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Re: stop breaking endmills

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  • aldesigns
    I am not cutting all the way through the plate maybe more accurate to call it a trough. If it was wood you would call it a dado cut. By breaking through I mean
    Message 1 of 14 , Jan 2, 2008
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      I am not cutting all the way through the plate maybe more accurate to
      call it a trough. If it was wood you would call it a dado cut. By
      breaking through I mean when the cutter reaches the end of the cut and
      starts to leave the work piece where a portion of the cutter is
      hitting air and the rest is still cutting steel. I use the recommended
      speed for that size of endmill perhaps the feed rate is to high. I
      just got a new powerfeed for the table and haven't figured out what
      the dial settings 1-9 mean in terms of sfm. When I use to crank by
      hand I know I would slow the feed at the end of a cut to keep the same
      kind of thing from happening. Something maybe loose either the vise
      or the table is allowing the cutter to push or pull work just slightly.

      shamas

      --- In mill_drill@yahoogroups.com, Rexarino <rexarino@...> wrote:
      >
      > Shamas, how are you holding the steel? When you say "breaking
      through", I
      > have a vision of a piece of steel clamped in a vice, with a slot
      extending
      > through the end of the steel, ultimately forming a U shaped
      workpiece. If
      > this is the scenario, the steel is deflecting into the end mill as you
      > finish the cut, causing vibration and breakage.
      >
      > Regardless, try clamping both sides of the steel down to the table
      with a
      > sacrificial piece of hardboard or sheet aluminum under it to protect the
      > table, rather than holding in the vice.
      >
      > If you are already clamping to the table rather than using a vice,
      I've no
      > suggestion.
      >
      > rexarino
      >
      > On Dec 31, 2007 11:19 AM, aldesigns <aldesigns@...> wrote:
      >
      > > Hi all
      > >
      > > When I am cutting a slot, in this case it was 3/8" wide 1/8" deep in
      > > mild steel, it cuts fine until the end where it starts to break
      > > through the material. This is when the endmill starts catching on the
      > > leading edge causing the work and table to vibrate slightly. in this
      > > case it caused the endmill to break. it was a unused new endmill, that
      > > hurts. I do tighten the jibs. So is there anything else I should be
      > > doing to keep this from happening in the future? Is it a problem with
      > > the operator or the machine? maybe the feed rate was too high or the
      > > work wasn't held secure enough? Any insights will be greatly
      appreciated.
      > >
      > > Thanks
      > > Shamas
      > >
      > >
      > >
      > >
      > >
      > >
      >
    • Glenn N
      I usually kill the power feed near the end of the cut and finish by hand. It always makes nasty sounds at the end as it is pulling the metal into the cut.
      Message 2 of 14 , Jan 2, 2008
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        I usually kill the power feed near the end of the cut and finish by hand.  It always makes nasty sounds at the end as it is pulling the metal into the cut.  Also helps to tighten the gibbs a bit to keep it from pulling the table.  When the slot opens, one side of the endmill is climb milling with about half the width of the cutter.  It takes a very ridgid setup to do that without breaking things.
        ----- Original Message -----
        From: aldesigns
        Sent: Wednesday, January 02, 2008 11:40 AM
        Subject: [mill_drill] Re: stop breaking endmills

        I am not cutting all the way through the plate maybe more accurate to
        call it a trough. If it was wood you would call it a dado cut. By
        breaking through I mean when the cutter reaches the end of the cut and
        starts to leave the work piece where a portion of the cutter is
        hitting air and the rest is still cutting steel. I use the recommended
        speed for that size of endmill perhaps the feed rate is to high. I
        just got a new powerfeed for the table and haven't figured out what
        the dial settings 1-9 mean in terms of sfm.  When I use to crank by
        hand I know I would slow the feed at the end of a cut to keep the same
        kind of thing from happening.  Something maybe loose either the vise
        or the table is allowing the cutter to push or pull work just slightly.

