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  1. #136
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    You are right, Tonto. A good cyclone is the bee's knees. I have a Clearvue 1800 that works very well, but it has a (I think) 3.3kW motor running at 60 Hz, and nothing smaller will do. Such a set up is great, but does not come cheap. BobL set about to optimise the performance of a common 2 HP dusty and to thus put reasonable (not great, but reasonable) dust collection within reach of most woodworkers. He did a great job. I love the work he has done and even though I run a cyclone I still follow this thread.

    One word of advice that BobL gave me as I was setting up my system was that the greatest restriction to the flow of air was nearly always the woodworking machines themselves ... their ports and guards. He was dead right. I measured the flow of air through my machines and confirmed BobL's statement. So, I spent a fair bit of time and effort modifying ports etc to maximise airflow. It worked very well. No dust collection system is perfect, but thanks to the Clearvue and BobL's guidance, mine is very good.

    EDIT: Here is a link to my port upgrades.
    Making 150mm DC ports for workshop machines

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  3. #137
    Join Date
    Feb 2006
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    Perth
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    The art of dust extraction - or trawling through the entrails

    For most woodworkers, controlling wood dust is a second, third or no rate issue.
    This is evidenced by the way most wood workers approach dust collection.
    Relatively little thought is given to the problem and they think it can be solved with a single magic bullet - like a bigger dust extractor.

    If only it was that simple.

    The most efficient way to control wood dust is to grab it right where its made because once it escapes into the shed its a right bugger to get rid of it.
    This means as big an air flow as you can manage at the source.
    The flow depends on 3 things, the extractor, the ducting and as JS say, the air flow through the machines themselves.

    With the extractor, apart from cost, the first hurdle is electrical power requirements. Some DIY don't even have 15A socket for use wth a 3HP DC.
    The next hurdle is the ducting, I know I have said this many times but 6" ducting is a minimum to carry enough air to control dust from bigger machines.
    Because most machines use 4" ports they have less air flow so to collect the chips the manufactures close down the gaps around the machines to increase the air speed and while this picks up the chips it leaves the fine dust behind. A 6" port and more gaps around the machine make a big difference. 6" ports are not always possible (e.g. BS) so multiple ports may be needed. Remember it takes 3 x 4" posts to carry the same air as 1 x 6" port.

    One aspect that is rarely referred to is, unless you have an automated system, to remember to turn on the DC and to have the gates set to actually extract the dust.
    It's inevitable that you will forget and some dust will escape into the shed so ventilation of some form or other is your friend. Yes you can use the extractor but that's noisy and expensive to run so a low power fan can be very efficient and quiet at the same time.

  4. #138
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    Quote Originally Posted by BobL View Post

    The most efficient way to control wood dust is to grab it right where its made because once it escapes into the shed its a right bugger to get rid of it.
    This IS the magik. Six inch lines ... high enough air flow ... ports/airflow through the machine that allow great capture at the source.

  5. #139
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    Sep 2005
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    Perth
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    52
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    143

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    Gday All

    Its been a long time coming but I finally got around to modifying my 2hp dusty. All I need now is to get some 6" pipe to be able to make the inlet to the impeller and complete the ducting.

    Legin
    Attached Images Attached Images

  6. #140
    Join Date
    Dec 2014
    Location
    Adelaide
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    BobL, first of all, thank you for the time and patience in explaining (and re-explaining!) the concepts of good dust collection. I believe i have a sound understanding now of what is needed to set up a decent dust collection system in my new workshop. I am moving house mid year and am lucky enough to have a dedicated workshop of 4.9 x 5.4m with rollerdoor access to the driveway. My current workshop is about 4 x 4.8m which is shared with lawn mowers / paint etc, and the only dust extraction is a shop vac with mini cyclone.
    I recently picked up for $100 a 1HP Ledacraft DC with a 4" inlet which i have hooked up to my table saw at present - i know now that this is only going to pick up bigger chips and leave the harmful finer dust behind ( i do get headaches after cutting a lot of wood). The bonus though of the buy was a 2HP Ledacraft motor and impeller combo that came with the purchase. I could set up my new DC with this motor / fan and spend $200 - 300 on a new drum / bags and rig up supports. Of course i would enlarge the ports on the machines with bell mouth and run 6"ducting.

    On the other hand, i could sell both units and buy something that would do a better job - so that is where my question is headed... For a workshop of my size, and only ever using one machine at a time with 6"ducting, where is the line where a bigger motor is not going to give me better performance? And if i am going to upgrade from a generic 2HP DC is it pointless going to 3HP generic if mods still need to be made, or should i go for better quality if funds allow (ie a 2 stage cyclone like a clearvue).

