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Thread: upcut or downcut for HDU

  1. #1
    Join Date
    Jun 2018
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    Pennsauken, NJ
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    32

    Question upcut or downcut for HDU

    So, for cutting out letters (usually in 20 lb material) and also the release cuts on finished signs - upcut or downcut when cutting HDU? When I cut aluminum I use an upcut Amana single flute bit to get the chips out of the way. But with HDU, does it really matter? I'm not talking about 3D carving, just cutting out letters. How about for PVC in thickness from 1/4" to 1".

    Thanks!

  2. #2
    Join Date
    Dec 2008
    Location
    Diamond Lake, WA
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    1,740

    Default

    I've always down cut with HDU. Creates a cleaner cut. That's my experience.
    Don
    Diamond Lake Custom Woodworks, LLC
    www.dlwoodworks.com
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  3. #3
    Join Date
    Mar 2013
    Location
    Memphis TN
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    Default

    With low temperature plastics like acrylic and especially PVC, I find the best results are with an upcut single flute running low rpm's and a fast speed. The chips have to be cleanly ejected or they may melt, decreasing the quality of the cut and possibly breaking the bit.

    PVC is really soft so I've found it can be cut aggressively and have a nice clean cut.
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  4. #4
    Join Date
    May 2005
    Location
    Londonderry New Hampshire
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    On PVC I use a "0" flute at low RPMS and cutting aggressively.
    Dick
    Aspire 10.5

  5. #5
    Join Date
    Mar 2008
    Location
    Radford VA
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    613

    Default

    I use downcut bits on HDU.
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