        shamas

        --- In mill_drill@yahoogroups.com, Rexarino <rexarino@...> wrote:
        >
        > Shamas, how are you holding the steel?  When you say "breaking
        through", I
        > have a vision of a piece of steel clamped in a vice, with a slot
        extending
        > through the end of the steel, ultimately forming a U shaped
        workpiece.  If
        > this is the scenario, the steel is deflecting into the end mill as you
        > finish the cut, causing vibration and breakage.
        >
        > Regardless, try clamping both sides of the steel down to the table
        with a
        > sacrificial piece of hardboard or sheet aluminum under it to protect the
        > table, rather than holding in the vice.
        >
        > If you are already clamping to the table rather than using a vice,
        I've no
        > suggestion.
        >
        > rexarino
        >
        > On Dec 31, 2007 11:19 AM, aldesigns <aldesigns@...> wrote:
        >
        > > Hi all
        > >
        > > When I am cutting a slot, in this case it was 3/8" wide 1/8" deep in
        > > mild steel, it cuts fine until the end where it starts to break
        > > through the material. This is when the endmill starts catching on the
        > > leading edge causing the work and table to vibrate slightly. in this
        > > case it caused the endmill to break. it was a unused new endmill, that
        > > hurts. I do tighten the jibs.  So is there anything else I should be
        > > doing to keep this from happening in the future? Is it a problem with
        > > the operator or the machine? maybe the feed rate was too high or the
        > > work wasn't held secure enough?  Any insights will be greatly
        appreciated.
        > >
        > > Thanks
        > > Shamas
        > >
        > >
        > >
        > >
        > >
        > >
        >




         
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      • aldesigns
        I will try that thanks Glenn good to know it does happen to others and not just me. Shamas ... hand. It always makes nasty sounds at the end as it is pulling
        Message 3 of 14 , Jan 2, 2008
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          I will try that thanks Glenn
          good to know it does happen to others and not just me.

          Shamas

          --- In mill_drill@yahoogroups.com, "Glenn N" <sleykin@...> wrote:
          >
          > I usually kill the power feed near the end of the cut and finish by
          hand. It always makes nasty sounds at the end as it is pulling the
          metal into the cut. Also helps to tighten the gibbs a bit to keep it
          from pulling the table. When the slot opens, one side of the endmill
          is climb milling with about half the width of the cutter. It takes a
          very ridgid setup to do that without breaking things.
          > ----- Original Message -----
          > From: aldesigns
          > To: mill_drill@yahoogroups.com
          > Sent: Wednesday, January 02, 2008 11:40 AM
          > Subject: [mill_drill] Re: stop breaking endmills
          >
          >
          > I am not cutting all the way through the plate maybe more accurate to
          > call it a trough. If it was wood you would call it a dado cut. By
          > breaking through I mean when the cutter reaches the end of the cut and
          > starts to leave the work piece where a portion of the cutter is
          > hitting air and the rest is still cutting steel. I use the recommended
          > speed for that size of endmill perhaps the feed rate is to high. I
          > just got a new powerfeed for the table and haven't figured out what
          > the dial settings 1-9 mean in terms of sfm. When I use to crank by
          > hand I know I would slow the feed at the end of a cut to keep the same
          > kind of thing from happening. Something maybe loose either the vise
          > or the table is allowing the cutter to push or pull work just slightly.
          >
          > shamas
          >
          > --- In mill_drill@yahoogroups.com, Rexarino <rexarino@> wrote:
          > >
          > > Shamas, how are you holding the steel? When you say "breaking
          > through", I
          > > have a vision of a piece of steel clamped in a vice, with a slot
          > extending
          > > through the end of the steel, ultimately forming a U shaped
          > workpiece. If
          > > this is the scenario, the steel is deflecting into the end mill as you
          > > finish the cut, causing vibration and breakage.
          > >
          > > Regardless, try clamping both sides of the steel down to the table
          > with a
          > > sacrificial piece of hardboard or sheet aluminum under it to
          protect the
          > > table, rather than holding in the vice.
          > >
          > > If you are already clamping to the table rather than using a vice,
          > I've no
          > > suggestion.
          > >
          > > rexarino
          > >
          > > On Dec 31, 2007 11:19 AM, aldesigns <aldesigns@> wrote:
          > >
          > > > Hi all
          > > >
          > > > When I am cutting a slot, in this case it was 3/8" wide 1/8" deep in
          > > > mild steel, it cuts fine until the end where it starts to break
          > > > through the material. This is when the endmill starts catching
          on the
          > > > leading edge causing the work and table to vibrate slightly. in this
          > > > case it caused the endmill to break. it was a unused new
          endmill, that
          > > > hurts. I do tighten the jibs. So is there anything else I should be
          > > > doing to keep this from happening in the future? Is it a problem
          with
          > > > the operator or the machine? maybe the feed rate was too high or the
          > > > work wasn't held secure enough? Any insights will be greatly
          > appreciated.
          > > >
          > > > Thanks
          > > > Shamas
          > > >
          > > >
          > > >
          > > >
          > > >
          > > >
          > >
          >
          >
          >
          >
          >
          > Yahoo! Groups Links
          >
        • Curt Wuollet
          Good fixturing is everything when milling. And it would be good to have as little tool deflection as possible when you break through. And you want to check
          Message 4 of 14 , Jan 2, 2008
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            Good fixturing is everything when milling.
            And it would be good to have as little tool
            deflection as possible when you break
            through. And you want to check again
            that you are using a smaller mill so that
            you aren't climb milling as that tends to
            snag on corners.

