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  • Bridgeport facing limitations(?)

    I have a 1980 model Bridgeport mill with the J-head and 2HP. I want to buy some facing shell mill cutters. I haven’t any at the moment and have never used a shell mill either. I do have a set of Bison arbors, which I got in a tool lot I purchased. I’m not sure what to buy, especially when it comes to their size/diameter. At what size will I be pushing my machines limitations for roughing and light finishing cutting? Don’t want to buy something I won’t be able to use.

    -SD:

  • #2
    Are you looking for shell mills or for facing mills? They are two different cutters. As I was taught years ago, you should not use any cutter larger than 2" dia. in a Bridgeport. I have and regularly use a 3" 5 insert facing mill in a Bridgeport mill with sucess. However, I am using it for aluminum and plastics only.
    Paying Attention Is Not That Expensive.

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    • #3
      I didn't mention I'm a complete novice. Mind telling me the difference between the two as far as usage. I thought a shell mill was used to face material, just like a end mill but larger diameter. I had no idea a Bridgeport was such a wimp'ie machine.

      -SD:

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      • #4
        James
        I would watch eBay for a Sandvik or kennametal facemill 3" or samllw <5 5 inserts if possible and most iportantly the face mill must be POSITIVE geometry to be of any use to you. This will reduce the HP requirement and allow you to cut more than you would normally be able to do with the HP that you have. Also the positive geometry is what you want for Aluminum - the more the better.

        Stay away from negative or neutral geometry tooling unless you need them for heavy duty cutting (Ti, refactory metals, etc.) - these are used mostly on high horsepower CNC machines and are of extremely limited use to the average machinist.

        If you need help selecting a facemill ask your nephew or email me if you find one that grabs your snappy. One thing to note is the arbor sizes that you possess now and to note the size used on the face mill.

        Be wary of facemills with weird inserts as they can cost you dearly topurchase them - this is your other consideation. Round inserts are the strongest, then square, then trilobular, then triangular. Round and square insert are cheap, square inserts are the best economy as you have 4-8 corners to use before tossing them.

        Avoid brazed facemills unless you have a diamond cup wheel and a tool grinder to resharpen them often.

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        • #5
          i would say SD that you are cautious.
          and you yourself will know when you are pushing the limits of the machine.
          listen to the machine .....let the machine tell you that you are overworking it.
          the bridgeport speaks to you in this way.
          if tou put a 3.5 inch mill into the machine, then ...just machine away.....you will know when you are overdoing it by the sound of the motor and vibrations.....I think that you nead not worry because I think you understand anyhows .......because you are asking this question in the first place.
          All the best.....mark

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          • #6
            If you are looking for a face mill for BP and not concerned about square corners Valenite has a series of cutters that take are designed specifically for low horse power machines like BPs. I'm not sure but I think they call them High Shear Mills. The inserts are layed over at about a 30 degree angle and present a 45 degree angle on the outside. As long as one insert is in the work they cut very quiet and will remove an impresive amount of material for that size machine. Are available with either R8 shanks or as mounteable cutter bodies. The R8 models with 4 inserts about 2.5" Diameter will work .100" deep at 75% of the diameter with no problem
            Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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            • #7
              As far as the difference between shell and facing mills, when I hear "shell mill" I think of shell reamers, as they have no capability of cutting across the face of a flat surface. A face mill will only cut across a flat surface. As long as a shell mill has end and side cutting faces like an endmill, you can use it as a facing mill. I wouldn't call a Bridgeport "wimpy", but it is not a high horsepower, high torque, metal hogging machine, such as a horizontal mill. You can remove a lot of metal, though it may take a lot of passes and some time. As aboard_epsilon said, your machine will tell you when you are trying to do too much.



              [This message has been edited by ERBenoit (edited 11-30-2004).]
              Paying Attention Is Not That Expensive.

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              • #8
                Man, can’t believe how much there is to learn, totally overwhelming, at times, it seems. I simply didn’t want to buy a 4â€‌ or 5â€‌ face mill, indexable or otherwise and not be able to use it. I know my machine will let me know its’ hurting, just didn’t want to hurt my slim pocket book to boot.

                Spin Doctor:

                What the heck does “be concerned about square cornersâ€‌ mean? Sorry, don’t understand what you mean.

                Thanks for the help,
                -SD:

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                • #9
                  <font face="Verdana, Arial" size="2">Originally posted by Smokedaddy:
                  What the heck does “be concerned about square cornersâ€‌ mean? Sorry, don’t understand what you mean.</font>
                  -He means the facing cutter uses square indexible carbide bits, mounted to the holder at an angle, so only one corner of each insert rides on the workpiece.

                  It's great for making flat surfaces, but due to the angled insert, you can't do a 90-degree ridge/edge/step with it.

                  Doc.
                  Doc's Machine. (Probably not what you expect.)

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                  • #10
                    And if ya got a lot of spare cash and want 1 face mill to do lots of jobs buy an Iscar Chameleon face mill. It takes 4 different insert shapes. Round, Octagonal, Square, And square with 45 degree corners.

                    http://www.iscar.com/ecat/familyHDR....1&lang=ENangle
                    Precision takes time.

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                    • #11
                      So if I have it right, on a positive geometry tool, using inserts, the cutting face of the insert is parallel with the material your facing. Anything "other" than that identifies a negative rake indexable facemill.

                      Thanks,
                      -SD:

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                      • #12
                        no.

                        assume directiopn of travel is to the right for symbols below -&gt;

                        positive is angled back \ (like you would angle a knife to cut into something, like a normal endmill it presents a sharp edge)

                        neutral is perpindicular |

                        negative is angled forward / (actually sort of smears material off.)

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                        • #13
                          For facing large plates I also use a 4" face mill.

                          It has 6 HSS bits clamped to it. The bits are 3/8" square and ground with pos. rake angle. Similar to how you would grind a bit for the lathe.

                          I don't "hog" big time with this setup but it produces a very fine finish on steels and aluminum.

                          Just another thought. JRouche
                          My old yahoo group. Bridgeport Mill Group

                          https://groups.yahoo.com/neo/groups/...port_mill/info

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                          • #14
                            <font face="Verdana, Arial" size="2">For facing large plates I also use a 4" face mill. It has 6 HSS bits clamped to it. </font>
                            I assume that it is necessary (or desirable) to carefully set the 6 bits so that they each contribute to the cut. If this is true, how do you go about doing it?
                            Don Kinzer
                            Portland, OR

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                            • #15
                              dsergison ...

                              A graphic illustration always makes it perfectly clear for me. Good news … my nephew gave me 3 Sandvik catalogs this morning with some outstanding graphical pictures. Hopefully I’ll be able to figure out all the coding.

                              Thanks,
                              -SD:

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