Announcement

Collapse
No announcement yet.

M head bridgeport mill, does the head slide forward?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • M head bridgeport mill, does the head slide forward?

    Just got an M head and know very little about it yet. I have only used a J head. Does the head slide in and out on the big shaft like J head? It has the crank handle to rotate the shaft that it would have to be splined to so I don't see how it could move much if at all. Information on these things is apparently quite rare. Also, have you heard of anyone putting a J head on an old M head.

  • #2
    The "big shaft" you describe is commonly known as the ram, and yes it does slide. However, rams are notorious for being a bit sticky if they havent been moved very much even on dovetail ram machines, and they typically dont get moved too often.

    One trick that I do occasionally when I notice the ram sticking on the typical Bport style turret mill is to remove the motor, then rotate the ram so the head is upside down and use the table to support it. I then unbolt the head from the ram (4 big bolts on the front face of the head), and lay it over on the table. With the head removed a lot of the cantilevered weight thats binding up the ram disappears, and a few gentle raps on the back-end of the ram with a small sledge/deadblow/hammer should free it up nicely. Lubricate the ram well and it should remain free for at least a couple weeks.

    As for installing a J-head in place of the M-head, a J is quite a bit heavier and physics works against you. Bport did a similar factory conversion, however they eliminated the rather tiny/weak "nod" knuckle and bolted the head directly to a special ram as shown below. When they came out with the dovetail ram machines, they used a newer, larger nod knuckle which I doubt would fit the earlier machines. Ive got one of the factory J-head/round ram machines and dont really miss the nod knuckle much, not sure how much work youd want to do to adapt a J in place of the M either as I see little benefit either way unless youre boring a lot. If yours is an early machine with the vertical split in the turret casting I wouldnt even consider swapping heads bc Ive heard from many that those castings are somewhat easy to break. Some folks think Im crazy, but one of these days Im going to stick an M on the other end of my machine's ram opposite the J, that way I can do weird angle milling easily w/the M and leave the J close(?) to tram.

    "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

    Comment


    • #3
      Yes, there were several variants of the turret assembly on the "round ram" Bridgeports. Earlier units had binder handles with a vertical split, while later ones after WW-II had two cap screws and the split was along the side. The hand wheel, which is often lost, allows you to rotate the ram right or left. To move the ram in or out you simple pushed or pulled it. The gear connected to the hand wheel is keyed to the ram allowing the ram to slide.

      Comment


      • #4
        Welcome! The one I owned had the split on top & was 110v from the factory. Worked fine but only 3.5" stroke of the quill & not R8 but came with a full set of collets.
        I have a 110v shaper for the rear but I'll put it in the J head.
        Last edited by flylo; 04-24-2015, 12:18 AM.
        "Let me recommend the best medicine in the
        world: a long journey, at a mild season, through a pleasant
        country, in easy stages."
        ~ James Madison

        Comment


        • #5
          That picture shows a rack cut in the ram and a vertical shaft to rotate a gear meshing with the ram. This would move the ram in and out. I have a Bridgeport with a geared round ram but the turret does not have provisions for the gear to drive it. The machine has a J head on it.
          Don Young

          Comment


          • #6
            I do have the type with the vertical split, guess I will forget that idea. Strong proponent of the if it aint broke don't fix (break) it. Not that me or any of us have tried to make something better and ended up ruining it....

            Comment


            • #7
              Originally posted by Don Young View Post
              That picture shows a rack cut in the ram and a vertical shaft to rotate a gear meshing with the ram. This would move the ram in and out. I have a Bridgeport with a geared round ram but the turret does not have provisions for the gear to drive it. The machine has a J head on it.
              Not sure why he picked that picture. I've seen lots of Bridgeports and I've never actually seen a mill with that configuration. I'm guessing that was an early attempt at a better mechanism prior to the decision to go with the dovetail ram we know today. Some people think the J heads were adapted to the round ram "M Head" machines, and in some cases that is true, but I believe that BP began selling the round ram miller body with the J head and after becoming aware of its deficiencies the new v way ram turret was designed to replace it. Evidence of this is suggested by all the factory art work showing round ram mills with J heads mounted, including manuals.

              Comment


              • #8
                Originally posted by leod12 View Post
                I do have the type with the vertical split, guess I will forget that idea. Strong proponent of the if it aint broke don't fix (break) it. Not that me or any of us have tried to make something better and ended up ruining it....
                Don't give up on it, loosen the bolts soak it with Kroil & it will turn & slide just fine. Just keep oiling it, trying to move it & don't forcr it & it will go. Patience is a virtue.
                "Let me recommend the best medicine in the
                world: a long journey, at a mild season, through a pleasant
                country, in easy stages."
                ~ James Madison

                Comment


                • #9
                  Originally posted by Ohio Mike View Post
                  Not sure why he picked that picture. I've seen lots of Bridgeports and I've never actually seen a mill with that configuration. I'm guessing that was an early attempt at a better mechanism prior to the decision to go with the dovetail ram we know today. Some people think the J heads were adapted to the round ram "M Head" machines, and in some cases that is true, but I believe that BP began selling the round ram miller body with the J head and after becoming aware of its deficiencies the new v way ram turret was designed to replace it. Evidence of this is suggested by all the factory art work showing round ram mills with J heads mounted, including manuals.
                  I chose that pic bc it was the first one I could find on Tony's site showing the head mounted directly to the ram and bc I was too lazy to wander out to the shop to snap a closeup of mine. Ive seen several instances of the rack gear on the ram, but as you mention its pretty rare. My 1952 round ram/J-head doesnt have it, not sure I care that its absent.

                  Bport sold the J-head on the round ram machines starting in 1951 and continued through sometime in 1956 when they started selling the smaller base with a unique dovetail turret on it. In 1957 they started selling the larger base. With the round ram+J-head, they never had a nod feature from the factory and used a special J-head without the head tilt-gear, but they did still sell M-head round rams w/nod throughout those years as well. Not sure I'd see either version as being deficient, theyre all good machines with the limiting factor being the head, not the machine itself.
                  "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

                  Comment

                  Working...
                  X