Hi there Hagar
the following is an extract from the Whaleback build on this forum, which I am doing.The propshafts are made from commercially available propshafts and I have made many of these type of propshafts and I have not had one fail yet. There are 3 of these type prop shafts in the MTB, which should be classed as a low-flying missile
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Here is a scribble to explain the method/possible method of constructing the cut-down prop shaft and the P bracket support - this is a method I have used several times, when we didnt have the facility of a lathe to manufacture the parts.
We commence by obtaining a 'shop purchased' prop shaft of the correct length that we require for our prop shaft. We remove the prop shaft from the tube; mark off on our tube the required length for our new prop tube - and, then cut it at our mark.
I normally cut the tubes in half with a small modellers pipe cutter - this does give a nice clean cut. I then remove all the burrs and dress the prop tube up.
The next stage is to remove the bush from our redundant piece of prop tube - what I normally use to remove the bush is a tube which fits pretty neatly inside our prop tube, or, I have used a discarded knitting needle (from the Mrs) and I tapped the bush out from the inside.
The next procedure is to warm up gently, normally on the cooker top, the end of the tube where the bush is going to fit. Prior to doing this, I normally put the bush into the freezer compartment of the frige and I divvent mean a bush from the back garden so while the bush is being frozen and contracting, the tube is going to be expanded with the heat. This makes it a lot easier to fit the bush back into our new section of tube. Let it cool down naturally, out of harms way......... yes I have tried to pick the tubing up when its still been RED HOT and yes, it does bring tears to the eyes.
The next stage, as you will see by the drawing, is to make the support bracket - this is basically 3 pieces of tubing. The inner tube must be the correct diameter to fit over your prop shaft and it must be not too tight of a fit, you must be able to spin the shaft in the tube.
Then, its a case of two pieces of tube which will fit over the tube over your first piece of tube. These are all cut to length slightly longer than one another - inner tube being the longest and these are then soldered - just with normal soft solder - then I make a mandrel up and shape as has been mentioned previously in this build - with a file and emery cloth and then I add the support leg.
I do hope this makes it a little clearer - and - I will add further scribbles as we go along - but, just as a side note - the rudder and rudder tubes are made up basically the same way as we make the P bracket up - and I will add a drawing to explain later on.
Now....just going back to fit the deck.
aye
john e
bluebird