            Regards

            cww

            aldesigns wrote:

            I am not cutting all the way through the plate maybe more accurate to
            call it a trough. If it was wood you would call it a dado cut. By
            breaking through I mean when the cutter reaches the end of the cut and
            starts to leave the work piece where a portion of the cutter is
            hitting air and the rest is still cutting steel. I use the recommended
            speed for that size of endmill perhaps the feed rate is to high. I
            just got a new powerfeed for the table and haven't figured out what
            the dial settings 1-9 mean in terms of sfm. When I use to crank by
            hand I know I would slow the feed at the end of a cut to keep the same
            kind of thing from happening. Something maybe loose either the vise
            or the table is allowing the cutter to push or pull work just slightly.

            shamas

            --- In mill_drill@yahoogro ups.com, Rexarino <rexarino@.. .> wrote:
            >
            > Shamas, how are you holding the steel? When you say "breaking
            through", I
            > have a vision of a piece of steel clamped in a vice, with a slot
            extending
            > through the end of the steel, ultimately forming a U shaped
            workpiece. If
            > this is the scenario, the steel is deflecting into the end mill as you
            > finish the cut, causing vibration and breakage.
            >
            > Regardless, try clamping both sides of the steel down to the table
            with a
            > sacrificial piece of hardboard or sheet aluminum under it to protect the
            > table, rather than holding in the vice.
            >
            > If you are already clamping to the table rather than using a vice,
            I've no
            > suggestion.
            >
            > rexarino
            >
            > On Dec 31, 2007 11:19 AM, aldesigns <aldesigns@. ..> wrote:
            >
            > > Hi all
            > >
            > > When I am cutting a slot, in this case it was 3/8" wide 1/8" deep in
            > > mild steel, it cuts fine until the end where it starts to break
            > > through the material. This is when the endmill starts catching on the
            > > leading edge causing the work and table to vibrate slightly. in this
            > > case it caused the endmill to break. it was a unused new endmill, that
            > > hurts. I do tighten the jibs. So is there anything else I should be
            > > doing to keep this from happening in the future? Is it a problem with
            > > the operator or the machine? maybe the feed rate was too high or the
            > > work wasn't held secure enough? Any insights will be greatly
            appreciated.
            > >
            > > Thanks
            > > Shamas
            > >
            > >
            > >
            > >
            > >
            > >
            >



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            "The liberty of a democracy is not safe if the people tolerate the growth of 
            private power to a point where it becomes stronger than their democratic State
            itself. That in it's essence, is Fascism - ownership of government by an 
            individual, by a group or by any controlling private power." But the 
            conviction of Standard Oil stood. Our government is already powerless
            against today's monopoly. Only the people can prevail.
            
          • leasingham_connelly
            ... to ... and ... recommended ... same ... vise ... slightly. ... The setting 1-9 will not give a repeatable sfm. If you leave the feed set at something low
            Message 5 of 14 , Jan 3, 2008
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              --- In mill_drill@yahoogroups.com, "aldesigns" <aldesigns@...> wrote:
              >
              > I am not cutting all the way through the plate maybe more accurate
              to
              > call it a trough. If it was wood you would call it a dado cut. By
              > breaking through I mean when the cutter reaches the end of the cut
              and
              > starts to leave the work piece where a portion of the cutter is
              > hitting air and the rest is still cutting steel. I use the
              recommended
              > speed for that size of endmill perhaps the feed rate is to high. I
              > just got a new powerfeed for the table and haven't figured out what
              > the dial settings 1-9 mean in terms of sfm. When I use to crank by
              > hand I know I would slow the feed at the end of a cut to keep the
              same
              > kind of thing from happening. Something maybe loose either the
              vise
              > or the table is allowing the cutter to push or pull work just
              slightly.
              >
              > shamas

              The setting 1-9 will not give a repeatable sfm. If you leave the
              feed set at something low and tighten the gib the motor will slow
              down significantly. However if you are pushing the motor hard by
              cutting with a high feed rate then slackening off the gib or
              breaking thru will cause an increase in feed speed which will likely
              result in the problem you are encountering.



