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Some really basic knee mill questions ...

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  • Some really basic knee mill questions ...

    I'm moving from a 3-in-1 mill/drill to a full size knee mill. So I have some
    really basic questions.

    Whats with the ram/overarm. It makes me want to extend it far out so that
    I can extend the saddle/table way out in front. To be convenient to work on.
    But something tells me that keeping it back more against the mill body helps the rigidity.

    Same thing with the quill. It would be nice to extend it down and lock it .. and
    lower the knee .. and do my milling that way .. so that the table is lower and
    more comfortable to work on. But .. I'm probably going to hear that it is better
    to have the quill all the way up and locked for that same rigidity thing.

    I have a bunch more ... but .. will ask them later
    John Titor, when are you.

  • #2
    Youy gut feeling is correct. Especially when it comes to the quill position.

    Comment


    • #3
      Quill is only for drilling and boring. Keep it in and locked. Only exception is when you cant reach something.

      Ram is usually set so the tool is in the middle of the travel.

      Comment


      • #4
        I made a transition from a round column mill-drill to a dovetail column mill with the head on the dovetail column. This may be similar to your change in that for no good reason, I at first assumed that the dovetail would keep the head aligned at all times. Not so: if the dovetail is not locked down, then the weight of the head will cock it outwards and you loose the spindle alignment. I found that it was necessary to keep the head locked for all setup and milling operations. Only in this way was the spindle position retained. I would think that a knee mill would have the same "problem" with the dovetail that the table rides on and it should be locked down for all operations.
        Paul A.

        Make it fit.
        You can't win and there is a penalty for trying!

        Comment


        • #5
          cool .. thanks .. no surprises ...

          except maybe the ram .. being in the middle of the work makes total sense.
          John Titor, when are you.

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          • #6
            Congratulations on the upgrade.

            Ken

            Comment


            • #7
              Yep congradulations from me too, you'll love the difference. I went from a X2 to a 3/4 sized Bridgeport clone. I was tempted to turn that X2 into chips.

              A knee mill is slightly different than a milling head that rides on a dovetail. Yes the knee can very slightly lean forward when the locks are slacked off. But you need to remember, you also have the knee feed screw that acts as a third support. On really critical work, you could if needed preload that feedscrew till the table was dead flat. A bit of testing would tell you how much to nod the head to allow for dead straight alignment with the table unlocked if it was needed.

              I keep my ram as far in as practical, that does make a noticeable difference. I've heard but can't verify that some knee mills aren't setup too well for the head lubrication with the head rotated over so the spindle is horizontal, it can be done, but it's not recommended on some mills for long periods of milling with the head in that position.

              You may already know this, but lots of the knee mills come with a zerk fitting on the side of the head. THEY DON'T TAKE GREASE!!!!! That zerk fitting is for oil.

              Pete

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              • #8
                I am actually starting to worry a bit. I think it may be a bit big for my needs. When I walk up to it
                in my shop .. I have this urge to say :

                Klaatu barada nikto

                I really wanted a millrite ... size wise and BP/R8 compatability wise. I dont have a problem with
                the collets .. no power feed is a real bitch though .. my arms are tired. And you just can't
                find powerfeeds available for this beast.

                Now I have this desire to have a mill that I can use manually ... or .. flip the switch and have
                CNC talk to it. I'm really tempted to throw some big steppers on this thing and do that .. but
                the size issue is still there. I think I will keep playing with this thing and keep looking for a
                slightly smaller Millrite type mill.


                John Titor, when are you.

                Comment


                • #9
                  You are the first I've heard wanting a SMALLER machine tool........ Don't you'll regret it!

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                  • #10
                    Originally posted by mikeamick View Post
                    When I walk up to it
                    in my shop .. I have this urge to say :

                    Klaatu barada nikto
                    Does that bring work to a standstill, or fire up your laser cutter?

                    Comment


                    • #11
                      Originally posted by macona View Post
                      Quill is only for drilling and boring. Keep it in and locked. Only exception is when you cant reach something.

                      Ram is usually set so the tool is in the middle of the travel.
                      I agree with you completely - but we have this argument regularly in the shop and one of our old time machinists here maintains it makes no difference because Bridgeport doesn't recommend one way or the other...so I looked all over the 'net and in Bridgeport's machine manuals and sure enough, he is right that it's not mentioned. Of course, I believe it was simply overlooked and he interprets it to mean the quill is designed to work in any position.

                      Comment


                      • #12
                        Originally posted by Euph0ny View Post
                        Does that bring work to a standstill, or fire up your laser cutter?
                        lol .. good one
                        John Titor, when are you.

                        Comment


                        • #13
                          Originally posted by mikeamick View Post
                          I really wanted a millrite ...
                          I can solve that problem, if you can bring that Cincinnati to Fort Worth

                          Comment


                          • #14
                            One of the coolest things about turret mills ("Bridgeport" is to "turret mill" as "Kleenex" is to "facial tissue") is seldom exploited by most users: the turret swivels and the ram extends and retracts. You can set up a large workpiece and access all past of it without shifting the set up.

                            Simply swivel the turret and extend the ram until the spindle is in the neighborhood of the new feature you wish to machine. You maintain tram. All you have to do is re-reference from a previously machined feature.
                            Last edited by Forrest Addy; 08-28-2012, 12:04 PM.

                            Comment


                            • #15
                              Your mill won't seem so big when you get it off the pallet that it's sitting on, I had a friend that was only 4' 11" he ran a vari speed BRPT had a little platform he worked off, the shop he worked at came out and saw what he was using and said NO, had there maint. shop build him a platform that stuck out about 24" and wrapped around the sides about 20" and they made it 60" long it was about 6" tall

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