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Machining Ball and Socket

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  • Machining Ball and Socket

    I bought a fullsize mill to do valve jobs, but the tooling required is rather pricey, so I've decided to attempt to make what I need to at least get me through a few jobs until I can afford to buy the real stuff.

    This is what I'm trying to make.

    http://www.tnsmachines.com/CylHeadEq...Tooling.aspx#d

    The picture on the right.

    I'm only concerned with making part B and C. I will buy pilots and buy the toolholders.

    Part C has a 1.000" ball on it with a drive pin and part B" uses a 1.000 socket in it.

    The ball is easy enough...ball turner on my lathe. The socket is somewhat troubling. I can make a lathe tool to cut it, or I can try and do it with a ball nose end mill on the mill. Problem with number 2 is that the Tree can only accomodate a 3/4" tool shank...and I'm having trouble finding a 1" ball nose with a 3/4" shank on it. I figure I'll make the socket first and hand polish it with emery cloth, then machine the ball and use the socket to test fit and sneak up on the finish size of the ball...when it almost fits, polish it with emery cloth till it does.

    Any better ideas?
    Last edited by lbhsbz; 11-29-2010, 06:57 PM.

  • #2
    I doubt the socket really needs to be spherical. Two conical surfaces at 60-80 degrees to each other should work just fine.
    Any products mentioned in my posts have been endorsed by their manufacturer.

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    • #3
      Depends on how much of a sphere you need to machine and other dimensions.

      You could take, for example, a 3/4" cutter with a 3/8" shank, not to picky about what kind as long as it cuts on the bottom corners. Mount the part on a rotary table or indexer, vertical or horizontal axis, and tilt the mill head over at an angle (or tilt the rotary table) until the edge of the cutting tool is on part center axis. Then rotate the work while turning the cutter. This can produce an inside hemisphere, maybe a little more than a hemisphere. If you need more than a hemisphere in one piece, you will never get the ball in, anyway.

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      • #4
        Ball & Socket

        Use a 1" ball end mill on the lathe either in the tailstock or in a boring bar holder on the toolpost. I got an ER40 collet chuck with a M3 taper shank and a set of ER40 collets for the lathe and an ER40 chuck with an R8 shank for the mill. This greatly expands my options on both. Maybe you could get an ER40 chuck with a 30 or 40 taper shank and turn it into a shank that will fit the Tree mill spindle. ER40 goes up to 1 inch/ 25mm. I think McMaster-Carr and MSC both have 1" ball end mills with 3/4 shanks.

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        • #5
          How much of the female hemisphere is there? These can be turned
          with a radius turner up nearly (I did say nearly) to a hemisphere. I've
          done some for a local "artist" and a matching male enough smaller
          radius to accomodate the thickness of the material he was pressing
          into a dome shape. The trick is to have the cutter at a 45° angle
          rather than straight on. I don't have any pix right now but if you are
          interested I can take a few later this week.
          ...Lew...

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          • #6
            What about using one of those impact wrench flex joints?
            Gene

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            • #7
              B-n-C

              Originally posted by winchman
              I doubt the socket really needs to be spherical. Two conical surfaces at 60-80 degrees to each other should work just fine.
              Agreed.

              All that is needed is two circles of contact on the ball in Part "B". Use "Teflon" or similar.

              Use a standard 1" ball - anneal and polish it. Drill for the driving pin/s.
              Silver-solder the ball to Part "C" and pin/s to the ball in "C".

              Comment


              • #8
                So...I just had another brilliant idea.

                First, I'm wondering if any of you have any idea why this operation uses a ball driver? I imagine it has to do with the fact that most of this type of work is performed on an air table and that the ball driver makes lining stuff up a bit easier. I've questioned some automotive machinists who said that with a rigid head, they saw more errors in seat/guide concentricity than with the ball driver.

                So, Say I use a thrust rated ball joint swivel bearing (like a one sided heim joint...press the socket end into my piece that fits in the chuck, and press the ball end over the secondary driver. Machine a slot in one and drill a hole in the other for a pin and I've got a drive set that costs me $50.

                I'd use the thrust rated setup so that I could use multiple secondary drivers, each with a different cutter on them...kind of like a quick change tool setup.

                Thoughts?

