Hybrid Ballast Tank/Piston System

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  • Monahan Steam Models
    Captain
    • Apr 2020
    • 755

    #46
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ID:	147679 Sneak peak of the project progress.

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    • Monahan Steam Models
      Captain
      • Apr 2020
      • 755

      #47
      Here is the current progress as of this moment on the WTC build experiment.

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      Backside of the forward end cap.

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      Different camera angle. The brass nipples were a press fit. All of the various holes were finish sized with a straight flute reamer prior to the test fitting the parts to the assembly.

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      Port side view.

      Here the brass emergency gas blow valve visible as well as the brass adjustable pressure regulator for the torpedo solenoids.

      The push rods used u-cup seals. I used Bob's trick to build them that he explains in detail on his YouTube channel. The only difference is i use an oil-lite bearing on either side of the u-cup seal. The bearings are held in place with a dab of blue Loctite.

      The IP68 one piece molded multi pin connector passes through the end cap using a IP68 rated cable gland. Silicon sealer will be used on the threads and sealing bit of the cable gland during final assembly. Not needed but extra insurance.


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      Starboard side.

      Both push rods travel very smoothly. Here you can see the other brass valve that vents the main ballast tank.

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      Underside.

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      Test fitting with the 90mm OD Acrylic WTC tube. Nice consistent O-ring squish all around.

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      Test fitting it to the hull to see how I did taking measurements and verifying what I designed in CAD land. Fits as planned. Guess I'm not fired today but there's always tomorrow.


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      This about catches up the work with the real parts to date. Need to wrap up a few minor details with the forward equipment shelves before I make those very soon. I had shifted focus recently in the CAD design to the rear compartment and motors but the forward compartment was so close I figure I should finish that first.


      Enjoy the weekend,

      Nick

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      • Monahan Steam Models
        Captain
        • Apr 2020
        • 755

        #48


        Got up early this morning and pulled the freshly finished lower pump equipment shelf out of the 3D printer. A quick clean up of a few holes with various sized straight flute machine tool reamers and it was time to test fir the peristaltic pumps and hoses to it.



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        Even if this whole experiment proves to be a huge failure, at least it was a learning experience and I'l have a pretty neat looking failure trophy to stare at. Hahaha!


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        I had purchased the raw materials to make most of these parts on my mill and lathe but decided to see how printing the parts would turn out first. The finishes of the prints are rough in areas as I am experimenting with printing in lower quality (faster) print settings. I will sand these parts at a later date or give them a vapor smoothing treatment. Still getting to know this machine even though I've made lots of parts with it over the last year.

        Prior to this Experimental WTC project, every part I printed was in the highest resolution and made from ABS due to many parts being small and having critical tolerances. The larger parts of the WTC would take forever if I printed them in the highest resolution. Still I know I could machine most these by hand much faster than the printer could print them at it's lowest (fastest) setting. The nice thing about the printer vs manual machining is, this allows me to focus my time in other areas.


        Nick

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        • Bob Gato
          Captain
          • Feb 2019
          • 826

          #49
          ...and it allows you to go to bed and wake up to a finished print...

          Comment

          • RCSubGuy
            Welcome to my underwater realm!
            • Aug 2009
            • 1768

            #50
            This is looking awesome, Nick! Great work!

            Comment

            • Monahan Steam Models
              Captain
              • Apr 2020
              • 755

              #51
              Quick build update. Was out of bed, vertical and working on the first cup of coffee thanks to the indoor cats and little rug rat deciding it was party time at 3am this morning.... With one eye barely open and the other still twitching open and closed I picked up where I left off on the upper equipment shelf build.

              Installed the port and starboard mounting brackets for the depth controller and the controller for the low pressure blower pumps to the underside of the upper equipment shelf.

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              The screws that hold these in place also hold the above linear pushrod blocks above in place. They act as stiffeners as well.


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              Above linear pushrod blocks. Only purpose is to lessen side forces on the bulkhead seal bearings from side force transmission from the servos. They are sleeved with a machined Delrin bushings with a few thou tolerance clearance.

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ID:	147774Last lazy pic of the day, of what I have so far. Waiting on critical small parts to show up for the next forward compartment mock up. So not many updates to follow until those parts get here. Look like they will trickle in over the next couple weeks. Until then I’ll find other areas of design to explore.

              Nick

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              • trout
                Admiral
                • Jul 2011
                • 3545

                #52
                Nick,
                I am enjoying your progression on this. Thank you.
                Peace,
                Tom
                If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

                Comment

                • Monahan Steam Models
                  Captain
                  • Apr 2020
                  • 755

                  #53
                  Thanks Tom!!!

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                  • Monahan Steam Models
                    Captain
                    • Apr 2020
                    • 755

                    #54
                    Quick update.

