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Re: [SherlineCNC] Re: plunge cut and chatter

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  • Vlad Krupin
    ... ... Third yorkshireman: Oh, you were lucky to write g-code by hand! We had to puch g-code instructions on punch cards! By hand. With a dull holepunch. ...
    Message 1 of 31 , Oct 1, 2006
      On 9/30/06, James Washer <washer@...> wrote:
      >
      > CAM package? What CAM package... REAL MACHINISTS(tm) write g-code by hand!


      ... Third yorkshireman:
      Oh, you were lucky to write g-code by hand! We had to puch g-code
      instructions on punch cards! By hand. With a dull holepunch.
      ...

      Sorry, could not resist...

      Vlad

      - jim
      >
      > On Fri, 29 Sep 2006 20:17:59 -0700
      > "Vlad Krupin" <vlad.cnc@...> wrote:
      >
      > > On 9/29/06, James Washer <washer@...> wrote:
      > > >
      > > > for the ramp, wouldn't it be a simple three axis linear iterpolation?
      > > >
      > > > G01 Xx Yy Zz;
      > >
      > >
      > > yes, I think it's as simple as that. Although you'd probably expect your
      > CAM
      > > package to take care of that, and not need to insert that g-code by hand
      > >
      > > Vlad
      > >
      > > On Fri, 29 Sep 2006 16:28:01 -0000
      > > > "Devin Cox" <Holyelvis@...> wrote:
      > > >
      > > > > --- In SherlineCNC@yahoogroups.com, "timgoldstein" <timg@...> wrote:
      > > > > >
      > > > > > --- In SherlineCNC@yahoogroups.com, "Devin Cox" <Holyelvis@>
      > wrote:
      > > > > > > When I plunge into the metal my
      > > > > > > sherline is chattering and shaking badly enough that I feel the
      > > > > part
      > > > > > > will start loosing steps.
      > > > > >
      > > > > > Biggest issue is you shouldn't straight plunge an end mill. The
      > > > > cut is
      > > > > > MUCH easier on the machine and the bit if you ramp the bit into
      > > > > the
      > > > > > metal at 10 - 15 deg. The problem with plunging is that the center
      > > > > of
      > > > > > the bit is not cutting even with a center cutting end mill. That
      > > > > then
      > > > > > keeps the tool from pushing into the metal and creates lots of
      > > > > > chatter, heat, and wear as the tool is rubbing. This type of
      > > > > straight
      > > > > > plunge is said to have a lot of tool pressure. I never really
      > > > > > understood the term until I was plunging a 1/2" bit through 1"
      > > > > > aluminum on the Haas. The holes were being created, but I was
      > > > > getting
      > > > > > a lens shaped piece of swarf coming out of the bottom of the home.
      > > > > It
      > > > > > was about 3/16" thick. That is what was being pressed out of the
      > > > > hole
      > > > > > punch press style because the bit could not cut it at the rate it
      > > > > was
      > > > > > advancing. Now if I am going to straight plunge I predrill a hole
      > > > > with
      > > > > > a drill bit that is about 1/2 the diameter of the hole. Or even
      > > > > better
      > > > > > I use a 15 deg straight or helical ramp so I am always cutting
      > > > > from
      > > > > > the side.
      > > > > >
      > > > > > Tim
      > > > > > A2Z CNC
      > > > > >
      > > > > > Quick Change Tool Post & extended travel upgrades for Sherline
      > > > > mills.
      > > > > >
      > > > > > www.A2ZCNC.com
      > > > > >
      > > > > Thanks for the post Tim. I am convinced that plunge cutting is bad
      > > > > but I am unsure how to do a helical or ramped cut. Is this a
      > > > > specific g code to insert before each plunge cut or is this a
      > > > > function of the post processor?
      > > > >
      > > > > Thanks,
      > > > > Devin
      > > > >
      > > > >
      > > > >
      > > > >
      > > > >
      > > > >
      > > > >
      > > > >
      > > > > Yahoo! Groups Links
      > > > >
      > > > >
      > > > >
      > > > >
      > > > >
      > > > >
      > > > >
      > > >
      > > >
      > > >
      > > > Yahoo! Groups Links
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > >
      > >
      > > --
      > > Vlad's shop
      > > http://www.krupin.net/serendipity/index.php?/categories/2-metalworking
      > >
      > >
      > > [Non-text portions of this message have been removed]
      > >
      > >
      > >
      > >
      > > Yahoo! Groups Links
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      > Yahoo! Groups Links
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      --
      Vlad's shop
      http://www.krupin.net/serendipity/index.php?/categories/2-metalworking


      [Non-text portions of this message have been removed]
    • James Washer
      yep On Mon, 2 Oct 2006 07:54:41 -0700
      Message 31 of 31 , Oct 3, 2006
        yep

        On Mon, 2 Oct 2006 07:54:41 -0700
        "KM6VV" <KM6VV@...> wrote:

        > Hi list,
        >
        > I normally let my CAD/CAM do it, but occasionally for 4-axis stuff
        > (machining the outside of a steam engine cylinder) I write the passes by
        > hand. And the pocketing I get gives a gradual depth increase into each
        > pass. Seems like all one would have to do is make the first cut also moves
        > in Z. The final pass could be repeated to remove the ramp in.
        >
        > Alan KM6VV
        >
        > > Behalf Of Jim
        > >
        > > Sure glad I am not a real Machinist, hard enough getting the software
        > > to write g-code like I want.
        > >
        > > Jim
        > > Abbotsford, BC
        > >
        > > PS: only wish I could write it LOL
        > >
        > > --- In SherlineCNC@yahoogroups.com, James Washer <washer@...> wrote:
        > > >
        > > > CAM package? What CAM package... REAL MACHINISTS(tm) write g-code
        > > by hand!
        > > >
        > > > - jim
        > > >
        > > > On Fri, 29 Sep 2006 20:17:59 -0700
        > > > "Vlad Krupin" <vlad.cnc@...> wrote:
        > > >
        > > > > On 9/29/06, James Washer <washer@...> wrote:
        > > > > >
        > > > > > for the ramp, wouldn't it be a simple three axis linear
        > > iterpolation?
        > > > > >
        > > > > > G01 Xx Yy Zz;
        > > > >
        > > > >
        > > > > yes, I think it's as simple as that. Although you'd probably
        > > expect your CAM
        > > > > package to take care of that, and not need to insert that g-code
        > > by hand
        > > > >
        > > > > Vlad
        > > > >
        >
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
        >
        >
        >
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