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Ideas for handling this locking pin?

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  • Ideas for handling this locking pin?

    Hey Everyone, you've been tons of help and I'm hoping someone has seen something like this before. I don't even know what to call this...

    Pic of the locking pin:
    Click image for larger version

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    And there are three short videos of it in action:
    https://goo.gl/N9DKqx

    What is the nomenclature for this mechanism? (so I can Google that)
    Any experience with what I can do to mechanically pull down on the pin to pull it out of the receiver? (then I would release it so the spring can work)

    I'm thinking to try and adapt a Stearns brake coil and plunger to pull down on the pin. Having dealt with those on the motors driving the arms which are on top of the turret's table, they "feel" at least 5 times stronger than I need. Then I'll set up limit switches to confirm its position. This can set up the start sequence: engage, pin down, contactor for motor on. Stop sequence can then be when the "up" position's limit breaks (as the pin ramps). I might need a short delay, but that's not a real problem...

    Thanks in advance for any thoughts!
    Chris
    Attached Files


  • #2
    I only see a Greese Fitting.. the 1/8 NPT threaded Fitting with the little ball in the Center..

    Cap

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    • #3
      You could do an air cylinder, either single acting with the spring pushing it up, or double acting and then apply air when you want to retract it.

      But how about a shock that you can place in the way and then take out when you want to rotate, or a Geneva or some means of controlled deceleration? There is a huge shock load on the pin mechanism (and the receiver and to some extent the stuff on the table). Mechanisms like that can wear from the constant abuse and become inaccurate or cease to operate. Even Geneva's will wear if not sufficiently beefy. You could even have a pin preloaded with a shock (possibly even on a horizontal or vertical rotary axis) that eventually bottoms out against a hard stop for repeatable position. You could even get a Camco table or build a facsimile.

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      • #4
        I'd look through THIS book.
        If you've done the very best you can, worrying won't make it any better - Walt Disney

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        • #5
          Cool book, Ridge! Definitely keeping a copy of that one.

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          • #6
            Originally posted by ControlsGuy View Post
            Cool book, Ridge! Definitely keeping a copy of that one.
            My dad gave me the four volume set of these books about 25-years ago. It's a great source for mech nerds like myself.
            If you've done the very best you can, worrying won't make it any better - Walt Disney

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            • #7
              Originally posted by ControlsGuy View Post
              You could do an air cylinder, either single acting with the spring pushing it up, or double acting and then apply air when you want to retract it.
              The original builder did employ an air cylinder and it would have acted similarly to my set with respect to load and shock. I'm trying to avoid running air to this table.

              Originally posted by ControlsGuy View Post
              But how about a shock that you can place in the way and then take out when you want to rotate, or a Geneva or some means of controlled deceleration? There is a huge shock load on the pin mechanism (and the receiver and to some extent the stuff on the table). Mechanisms like that can wear from the constant abuse and become inaccurate or cease to operate. Even Geneva's will wear if not sufficiently beefy. You could even have a pin preloaded with a shock (possibly even on a horizontal or vertical rotary axis) that eventually bottoms out against a hard stop for repeatable position. You could even get a Camco table or build a facsimile.
              I did not know that was called a Geneva, thanks! This will give me something to ponder. Also didn't know of Camco rotary parts; this is the closest I could find to my application, though I believe the 2 inch thick 6 foot across hexagon table top I have weighs a touch more than that machine's table.

              Originally posted by Ridgeline Mach View Post
              I'd look through THIS book.
              Ridgeline: You da man, thanks! I saw your other post with the Not "How It's Made" Machine. "How It's Made" is great, and then there are the shows where I'm thinking forget the product, show me how the machine making it is made.

              Thanks,
              Chris

              Comment



              • #8
                I thought I'd share what I came up with. I put a video up on facebook: https://www.facebook.com/cacyclework...4682535528888/

                » At the top is the pin.
                » Below it is a cup spacer I made which keeps the bottom of the pin 1/2" from the bottom of the sleeve it rides in.
                » Next you see the silver 3/4"-16 jamb nut and the bolt threaded into the pin. These were the threads at the top of the pneumatic cylinder from the previous design.
                » And the Gold head of the 3/4"-16 bolt. From the head, I drilled and tapped M8 threads to accept the bolt which runs down to the solenoid.
                » There's a M8 nut and washer.
                » The spring is held up by the SuperStrut angle piece.
                » Below, the head of the M8 hex head cap screw (100mm long) has been cross drilled with a 3/16" hole.
                » I use a "half link" for a #50 chain to adapt to the T piece of the solenoid.
                » Finally, the Stearns Brake solenoid and coil. It is a substantial unit part of their 75 ft-lb brake unit.
                » The coil is a 115V variant.

                On the left is a limit switch I use to confirm the pin is down before rotating. The pivot and lever are from a limit switch in a Honeywell Fluid Power Gas Valve Actuator that I had replaced. Microswitch is a generic retrofitted from spares. I set it so that it is activated by the washer on top of the spring.


                Here's a pic of the mechanical design:
                Click image for larger version

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                • #9
                  The electrical controls are mounted on a plastic sheet until I decide on their permanent home... The 11 pin socket takes a Fuji mini timer that I have set for One Shot mode. A PDF of the electrical design is attached with some explanations.

                  The far right relay is ER4 and it is activated when any of the arms are "home" and the pin is up. Middle relay is the Rotate Request relay. Left one is the Pin is Down relay.

                  Some year I'll have a PLC running it with an HMI that talks to the oven and the turret and can coordinate things. And I'll keep dreaming.

                  Click image for larger version

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                  Attached Files

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                  • #10
                    My experience with this mechanism is a shot pin. We used them for locating rotating fixtures for welding. They were uses to lock the fixture into a static position for robotic welding applications.

                    I do not know if that is what you are doing but that looks similar to what I did in the past.

                    Thanks
                    Adam

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                    • #11
                      Very nice! I love recycling parts like that.
                      -Lee

                      “Felix, qui potuit rerum cognoscere causas” - Happiness is understanding how things work.

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