    What advice i guess i am after, is what is the best setup i can put into my workshop that is not overkill for running 6"lines and only running one machine at a time? Obviously if i mod my 2HP unit performance would be ok, but not great, but then on the other hand an industrial unit that could run multiple lines at the same time would be overkill. I am confused about which way to go!!

    Also, could people point me to a thread that could help me out with workshop layout combing best location for DC and ducting?

    Thanks in advance !

    Cheers, Sandy

  7. #141
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    Quote Originally Posted by Sandy Taylor View Post
    - so that is where my question is headed... For a workshop of my size, and only ever using one machine at a time with 6"ducting, where is the line where a bigger motor is not going to give me better performance?
    Unfortunately there is no hard and fast line.
    Performance will degrade along a more or less smooth continuum - its up to you to determine your total risk based NOT just on the performance of the DC.
    Factors that come into play include, size of shed, how long you spend in a shed, what you do in the shed, what machines you use, natural ventilation etc.

    The easiest KPI to understand is 1000 CFM at the source (this takes into account Ducting size-length-junctions, machine ports and breathability)
    You need to be aware that 1000 CFM is just a nominal figure. It covers almost all DIY machines but, for example, it will not be anywhere near enough for a 1m wide twin drum sander.

    A modified 2HP will simply not draw 1000 CFM.
    The only reason I modified the 2HP DC was to see what could be done with a DC on a 10A power socket since this often restricts the choice of DC for many DIY.
    A modified 2HP DC with a clean pleated filter moves around 925 CFM and its ALL downhill from there as ducting, flexies and junctions are added and this is even before the machines are added
    This then sort of answers your other question.

    A 3HP DC with a full 6" ducting over short runs (<6m) and minimal junctions MAY be able to meet KPI.
    If it has full 6" ducting it should be able to generates about 1250 CFM and once again its ALL downhill from there as ducting, flexies Yadda- Yadda ar added.

    If you have ducting runs longer than 6m you should be prepared to accept less than 1000 CFM, and in some cases that much may not even be needed.
    For a small sander 500 CFM may be more than enough so put that on the end of your line rather than the beginning.
    If you are not prepared to accept anything less than 1000 CFM then you will need a 4 or 5 HP with 15 or 16" impeller.


    could people point me to a thread that could help me out with workshop layout combing best location for DC and ducting?
    There is no thread I can recall but here are some ideas.

    1) Best location for a DC is either outside your shed diametrically opposite your largest air intake (door window) OR enclosed inside the shed in an air tight enclosure that is vented outside the shed.
    This is THE single most important thing you can do for any DC setup.

    2) Try to get all your machines connected directly to a single (straight) trunk line. Avoid daisy chaining the ducting for machinery together as this leads to longer ducting runs with more bends.
    It may cost you a bit more in ducting but this reduces the number of blast gates needed and then the eventual operational need of two switching more than 2 gates when using different machines.

    3) Connect to the trunk line using a Y + 45º junction. Install spare junctions and just block them off if not required

    4) Blast gates should be attached to the Y junction into the trunk line NOT down near machine. If your ducting is too high to reach gates use a rocker style gate.

    5) Use as much hard PVC as possible and as least flexy as possible.

    6) Connect to machines and make junctions using as shallow an angle of ducting as possible. Use as large a radius of curvature as is practicable for ducting bends

    7) There is no need to gaffer tape connections as the air loss from tight fitting PVC junctions is miniscule.

    I hope that helps.

  8. #142
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    Jan 2014
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    Sydney Upper North Shore
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    What could cause a dusty motor rated at 240V, 7.7A, 2HP to draw 2.8A.?

  9. #143
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    The rating on the motor plate gives the maximum power rating of the motor, the current drawn is the actual power being used by the motor. The more restricted is the air flow the lower the current. For your current configuration you could use a 1HP motor.

    Your motor is only putting out 0.9HP so that should indicate to you the condition of the system, that is the restriction on the system of the ducting size, the number of bends, the filter/cyclone etc.

    If you remove the ducting from the fan intake and exhaust you should see the current shoot up to the max that the fan can use.

  10. #144
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    Quote Originally Posted by Bohdan View Post
    If you remove the ducting from the fan intake and exhaust you should see the current shoot up to the max that the fan can use.
    As Bohdan said.

    It seems counter-intuitive but the more your blower is choked the less power it uses. You would think it would be the other way around, but since it is pushing LESS air it uses LESS power.6" ducting, sufficient flow through the machine cabinet, a separation system that does not choke the blower and flow will increase, and power consumption along with it.

    CHeers

    Doug
    I got sick of sitting around doing nothing - so I took up meditation.

