Monday, 12 May 2014

More work on the Tiller fitting...

First stop at the weekend was at Mike the foundry man.

He explained the modifications I needed to make to the existing plugs and the requirement for a core box. He also provide me with a couple of sketches which was just as well because despite his patient explanations I only half understood. I didn't want to disturb his Saturday morning any further and hoped that it would sink in with further study of the diagrams.

Here are the modifications to the plus which I managed to complete by about 2pm



The extra bits shaped in and stuck on with marine filler are to required in order to get the things out of the sand without damaging the sand mold left behind.

Next up was making the "core box". This is what's needed to form a sand core of the same (hopefully) dimensions of the shaft and which is then inserted into the molds created by the plugs. This was what took me the longest to get my head around and I still can't say I completely understand it far less explain it properly. 

Quite how to go about making this thing was the next challenge. Luckily Chris dropped by as I was deep in head scratching mode and suggested casting it from the previous inside-out version (see previous post). That however required extending it which I achieved by extending both ends with stiff cards and then pouring in resin:


The resulting shape required a lot of tidying up before it could then be place in a container (an empty marine filler tube provided by Chris into which I then poured more resin (having previously waxed all the surfaces:


That got so hot (the resin hardens as a result of a chemical reaction with the hardener and that produces heat) at one point that it started to smoke and I was worried the whole boat might go up in flames.

That was the last job on Saturday at about 7 pm before going out for a curry with Alan.

After a lousy night's sleep (there was gale blowing all weekend which added to the affects of the curry and my increasingly frustrated state of mind I think took their toll) the first job was to cut the mold off.

This I managed but the resin did not pour properly and left cracks and this was the result after removing the mold and cutting out the plug:


However, by lunchtime after a great deal of work I had repaired the two halves and added the internal tapers required by Mike:


The bit in the middle is the extended plug from which I made the cast.

I spent the rest of the day filling the holes where the anode bolts had been (see a previous post for why); removed the flexible water tank for repairs/replacement and the old log impeller which I'm going to replace.

On the way home I dropped off the plugs and core box at Mike's. Unfortunately he was not in so I was not able to establish whether my work would do or not. As of the time of writing this I have not heard from him and so am hoping no news is indeed good news. Of course whether the resulting casting will fit the rudder post is yet another matter.

To be continued....