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Re: [SherlineCNC] Backlash?

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  • Marcus and Eva
    Hi Tim: You ve almost certainly got a programming error. Are you SURE you used the size of cutter that you told the machine you were using? (Ask me how I know
    Message 1 of 6 , Apr 1, 2004
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      Hi Tim:
      You've almost certainly got a programming error.
      Are you SURE you used the size of cutter that you told the machine you were
      using? (Ask me how I know about this one!!)
      The other possibility that springs to mind, is that you set the cutter speed
      too high and remelted the chips back onto the wall of the hole.
      Cheers

      Marcus

      ----- Original Message -----
      From: "timxdunn" <dunntim@...>
      To: <SherlineCNC@yahoogroups.com>
      Sent: Wednesday, March 31, 2004 8:06 PM
      Subject: [SherlineCNC] Backlash?


      > Hello,
      >
      > I wonder if anybody can shed some light on a problem that I just
      > encountered.
      >
      > I needed to make 37 holes in an ABS instrument case. The holes are 4
      > different sizes. I thought that rather than change tools I could
      > simply plunge an end mill through the ABS and then describe a circle
      > of the appropriate radius (taking into account the end mill size).
      >
      > The program ran just fine but the holes came out undersize by about
      > 0.02". I foolishly expected that the endmill would cut oversize if
      > anything, perhaps if it were not quite centered in it's holder for
      > instance.
      >
      > Would backlash in x or y or both cause this? The holes look round and
      > do not appear to have a step at the start/finish point, which I
      > thought backlash would cause.
      >
      > It is late now, but tomorrow I will measure the backlash.
      >
      > Although I have not given up thinking yet I must confess to being
      > mystified right now. Any advice from old hands would be greatly
      > appreciated.
      >
      >
      >
      > -Tim
    • timxdunn
      Marcus, Well, it was not exactly a programming error, but every bit as stupid. I picked up an old program with the same name from another directory. Needless
      Message 2 of 6 , Apr 6, 2004
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        Marcus,

        Well, it was not exactly a programming error, but every bit as
        stupid.

        I picked up an old program with the same name from another directory.
        Needless to say the old program was for a different tool size.

        From now on I will try to remember to include a comment in the
        program regarding what tool should be in the machine.

        Luckily the mistake made undersized holes so I could recover. More
        luck than I deserved.

        Thanks to both of you that offered help.

        -Tim



        --- In SherlineCNC@yahoogroups.com, "Marcus and Eva" <implmex@a...>
        wrote:
        > Hi Tim:
        > You've almost certainly got a programming error.
        > Are you SURE you used the size of cutter that you told the machine
        you were
        > using? (Ask me how I know about this one!!)
        > The other possibility that springs to mind, is that you set the
        cutter speed
        > too high and remelted the chips back onto the wall of the hole.
        > Cheers
        >
        > Marcus
        >
        > ----- Original Message -----
        > From: "timxdunn" <dunntim@a...>
        > To: <SherlineCNC@yahoogroups.com>
        > Sent: Wednesday, March 31, 2004 8:06 PM
        > Subject: [SherlineCNC] Backlash?
        >
        >
        > > Hello,
        > >
        > > I wonder if anybody can shed some light on a problem that I just
        > > encountered.
        > >
        > > I needed to make 37 holes in an ABS instrument case. The holes
        are 4
        > > different sizes. I thought that rather than change tools I could
        > > simply plunge an end mill through the ABS and then describe a
        circle
        > > of the appropriate radius (taking into account the end mill size).
        > >
        > > The program ran just fine but the holes came out undersize by
        about
        > > 0.02". I foolishly expected that the endmill would cut oversize if
        > > anything, perhaps if it were not quite centered in it's holder for
        > > instance.
        > >
        > > Would backlash in x or y or both cause this? The holes look round
        and
        > > do not appear to have a step at the start/finish point, which I
        > > thought backlash would cause.
        > >
        > > It is late now, but tomorrow I will measure the backlash.
        > >
        > > Although I have not given up thinking yet I must confess to being
        > > mystified right now. Any advice from old hands would be greatly
        > > appreciated.
        > >
        > >
        > >
        > > -Tim
      • Alan Marconett KM6VV
        Hi Tim, Marcus, I ve taken to putting a title, date, tool needs and even the location of the origin for the part. I normally use the lower left hand corner of
        Message 3 of 6 , Apr 6, 2004
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          Hi Tim, Marcus,

