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  1. #1
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    Default Mitre Saw Dust Hood or Big Gulp

    Hi everyone
    I have persevered with a home made dust shroud, and recently I have removed it as it is not effective.
    I can purchase purpose made shroud for around $240.00 or get a small dedicated DC with a big gulp accessory that is fixed close to the back of the blade.
    Any suggestions is welcome and appreciated.

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  3. #2
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    Mitre saws are one of the dustiest machines in a shed.
    Some saws are better than others at extracting dust at source using a shop vac but none have built in attachments that capture everything especially if these involve only a vacuum cleaner.

    There are several options for mitre saws dependent on a bunch of things.

    1) To start with I would look closely at where the sawdust coming off the blade impacts the back of the saw. Some saws like Metabos generate sawdust streams that strike slap bang against a Vac port that may be covered with a grille, but most of the sawdust ends up bouncing back at the operator - if you have one of these arrangements completely remove the grill.

    2) If the sawdust stream strikes another part of the saw you may be able to deflect this stream using a suitably shaped deflector towards the vac port or the back of any shroud so that this dust is more easily caputured. The Bosch glide saw really benefits from a deflector that shoots the stream up int the vac port. I use a custom 3D printed deflector but they can also be easily be made out of PVC or wood.

    3) The attachment for a vac may do a fair job at catching chips but they usually fail at capturing the fine dust. If you have a vac port you can help remove the chips use a hose from that port and stuff it down the DC connection - no vac required.


    5) An effective general solution for fine dust capture is a shroud that covers the back of the saw and all the possible angles the saw can be put through,
    To be effective against fine dust escape this requires a pretty beefy DC and the bigger the saw the bigger the shroud, and the bigger the DC required.usng a Bell mouth hood as an attachment to a shroud will help maximise air flow
    There are plenty examples of effective shrouds in the dust forums, Chris Parks and John Samuels are two that I know of.

    A small DC even with a Big Gulp will simply not move enough air to be effective against fine dust - also it needs to be vented outside a shed as they all (eventually) leak.
    A large DC vented outside a shed attached to bell mouth hoods will work.

    If you still have problems, using a combo of 3 and 4 will help. If your DC is too small to make effective use of a shroud - add general ventilation that completely extracts air from the sed.

    I don't have space for my Glide Saw on a bench so I store it on a pump up trolley which makes it difficult to use a shroud. I went to a lot of trouble to fit twin bell mouth hoods connected to my DC and these worked well but I knew that I would simply not use them as I would have had to set them up every time I used it - even for one cut.

    As usually only make a few cuts at a time I just hook up a shop vac and use a chip deflector to assist chip collection AND run a ventilation fan while making the cuts - fine dust levels never get up to anything serious provided I make less than a dozen or so cuts. If I have to do any more than this I wheel it outside.

  4. #3
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    Default

    Thanks Bob,
    I have this saw GCM 12 SDE Sliding Mitre Saw | Bosch Professional

    To be honest it kicks dust in front, sides and back. I have removed the home made shroud which was useless and connected to the factory fitting, also useless. I have a cyclone separator also, a diy one which works ok for the dust it manages to collect.

    I should acknowledge that part of my problem is that I run a Flai blade with a thick kernel, my reasoning is a lot of my work is with 45 angle with the blade leant to the left and I wanted to minimise blade deflection.
    I want to re read your thread again and comprehend your guidance.

    I don't have a lot of room but, I have a large 2 bah Dust extractor which I can pipe to the mitre saw and instal a spare blast gate or persevere with the old Hitachi vacuum.

  5. #4
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    Quote Originally Posted by tomartomau View Post
    Thanks Bob, I have this saw GCM 12 SDE Sliding Mitre Saw | Bosch Professional
    To be honest it kicks dust in front, sides and back. I have removed the home made shroud which was useless and connected to the factory fitting, also useless. I have a cyclone separator also, a diy one which works ok for the dust it manages to collect.
    If its the rubber hood immediately under the dust pick up point, then in my thread on this I discuss the deflector and a different larger shroud which helps but not much on 45 blade tilts.
    SCMS extraction.

