partly because it is just more pleasant in the Brisbane climate.

    Which way should the fan be blowing air? Out the front door?

    I could get one of those big powerful fans and site it in front of the back window to suck clean air in and direct it to the front. That would also make it a more pleasant environment. I could even add a second one or a blower to sit in the doorway to keep the air moving on out of the shed.

    The SCMS is in front of a side window. I could modify that to allow more of the dust to blow out and down. Plus use the shop vac. I sweep the floor dust around that side of the shed anyway.

    The table saw would remain an issue.

    I have bought a wheel kit for the bandsaw. I could wheel that to the entrance when in use.

    I want to get some small sanding machines but these could also be used on the table in the car port.

    One great thing about working in carport is that there is basically no clean up.

    We really would prefer to work towards moving than spend more on this place.

    How does that sound?

    Sent from my SM-G935F using Tapatalk
    My YouTube channel: https://youtu.be/2_KPRN6I9SE

  6. #5
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    Quote Originally Posted by DaveVman View Post
    Which way should the fan be blowing air? Out the front door?
    It depends how much fan grunt you have.

    For a smaller fan and/or large space, a fan works better sucking dust out and letting fresh air come into other openings.

    If you blow fresh air in it mixes with the dust and you end up stirring up the dust more than necessary and venting times are slower.

    If you have a large fan or fans, and/or a small space, fan direction doesn't matter as you will pump so much air through the stirred up dust will be stripped straight of of the shed.

    If you have enough fan grunt wouldn't worry about leaving the TS inside the shed.

    BTW fans are much easier to take with you, ducting etc consumes a lot of time not only to install but also to break it down and put it up again.

  7. #6
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    For about 4 months of the year, I'd like nothing better than a roaring gale running through the shed. So perhaps I should aim for that approach.

    As you say, fans are so much easier to move.

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  8. #7
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    I have been thinking about this fan idea a bit further. I suspect that I might need a fairly significant airflow through the shed for this to be effective.
    How many m/s minimum at the exit should I be aiming for?


  9. #8
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    Quote Originally Posted by BobL View Post
    It depends how much fan grunt you have.

    For a smaller fan and/or large space, a fan works better sucking dust out and letting fresh air come into other openings.

    If you blow fresh air in it mixes with the dust and you end up stirring up the dust more than necessary and venting times are slower.

    If you have a large fan or fans, and/or a small space, fan direction doesn't matter as you will pump so much air through the stirred up dust will be stripped straight of of the shed.

    If you have enough fan grunt wouldn't worry about leaving the TS inside the shed.

    BTW fans are much easier to take with you, ducting etc consumes a lot of time not only to install but also to break it down and put it up again.
    Hi Bob,

    What do you define as a large fan?
    I recall you mention something about squirrel cage fans in the previous posts but they're pretty much impossible to find.

    Do the Industrial ventilators count as a large fan? eg

    https://www.bunnings.com.au/dynabree...n-fan_p4440782

    or

    this?

    https://www.bunnings.com.au/dynabree...m-fan_p4440781

  10. #9
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    Quote Originally Posted by DaveVman View Post
    I have been thinking about this fan idea a bit further. I suspect that I might need a fairly significant airflow through the shed for this to be effective.
    How many m/s minimum at the exit should I be aiming for?
    Air speed is relevant for ducting if you want to hold large chips suspended inside the duct, but not that relevant for ventilation where all you want to remove from the air is the fine dust which stays suspended in air for many minutes.

    What really matters is the CFM.

    Measuring the air speed of fan air is fraught with problems - it's much better to measure the air speed at vents in/out of the shed
    0.5 m/s through a 1m x 1m window is 0.5 cubic m/s, or 1060 CFM.
    For a 6 x4 x 2.7m shed that will in theory be vented every two minutes, in practice it will be about twice that or 15 shed changes per hour.

    The amount of ventilation depends on what you are doing, if you have a DC and how effective it is, also the degree of cross flow available.
    If you don't use a DC at all and are relying on ventilation I would be looking at about 30 room air changes per hour.

    Tonzeyd, A large fan is one that can produce >~20 room air changes per hour.

    In this thread M&J and I discusses ventilation and dust measurements and you will see how significant it is in fine dust control.
    Dust Concentration Measurements

    I advocate using squirrel cage fans for ventilation instead of DC because they are quiet and use relatively little power and axial fans make a bit too much noise for my liking.

    Aside from my DC I have up to 2800 CFM of ventilation in my shed venting the shed at roofline level. This gives me up to 15 room air changes per hour but usually I vent at 2/3rd speed so I get about 10 room changes per hour.

  11. #10
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    I am guessing my shed is less than 100m3. A fan that pushes 1m3/sec would in a perfect world change the air about 40 times an hour. I expect I'll need a pedestal blowing at one end and an axial sucking at the other. Even then with eddies etc it would be a lot less but I would be changing the air many times an hour.

    I wonder if I should also get a dusty with flex hoses to help reduce the dust lying around and getting into the air in the first place. Not an ideal setup but more just a step in the right direction.

    Sent from my SM-G935F using Tapatalk
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  12. #11
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    Quote Originally Posted by DaveVman View Post
    I am guessing my shed is less than 100m3. A fan that pushes 1m3/sec
    It matters little what the fan pushes/pulls - it's what goes through the vents in the shed that counts.
    Then you know its real air movement.
    The means locating the fan not freestanding just in the middle of an open doorway or large opening, but making sure it its inside a close fitting housing so that it does not just recirculate the air around itself which is what most free standing fans do - they also stir up dust inside but remove very little dust from the shed.

    Fill in one of your openings with a sheet of ply or MDF or for extra light made a frame holding some translucent/transparent plastic sheeting and cut out a hole to fit the exact fan you are going to use and install the fan blades so the tips are within a few mm of the edges of the hole.
    For added directionality, line the hole with some sheet metal to make a tube 200 - 300 mm long.

    That's another reason why (unless the fan is a howler) sucking out is better than blowing in.

    I wonder if I should also get a dusty with flex hoses to help reduce the dust lying around and getting into the air in the first place. Not an ideal setup but more just a step in the right direction.
    Sure even if it just picks up the chips.

  13. #12
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    Quote Originally Posted by DaveVman View Post
    Hi guys,
    As mentioned on another thread I am looking to buy a Hafco DC7 this week.
    Better get in there by Saturday. They've got their annual sale on now.

    I just drove home from there and found a BP-355 bandsaw in my trailer... I must've accidentally bought it.

    As I was walking out, I accidentally bought a Scheppach bobbin sander too.

    It just happened. Honest!

  14. #13
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    Quote Originally Posted by muzza View Post
    I just drove home from there and found a BP-355 bandsaw in my trailer... I must've accidentally bought it.

    As I was walking out, I accidentally bought a Scheppach bobbin sander too.

    It just happened. Honest!
    Now there is a bloke who has forgotten that he bought some raffle tickets. Just boast about your good luck to SWMBO when you get home, saves a lot of dramas and explanations!

    Alan...

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