My primitive way to cast aluminium or how I made a knife guard out of scrap aluminium. Part one.
One of my knife was fairly balanced and due to its design, it was beginning to be heavy. So I decided to make the guard out of aluminium. Yes of course I can take a flat piece of aluminium and use it for the guard but were is all the fan?
So, true to my recycle(ist) nature I set about to make the aluminium bar by myself. I have all sort of scrap aluminium, I have a little NC two burners gas forge, I have a casting metal ladle and I have a few construction grade sand bags. Perfect.
Here is what you need to do (if you want to do it at all that is).
First you need to do the moulding plug. I used piece of wood the thickness of my finished guard plus 2mm. I traced marking line slight bigger than the finished guard size and screwed two screws to help me to take it out of the mould box. I purposely left one side flat. More about it in the second post.
Then I build a wooden moulding box. You don’t have to build it but you need container big enough to allow two centimeters of sand around the plug.
Fill up the mould with sand all the way to the bream and tamp it to compact the sand (it is helping to dampened the sand a little bit, it help to bind it together. The finer the sand you can use the better.
Use a teaspoon t0 dig into the sand and bury (not berry) the plug all the way to the plug upper side. Pack the sand all around the plug. Now, very carefully draw out the plug from the sand. If the hedge of the plug impression is ruined to some degrees try and repair it with you teaspoon.
Stand the box near your forge and make sure its leveled to the universe.
Cut the aluminium pieces to the size that the ladle can take snugly.
How much aluminium do you need, you may asked. Archimedes asked himself the same question and he also found the answer. Anyway I won’t bore you with his principals, instead all you have to do is to weight a guard that you got from previous knife and roughly estimate the weight. If you really want to be scientific about it, you can read on that web-site ‘http://www.schoolphysics.co.uk/age11-14/Matter/text/Archimedes_/index.html’.
The above technique by Archimedes is good if you don’t have like for like guard sample. You made one from other material like wood, clay or wax and you need to know the volume of the guard to assess its weight.
Load the ladle with the same weight plus thirty present more with the aluminium pieces. Fire up the forge (or any other heat source that is hot enough) put the ladle inside and melt the metal. Some people will say that you need to add borax to the metal to help with the cleaning and the flow of the metal during the casting process. I didn’t. But it worked fine however.
Cast it in to the sand mould and let it overflow, to make sure you have the proper width.
After it been cooled down you need to grind it to the wonted thickness, but more about it in the second part of that post.
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