1. #1
    Hi.

    I am cutting furniture out of 12mm MDF using Straight 6mm 2 flute carbide bits.

    I usually take 4 passes (3mm each). The bits last on average about 80 mins before sounding 'wrong' and emitting burning smell.


    Is this about right? or should they last longer. I have tried various ones from UK and from China, but they are all about the same.


    Just wanted to know if this sounded normal, or wildly out.

  2. #2
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 7 Hours Ago Has been a member for 6-7 years. Has a total post count of 607. Received thanks 83 times, giving thanks to others 0 times. Referred 1 members to the community.
    If it's burning, then RPM is too high, or feedrate is too low. Either causes excess heat, which dulls tools faster.
    I'd make 2 passes at 6mm per pass, too.
    Gerry
    ______________________________________________
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    JointCAM - CAM for Woodworking Joints

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  4. #3
    Thanks Gerry.

    But when I touch the blade after it has stopped. Its not even slightly warm. I only smell a slight burning when it has got near the 80 mins use.

    The ones from China are about 3 each, so maybe that isn't so bad?

    btw, the spiindle is running at 23,000rpm. I was advised by the manufactured of the CNC machine to go that speed for MDF.
    Last edited by Millatime16; 14-07-2018 at 08:11 PM.

  5. #4
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 7 Hours Ago Has been a member for 6-7 years. Has a total post count of 607. Received thanks 83 times, giving thanks to others 0 times. Referred 1 members to the community.
    What feedrate are you using? I cut 12 meters/min at 17,000 rpm. 23,000 is likely way too high.
    Gerry
    ______________________________________________
    UCCNC 2017 Screenset

    Mach3 2010 Screenset

    JointCAM - CAM for Woodworking Joints

  6. #5
    I will check tomorrow. The manufacture set it all up. Is it shown in the MACH 3 software?

    (The RPM is set on the Kress spindle itself).

  7. #6
    Quote Originally Posted by Millatime16 View Post
    Hi.

    I am cutting furniture out of 12mm MDF using Straight 6mm 2 flute carbide bits.

    I usually take 4 passes (3mm each). The bits last on average about 80 mins before sounding 'wrong' and emitting burning smell.


    Is this about right? or should they last longer. I have tried various ones from UK and from China, but they are all about the same.


    Just wanted to know if this sounded normal, or wildly out.
    What is the power of your spindle and what feeds and speed are you using. I have been cutting 9mm mdf with a 3mm alibond on top and using a single flute 4mm carbide with 6.5mm doc and about 3.5 mtr/min without any problems spindle speed 2200rpm 2.2 kW I think we did about 15 8x4 sheet with many profiles within in one day

    Edit these are the bits :- https://www.ebay.co.uk/itm/4mm-SOLID...1e30%7Ciid%3A1
    Last edited by Clive S; 15-07-2018 at 07:59 AM.
    ..Clive
    The more you know, The better you know, How little you know

  8. #7
    Its a Kress 1050.

    Where do I find the feed rate etc? I only know the basics of MACH 3 so far. (Its an A1 machine).

  9. #8
    Spiral bits are generally better for CNC use, as they evacuate the chip (upcut bits) and surface edge finish can be superior.

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