  11. #145
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    Quote Originally Posted by Lappa View Post
    What could cause a dusty motor rated at 240V, 7.7A, 2HP to draw 2.8A.?
    I would only expect that motor to get near those those currents when it's inlet was fully blocked.

    I have tested mine when it was fully sealed and it was something like like about 4.5A, so 2.8A seems low.

    If it is fully open then the only thing I can think of is it may have the start and run coils wired the wrong way around?

  12. #146
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    Mar 2015
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    Melbourne, Vic, Australia
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    In fact, if drawing 2.8 amps the motor is only putting out about 0.76 hp as the motor is probably only about 85% efficient.

  13. #147
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    My standard, unmodified, Carbatec 2HP unit was drawing 3.8 amps with no ducting connected (just the 4" port open to the impeller) before I got rid of it for the Clearvue.

  14. #148
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    After a series of ammeter measurements on my "2HP" dusty, I would suggest if buying one, you take a measurement lead and an ammeter and have a test run.
    These are my figures with a system that has approx. 7 meters of 6" PCV including 2 x 90 degrees and one 45 degree. There is also 2 metres of 160mm flexy to the table saw and a pleated filter. The dusty has a 5" inlet and a 5" outlet which I am currently changing so I will do more testing but don't expect much improvement re the total system.

    - Average CFM in the long PCV run in the ceiling is approx 440-460CFM. This is over a series of tests done on different days, weather conditions and vertical and horizontal readings.

    - all connected to table saw - 2.76A
    - table saw disconnected. - 2.78A
    - same but with pipe to filter disconnected - 3.30A
    - same but with ducting removed from inlet of impellor - 3.36A
    - front off ie. naked impellor - 4.05 A
    - plastic outlet off housing so large rectangular outlet is exposed - 4.55A

    I know the pipes are long but the motor unit itself is Bloody woeful in my opinion. If I'd bought it new instead of getting it cheap, I'd be demanding a refund.

  15. #149
    Join Date
    Nov 2013
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    Caboolture QLD AU
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    Thanks for these detailed results.

    Assuming the filter is not compromised from age and cleaning etc. A few thing really stand out, like the difference with the filter disconnected, it looks like the DC also has a bad fan curve and flow rate is dropping off really quickly under load (flow restriction). As you say, that 5" restriction is also contributing to the problem.

    IMHO it reinforces why we really need a minimum of 3HP just to overcome ducting, connections and port restrictions in order to get a half decent flow rate required to collect finer dust. But I find that even 3HP leaves me little flowrate headroom needed to overcome dirty filter restriction, which starts to appear in a very short time in my case, so it's monthly filter cleaning for me until I can get or build a 4 or 5hp cyclone.

    Please keep the info and data coming, it really is useful and interesting data to have for reference.
    Last edited by MandJ; 3rd February 2017 at 02:34 PM. Reason: Wording.

  16. #150
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    Dec 2014
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    Adelaide
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    Quote Originally Posted by BobL View Post
    1) Best location for a DC is either outside your shed diametrically opposite your largest air intake (door window) OR enclosed inside the shed in an air tight enclosure that is vented outside the shed.
    This is THE single most important thing you can do for any DC setup.

    2) Try to get all your machines connected directly to a single (straight) trunk line. Avoid daisy chaining the ducting for machinery together as this leads to longer ducting runs with more bends.
    It may cost you a bit more in ducting but this reduces the number of blast gates needed and then the eventual operational need of two switching more than 2 gates when using different machines.

    3) Connect to the trunk line using a Y + 45º junction. Install spare junctions and just block them off if not required

    4) Blast gates should be attached to the Y junction into the trunk line NOT down near machine. If your ducting is too high to reach gates use a rocker style gate.

    5) Use as much hard PVC as possible and as least flexy as possible.

    6) Connect to machines and make junctions using as shallow an angle of ducting as possible. Use as large a radius of curvature as is practicable for ducting bends

    7) There is no need to gaffer tape connections as the air loss from tight fitting PVC junctions is miniscule.

    I hope that helps.
    Thanks Bob, that helps a lot. I'm leaning to a bigger unit like the CV 1800 for a few reasons. First of all, this is a long term investment, and i want to be able to add to my workshop, so i want the reserves in CFM for this. Also, the brick workshop is built on the boundary and has a hobby room joined to it with a stud wall, so getting the DC outside may be a problem. I was thinking of having the cyclone and motor inside the shed, with it venting out of the roof. Would i still need to enclose the cyclone if i was to do this, or are they pretty well leak free if constructed well? I have started to layout the workshop on sketchup, so if people dont mind, i might post a picture for people to comment on my setup - any help will be greatly appreciated!

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