My R-C Model Boat Site

Propellor shafts. March 20, 2010

I am writing these updates a little “out of sync”, but the end result is still the same, But whilst i was waiting for the prop shafts, propellers and rudder  kits to arrive, I carried on and built the upper deck works ans treated a lot of things to some paint [more of which to follow].

So, 3 motors, 3 propellor shafts, 3 rudders. Thats the criteria I wanted and I also wanted it to look authentic with 3 props, rather than some “lame game” running single propellor power.

I am using graupner speed 400 motors, with “PT boat” open prop shafts and prop shaft supports [with bearings] and of course, 3 rudders.

The propshafts and brass propellers were  sourced through a local company to myself called “SHG Model supplies”, they also supplied the rudder kits and a bit of advice too as they were responsible for supplying the “model boat magazine” with the drive items when they did a magazine spread back in December 2007, So I knew at least I was using the right kit of bits so to speak.

I wanted to keep the prop shafts looking right and didn’t want them to stand too low below the hull to spoil its appearance when out of the water [on display], So spent several hours deciding on a plan of attack to ensure my designs were going to plan. I firstly mounted the rudder pivot tubes, as this gives me the “end point” for where the tip of the propellers will have to sit. the set about converting the prop shaft supports I have purchased from ” N M Models”. these were white metal items so fairly soft to drill and cut [please be wary of this it caught me out using too low a drill speed].  I sourced some brass bushes for the prop shafts [ 2mm dia] as the prop shaft supports were drilled to 5mm diameter [internally] and being as my outer propellor shafts didn’t run all the way to the propellor blades, I had to make some decent supports up that would not damage the shafts or cause them to bind. These were purchased from a model train spares shop, as these brass bushes are used as “axle bushes” for 4mm scale trains ! perfect machine fit to the propellor shafts and after drilling a slight indent in to each end of the prop shaft supports, these brass bearings were glue bonded in with some superglue. Ensuring they were in alignment before the glue sets with a 2mm drill bit [ no, not the propellor shaft itself!].

I then cut down the outer lower support mount of the propshaft supports, to allow me to get the preferred ride height for the propellers I wanted before bonding the 2 outer shafts to the hull, via the propellor shaft supports [only] for now. this is a temporary bond, as I will be using stabilit express to make the full bond, now I know all is in alignment, but being as this glue is both expensive and you only have a few minutes to use before it starts to set, I much prefer to “tack in place” first.

My next job will to be to install the inner propellor shaft and supports, then i will glue bond all 3 in fully. next task will be to shape the 3 rudder faces and get their profiles correct before attaching the rudder control horns and servo.