Casting, pattern making and machining are my hobby and job. So if I get a little carried away just say so. To cast a twostroke cylinder first you need cores then a pattern. I make my cores often with a rubber mold of a cylinder I like the port shape of, then copy into a two pot casting resin. So you end up with ( male ) transfer port shapes like this.
Then these need to be copied back into a core box, so you can make more of them ( in casting resin for the cylinder pattern itself ) and ultimately these boxes will make the hard sand cores you cast with. Basically you manufacture the cores first ( in casting resin ) stick them all together, then add thickness on top of that.
This is the pattern being made up of the resin core prints. What is solid here will be holes in the casting ( when done in sand ).
This is the main cylinder and exhaust port as one core, here is the box it's made in.
Here is the pattern made with all the smaller cores glued inside. You can see the core prints ( tapered bits on the ends) sticking out. This gets invested into sand then removed. While the sand mold is apart, hard sand cores are fitted ( transfers / water gallery etc ) They will fit neatly into the core prints provided by the mold as it was invested. With the mold back together and cores in place, metal is poured in. Where there is sand ( as in a core ) there will be a hole ( port ).
Thought I had some pictures of the sand mold set up and pouring, but must have deleted them?
I have others but not of twostroke parts.
