So, finally to the build.
First job will be to clean all the moulding marks from the belting and the keel and stem/stern posts ( of which I have omitted to do on the prototypes at the moment.
Next is to fit the running gear of prop shafts,A frames and then rudders.
I found that I only had one set of brackets for the Watson, and had had to in the past, make up a new set ( as there were no generic ones to fit ) for the Barnett, Mary Stanford....and so I'll just run through the steps to make a set of brackets first. these would also be normally cast in white metal after moulding.
Take a round of brass to make the bearing that will be inserted into the boss of the A bracket, and using a laithe, drill the centre with the diameter of the propeller shaft, ( in this case 4mm) and then shape the bearing in the laithe, putting on a flange at one end, and the outer diameter to ( in this instance) 6mm. set aside.
Take a round of brass for the hub of the bracket boss, and centre drill for the hole to take the bearing, which will be a 6mm hole to take the 6mm outside diameter of the bearing. The bearing will then eventually slide into the boss.
Shape the boss in the laithe to that shown on the set of plans, use carburundum tape to clean up, and then using a parting tool, cut off the boss from the brass round. Repeat this process for the second boss for it's twin A frame.
Take some length of flat bar ( or if needed shape the bar with a file,/grinder/sander if you want to get the profile of the legs exactly as per boat....but that's for the purist) and jigging up, silver solder the legs to the boss at the correct angle required on the plans. cut the legs to fractionally over length, and set aside for a few minutes.
Take a length of nylon rod about 10mm longer than the length of the boss......this is to go through the boss of the A frame which will go into the rubber mould with the A frame assembled.
Make a rubber mould from two layers of RTV rubber as in the pictures, using lego boxes and plastecine for the process of moulding.
The box is made and a layer of plastecine is put into the box...............the part to be moulded is pressed into the plastecine half way ( this is the process, using RTV rubber for any fitting part) and the round of nylon is moulded in the rubber.Also small impressions are made into the plastecine for locating pins to form in the rubber, in order to stop the mould from sliding later when moulding, ( thus giving an overlapped mould, which would be useless)
Rubber is poured into the exposed half of the fitting and alowed to set, usually overnight.
Once set, the plastecine is removed to expose the unmoulded half and the exposed rubber of the first half is sprayed with a release agent, so thet the two halves of the mould won't stick together. Pour into the seconf half the RTV rubber again to finally cover the master that you have made.
Once cured, remove the rubber from around the master revealing a berfect female mould of your master.
Cut track ways for the metal to flow in, airways for the trapped air to escape, take the nylon out of the master and put back into the rubber mould, put the mould between a sandwich of two pieces of 4- 6 mm ply , hold together with clamps and pour into the access hole your white metal......allow to cool and then remove the moulding from the mould.............remove the nylon rod from the mouylding....and Hey presto...you have an A frame with a hole running through it for the bearing.
The process is shown below for making an A frame in pictures. the brazing hearth is a constitute material called Vermiculite and obtained from such a place as this... http://www.ebay.co.uk/itm/Soldering-Mat-Pad-Brick-Board-Brazing-Hearth-/120799566544?_trksid=p3284.m263&_trkparms=algo%3DSIC%26its%3DI%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D21%26pmod%3D260898624510%26ps%3D54
and is very cheep for what it is..can be cut with a saw, made into any shape and is just superb for brazing.