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bad collets? - wrenches.jpg

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  • Ole Rosted
    Hi group, Today I started to mill the final parts for my first turnout-jig. I ruined the whole lot. These parts are ment as support for the ties during
    Message 1 of 6 , Feb 2, 2001
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      Hi group,

      Today I started to mill the final parts for my first turnout-jig.

      I ruined the whole lot. These parts are ment as support for the
      ties during soldering and as the ties are only 0,7 mm "high" the
      grooves where they are placed must be reasonably accurate.

      The old gost pulling the mills out from the collet reappeared,
      however, and the grooves are not accurate - to put it mildly.

      I don't understand this. The toy-wrenches that came with the mill are
      - as can be seen to the left in the attached pic - not very good. So I
      bought the two to the right. The collet in my mill is - I think - what
      the Sherline catalog calls: a "WW collet" I don't know what the WW
      stands for, but I do think, that a Morse tapered collet would have
      been better. But WW collets are what I have.

      The endmills I use are high quality 4-flute OSG Micrograin mills with
      a shaft diameter of 3 mm. My digital caliper says they are 2,99 mm.
      The collet is marked: 3mm.
      After I had bought the new wrenches I thought for a moment, that the
      problem with pulled-out-mills was gone. But no! My 1.5 mm (= N-scale
      pcb tie) mill was pulled out several times :-(((

      I may be doing something wrong? Is there anything to take into
      consideration when milling slots as wide as the mill's diameter.
      Should I mill the slots with a smaller dia. mill repeatedly until I
      get the slot as wide as I want?

      I simply don't understand that so much force must be used to tighten
      the collet. A pic of the collet carrier and a collet is inset.

      The picture is low quality, but you'll be able to see what it is, I'm
      talking about.

      regards Ole Rosted
    • Nelson Snedeker
      Hi Ole: From your pictures your collet seems to just have one slot across center. I use blank collets and put custom holes in them to hold odd size materials.
      Message 2 of 6 , Feb 2, 2001
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        Hi Ole: From your pictures your collet seems to just have one slot across
        center. I use blank collets and put custom holes in them to hold odd size
        materials. and with out a precision grinder .00 tolerance is not possible so
        it is necessary to split the collet into 4 segments. Otherwise it will be
        tight only in the North/ South axis and free to oscillate in the East/West
        axis and will lose its setting every time. Buy collets with two slots 90
        degrees to each other or add another slot to your existing collets if that is
        possible.That will compensate, usually for the 1mm difference between the tool
        shaft and the collet bore. Hope this helps Nel

        Ole Rosted wrote:

        > Hi group,
        >
        > Today I started to mill the final parts for my first turnout-jig.
        >
        > I ruined the whole lot. These parts are ment as support for the
        > ties during soldering and as the ties are only 0,7 mm "high" the
        > grooves where they are placed must be reasonably accurate.
        >
        > The old gost pulling the mills out from the collet reappeared,
        > however, and the grooves are not accurate - to put it mildly.
        >
        > I don't understand this. The toy-wrenches that came with the mill are
        > - as can be seen to the left in the attached pic - not very good. So I
        > bought the two to the right. The collet in my mill is - I think - what
        > the Sherline catalog calls: a "WW collet" I don't know what the WW
        > stands for, but I do think, that a Morse tapered collet would have
        > been better. But WW collets are what I have.
        >
        > The endmills I use are high quality 4-flute OSG Micrograin mills with
        > a shaft diameter of 3 mm. My digital caliper says they are 2,99 mm.
        > The collet is marked: 3mm.
        > After I had bought the new wrenches I thought for a moment, that the
        > problem with pulled-out-mills was gone. But no! My 1.5 mm (= N-scale
        > pcb tie) mill was pulled out several times :-(((
        >
        > I may be doing something wrong? Is there anything to take into
        > consideration when milling slots as wide as the mill's diameter.
        > Should I mill the slots with a smaller dia. mill repeatedly until I
        > get the slot as wide as I want?
        >
        > I simply don't understand that so much force must be used to tighten
        > the collet. A pic of the collet carrier and a collet is inset.
        >
        > The picture is low quality, but you'll be able to see what it is, I'm
        > talking about.
        >
        > regards Ole Rosted
        >
        >
        >
        >
        > "Z" WARNING! HANDLE WITH CARE! Highly addictive in Small DoseZ!
        >
        > ------------------------------------------------------------------------
        > Name: wrenches.jpg
        > wrenches.jpg Type: JPEG Image (image/jpeg)
        > Encoding: base64
      • Ole Rosted
        On Fri, 02 Feb 2001 13:33:30 -0800, you wrote: Hello, Thank you for your reply to my letter! ... Actually there is three slots in the collets evenly spaced.
        Message 3 of 6 , Feb 2, 2001
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          On Fri, 02 Feb 2001 13:33:30 -0800, you wrote:


          Hello,

          Thank you for your reply to my letter!

