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  • Machining question

    Looking for suggestions on machining off the very top of this to expose the inside 'and' how to hold it? Either a lathe or Bridgeport. I realize I could grind it off but I'd like to keep it as clean as possible 'inside'.

    https://secure2.pbase.com/smokedaddy/image/166766926

    Thanks in advance,
    -SD:

  • #2
    That looks like a lathe job to me. Some chuck jaws have grooves in them that the flange would fit into. If not, make a ring out of plastic or alum. that's a close slip fit to the main diameter. Cut a slot in the ring so it can compress, put it on the part and put the assembly in the chuck. I would use a very sharp parting tool to cut the crimp off.

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    • #3
      Originally posted by Toolguy View Post
      That looks like a lathe job to me. Some chuck jaws have grooves in them that the flange would fit into. If not, make a ring out of plastic or alum. that's a close slip fit to the main diameter. Cut a slot in the ring so it can compress, put it on the part and put the assembly in the chuck. I would use a very sharp parting tool to cut the crimp off.
      A very fine slitting saw held in a Foredom/Dremel on the toolpost might be a bit more controllable than a parting tool.
      Regards, Marv

      Home Shop Freeware - Tools for People Who Build Things
      http://www.myvirtualnetwork.com/mklotz

      Location: LA, CA, USA

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      • #4
        Use a can opener:

        https://www.thorlabs.com/newgrouppag...tgroup_id=1830

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        • #5
          I've opened one like that by filing off the crimp lip next to your fingers. That way the entire cap comes off and exposes all of the chip.
          Ernie

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          • #6
            Who wodda thumk?



            Originally posted by tomato coupe View Post
            Paul A.

            Make it fit.
            You can't win and there is a penalty for trying!

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            • #7
              I hate to ask but WHAT IS IT. Perhaps a few more clearer photo's . Al
              Please excuse my typing as I have a form of parkinsons disease

              Comment


              • #8
                I'll second the "whoda thunk" on the actual "can opener" though I guess as cutting these open is not all that uncommon it's inevitable that someone makes a tool.

                I have also done what Marv mentioned, and use a very fine saw or abrasive disk i n a dremel works just great. I cut maybe 100 or more of them open in that manner way back when at a place I once worked. Quick and easy. If you are careful and slit around the outer circumference, almost nothing ends up inside.

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                • #9
                  Originally posted by Toolguy View Post
                  That looks like a lathe job to me. Some chuck jaws have grooves in them that the flange would fit into. If not, make a ring out of plastic or alum. that's a close slip fit to the main diameter. Cut a slot in the ring so it can compress, put it on the part and put the assembly in the chuck. I would use a very sharp parting tool to cut the crimp off.
                  Thanks for the idea. I'll draw something up and 3D print it and let you know how it works.

                  -SD:

                  Comment


                  • #10
                    Thanks for the suggestions. I didn't try removing the tab, obviously the simplest way. Guess I should of waited for all the suggestions. I ended up drawing a fixture up that worked and parted it off.

                    https://secure2.pbase.com/smokedaddy...67659/original

                    https://secure2.pbase.com/smokedaddy/image/166767646

                    https://secure2.pbase.com/smokedaddy/image/166767650

                    and 'one' of the reasons I was doing this (below).

                    https://squattingdog.smugmug.com/Sem...cs/i-xcsWmQm/A

                    -SD:

                    Comment


                    • #11
                      I'd try another TO-5 transistor first but I'm thinking hold the top and a little of the sides in a collet and sneak in with a very fine pointed cutter. I'd go with pointed because the chip it removed would be less load on the grip than a flat nosed parting tool regardless of it being a really small one. So that'll put the part down near the base but it should be enough to lift off the header and expose the chip and the hair wires.

                      Comment


                      • #12
                        Originally posted by Smokedaddy View Post
                        Thanks for the suggestions. I ended up drawing a fixture up that worked and parted it off.
                        Dear Mr Daddy

                        We are always very happy to hear from our customers. However, I am afraid I am going to have to give you bad news. Cutting off the top of the Op Amp has voided the warranty, and we cannot replace it for you. However, you can find new ones at Digikey for a very reasonable price.

                        Signed
                        Customer Service
                        Analog Devices


                        .....

                        P.S., the data sheet has a metalization diagram that looks just like what you found.

                        http://www.analog.com/media/en/techn...eets/AD741.pdf

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                        • #13
                          Darn ... thanks for the data sheet, that's what I was going to look for next. Here's a little better view of it.

                          https://squattingdog.smugmug.com/Sem...cs/i-CmhK9M4/O

                          -SD

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                          • #14
                            When I was young, I used to remove the top of the 2n3055 transistors to make little solar cells. Some sandpaper on a flat surface and after a few strokes the top was so thin it wold rip off clean with the tip of a knife.
                            Helder Ferreira
                            Setubal, Portugal

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                            • #15
                              I've done it with a lathe on slowest speed and a hacksaw.

                              Sent from my SM-G930W8 using Tapatalk

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