Friday, 19 October 2012

Finished article.

The casting is knocked out of the sand and then quenched in cold water to harden it, the sprues are cut off and the back machined flat. Any flashing is filed off and then rubbed down a bit and polished.

The pouring cups feed the casting as it starts to solidify.

The core in place. Cores are made with sand mixed with sodium silicate packed into the core box and then squirted with CO2 to harden them, they are washed out after casting.

The pattern needs to have a draft or be tapered so it can be removed from the sand. The coil cover could've done with a bit more and is a bit tight. Clean removal relies on a steady hand and is dependant on how many beers I had last night.

The Aluminium I use is mostly old cylinder heads and crank cases.
Patterns can be made out of various materials. The rocker covers were carved out of body filler, the badges were ripped off the back of the originals by pouring silicone rubber over them. Patterns need to be bigger than the finished casting to allow for shrinkage.


  1. My dad who did his apprenticeship as a pattern maker was explaining how they did this only last week after I found a box of patterns at the local carboot. I bought him one as a talking point. Seemd to do the trick. Love that coil cover!
    Regards Craig

  2. Thanks Craig, I'm sure he could teach me a thing or two!