          >Buy collets with two slots 90
          >degrees to each other or add another slot to your existing collets if that is
          >possible.

          Actually there is three slots in the collets evenly spaced.
          Unfortunately this cannot be seen in the photo. 2 more inches added to
          the camera elevation, and the slots would have been clearly visible.
          How stupid of me!

          The slits are *very* narrow. I have a friend in Copenhagen. He has a
          lathe, but I'm not sure he can work on tool-quality steel. If he can
          I'll ask him to make me a more accurate3 mm collet - or perhabs the
          slits in those I have can be made a tiny fraction of a mm wider. (If
          that will be of any help)

          regards Ole Rosted
        • Nelson Snedeker
          OK Ole: That is another posibility if you have 3 slits in your collets.they may need to be wider. or any chips in them may make them close unevenly. Try
          Message 4 of 6 , Feb 2, 2001
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            OK Ole: That is another posibility if you have 3 slits in your collets.they may
            need to be wider. or any chips in them may make them close unevenly. Try closing
            the collet without a tool in it and see if you can start pushing a tool into it.
            Because you have had this problem for some time, the collet hole may be
            bell-mouthed and if you can start a tool into it when it is closed it is either
            that or the collet bore is tapered
            Good luck Nel PS: The original tools should have had
            enough torque to close a good collet

            Ole Rosted wrote:

            > On Fri, 02 Feb 2001 13:33:30 -0800, you wrote:
            >
            > Hello,
            >
            > Thank you for your reply to my letter!
            >
            > >Buy collets with two slots 90
            > >degrees to each other or add another slot to your existing collets if that is
            > >possible.
            >
            > Actually there is three slots in the collets evenly spaced.
            > Unfortunately this cannot be seen in the photo. 2 more inches added to
            > the camera elevation, and the slots would have been clearly visible.
            > How stupid of me!
            >
            > The slits are *very* narrow. I have a friend in Copenhagen. He has a
            > lathe, but I'm not sure he can work on tool-quality steel. If he can
            > I'll ask him to make me a more accurate3 mm collet - or perhabs the
            > slits in those I have can be made a tiny fraction of a mm wider. (If
            > that will be of any help)
            >
            > regards Ole Rosted
            >
            >
            > "Z" WARNING! HANDLE WITH CARE! Highly addictive in Small DoseZ!
          • Don Bouchard
            Ole, The problem you are having is not your fault. Carbide end mills have a nasty habit of walking out of collets even on Bridgeport mills. An easy way to
            Message 5 of 6 , Feb 2, 2001
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              Ole,
              The problem you are having is not your fault.
              Carbide end mills have a nasty habit of "walking out of collets even on
              Bridgeport mills. An easy way to cure this problem is to either bead blast
              or scuff up the shank of the cutter with a diomond file or a silican carbide
              stone. to answer your other question, normaly we do use an under size cutter
              and finish with a second or third cut. By the way you will notice that the
              cutter leaves a better finish in one direction.
              be careful of which way you feed the cutter into the work, heavier cuts
              should be "conventional" meaning the cutter turns toward the direction of
              cut, finish cuts will feed in the opposite direction or what we call "climb
              cutting".
              A little off topic but I hope it helps
              Don


              >From: Ole Rosted <Ole.Rosted@...>
              >Reply-To: z_scale@yahoogroups.com
              >To: z_scale@yahoogroups.com
              >Subject: [z_scale] bad collets? - wrenches.jpg
              >Date: Fri, 02 Feb 2001 21:41:37 +0100
              >
              >Hi group,
              >
              >Today I started to mill the final parts for my first turnout-jig.
              >
              >I ruined the whole lot. These parts are ment as support for the
              >ties during soldering and as the ties are only 0,7 mm "high" the
              >grooves where they are placed must be reasonably accurate.
              >
              >The old gost pulling the mills out from the collet reappeared,
              >however, and the grooves are not accurate - to put it mildly.
              >
              >I don't understand this. The toy-wrenches that came with the mill are
              >- as can be seen to the left in the attached pic - not very good. So I
              >bought the two to the right. The collet in my mill is - I think - what
              >the Sherline catalog calls: a "WW collet" I don't know what the WW
              >stands for, but I do think, that a Morse tapered collet would have
              >been better. But WW collets are what I have.
              >
              >The endmills I use are high quality 4-flute OSG Micrograin mills with
              >a shaft diameter of 3 mm. My digital caliper says they are 2,99 mm.
              >The collet is marked: 3mm.
              >After I had bought the new wrenches I thought for a moment, that the
              >problem with pulled-out-mills was gone. But no! My 1.5 mm (= N-scale
              >pcb tie) mill was pulled out several times :-(((
              >
              >I may be doing something wrong? Is there anything to take into
              >consideration when milling slots as wide as the mill's diameter.
              >Should I mill the slots with a smaller dia. mill repeatedly until I
              >get the slot as wide as I want?
              >
              >I simply don't understand that so much force must be used to tighten
              >the collet. A pic of the collet carrier and a collet is inset.
              >
              >The picture is low quality, but you'll be able to see what it is, I'm
              >talking about.
              >
              >regards Ole Rosted
              >
              >
              ><< wrenches.jpg >>

