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When Should I Use Bridges?

Discussion in 'CNC Mills/Routers' started by Scott Thompson, Jul 8, 2021.

  1. Scott Thompson

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    I have been using bridges in all my cutout profiles for fear that an unbridged part will come flying out of my machine and break something. One day I was doing a cutout of a small 4 x 6 inch part and I forgot to use bridges ... nothing happened. The part just sat there with no issues. I then did a cutout of a larger piece (8 x 16 inches) without bridges and the same ... no issues ... hence my question. Do I even need to worry about bridging a part?
    Thanks,
    Scott
     
  2. Alex Chambers

    Alex Chambers Master
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    If the piece is being completely cut out and not held down you should use bridges (AKA tabs) - if it does fly across your shop it could be something important (like your eye) that stops it. If it happens once that's once too often.
    Alex.
     
  3. Rob Taylor

    Rob Taylor Master
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    Sounds like you happened to get lucky with the part size, tool size, cutting direction, etc. I'd use at minimum two tabs on a flat piece to make sure the part can't rotate into the tool if it gets vibrated. They don't need to be big to withstand the forces on finishing ops.
     
    Alex Chambers likes this.
  4. jeffmorris

    jeffmorris Journeyman
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    There is a way of checking to see if you need tabs. For example, I'm making a name sign. After creating toolpaths and inserting tabs in VCrave, I preview the toolpaths to see if I need tabs. If I need them, I put them in. If I don't them, I take them out. In the screenshot, the letters A and B don't need tabs in the holes (?) but the letters D and O need them.
     

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  5. Scott Thompson

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    Thanks for the feedback guys
     

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