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  1. #1
    Join Date
    May 2010
    Posts
    222

    Broke 1/4" straight routerbit

    Ok i was cutting piece maple ply feed rate was 30 ipm 24000 rpm 1/8" depth of cut broke after cutting approximately 20" was steel body carbide tipped bit!
    any thoughts as this should not have been strain on this bit!

  2. #2
    Join Date
    May 2005
    Posts
    3920

    Re: Broke 1/4" straight routerbit

    Possibly the bit wasn't ground right for the feed rate.

    I'd look closely at the bit to see if material had accumulated in the flights. If a bit plugs up it will snap pretty quickly.

    A manufacturing defect is always possible. You would need to look closely at the break to see if this is a factor.

    A sudden acceleration from a stepper or servo based system could snap a bit. This could come from noise in the system or something else.

  3. #3
    Join Date
    May 2010
    Posts
    222

    Re: Broke 1/4" straight routerbit

    it was brand new bit was clean as said cutting at slow rate of feed and only 1/8" deep and just fell apart like it was cheap Chinese piece junk lol!
    feed rate 30 ipm is slow like snail

  4. #4
    Join Date
    May 2005
    Posts
    3920

    Re: Broke 1/4" straight routerbit

    Quote Originally Posted by R L Harris View Post
    it was brand new bit was clean as said cutting at slow rate of feed and only 1/8" deep and just fell apart like it was cheap Chinese piece junk lol!
    Maybe it was!


    feed rate 30 ipm is slow like snail
    If there was something wrong feed rate wouldn't matter much. Post some pictures, there are a few guys with experience with metal failures on here that might help. This include pictures of the cut.

  5. #5
    Join Date
    Mar 2003
    Posts
    35538

    Re: Broke 1/4" straight routerbit

    Going too slow can generate a lot of heat and cause failure.

    Where did the bit break? At the collet? Or somewhere else?

    1 flute or 2?
    I've always found small carbide tipped bits to be rather fragile.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  6. #6
    Join Date
    May 2010
    Posts
    222

    Re: Broke 1/4" straight routerbit

    This is the end of cut where bit broke the cut was 1/8" deep in 3/4" maple ply feed 30 ipm bit rpm 24000
    and the bit pieces with break points showing
    the bit pieces were not hot as picked it up with bare hand it just sheard floped over like it was weak at break point

  7. #7
    Join Date
    May 2010
    Posts
    222

    Re: Broke 1/4" straight routerbit

    I am going to get solid carbide bit and drop rpm 18000 and increase the feed to 40ipm

  8. #8
    Join Date
    Apr 2004
    Posts
    5728

    Re: Broke 1/4" straight routerbit

    What kind of machine are you using? What sort of spindle? For a dedicated wood router, 30 ipm (or even 40) is really slow. Most wood-cutting toolpaths run about 10 times that fast.
    Andrew Werby
    Website

  9. #9
    Join Date
    May 2010
    Posts
    222

    Re: Broke 1/4" straight routerbit

    I am bumping up speed to 100 ipm i would go higher if it had long cuts but this is only 12" x 12" part with bunch turns in it!

  10. #10
    Join Date
    Mar 2003
    Posts
    35538

    Re: Broke 1/4" straight routerbit

    What brand bit was that?

    I am going to get solid carbide bit and drop rpm 18000 and increase the feed to 40ipm
    At 40 ipm, you should drop the rpm to 10,000.
    I usually cut at 125-150ipm and 12,000 rpm.

    At work, we cut at 450ipm with 1/4" solid carbide bits at 18,000 rpm.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  11. #11
    Join Date
    Nov 2010
    Posts
    520

    Re: Broke 1/4" straight routerbit

    Does this bit have a cutting edge all across the bottom?

    Most of my work is small, so I keep the IPM down to the 30 IPM range, the speed in the 10K range and I ramp down to the cutting depth. I also use a solid spiral up-feed bit. I know carbide is brittle, but I have never broken a bit, as he knocks on some wood.

  12. #12
    Join Date
    May 2010
    Posts
    222

    Re: Broke 1/4" straight routerbit

    Ok bought upcut spiral as i can radius the edge little all went well rpm was 18000 feed 100 ipm
    Attachment 332802

  13. #13
    Join Date
    Feb 2005
    Posts
    829

    Re: Broke 1/4" straight routerbit

    I have been using Amana and Onsrud bits in my CNCRouterparts machine. I have been feeding a 1/4 compression bit at upto .375 Depth of Cut, at 160-200IPM at 24,000RPM and have been really really happy with the surface finish of the cuts. I Have been surfacing the table at 400IPM with a 2in Magnate Surfacing bit at .025 DOC no problems also.

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