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SWM Propulsor Shaft Replacement

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  • SWM Propulsor Shaft Replacement

    I was in need of replacing the original propulsor shaft for my 1:96 HMS Trenchant, so the following is what I did. The original was a length of epoxy-filled brass tube cast into the propulsor rotor and was no longer within acceptable radial run-out (it was slightly bent!). I asked about removal methodology in the forums and HWSNBN mentioned using heat, as in heat the shaft and pull. I varied a bit, but with good result. The rotor has what looks like a nozzle opening in the area we would call a "dunce cap" and knowing the shaft to be a piece of tube, I opted to use a drill bit and drill through that opening. My thought was to either thin the tube enough to cause it to collapse, or by drill bit friction create a more manageable source of heat to cause the epoxy(?) compound the rotor is made from to release the tube. I started with a 7/64 and holding the rotor in the opposite hand. My great concern was breaking rotor blades off and creating a whole new logistics problem for the project, so I went at the drilling process at a cautious pace. After a few minutes of drill and inspect and dumping out brass chips, the shaft came free! Yay! The original also had a length of 1/16" brass rod inside as a stiffener/filler. I then sized up a length of 1/8" shaft rod I had with a set-screw flat on one end and checked the rotor hole for concentricity. All good! My diligence paid off there! I then determined the depth I need in the rotor to reach a good spot for a 2-56 setscrew. I found a good place to be 1/16" aft of the rotor blades, centered between 2 blades. I then drilled and tapped and tested the said setscrew and life is golden!!! The rotor spins very nicely in the stern bearing, though I think that bearing is actually in need of replacement itself. I would love to replace the oil-lite bearing that is there now with a super-slick Rulon unit, but that's one of those "maybe someday" things.

    I have no idea how many of these SWM Trafalgar class hulls are out in the universe, but I hope this might help someone revive the sub model for use. I know this one brought me many enjoyable days of running in her heyday. I am determined that she will live again!!!