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Thread: Fuzzy edge while v bit engraving

  1. #1
    Member Snehal_Shah's Avatar
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    Default Fuzzy edge while v bit engraving

    Hello guys,
    I am having issues while doing V bit engraving in wooden parts on my CNC (a Chinese one).
    Following are the parameters set while machining.
    Feed rate: 200 ipm
    RPM: 5000-6000
    Tool: V bit 30 degree
    Spindle power: 9kW
    Material: Teak wood and birch plywood

    Please refer attached photos that shows a fuzzy top edge. (Birch ply looks awful !)
    Sanding will reduce the burrs but rather it should be machined smoothly.
    I have seen many videos where they get a crisp edge with a V bit !
    I am relatively new to engraving with V bits. I know a DC endmill will resolve the problem but I need sharp corners, that's why I am using a V bit.

    Thanks
    Snehal

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Fuzzy edge while v bit engraving-birch-plywood-jpg   Fuzzy edge while v bit engraving-teak-wood_1-jpg   Fuzzy edge while v bit engraving-teak-wood_2-jpg  


  2. #2
    Member CitizenOfDreams's Avatar
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    Default Re: Fuzzy edge while v bit engraving

    Your chipload seems to be way too high, especially if you have a single edge "half circle" type V-bit. I would try at least 5 times slower, 40ipm@6000rpm.



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    Default Re: Fuzzy edge while v bit engraving

    If the bit is high speed steel and has been used to cut birch ply (baltic birch perhaps) your edge won't last very long regardless of feed or spindle speed. Start with a sharp carbide bit made for cutting wood. I would also slow your feed a bit, but would also increase the spindle speed to something on the order of 15,000 rpm.



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    Community Moderator ger21's Avatar
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    Default Re: Fuzzy edge while v bit engraving

    Lower feedrate, higher RPM, sharper bit.

    I'd go for 75ipm at 14,000 rpm. With a new, SHARP bit.

    Gerry

    UCCNC 2017 Screenset
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    http://www.thecncwoodworker.com/2010.html

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    Member machinehop5's Avatar
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    Default Re: Fuzzy edge while v bit engraving

    ...what temperature is your machine room? is the wood frozen? anyone try that yet?



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    Default Re: Fuzzy edge while v bit engraving

    Hmmm... How about cryogenic wood machining? I know they do it with rubber...



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    Member Snehal_Shah's Avatar
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    Default Re: Fuzzy edge while v bit engraving

    Quote Originally Posted by MARV View Post
    If the bit is high speed steel and has been used to cut birch ply (baltic birch perhaps) your edge won't last very long regardless of feed or spindle speed. Start with a sharp carbide bit made for cutting wood.
    My bit is HSS (2 flutes) which seems to be the root cause.
    The chip load with current parameters is 0.017", is it too high? I would surely try out lower feedrate and higher rpm in accordance with all of you.

    Thinking whether the grain structure of "teakwood" has a role in it?

    The machine room ambient temperature is 100 degree F and wood is in normal weather conditions, so its definitely not cryogenic!!

    Thanks for all the inputs, will revert soon with outcome by applying suggested parameters.

    Snehal



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    Default Re: Fuzzy edge while v bit engraving

    Quote Originally Posted by Snehal_Shah View Post
    My bit is HSS (2 flutes) which seems to be the root cause.
    The chip load with current parameters is 0.017", is it too high? I would surely try out lower feedrate and higher rpm in accordance with all of you.
    If it's a "half moon" V-bit, it only has one cutting edge, so it's single flute. 0.017" (0.43mm) is already too high, and if you really have a single flute cutter, then it's 0.86mm - definitely too high.



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    Default Re: Fuzzy edge while v bit engraving

    Teak will eat HSS. Get a new carbide bit.



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    Default Re: Fuzzy edge while v bit engraving

    A coat of finish will also help keep the fuzzies away.



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    Default Re: Fuzzy edge while v bit engraving

    Hi SS - I use a 50/50 mix of PVA glue to seal the surface before I do fine work. The PVA binds the grain together and it cuts better. You can use other sealers as well that are compatible with the top coat. sharp tools always...plus a rough cut then a finish cut is helpful for grumpy grain...cheers Peter



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