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Help making driveshaft watertight

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  • Help making driveshaft watertight

    Hi all

    I was hoping I could get some help from some people with real experience because I am new to this hobby and I have no idea what I am doing.

    I want to make a DPV (Diver Propulsion Vehicle) and I came to this site because I figured they are very similar to the kind of RC submarines that are made on this site just a whole lot simpler. I am having trouble figuring out what the best way to stop water from leaking through the drive shaft but everything I have looked at is either to expensive or wont work. I say too expensive because have a huge budget and the whole idea is to make something that is cheaper to build then to buy a ready made vehicle from a manufacturer.

    I am running a 14.4 volt motor I salvaged from an old battery drill (that still works :D) that runs at 1400rpm. This will be powered by the same battery that the drill runs off and will be controlled by a simple momentary action switch mounted to the outside of the WTC. The motor and battery will be housed inside a PVC pipe with an end cap at one end that the driveshaft will go through and a watertight threaded cap on the other end so I can access the motor and replace the battery.

    Does anyone have any good ideas for making sure the driveshaft is watertight however? I was thinking of using a stuffing tube but I am worried it will be too weak and will just snap off. I have also considered using a mechanical/shaft seal similar to what they use on larger boats just scaled down so they fit inside water pumps.

    Sorry if all this seems like nonsense, I am very new to this but I love to build things. Thank you for taking the time to read my post!

  • #2
    Don't know what you're doing?!!!

    Shut up, take a number, sit down,and wait your turn.

    OK, are we talking about a unit that drags you behind it as you cling desperately to the units handles?

    Anyway ...

    The efficiency of the seal to keep out water improves with shaft size and (if using a cup type rubber seal) depth. The higher the differential pressure, the tighter the cup-seal seats against the rotating shaft and standing part of the seal body.

    Use a pair of cup-seals, for redundancy.

    Something like this:

    Or you can go with some standard plumbing fittings and make a compression packing like this:

    If you go the compression packing route, use a 'quad' type rubber seal, not the typical o-ring. The quad-seal is the one in the center, flanked by a cup seal and classic o-ring seal. O-rings are not recommended for rotating parts.

    I have spoken! So, let it be written [crash of thunder].

    Last edited by He Who Shall Not Be Named; 02-19-2018, 06:51 PM.
    "... well, that takes care of Jorgenson's theory!"


    • #3

      Another method.....

      RC Submarine 3/16" Shaft Seal Assembly

      "Sub" Ed
      NEVER underestimate the power of a Sailor who served aboard a submarine.