          I've taken to putting a title, date, tool needs and even the location of
          the origin for the part. I normally use the lower left hand corner of
          the part, but sometimes that is impossible, or not desirable. The
          center of a hole, or referencing from the back corner (if the stock is
          WAY LARGE for the table).

          I've got about 80+ part files for the Baby Beam Engine I just got
          running. I WISH I'd made a spread sheet or index to the contents of all
          the files! I'm going to generate a BOM (bill of materials) for all the
          parts, and reference the drawings and part files on it.

          Live and learn!

          Alan KM6VV


          timxdunn wrote:
          >
          > Marcus,
          >
          > Well, it was not exactly a programming error, but every bit as
          > stupid.
          >
          > I picked up an old program with the same name from another directory.
          > Needless to say the old program was for a different tool size.
          >
          > >From now on I will try to remember to include a comment in the
          > program regarding what tool should be in the machine.
          >
          > Luckily the mistake made undersized holes so I could recover. More
          > luck than I deserved.
          >
          > Thanks to both of you that offered help.
          >
          > -Tim
        • Marcus and Eva
          Hi Guys: I have my post processors set up to give me all the basic information I need to re-run any program at any time. I know automatically, the tool names
          Message 4 of 6 , Apr 7, 2004
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            Hi Guys:
            I have my post processors set up to give me all the basic information I
            need to re-run any program at any time.
            I know automatically, the tool names and numbers, the date, the title etc.
            I got into the habit of editing in other relevant info like where the origin
            is, what the stock size is, how far above the vise it has to sit etc etc.
            Having said all that, I still don't trust old programs that much, and will
            still often re-post them from the original CAM file.
            It takes less time to do that than to fully check out an old program, and
            FAR less time than to fix a crash.
            Fortunately, I've invested enough in my CAM setup that I can do this in a
            matter of minutes.
            The hardest part now, is to remember where the Devil I've put the file I
            want.
            I've got thousands of files from all the prototyping and moldmaking I've
            done.
            Cheers

            Marcus

            ----- Original Message -----
            From: "Alan Marconett KM6VV" <KM6VV@...>
            To: <SherlineCNC@yahoogroups.com>
            Sent: Tuesday, April 06, 2004 2:15 PM
            Subject: Re: [SherlineCNC] Re: Backlash?


            > Hi Tim, Marcus,
            >
            > I've taken to putting a title, date, tool needs and even the location of
            > the origin for the part. I normally use the lower left hand corner of
            > the part, but sometimes that is impossible, or not desirable. The
            > center of a hole, or referencing from the back corner (if the stock is
            > WAY LARGE for the table).
            >
            > I've got about 80+ part files for the Baby Beam Engine I just got
            > running. I WISH I'd made a spread sheet or index to the contents of all
            > the files! I'm going to generate a BOM (bill of materials) for all the
            > parts, and reference the drawings and part files on it.
            >
            > Live and learn!
            >
            > Alan KM6VV
            >
            >
            > timxdunn wrote:
            > >
            > > Marcus,
            > >
            > > Well, it was not exactly a programming error, but every bit as
            > > stupid.
            > >
            > > I picked up an old program with the same name from another directory.
            > > Needless to say the old program was for a different tool size.
            > >
            > > >From now on I will try to remember to include a comment in the
            > > program regarding what tool should be in the machine.
            > >
            > > Luckily the mistake made undersized holes so I could recover. More
            > > luck than I deserved.
            > >
            > > Thanks to both of you that offered help.
            > >
            > > -Tim
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