              Stan Stoker wrote:

              Just remember, no plunging with four flute end mills! They
              can NOT center cut.

              Sorry Stan, you are not 100% correct on this one. I have both 3 and
              4 flute centre cutting end mills as well as some that do not centre
              cut.

              Martin
            • Rexarino
              I m not sure a wedge would help, as the vibration of breaking through might let the wedge fall out, or worse, fall into the milling cutter. Shamas later post
              Message 6 of 14 , Jan 3, 2008
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                I'm not sure a wedge would help, as the vibration of breaking through might let the wedge fall out, or worse, fall into the milling cutter.

                Shamas' later post indicates that he is feeding under power as he breaks through, and the speed and unavoidable backlash are probably the largest problem, as pointed out by others.

                I don't like to cut slots with the work held in the vise, unless the slot is substantially smaller than the remaining supporting metal, or the slot is not "within" the vise jaws - in other words, above the vise jaws, or left or right of the vise - but that's just my opinion. 

                I would never cut a slot 1/8 inch deep in 3/16 inch thick steel held in the vise.  The remaining 1/16 inch of steel isn't strong enough to resist compression as you reach the end of the cut.  I would cut a 1/8 inch thick slot in 3/8 steel or aluminum in the vise, but I would prefer to clamp down to the table and avoid any chance of compressing the slot as I cut it.

                Remember also that a nicely squared block in a high quality vise will have many points of contact, but a piece of sheared scrap in a Harbor Fright cheapo vise may only be held in one or two places, with the resultant high compression points, which can creep all over as your cut relieves the contact pressure.

                But sometimes, you can get away with amazing oversights, too,

                Enjoy,
                rexarino

                On Jan 1, 2008 11:32 PM, ron Pat <ronpat0471@...
                > wrote:
                Do you think maybe putting the unsharpened end of a
                mill the same size in the cut before he gets to the
                end will hold it apart?  Or maybe a wedge?



                --- Rexarino <rexarino@...> wrote:

                > Shamas, how are you holding the steel?  When you say
                > "breaking through", I
                > have a vision of a piece of steel clamped in a vice,
                > with a slot extending
                > through the end of the steel, ultimately forming a U
                > shaped workpiece.  If
                > this is the scenario, the steel is deflecting into
                > the end mill as you
                > finish the cut, causing vibration and breakage.
                >
                > Regardless, try clamping both sides of the steel
                > down to the table with a
                > sacrificial piece of hardboard or sheet aluminum
                > under it to protect the
                > table, rather than holding in the vice.
                >
                > If you are already clamping to the table rather than
                > using a vice, I've no
                > suggestion.
                >
                > rexarino
                >
                > On Dec 31, 2007 11:19 AM, aldesigns
                > <aldesigns@...> wrote:
                >
                > > Hi all
                > >
                > > When I am cutting a slot, in this case it was 3/8"
                > wide 1/8" deep in
                > > mild steel, it cuts fine until the end where it
                > starts to break
                > > through the material. This is when the endmill
                > starts catching on the
                > > leading edge causing the work and table to vibrate
                > slightly. in this
                > > case it caused the endmill to break. it was a
                > unused new endmill, that
                > > hurts. I do tighten the jibs.  So is there
                > anything else I should be
                > > doing to keep this from happening in the future?
                > Is it a problem with
                > > the operator or the machine? maybe the feed rate
                > was too high or the
                > > work wasn't held secure enough?  Any insights will
                > be greatly appreciated.
                > >
                > > Thanks
                > > Shamas
                > >
                > >

              • cuttysark71
                Shamas, I m assuming that you are cutting the slot that does not go the full length of the work piece. If that is true, simply start at the other end of the
                Message 7 of 14 , Jan 3, 2008
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                  Shamas,

                  I'm assuming that you are cutting the slot that does not go the full
                  length of the work piece. If that is true, simply start at the
                  other end of the part and end the cut against 270 degree contact
                  between the part and the endmill.