                    Parts have arrived and here is the current state of the forward compartment equipment assembly as of today. Almost finished with the initial assembly mock up of the forward compartment. Just need to add the main depth sensor, main power harness and finish the torpedo command circuits. Will try to write a more detailed report of the build when I get a chance.

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                    • Monahan Steam Models
                      Captain
                      • Apr 2020
                      • 755

                      #55
                      Got the main pressure depth sensor installed and hooked up. It’s on the starboard side near the ballast pushrod penetration just forward of the starboard signal junction buss. The torpedo harness is also connected to the TCP module.

                      On the port side you can see the 5v positive and ground junction buss with TCP in the middle. The dual esc for the trim peristaltic pumps is just aft of the TCP module. Might dump this esc and replace it with a H-bridge unit. (Not happy with the cheap esc)


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                      A view from the bottom side shows the completed pump wiring and the main 3 wire power connection. One ground, a 5volt positive and a 11.2 positive.


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                      Nick​
                      Last edited by Monahan Steam Models; 03-04-2021, 12:00 PM. Reason: Photos did not post.

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                      • Monahan Steam Models
                        Captain
                        • Apr 2020
                        • 755

                        #56
                        Sometimes ya win some, sometimes ya lose some....

                        Machined the bulkheads for the central ballast tank. Carefully made the drain holes and the vent hole in the WTC tube. Everything fit up perfectly and turned out well.

                        That was until the final step of applying the welding solvent...

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                        Things went crazy.... Literally.

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                        The WTC tube crazed where ever the Weld-on 4 came in contact with it. The bulkheads and smaller conduit tubes did not suffer the same fate.

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                        Any ideas what went wrong? The tube is from the original Arkmodel piston tank WTC kit.

                        Nick

                        Comment

                        • Subculture
                          Admiral
                          • Feb 2009
                          • 2119

                          #57
                          That’s rotten luck. Perhaps there were some residual stresses in the tube, or it’s poor quality plastic, clear plastics can be fussy. I prefer to use pvc or polypropylene tube which tends to be filled or is at best translucent, so what! Cheap, tough as old boots and doesn’t craze.

                          Comment

                          • Bob Gato
                            Captain
                            • Feb 2019
                            • 826

                            #58
                            Crap is right-I feel your pain man! If you search hard on the net, there is a such thing as clear PVC-but most are as thick as standard schedule 40 pipe-search more and you can find 1/8' UPVC-" (schedule 30) Also PET is a great clear contender for a subdriver.- I try to find a link (I have a link management problem)-BG
                            Last edited by Bob Gato; 03-07-2021, 02:26 PM.

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                            • Monahan Steam Models
                              Captain
                              • Apr 2020
                              • 755

                              #59
                              Originally posted by Bob Gato
                              Crap is right-I feel your pain man! If you search hard on the net, there is a such thing as clear PVC-but most are as thick as standard schedule 40 pipe-search more and you can find 1/8' PVC-"
                              Did some searching this morning for clear PVC pipe and tube. Lots of schedule 40 out there! Trickier to find the 1/8" wall stuff! Might be hard to find a 1/8" wall clear PVC tube close to the dimensions of this 90mm acrylic tube. The 90mm tube I'm using currently measure 3.562" in OD which is just a bit over 90mm. The boat hull was designed to accept 90mm. You could get away with a tube slightly larger than this but not much larger.

                              I have a six foot length of 3.5" x 1/8" extruded acrylic tube on hand but I would need to redesign and remake some of the equipment shelves to use this material. It might also craze since it is extruded and not cast. This same size material is available in cast but is almost four times the cost.

                              I found a supplier this morning in the UK who sells 90mm OD X 3mm wall cast acrylic tube in 2000mm (78"+) lengths for a lesser price to what I've found in the States for a 24" piece of 1/8" wall 3.5"OD or 3.625" OD cast tube.




                              Although the crazing on the central ballast tank looks dreadful, I was surprised to find that the tank was water tight after some tests this morning! I first filled the tank up completely and let it sit for an hour. No leaks. Then with it still full I added some pressure. Still no leaks!

                              At least for now I can keep moving progress forward, eventually towards testing with the tank like this. I'll replace it when I can get my hands on a suitable replacement material in a similar size.

                              Comment

                              • Subculture
                                Admiral
                                • Feb 2009
                                • 2119

                                #60
                                Usually when clear tube based ballast tanks have bonded/welded ends, the tubing is cut and bulkheads and machined with a step in them , then solvent welded onto the end of the tubing with a minimum of solvent. A good example are the OTW modules. R&R modules side step the problem by using a smaller tank that has o-ring sealed caps and that slides inside the larger diameter tube for the main module.

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