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  • Bridgeport to HBM conversion?

    Hi all,

    i have a task coming up and i'm not sure of the best way to tackle it. Its a cylinder for a traction engine, the big lump on the floor here...


    I need to bore out the cylinder to 3-1/8" and cut the saddle to a 6" radius. The only machine it will fit on realistically is my Bridgeport. The saddle length is about 10" and cylinder depth is about 7-1/2"

    I have successfully cut a 6-1/2" radius on a shorter length saddle before and that worked well, it was done in two parts using the quill feed and a 3" boring head with 3/4" tooling.

    This job is much larger though. The quill wont fit into the cylinder so i cant use the boring head on this. I had thought of turning the BP head 90deg and using a home made boring bar with some sort of sliding tailstock a bit like a horizontal borer, the tailstock idea was just to take some strain off the quill. This would mean i could use the table powerfeed and keep the quill locked in. I dont know if this would work or not or is there a better way? It would mean running the mill at 90deg for some time.

    The other option is to make a longer boring bar and use the mill vertically, cutting from the knee lift, this sounds very tedious as i dont have a power knee lift.

    Any ideas on a good setup?

    Much appreciated
    Dave
    If it does'nt fit, hit it.
    https://ddmetalproducts.co.uk
    http://www.davekearley.co.uk

  • #2
    I sure like your steam tractor, nice job.
    It's only ink and paper

    Comment


    • #3
      Originally posted by Carld
      I sure like your steam tractor, nice job.
      Thanks for that, i'm selling it now to provide funds for the big engine, i was hoping to keep it but you cant always do what you want i suppose.

      Dave
      If it does'nt fit, hit it.
      https://ddmetalproducts.co.uk
      http://www.davekearley.co.uk

      Comment


      • #4
        If you have a lathe large enough, could you use it in the HBM role? Might be a bit tedious to set up, but would probably work well.

        Comment


        • #5
          i could sell you an engine boring bar ..

          needs motor and handle to be operational

          £35 and its yours

          all the best.mark

          Comment


          • #6
            Good job for a line boring rig

            Comment


            • #7
              Hi all,

              thanks for the ideas so far, no it wont fit in the lathe as its, well i could do the cylinder in the lathe but not the saddle and both must be parallel and true to each other. I dont have a line boring rig. Thanks for the offer of the cylinder borer, is there a picture anywhere?

              Dave
              If it does'nt fit, hit it.
              https://ddmetalproducts.co.uk
              http://www.davekearley.co.uk

              Comment


              • #8
                Can't you make up a long boring bar for your boring head, one with a cutting edge which comes just outside the head profile? You can make it thicker than your boring head fitting, just reduce the dia to fit in the head, that'll make it a bit stiffer. Even if the quill won't fit into the bore I presume the actual boring head will do so if you get the bar right, so the bar won't need to be the full length of the cylinder?

                Tim

                Comment


                • #9
                  Originally posted by Davek0974
                  ...I had thought of turning the BP head 90deg and using a home made boring bar with some sort of sliding tailstock a bit like a horizontal borer...

                  The other option is to make a longer boring bar and use the mill vertically, cutting from the knee lift, this sounds very tedious as i dont have a power knee lift.
                  Something a bit like this?

                  http://www.wrexham.gov.uk/images/mus...machine_lg.jpg

                  Instead of a sliding tailstock, it might be easier to to have a fixed bar support (or even two, one either end of the cylinder and tight to it) and arrange for the bar to slide through it on a bearing. Hydraulic ram material is available in many diameters and might be good for the bar.

                  Could you rig up a cordless drill to provide a power knee?

                  In both cases, I'd be tempted to bore such that the bar is in tension when cutting (i.e. drop the knee/feed away from the head).

                  If you can do the cylinder in the lathe (either on a big faceplate or by clamping to the saddle and using a between centres bar), setting up to do the saddle shouldn't be too difficult. A parallel bar through the cylinder (again, hydraulic ram material), bushed if necessary, and supported on matched V-blocks would do, and you can indicate the bar in two planes to ensure it is aligned with the mill's axes.

                  Comment


                  • #10
                    What about an extension to fit your boring head?





                    Far more rigid than a sticky out bar. Just make it deeper to suit your travel.

                    .
                    .

                    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                    Comment


                    • #11
                      Clearly you need a 3" boring head rather than a 4". Why not bore the first 5" (BP quill travel), then raise the knee 3" or so with the head inside to to get the last couple of inches. You may need to crank the knee a bit to make the adjusting screw visible.

                      Comment


                      • #12
                        Originally posted by John Stevenson
                        What about an extension to fit your boring head?





                        Far more rigid than a sticky out bar. Just make it deeper to suit your travel.

                        .
                        That i think is the answer, a couple of longer shafts and a bar to take a tool should do it. I can use quill and knee for the cut and make a longer base bar for the big radius, should be better than a long tool.

                        Thanks for that

                        Dave
                        If it does'nt fit, hit it.
                        https://ddmetalproducts.co.uk
                        http://www.davekearley.co.uk

                        Comment


                        • #13
                          Originally posted by kvom
                          Clearly you need a 3" boring head rather than a 4". Why not bore the first 5" (BP quill travel), then raise the knee 3" or so with the head inside to to get the last couple of inches. You may need to crank the knee a bit to make the adjusting screw visible.
                          Yes the head is a 3" one, as said above i'll make a version of that head adaptor with some 1" rod supports and try that with part quill and part knee, should do the job.

                          Dave
                          If it does'nt fit, hit it.
                          https://ddmetalproducts.co.uk
                          http://www.davekearley.co.uk

                          Comment


                          • #14
                            Dave
                            just a heads up
                            When you tram the head in before doing the long bore work,
                            Put two angle plates on the table at right angles.
                            using a Dial indicator run the quill up/down and check for perpendicularity.
                            Then, without moving anything, raise the knee and see if you get movement.
                            If you do, lock the knee and see how much change you get. Hopefully it goes to zero.

                            We did long bores at work and when a knee wears, it can throw off the job.
                            You also may want to consider starting at the bottom ( !) and boring upwards ....
                            You gain two things.
                            No swarf buildup, as it stacks up in the area already cut , and second,
                            the knee is much smoother going down.( if it isn't worn to badly)
                            A bridgeport will cut in either direction.
                            Rich
                            Green Bay, WI

                            Comment


                            • #15
                              Originally posted by John Stevenson
                              What about an extension to fit your boring head?
                              ....Far more rigid than a sticky out bar. Just make it deeper to suit your travel.
                              Again I learn something new on this forum. Great idea, thanks for posting.

                              Comment

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