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            • Jay & Anne Greer
              Hi Ole, I have been following your letters about the problems you have been having with your mill and sharing in your frustration. All of the advice sent to
              Message 6 of 6 , Feb 4, 2001
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                Hi Ole,
                I have been following your letters about the problems you have been having
                with your mill and sharing in your frustration. All of the advice sent to
                you I have read is valid. I will also give you a little input here. The WW
                Collets by Sherline are lathe collets that are designed to hold a long piece
                of stock that passes through the collet and into the hollow draw bar
                assembly. The mill collets that I purchased with my metric mill are three in
                number, being 3,4 and 6mm they are a #1 Morse taper and are taken up with a
                draw bolt. The collets are not designed to have the end mill cutters pass
                through them. Now, you have a different kind of collet chuck that is taken
                up by tightening a threaded collar rather than using a draw bolt. Several
                things can happen here. Assuming that the collet has not been damaged by the
                end mill walking out of it and damaging the bore, you should have a slip fit
                of between the cutter and the collet of approx. .025mm before it has had any
                pressure applied. That means that you should feel a slight drag when putting
                the tool into the collet. If the tool is loose in the collet before take up
                it will distort a little and cause the tool to wobble. A light film of wiped
                on oil will help the collet slide on it's taper but don't oil the tool
                gripping surface. Now, before you tighten the holder with the wrenches,
                make sure that the tool has not bottomed out in the holder. Leave yourself
                about 1mm clearance here or you will be forcing the shank of the cutter
                against the bottom of the holder and when you start applying pressure, that
                can cause the whole works to go out of whack because you are trying to force
                the bottomed out tool further down whilst trying to grip it. The cutter
                should be smaller than the width of the cut you want to make and should move
                in against the direction of tool rotation just as your razor trims your
                beard or a wood plane cuts. Your cuts should be light until you develop a
                feel for the tool. It will talk to you through your hands and you will
                unconsciously develop an inner sense for what you are seeing happen. Take
                your time and don't try to hog out more material than your tool can handle
                in one pass. I mentioned to you in an earlier letter that a dial indicator
                can be a good thing. It will tell you if your tool holder is running
                concentricly by mounting it on the table, running it up against a piece of
                drill stock held in the tool holder and slowly rotating the machine by hand
                or running it on "granny" (really slow).
                I know what you must be going through but just be patient and I am sure you
                will be successful! You might also have that machinist friend check out your
                mill for you. There are also collets that have an extra set of slots cut
                from the back side but they are very expensive and I don't think they are
                called for here.
                I hope this helps a little.
                Best Wishes,
                Jay Greer/Der Wegmann

                > From: Ole Rosted <Ole.Rosted@...>
                > Reply-To: z_scale@yahoogroups.com
                > Date: Sat, 03 Feb 2001 01:06:16 +0100
                > To: z_scale@yahoogroups.com
                > Subject: Re: [z_scale] bad collets? - wrenches.jpg attn: Nelson Snedeker
                >
                > On Fri, 02 Feb 2001 13:33:30 -0800, you wrote:
                >
                >
                > Hello,
                >
                > Thank you for your reply to my letter!
                >
                >> Buy collets with two slots 90
                >> degrees to each other or add another slot to your existing collets if that is
                >> possible.
                >
                > Actually there is three slots in the collets evenly spaced.
                > Unfortunately this cannot be seen in the photo. 2 more inches added to
                > the camera elevation, and the slots would have been clearly visible.
                > How stupid of me!
                >
                > The slits are *very* narrow. I have a friend in Copenhagen. He has a
                > lathe, but I'm not sure he can work on tool-quality steel. If he can
                > I'll ask him to make me a more accurate3 mm collet - or perhabs the
                > slits in those I have can be made a tiny fraction of a mm wider. (If
                > that will be of any help)
                >
                > regards Ole Rosted
                >
                >
                >
                >
                > "Z" WARNING! HANDLE WITH CARE! Highly addictive in Small DoseZ!
                >
                >
                >
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