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  • Holding end mills in the lathe

    .........I bought a Palmgren #250 milling attachment for my 11" Logan and would like some input as to how to hold endmills etc.

    First I'd like to add that the lathe has a 5C lever collet closer and I have an adjustable collet stop. I also have a spindle insert to accept a 3MT. So knowing that, suggestions?

    Thanks,
    Rick
    Son of the silver stream ..... Bullet caster.

  • #2
    Rick, I also have a Logan 11" with a collet closer and a homemade milling attachment. I use collets to hold endmills. This method is not the 'approved' way to hold an endmill, but in a lathe you're not taking big cuts (right?) so you can get away with it. Light cuts, slow feed, and I have been getting good results.

    Good Luck

    Alex
    Alex

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    • #3
      End mills have "crept out" on my Logan 10" using the Palmgren 250, and it wasn't pretty. Busted the work and the end mill.

      I wised up and got an end mill adapter with drawbar. It uses a setscrew in the "Weldon groove".

      I set it half-snug, and tug on the E/M so it is out against the screw before tightening setscrew all the way. No more creeping and crashes.
      1601

      Keep eye on ball.
      Hashim Khan

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      • #4
        <font face="Verdana, Arial" size="2">Originally posted by J Tiers:
        End mills have "crept out" on my Logan 10" using the Palmgren 250, and it wasn't pretty. Busted the work and the end mill.

        I wised up and got an end mill adapter with drawbar. It uses a setscrew in the "Weldon groove".

        I set it half-snug, and tug on the E/M so it is out against the screw before tightening setscrew all the way. No more creeping and crashes.
        </font>
        .........Okay, so if I understand you're saying I should use the 3MT spindle insert with a 3MT endmill holder that takes a drawbar I stick through the spindle and tighten?

        Regards,
        Rick

        Son of the silver stream ..... Bullet caster.

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        • #5
          Yes.

          Holding one piece of hardened steel (end mill) clamped between other pieces of hardened steel (collet or chuck jaws) just dowen't work very well. Things slip, and the end mill wants to pull out due to the spiral flutes.

          If your 3MT adapter is good, the runout won't be excessive. The setup is so floppy anyway that a little runout probably wouldn't even be noticeable.
          1601

          Keep eye on ball.
          Hashim Khan

          Comment


          • #6
            Pardon my ignorant newbie question: On a small (8x16) lathe with a milling adapter, can you just chuck your milling cutter in the regular 3-jaw? My usage would be to make light cuts in aluminum. Is it the concern that the cutter will slip that makes this practice a no-no?

            Thanks!
            Milton

            "Accuracy is the sum total of your compensating mistakes."

            "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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            • #7
              I use a #3MT taper mill holder that is friction fit into the spindle. The holder, with it's precision bore and set screw, does a good job of centering and securing the mill. However, I also have had some "creap out" events where the mill holder comes loose from the spindle. Fortunately, none of these events were disasterous. I agree that the drawbar type holder is the way to go for safety and security.

              The palgren 250 is just OK for simple milling tasks. As others have said the setup is "floppy". This is the biggest problem with toolpost mounted milling attachments, lack of rigidity. You will be limited to very light cuts with slow feeds. Aluminum is much easier to mill with the toolpost attachment than is steel. Don't try to make any single pass cuts for slots and the like, else your lathe is going to bounch all over the place and the slot will look like someone beat it with a ballpeen hammer.

              I finally got the milling attachment made for my latthe (atlas 10F) that mounts directly on the cross slide. This setup improves rigidity significantly, but is still pretty flexible.

              One day, my own milling machine...

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              • #8
                I use MT3 collets in my SB9 with a drawbar and have had no problems, so far. Absolutely no sign of "creep".
                Free software for calculating bolt circles and similar: Click Here

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                • #9
                  <font face="Verdana, Arial" size="2">Originally posted by DICKEYBIRD:
                  Pardon my ignorant newbie question: On a small (8x16) lathe with a milling adapter, can you just chuck your milling cutter in the regular 3-jaw? My usage would be to make light cuts in aluminum. Is it the concern that the cutter will slip that makes this practice a no-no?
                  Thanks!
                  </font>
                  <font face="Verdana, Arial" size="2">
                  I use MT3 collets in my SB9 with a drawbar and have had no problems, so far. Absolutely no sign of "creep".
                  </font>
                  I have used them in a 3 jaw, and been OK also. And my vertical mill head has a MT2 spindle, so I use collets too.

