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  • Z Axis Burn Marks


    I'm getting these two types of burn marks (see photos) on this 1/2" Maple plywood. The two parallel marks on the outside of the disc is caused when the tool comes to a stop to go up and over and create the tabs. The marks inside the holes are caused when for some reason I don't understand, the cutter pauses and then resumes. When I did tests cutting in inexpensive Home Depot plywood, I didn't get the burn marks at all.

    About the machine- It's a Stinger One run with WinCNC and a Amana Spectra 1/4" compression end mill. The design and .tap file were created by Vcarve Pro 11.0.

    About the cut- I did two rough cut passes with a .050 allowance last pass. Then there was a finish cut in one pass at -.005. The feed is 150 and the plunge is 75. It's climb cut profiles with with a smooth ramp. RPM is 18,000.

    Is there a way to do this without the burns? They're a pain to sand out.

    Thanks for the help!
    Attached Files
  • #2

    Rpm seems a little high for that slow of a feed rate. Have you tried a conventional cut?
    Last edited by Pete marken; 09-04-2022, 05:50 PM.
    Stinger II SR44 with servos
    Recoil Prep
    3KW spindle
    7 Watt Laser
    Pro Option Pack
    Hand Held Keypad
    T-Slot Table with Hurricane Vacuum.
    Aspire 10.5
    WinCnc

    Comment

    • #3

      If you are not using them, try 3D tabs. They may keep things moving and prevent the burn marks. Another option might be speedeng up the feed rate or changing direction as suggested above.
      Pete
      ----------
      2021 Stinger I SR-24, 1kW Spindle
      Performance Pkg w/Gantry Lift, FTC
      Phenolic Top, Storm Vac, JTech Laser
      VCarve Pro 11.0
      www.gotoguysmarine.com

      Comment

      • #4

        Originally posted by gtgmarine View Post
        If you are not using them, try 3D tabs. They may keep things moving and prevent the burn marks. Another option might be speedeng up the feed rate or changing direction as suggested above.
        I haven't tried any changes yet. I'm still a beginner at this stuff. I wasn't even aware of the "3-D tab", so I will look for that option. It sounds good. The speeds and feeds are just what Amana suggested. Other than the burns caused by the tool stopping, I'm satisfied by the results. Any idea why the tool would pause when cutting circle profiles? Is it a processing problem? Would using a spiral ramp help? I've read about a "constant velocity" mode, or a G64 code with other controller software, does WinCNC have that?

        Thanks again!

        Comment

        • #5

          Try ramping in or lead in and out

          Comment

          • #6

            Ramping and 3D tabs are really important for "sugar rich" woods like maple because any pause of the spinning tool will cause burning just as it would on a table saw or other spinning (and hot from friction) cutter.
            ---
            Jim Becker

            SR-44 (2018), 1.7kw spindle, Performance Premium, USB, Keypad, T-Slot table (y-axis configuration), WinCNC, VCarve Pro upgraded to Aspire

            Non CNC stuff...

            SCM/Minimax
            Festool "a good collection"
            Stubby - lathe
            Oneida Cyclone
            more...

            Retired from full time work in the telecom industry 9/2017
            Occasional commission work for others, but mostly for me...furniture/tack trunks/signage/guitars
            Located Bucks County PA

            Comment

            • #7

              Originally posted by Jim Becker View Post
              Ramping and 3D tabs are really important for "sugar rich" woods like maple because any pause of the spinning tool will cause burning just as it would on a table saw or other spinning (and hot from friction) cutter.
              I am using a smooth ramp for the plunge moves and it works. I was not aware of the 3-D tabs, but I will set that up for sure. Now if I can just figure out why the machine randomly pauses when cutting circles, I'd likely have all the problems solved.

              Comment

              • #8

                If you are using Vectric software for design, look at the circles using node editing feature. I would expect a circle to have four points.
                Charlie L
                Stinger II, 48 by 48, 1.7 kW Spindle, FTC + Laser + Recoil + Vacuum, July 2012
                WinCNC 2.5.03, Aspire, PhotoVCarve, Windows 7 Pro SP1

                Comment

                • #9

                  Originally posted by Charlie_L View Post
                  If you are using Vectric software for design, look at the circles using node editing feature. I would expect a circle to have four points.
                  Yeah, that's what I use and I have seen the four nodes on circles in the past. I haven't looked at these ones though. Why would they matter though? Are you suggesting maybe my machine is stopping at a node?

                  Comment

                  • #10

                    Sometimes when I import someones vectors via dxf cad drawings there are a ton of nodes. If there is a little bend in the tiny line that makes the circle it slows down to turn.
                    Charlie L
                    Stinger II, 48 by 48, 1.7 kW Spindle, FTC + Laser + Recoil + Vacuum, July 2012
                    WinCNC 2.5.03, Aspire, PhotoVCarve, Windows 7 Pro SP1

                    Comment

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