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Thread: Ducting update.

  1. #91
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    Hi Bob,

    In your experience do you know the trajectory path of dust as its pulled up from the cabinet? Does it follow quite closely the path of the blade? I recall your comment a while back about it spraying like a sprinkler

    The reason why i ask is I wonder the merits of creating a almost inverted zero clearance plate or using the stock blade guard/cutting it shorter and used in conjunction with the overhead guard. My thoughts are this will direct more of the dust towards the dust port and reducing turbulence in the overhead guard Or is this overkill?

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  3. #92
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    Quote Originally Posted by tonzeyd View Post
    Hi Bob,

    In your experience do you know the trajectory path of dust as its pulled up from the cabinet? Does it follow quite closely the path of the blade? I recall your comment a while back about it spraying like a sprinkler
    The fine particles follows air paths and the larger particles follow a straight line trajectory i.e. sprinkler. There's not many larger particles being dragged up out of the cabinet by a blade - it's mostly fine stuff and that scatters/diffuses out and upwards because its usually warmer than shed air.

    One draw back with my current setup is some dust still does escape out the back because the guard is not long enough and/OR not far back enough
    Green arrow behind the blade shows escape path.
    I need to move the whole guard back a bit as shown by the other green arrow.
    It's temping to pout a cover on the back of the guard but that needs to be open to allow for sufficient air to get inside the guard to clear the dust generated at the front of the blade.

    TSguard4.jpg


    The reason why i ask is I wonder the merits of creating a almost inverted zero clearance plate or using the stock blade guard/cutting it shorter and used in conjunction with the overhead guard. My thoughts are this will direct more of the dust towards the dust port and reducing turbulence in the overhead guard Or is this overkill?
    Not sure what you mean with this, maybe draw me a picture of it?

  4. #93
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    Below is a shot of Domau's dust guard.

    I was thinking of adding something that is attached to the riving knife, that will more or less follow the blade like how the stock blade guide does or even using the stock blade guard and chopping the front of it off to where the dust port is.

    My thoughts are that this will capture alot of the spray coming out the back of the blade and direct it forward towards the main overhead guard extraction point.

    Dust Guard.jpg

  5. #94
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    Sorry still not that clear to me.

    Do you mean like an extra long riving knife that extends forward along the top of the blade?
    OR
    A flat plate attached to the riving knife that extends forward along the top of the blade and say 25mm either side of the top of the blade?

  6. #95
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    Found an image on google kind of explaining what I'm thinking of.

    Not quite a flat plate but something like the below that encloses the blade, you could take it to the next level and have the sides lift like the overhead guard does. My logic is to make an area around the blade that most of the air movement is caused by the spinning blade. This will hopefully push the dust forwards towards the end of the guard where it'll get picked up by the overhead guard extraction point.

    Or will the dust just hit the top of the secondary guard and just bounce all over the place
    dust guard 2.png

  7. #96
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    Quote Originally Posted by tonzeyd View Post
    Found an image on google kind of explaining what I'm thinking of.

    Not quite a flat plate but something like the below that encloses the blade, you could take it to the next level and have the sides lift like the overhead guard does. My logic is to make an area around the blade that most of the air movement is caused by the spinning blade. This will hopefully push the dust forwards towards the end of the guard where it'll get picked up by the overhead guard extraction point.

    Or will the dust just hit the top of the secondary guard and just bounce all over the place
    dust guard 2.png
    I'm not sure how that is any different to what most guards are already supposed to do?
    If anything I would be concerned would get in the way of the airflow that is supposed to be coming in from the back of the guard to sweep up all the dust including the one spinning off the blade itself.

    I have posted something like this before for my old TS guard but I thought it might be instructive to see how the new one performs.

    This is what's happening with the direction and strength of the air flow with the TS on, but the DC off.
    IMG_2252.jpg
    The blade is dragging air from the back and back/mid sides of the guard and pushing it out the front and front sides of the guard.
    The cross over pointing the sides between where the air being sucked "in" and being blow "out" is just in front of the blade.

    Now turn the DC on.
    All the flow indicators now move inside the guard.
    The indicators really waggle in the breeze signifying greater much greater air flow
    The most important ones are those at the front of the guard but also look at the ones at the backand see how they are much more they are pulled into the flow
    IMG_2253.jpg

    Here's a couple of close ups of that end/side
    IMG_2255.jpg

    IMG_2257.jpg
    In practice I have the guard further back so it covers more of the blade.

    The flow indicators suggest that no fine dust will escape this hood, but some chips do escape from the back.
    Chips don't worry me too much because dust that can be seen doesn't really hurt you.
    What I might do is just extend the top of the guard further back angled slightly down so it scatters and chips coming off the blade in a forward direction.

  8. #97
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    Thanks for the informative comments.

    That was my intention with the secondary splitter guard, rather than extending the overhead guard adding a slimline blade guard/deflector which captures the chips and directs them forward.

  9. #98
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    Quote Originally Posted by tonzeyd View Post
    Thanks for the informative comments.

    That was my intention with the secondary splitter guard, rather than extending the overhead guard adding a slimline blade guard/deflector which captures the chips and directs them forward.
    I think it would be much easier to extend the top of the guard than add something that blocks air flow and get in the way of trench/slot cuts etc.
    I would have just made the top of the guard longer from the start if I had the polycarbonate to do it. I now have some more pieces so I can add it on.

  10. #99
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    yeah I know its an old thread and I havent finished but BobL page1 #15 you have a great little dust collector on your router... is this still working or (surely) its been updated
    I would love to grow my own food, but I can not find bacon seeds

  11. #100
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    Quote Originally Posted by Tonto View Post
    yeah I know its an old thread and I havent finished but BobL page1 #15 you have a great little dust collector on your router... is this still working or (surely) its been updated
    I'm not a big router user, I maybe use it once a month and every time I go to use it I say to myself "must upgrade the under table dust collection" but it doesn't seem to get much higher on the todo list.
    Last edited by BobL; 24th March 2019 at 08:32 PM.

  12. #101
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    question please BobL...hopefully (for me( the answer is not here but your MDF blast gate what thickness are they?
    I would love to grow my own food, but I can not find bacon seeds

  13. #102
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    Quote Originally Posted by Tonto View Post
    question please BobL...hopefully (for me( the answer is not here but your MDF blast gate what thickness are they?
    All the blast gates except one were made with PVC or Al (not recommended).
    I have made one gate completely out of 3mm (melamine coated on one side) MFD

    I've made a few mixed gates with 3mm MDF/PVC

    One of teh better all MDF gates are these
    Blast gate gallery

    All of these are in the blast gate gallery Blast gate gallery maybe read the whole thread for ideas.

  14. #103
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    I just finished a 1 hour Zoom presentation on dust to Mens Shed WA members.

    One of the demos I presented was the pink wool streamer demo around a TS blade guard see pic below and full details Ducting update.

    The streamers show the air flow around the guard with the blade running, and with and then without the DC running/

    Quote Originally Posted by BobL View Post
    This is what's happening with the direction and strength of the air flow with the TS on, but the DC off.
    IMG_2252.jpg
    anyway I was a bit disappointed in how it worked, although it did work it was not as clear cut as usual.

    I just used the TS to cut some timber and noticed that the OH guard was not sucking that well and then I realised, the OH guard gate was almost completely closed.

    Normally my pressure switch interlock (TS won't start unless suck is present at OH guard and at cabinet) would have picked this up but I had bypassed the pressure switch to be able to perform the demo.

  15. #104
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    Quote Originally Posted by Sawdust Maker View Post
    yeah hard to take a photo of frustration
    This comment wins “Comment of the year”.

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