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  1. #1
    I'm running a job machining badges on my Emach cnc router and am breaking cutters frequently. Wasn't too bad on the original stock that I had -duraluminium I think -but now I'm using 5251H22 cutter life is dire.
    Details are:
    Cutting tool speed 21000 rpm
    Cutter travel speed .25m/ min
    Cutter pas depth .3mm
    Tool = 2mm single flute carbide cutter from ITC Ltd
    Coolant = ITC coolant via mister

    I can't increase the cutter size due to the small radius on some of the letters. Am I better using a softer grade of aluminium or will I then get chip clogging?

    Any thoughts where I'm going wrong? It's getting a bit pricey at 20+ per cutter

  2. #2
    Find a cheaper cutter :naughty:

    You want about 250-350 ft/min for aluminium. 432 ft/min is pushing it.

    I suspect you have clag building up on the tool edge, some alloys are worse than others. Get your magnifying glass out, does the finish become progressively icky before the tool break?

  3. #3
    Quote Originally Posted by Robin Hewitt View Post
    Find a cheaper cutter :naughty:

    Try these
    John S -

  4. #4
    Quote Originally Posted by John S View Post
    Try these

    I think I'd go for a stub length slot drill to engrave text. Anything to reduce flex in the system.

  5. #5
    Personally I'd go for a Vee cutter, far stronger, only the very tip is small
    John S -

  6. Im with john on that one! but if you manage break a vee cutter then you doing something wrong.

  7. #7
    Quote Originally Posted by John S View Post
    Personally I'd go for a Vee cutter, far stronger
    As long as you don't get one with a very acute angle...

  8. #8
    To be honest I have found that most of these carbide engraving cutter take the tip off far to easily, makes sense when you think about it as carbide is a sintered powder and has no grain as such.

    Recently I have been grinding my own up from 6mm HSS drill blanks, don't last as long as carbide but once you have the D shape they cam be resharpened in about 2 minutes. Plus bit is you don't scrap a job because it takes the tip off 1 hour into a 3 hour job.

    Click image for larger version. 

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    8" x 3/4" all done with HSS tool.
    John S -

  9. #9
    Think I've seen that photo before somewhere ...

    I'll have to try the drill regrinding suggestion. I've kept any drills I have snapped (thankfully few) to regrind into spot drills. They seem ideal for that.
    Oh just noticed you said drill blanks, not drills. Just a D shape?

  10. #10
    or the broken shanks of HSS end mills and slot drills
    John S -

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