                  You can get away with nearly anything for a while. Then one day it gets you. And there are exacerbating conditions also.

                  It seems to have something to do with rigidity, or lack thereof. A rigid setup, such as my mill head, tolerates the collets pretty well. And, R8 collets are, after all collets, and they hold decently.

                  If there is a looseness in the structure, that seems to allow a repetitive catch/release cycle. It appears that the edge of the cutter digs in, pulls in, and then releases and springs back as the chip is cut. The torque on the cutter varies wildly during this cycle.

                  Basically it is a chatter cycle, even if you don't see/hear chatter. Chatter can act like an impact wrench, causing a little slip each cycle.

                  Once there is any slip, you don't know the direction of slip. If the cutter can turn in the collet, it may also slide out a little as it turns. The static friction has been released to sliding friction. So pull-out can occur more easily.

                  The Palmgren is loose enough (looking at whole setup) that it is certainly susceptible to that cycle. Therefore I would expect it to cause more trouble.

                  Evan's setup is ungodly rigid by comparison, and may be nearly immune to the problem.

                  1601

                  Keep eye on ball.
                  Hashim Khan

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                  • #10
                    Don't try to make any single pass cuts for slots and the like, else your lathe is going to bounch all over the place and the slot will look like someone beat it with a ballpeen hammer.

                    I agree with you. IF you do wish to to take anything more than light cuts, use a roughing end mill. It is amazing how much better it will work. I can even get by with a fine tooth roughing end mill and get an acceptable finish on many things I machine yet I am able to machine much more at a pass.

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                    • #11

                      "Don't try to make any single pass cuts for slots and the like, else your lathe is going to bounch all over the place and the slot will look like someone beat it with a ballpeen hammer."

                      I agree with you. IF you do wish to to take anything more than light cuts, use a roughing end mill. It is amazing how much better it will work. I can even get by with a fine tooth roughing end mill and get an acceptable finish on many things I machine yet I am able to machine much more at a pass. [/B][/QUOTE]



                      [This message has been edited by sidneyt (edited 04-26-2004).]

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                      • #12



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                        • #13
                          Just a thought here- it's a useful practise to lightly oil cutters and holders against rust, and to clean them before using. This should leave only a very thin film of oil so slippage shouldn't be a problem. The thought that came to mind is that there are so called 'traction' oils. Maybe there would be an advantage to using such a type of oil for this purpose. It grips under tension instead of slipping, so it seems to me anyway to be a natural for reducing or eliminating cutter creep. Obviously it won't improve a lack of rigidity in the setup, but just help to keep the cutter from moving.
                          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                          • #14
                            Traction oil would certainly work in that application. I have a good supply of it and use on various things. It is interesting stuff, it lubricates just fine for rolling contact but has very high shear strength and greatly reduces the chance of slippage. I haven't needed it for the milling bits but it would help for sure if you had a slipping problem. I make sure the collets and cutter are clean and with next to no oil on them as well as the spindle bore.

                            [This message has been edited by Evan (edited 04-26-2004).]
                            Free software for calculating bolt circles and similar: Click Here

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                            • #15
                              <font face="Verdana, Arial" size="2">Originally posted by sidneyt:
                              Don't try to make any single pass cuts for slots and the like, else your lathe is going to bounch all over the place and the slot will look like someone beat it with a ballpeen hammer.

                              </font>
                              That is true, and also suggests that the usefulness of the milling setup is less than it seems.

                              One quite often wants to start a slot in solid material, even if it is widened later. The combination of climb and down milling involved in starting a slot in solid material can even break cutters in a floppy setup like the Palmgren.

                              One more strike against them. Rigidity rules.
                              1601

                              Keep eye on ball.
                              Hashim Khan

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