                  If my assumption is not correct and the slot goes the full length of
                  the part, mill part way from one end, retract the quill, and finish
                  the cut from the other end. I think that will solve the problem.

                  Jeff

                  --- In mill_drill@yahoogroups.com, "Glenn N" <sleykin@...> wrote:
                  >
                  > I usually kill the power feed near the end of the cut and finish
                  by hand. It always makes nasty sounds at the end as it is pulling
                  the metal into the cut. Also helps to tighten the gibbs a bit to
                  keep it from pulling the table. When the slot opens, one side of
                  the endmill is climb milling with about half the width of the
                  cutter. It takes a very ridgid setup to do that without breaking
                  things.
                  > ----- Original Message -----
                  > From: aldesigns
                  > To: mill_drill@yahoogroups.com
                  > Sent: Wednesday, January 02, 2008 11:40 AM
                  > Subject: [mill_drill] Re: stop breaking endmills
                  >
                  >
                  > I am not cutting all the way through the plate maybe more accurate
                  to
                  > call it a trough. If it was wood you would call it a dado cut. By
                  > breaking through I mean when the cutter reaches the end of the cut
                  and
                  > starts to leave the work piece where a portion of the cutter is
                  > hitting air and the rest is still cutting steel. I use the
                  recommended
                  > speed for that size of endmill perhaps the feed rate is to high. I
                  > just got a new powerfeed for the table and haven't figured out what
                  > the dial settings 1-9 mean in terms of sfm. When I use to crank by
                  > hand I know I would slow the feed at the end of a cut to keep the
                  same
                  > kind of thing from happening. Something maybe loose either the
                  vise
                  > or the table is allowing the cutter to push or pull work just
                  slightly.
                  >
                  > shamas
                  >
                  > --- In mill_drill@yahoogroups.com, Rexarino <rexarino@> wrote:
                  > >
                  > > Shamas, how are you holding the steel? When you say "breaking
                  > through", I
                  > > have a vision of a piece of steel clamped in a vice, with a slot
                  > extending
                  > > through the end of the steel, ultimately forming a U shaped
                  > workpiece. If
                  > > this is the scenario, the steel is deflecting into the end mill
                  as you
                  > > finish the cut, causing vibration and breakage.
                  > >
                  > > Regardless, try clamping both sides of the steel down to the
                  table
                  > with a
                  > > sacrificial piece of hardboard or sheet aluminum under it to
                  protect the
                  > > table, rather than holding in the vice.
                  > >
                  > > If you are already clamping to the table rather than using a
                  vice,
                  > I've no
                  > > suggestion.
                  > >
                  > > rexarino
                  > >
                  > > On Dec 31, 2007 11:19 AM, aldesigns <aldesigns@> wrote:
                  > >
                  > > > Hi all
                  > > >
                  > > > When I am cutting a slot, in this case it was 3/8" wide 1/8"
                  deep in
                  > > > mild steel, it cuts fine until the end where it starts to break
                  > > > through the material. This is when the endmill starts catching
                  on the
                  > > > leading edge causing the work and table to vibrate slightly.
                  in this
                  > > > case it caused the endmill to break. it was a unused new
                  endmill, that
                  > > > hurts. I do tighten the jibs. So is there anything else I
                  should be
                  > > > doing to keep this from happening in the future? Is it a
                  problem with
                  > > > the operator or the machine? maybe the feed rate was too high
                  or the
                  > > > work wasn't held secure enough? Any insights will be greatly
                  > appreciated.
                  > > >
                  > > > Thanks
                  > > > Shamas
                  > > >
                  > > >
                  > > >
                  > > >
                  > > >
                  > > >
                  > >
                  >
                  >
                  >
                  >
                  >
                  > Yahoo! Groups Links
                  >
                • Bob
                  I do not know if anyone has mentioned this or not. Couldn t the rpm of the end mill have a significant affect on breaking end mills? I know I usually guess
                  Message 8 of 14 , Jan 5, 2008
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                    I do not know if anyone has mentioned this or not. Couldn't the rpm of
                    the end mill have a significant affect on breaking end mills? I know I
                    usually guess much too slow compared to what is recomended by the
                    tables I have read
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