    I don't have a lot of room but, I have a large 2 bah Dust extractor which I can pipe to the mitre saw and instal a spare blast gate or persevere with the old Hitachi vacuum.
    I would set up a canopy as per John Samuel or Chris Parks.

  6. #5
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    I did a search for both Chris and John.
    I saw Chris develop a shroud that went around the back of the saw in a concave fashion. I couldn't find John's when I searched I am going to lay some paper out and see where all the dust is settling and using a bit if cardboard to see if and where a a deflector might be useful.

    May I ask you initial thought on this unit as a stand alone for the mitre saw.

    SABER 1200W 50L Dust and Chip Collector SABDC50 | Total Tools

  7. #6
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    Quote Originally Posted by tomartomau View Post
    I did a search for both Chris and John.
    I saw Chris develop a shroud that went around the back of the saw in a concave fashion. I couldn't find John's when I searched I am going to lay some paper out and see where all the dust is settling and using a bit if cardboard to see if and where a a deflector might be useful.

    May I ask you initial thought on this unit as a stand alone for the mitre saw.

    SABER 1200W 50L Dust and Chip Collector SABDC50 | Total Tools
    You'd be better off hooking up your DC. Have you converted it to use 6" ducting ? If not that will make a big difference.

  8. #7
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    No, just the standard 4". I will do a search and see how its done.
    Thanks Bob

  9. #8
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    Quote Originally Posted by tomartomau View Post
    No, just the standard 4". I will do a search and see how its done.
    Thanks Bob
    That is going to be an issue for fine dust collection from most machinery but especially a mitre saw.

    Most DCs can only extract a max of ~425 CFM through 4" ducting,
    If the DC is up for it the same DC can extract about 1250 CFM through 6"

  10. #9
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    Default

    probably really impracticable, but I wonder how hard it would be to get one of those portable style hoods (or make your own) and adapt some sort of "air curtain" at the front, try to trap any dust until it can be moved by a proper dust collector at the rear of the saw.

    i guess the main problem being any dust that doesn't get moved to the rear of the saw also won't make it past the curtain.

  11. #10
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    I have a baby tent from kart, but I haven't done anything with it. I was going to see if I could modify but uncertain as to its effectiveness.

    https://www.kmart.com.au/webapp/wcs/...atalogId=10102

    I have been looking at 150mm pvc and it is around $100 per 6 m length.
    How do I convert the outlets on the machinery to 150mm or do I use a reducer?

  12. #11
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    Quote Originally Posted by tomartomau View Post
    I have a baby tent from kart, but I haven't done anything with it. I was going to see if I could modify but uncertain as to its effectiveness.

    https://www.kmart.com.au/webapp/wcs/...atalogId=10102

    I have been looking at 150mm pvc and it is around $100 per 6 m length.
    Wow! its really gone up in price.
    Just 12 months ago I got 6m for ~$50
    was that DWV or stormwater, I think you will find that latter is cheaper
    I got mine from here.
    PVC PIPE - STORMWATER PIPE - Pipe Online - Retic Fittings , Plumbing Fittings, Reticulation Supplies supplied Australia wide
    They have it for $78.

    That mob have have agents in other states that might be able to supply

    How do I convert the outlets on the machinery to 150mm or do I use a reducer?
    Look here Improving machine cabinet dust ports

  13. #12
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    Default

    Thanks Bob.

  14. #13
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    My cabinet for the SCMS works very well. It's connected to a ClearVue Max so there's plenty of grunt to support its efficiency. Rather than angling side walls towards the centre, I ended up opting for parallel sides so the Plan View is not exactly accurate.

    SCMS Cabinet Wings.jpg Rear view of cabinet.jpg SCMS Elevation.jpg

    SCMS Cabinet - Plan View.jpg Candle test outside cabinet.jpg

    mick

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