Loading ...
Sorry, an error occurred while loading the content.

Re: [z_scale] bad collets? - wrenches.jpg attn: Nelson Snedeker

Expand Messages
  • 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 1 of 6 , Feb 2, 2001
    • 0 Attachment
      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 2 of 6 , Feb 2, 2001
      • 0 Attachment
        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 3 of 6 , Feb 2, 2001
        • 0 Attachment
          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 >>

          _________________________________________________________________
          Get your FREE download of MSN Explorer at http://explorer.msn.com
        • 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 4 of 6 , Feb 4, 2001
          • 0 Attachment
            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!
            >
            >
            >
          Your message has been successfully submitted and would be delivered to recipients shortly.