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IndustryArena Forum > MetalWorking Machines > Uncategorised MetalWorking Machines > CNC'd LMS High Torque Mill Surface Finish Question
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  1. #1
    Join Date
    May 2015
    Posts
    4

    CNC'd LMS High Torque Mill Surface Finish Question

    Hi all! I recently completed a LMS 3990 CNC conversion and I've started playing around with some of the wizards in Mach3. I've come across something kind of strange and I'm hoping someone can provide some advice. I was running a rectangular pocket wizard using a 1/4" 4 flute end mill to surface a piece of aluminum that's firmly held in a vice and I'm getting odd results. Hopefully you can see from the attachments, but one side machines perfectly and the other side is left with a pattern of evenly spaced circular marks that I can feel if I scrape my fingernail over the surface. I flipped the part over and ran the code again, and got the same results. Does anyone have an idea why this is happening? I'm new to all of this so I'd really appreciate some advice.

  2. #2
    Join Date
    Dec 2011
    Posts
    34

    Re: CNC'd LMS High Torque Mill Surface Finish Question

    That looks like chatter.check the rigidity of your work holding.maybe a screw jack under the part damping the vibration.it seems to be on the part where the vise isnt directly under it.I am just throwing out ideas going off the pictures...good luck

  3. #3
    Join Date
    May 2015
    Posts
    4

    Re: CNC'd LMS High Torque Mill Surface Finish Question

    Thanks for the response MetalCarpenter! Yeah, I was thinking it was some kind of chatter or harmonics too. What has me scratching my head though is it only happened on the right side of the piece. The piece of aluminum is centered in the vice, so the same amount is hanging off unsupported on the left side as the right. I would think if it was something like chatter, it would happened somewhat evenly on both sides. As you can see from the first attachment however, the left side came out pretty much perfectly. It's weird. I'm going to try a different piece of aluminum and see if I get similar results. Who knows, the right side of the plate might have been slightly narrower than the left, so the vice wasn't clamping it as tightly...

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