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Moebius Skipjack

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  • Hey Ken,
    Consider using a plastic Sullivan type flex control rod Keep the box slide but shorten it way up... just big enough the keep the triangle plate ridged-the nyrod will flex plenty to account for the arc of the control arm (no need for the spring loaded telescoping arm)-you'd still have to use an idler to change your travels and mechanical advantage-but you have that already. Brass on brass doesn't play well together If you want to keep existing design-try brass and stainless steel-
    Last edited by Bob Gato; 03-06-2021, 06:57 AM.

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    • Originally posted by JHapprich View Post
      Use a knee-lever or Install the pivot further sternwards, the lever must not exceed movement sternwards of the pivot. Better use round rod and tubing, the squares will cause microfriction at the edges. That spring increases friction. Better install the bearings of the pivot rod up- and downwards at its end's and the levers in between to avoid bending. Do not apply grease, the mechanism should run well dry.grease will cause the parts to stick, i believe.
      Some math... the servo travel is 3/4. The rail needs to travel 1-3/16 in order for the doors to open. So the telescoping sq tube is giving me the multiplication factor. Also, the nylon pivot is high in the hull since the push rod from the servo is coming off of the topmost part of the SD. Can't be routing push rods all over the place.

      You are saying to move the pivot point aft so that the pivot point is 90 degrees to the rearmost point of the rail travel. Then when the rail moves forward to close the doors, wouldn't there be more 'friction' to get the pivot arm to move aft since the sq tube lever has now extended out even further than I have it now. I was looking to keep the telescoping sq tube the minimum amount of extension by putting it in the middle.

      And go to round with no grease.

      Click image for larger version

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      • Originally posted by Bob Gato View Post
        Hey Ken,
        Consider using a plastic Sullivan type flex control rod Keep the box slide but shorten it way up... just big enough the keep the triangle plate ridged-the nyrod will flex plenty to account for the arc of the control arm (no need for the spring loaded telescoping arm)-you'd still have to use an idler to change your travels and mechanical advantage-but you have that already. Brass on brass doesn't play well together If you want to keep existing design-try brass and stainless steel-
        I can't shorten the sq rail slide. That rail needs to travel 1-3/16 and it has an internal adjustment to line up the upper and lower hulls (see previous pics). It needs some support. Opening 4 doors in hull halves that need to come apart is challenging. Was going to use that flex rod between the servo and this door mechanism along the top of the SD. Will think about how to do what you describe. Guess I need to minimize the amount of brass contact.

        Challenging is good = makes you think = keeps that brain functioning

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        • OK instead of the long brass square guide -what if you cut some square holes in Delrin and had two or maybe three guides bolted where the square guide is now...and leave everything else as is?

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          • Good thought Bob, minimize any contact. Have a few things to try out. Open to any other ideas as well so keep them coming.

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            • How about replacing the spring and upper arm with a servo arm with a slot.
              Something like the picture. The pin should slide in the slot not the hole.

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              • Was going for something like that with the sliding tube. What you suggest should be less friction. Added to my list of things to try. Thanks Scott.

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                • Ken,

                  I've used wires and mechanical rods for opening the doors, the type XXIII has a rod steered system, my type VII uses simple pull wires, the only snag with using wires is, the doors are being closed by a spring with light tension.
                  I would go that way, on the other hand your designed contraption will make Rube Goldberg proud, i like to keep those things simple, meaning less maintenance, nice catch with those "hidden" screws, did pretty much the same for splitting my type XXIII.

                  Manfred.
                  Fertig zum unterwasser.

                  Comment


                  • Good to hear from you Manfred! Rods, gears, wires many ways to accomplish this. Didn't think gears or wires would work in my application so went with rods. One thing about my doors is they require a 'snap' to actually close, or bit of a force to snap into place. With how fragile the doors can be with many opening and closing didn't want to put too much preasure on them. And have limited space. Could I have done this simpler? Maybe, if I spent weeks or a month on it. Next week I'll post a video how this works, or doesn't work. Like I said, challenging to get four doors to open simultaneously.

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                    • You found a solution for opening all doors together which work for you, opening the doors independently asks for more servo's which is a bit of a issue with using a standard SD, the modular SD gives more room for that, it worked for me with the type XXIII with a standard SD.
                      The big type VII is a different ball game, a dryhull with plenty of room and a different lay-out, but the reward is, independed steering of the doors, i'm looking forward to your video, i know you good enough that it will work as intended.

                      Manfred.
                      Fertig zum unterwasser.

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                      • Here a quicky video on the torpedo door opening mechanism.

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                        • Ken,
                          I have no doubt you will beast the mechanism into submission.
                          Peace,
                          tom
                          (that was supposed to be beat - I hate spell check at times)
                          Last edited by trout; 03-09-2021, 11:04 AM.
                          If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

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                          • Thanks for the vote of confidence Tom!

                            Lot's of interesting ideas here! ....... https://www.google.com/search?q=conv...w=1565&bih=855

                            and here..... https://www.youtube.com/results?sear...+linear+motion

                            With this one use my existing mechanism and extend the square tube further out and slot it for the pin..... https://www.youtube.com/watch?v=UuTNtg7-Bwg
                            Last edited by Ken_NJ; 03-09-2021, 02:44 AM.

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                            • Some ideas:

                              https://m.youtube.com/watch?v=9M2QqaGbPCw

                              Best Regards!
                              Jörg

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                              • Thanks Jorg

                                Success! Have it working pretty good at this point. Replaced the telescoping arm with an articulating arm and moved the pivot point. Also filed the four sides of the two square inner tubes so there is less friction sliding in the tube.

                                Made another video. I seem to stumble trying to explain things.

                                Video not embedding properly so watch on Youtube.... https://www.youtube.com/watch?v=2g05xOL1ezA
                                Last edited by Ken_NJ; 03-10-2021, 05:48 PM.

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