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                • #9
                  Originally posted by topct
                  What about using one of those impact wrench flex joints?
                  I'd like a little greater level of concentricity than those will afford I think.

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                  • #10
                    I have an old Black & Decker valve grinder outfit. It came with a seat grinder driver (looks about like a 3/8" drill motor) that has a hexagonal stub arbor that's rounded into a ball shape. IE: a ball that has 6 'corners', if you will. The stone holders have a hexagonal socket. Unfortunately, the driver's hex has the corners worn off, so it doesn't work. Fortunately, the setup also included a flexible driver that can be chucked in a regular drill motor. The driver is sort of like this: http://www.stanleyproto.com/default....+Socket+Driver

                    It's just a heavy-duty flexible spring/cable with a short shank on one end and a hex piece on the other. I'd bet you could find something similar, or adapt one of those flexible screwdrivers.

                    This thing is interesting to grind seats with: you put it on the pilot, drive it with a bit of pressure, and when the seat is fully ground, the thing chatters like a b****h. The finish looks pretty much OK and I've never had a problem with a valve job I've done, but it sure sounds terrible when doing it.

                    Comment


                    • #11
                      I'm thinking the ball goes into the end of a cylinder, and needs to seat against a hemispherical seat. Why not bore the cylinder part, then fill the bottom of the cavity with a filled epoxy. If you put some mold release on the ball, it can be used to form the epoxy blob to a perfect hemisphere. My thinking is to use a metal filled epoxy and add some graphite powder to it for some self-lubricating action.

                      By the way, if for any reason you wanted to make the ball permanently captive in the socket, you might mold some wax behind the ball, then turn it to leave a cone shape. After the first half of the socket is made, the ball is inserted, held straight, and the cavity left is filled with the epoxy mixture. When it's fully set, you melt the wax out and you're left with a certain amount of room to angle the ball shaft in any direction.

                      Adding to this whole idea, you could turn a pair of half-sockets from your metal of choice, then cut one of them in half. The whole one gets epoxied into the bottom of the bore, while the two halves are then assembled behind the ball, then this assembly is epoxied into place. Mold release still required, but the end result is basically a metal on metal ball and socket. Nothing stops you from drilling a few radial holes around the 'back' part and epoxying some music wire pins into place, for some extra insurance against the parts coming loose and falling out.
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                      • #12
                        What keeps the tool concentric is the pilot not the drive joint. In fact I will guess their joint, as nice as it looks, has a bit of slop in it.
                        Gene

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                        • #13
                          Originally posted by Toolguy
                          Use a 1" ball end mill on the lathe either in the tailstock or in a boring bar holder on the toolpost. I got an ER40 collet chuck with a M3 taper shank and a set of ER40 collets for the lathe and an ER40 chuck with an R8 shank for the mill...
                          I did exactly the same thing: Morse taper, Cat-40 and R-8 collet chucks + the full set of collets. The ER-40 system is now the "standard" on both of the mills and the lathe (spindle AND tailstock) ! It's an excellent system and one of my "good" decisions, LOL.



                          Cheers,
                          Randy C

                          Comment


                          • #14
                            Do you have a picture or link that shows that tool (from post #1) being used? I'm having a hard time visualizing how it's positioned on the cylinder head.

                            The tool holder clamped to the small pin on the bottom just doesn't look substantial enough to give accurate results, but seeing exactly how it's used would probably clear that up.
                            Any products mentioned in my posts have been endorsed by their manufacturer.

                            Comment


                            • #15
                              Originally posted by winchman
                              Do you have a picture or link that shows that tool (from post #1) being used? I'm having a hard time visualizing how it's positioned on the cylinder head.

                              The tool holder clamped to the small pin on the bottom just doesn't look substantial enough to give accurate results, but seeing exactly how it's used would probably clear that up.
                              That's the tool setting fixture. It's used to set the angles/position of the cutters.

                              The thing I'm having a problem with is that everything is going to have to fit very tight but also let the pilot spin in the guide. With only one cutter there will be side forces to deal with. There is mention of a pilot lock screw so I am assuming that's what they are doing. I always thought the pilot should not spin so that any material removed is not dragged down into the guide by having the pilot itself move up and down in it.

                              Am I having one of my uh-oh moments?
                              Gene

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