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  • work holding

    I am trying to make sixty of these end caps in brass.They need a hex on the end and i used a dividing head and chuck to hold it. It is a small chuck and slipping in the chuck. How could i make a jig to cut the hex for a 36mm socket spanner.
    Also how long do you think it should take to make one and what steps would i use to do this. I am wondering if I made a soft jaw type setup in aluminium to hold this. If I made a hex in alu with a hole in it and split it so I could then squash it in a vice should that work.
    The dimensions are 21mm long The 36mm hex is 4mm deep. The OD of the part is 48,5mm and the thread is 44mm x1,5mm and 14mm deep. Click image for larger version

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  • #2
    This is the other side.
    It would be a great help if I can get some advice on this and greatly appreciated as i seldom do work like this Thankyou. Click image for larger version

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    • #3
      You do not mention what type of machines you have to use.
      If you have a simple 2 axis mill simply mill 2 pockets in soft jaws in a vice, clamp the parts and mill the hex twice per setup.

      I often mill such parts held in 3 vices, 2 parts per vice, six parts finished between each start and stop cycle.

      Bolt jaws onto the vices and mill the pockets, use as many vices as the machine will allow, find the part centers and clamp the parts.

      Last edited by Bented; 10-06-2021, 07:11 AM.

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      • #4
        I should have mentioned it. I have a small one meter lathe and an iso 40 turret mill with a small 4 inch vise. I dont understand how to index it then .

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        • #5
          A strip of abrasive cloth wrapped around the part ( don't overlap the ends ) might give you enough grip for the chuck jaws to hold it during the milling operation.

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          • #6
            Threaded stub to screw them on, and a lock ring for hook spanner seems quick, looks like the ends of air transport system canisters I used to make ( Larmson air tube )
            mark

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            • #7
              Are you machining from solid, or just machining the hex on a purchased item?

              If from solid, change the order of operations to do the hex first, and the id work 2nd. You can grip the solid tighter before it's hollowed out. The spin it around in the lathe and do the id work.

              If the id work is already done, make up a solid dummy plug to thread into it, so you can snug it down tighter without fear of crushing it.

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              • #8
                Make the hex before the ID threads.
                Use a drawbar to hold the part in the dividing head.
                The temporary drawbar threads get machined away
                when you bore and make the ID threads. Use a 3/8"
                drawbar or something small. All you need.

                -D
                DZER

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                • #9
                  I would make the aluminum hex with a hole to fit the part OD and split in it like you said above. Make a flat bottom or ledge in the hole to set a consistent height. Put a pinch bolt across the split to clamp the part so it can't move in the jig until you're done. Make sure the bolt doesn't protrude above the surface of the hex.

                  Put the hex in the vise and clamp on 2 of the flat sides. Mill in X axis parallel to the fixed jaw. The hex on alum. OD indexes the part. Turn the hex with part 1/6 turn, mill in X again. Turn and mill until all sides are done. Loosen bolt, trade parts, repeat. No need to move Y or Z axis, just mill a straight line 6 times.

                  This will be fast to change and index parts, and very low chance to mess one up.
                  Last edited by Toolguy; 10-06-2021, 02:12 PM.
                  Kansas City area

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                  • #10
                    Originally posted by boslab View Post
                    Threaded stub to screw them on, and a lock ring for hook spanner seems quick, looks like the ends of air transport system canisters I used to make ( Larmson air tube )
                    mark
                    I was going to suggest the stub to screw them on to and reduce one end of the stub to fit a collet and use a hex block to index. However using the threaded stub method the hex may not end up perfectly centered, if that matters.

                    However I think the way your doing it with the index fixture is the way to go without having to make any fixtures. Try taking lighter cuts and use a good sharp end mill. It doesn't look like a very deep cut.

                    JL.............

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                    • #11
                      Do you have any type of indexing equipment? Rotary table, indexing blocks etc.
                      The shortest distance between two points is a circle of infinite diameter.

                      Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                      Southwestern Ontario. Canada

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                      • #12
                        Since you have 60 of these it warrants making up some tooling. I would make a set of soft jaws up for the mill similar to what bented has pictured. You will get 2 of the flats in that setup.

                        Then do some calculations and make a lever arm with a pivot into the soft jaw. You can then rotate the part and line it up with the arm and do the next 2 flats and rotate once more for the final.

                        Here is a very poorly done drawing to try and show what I’m saying


                        You may only view thumbnails in this gallery. This gallery has 1 photos.

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                        • #13
                          Originally posted by plunger View Post
                          I should have mentioned it. I have a small one meter lathe and an iso 40 turret mill with a small 4 inch vise. I dont understand how to index it then .
                          You do not have to index the part unless there is an existing feature that requires a close relationship to the hex sides.
                          Otherwise simply mill the hex feature in one movement around the part, if the machine will not do wrench flats in one shot then rough and finish using 2 tools.

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                          • #14
                            Originally posted by Toolguy View Post
                            I would make the aluminum hex with a hole to fit the part OD and split in it like you said above. Make a flat bottom or ledge in the hole to set a consistent height. Put a pinch bolt across the split to clamp the part so it can't move in the jig until you're done. Make sure the bolt doesn't protrude above the surface of the hex.

                            Put the hex in the vise and clamp on 2 of the flat sides. Mill in X axis parallel to the fixed jaw. The hex on alum. OD indexes the part. Turn the hex with part 1/6 turn, mill in X again. Turn and mill until all sides are done. Loosen bolt, trade parts, repeat. No need to move Y or Z axis, just mill a straight line 6 times.

                            This will be fast to change and index parts, and very low chance to mess one up.
                            I made a similar type collar to clamp around the cover of one of my flow meters so I could remove it without damaging it. It worked great. I believe this is what your referring to. This same idea can be applied to hold the brass caps in the indexers chuck without damaging them. It shouldn't slip.

                            JL...................

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                            • #15
                              Originally posted by Bented View Post

                              You do not have to index the part unless there is an existing feature that requires a close relationship to the hex sides.
                              Otherwise simply mill the hex feature in one movement around the part, if the machine will not do wrench flats in one shot then rough and finish using 2 tools.
                              I don’t think you are milling the hex in one movement around the part without a cnc.

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