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Oblong Holes...where should I start?

Discussion in 'CNC Mills/Routers' started by Rob J, Jul 9, 2022.

  1. Rob J

    Rob J New
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    Good Day All,
    Working on a project and experiencing some issue making holes...grin. Simple right? I'm still new and learning everything on my own so please bear with me if I misspeak. What I'm looking for right now is advice/instruction on what to try/research first. Here's the basics:
    Using a 1010 with a Dewalt 611
    Material is walnut .29" thick.
    Bit is a Sharkbit 1/8 Downcut 2 Flute
    Cut is a .235" diameter hole through the material.
    I set the pocket toolpath to 6 passes (.0485 depth per pass) [trying to stay conservative]

    My issue is the holes appear oblong or oval shaped. I'm very happy with other cuts and precision.

    Where should I start...feed rates? Machine alignment? Something else?
    Thanks for any/all help,
    Rob
     
  2. Alex Chambers

    Alex Chambers Master
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    You didn't mention what controller or control software you are using, which would let us give you some specific advice, but the first step is calibrating your steps/mm. It would also help us advise you if you could post a pic of the holes with the axes labelled.
    Alex.
     
  3. Rob J

    Rob J New
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    Update: Tried two things and one or both did the trick. (I know one variable at a time...grin). Recently pulled my router out to replace brushes so the first thing I did was tighten the mount screws. Second and what I think actually did the trick...new bit. The first bit was the one I bought with the machine over a year ago. Any recommendation for how to track the lifetime of a bit?

    Alex, Thank you for your response. I will try to remember to include those in future posts. In this case...I build my projects using Aspire. The OpenBuilds control software says v1.0.321. Firmware on the interface is latest 1.52. Left image was original. Right is after bit replacement. 20220710_142850~2.jpg
     
  4. Alex Chambers

    Alex Chambers Master
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    If you shine a bright light on the cutting edge of a bit and see a bright line your bit is blunt.
    Alex.
     
  5. Rob J

    Rob J New
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    Sure enough, there was a line. Thank you Sir. In addition to being conservative with the amount of material (depth of my cut), is there anything you recommend to preserve the life of a bit.
    Respectfully,
    Rob
     
  6. Alex Chambers

    Alex Chambers Master
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    Keep the bit clean, but above all keep the cutting area clear of chips (and you should be cutting chips, not making dust).
    As for being conservative with your depth of cut, that depends on the toolpath you are using. Adaptive toolpaths, where the limiting factor is the width of cut, benefit from much deeper cuts as you are then using more of the cutting edge.
    Alex.
     
    David the swarfer likes this.

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