I gave a link earlyer to an article on type and sizing of aggreate.Search Google....machine design polymer castings....I guess nobody read it as there is still questions about aggregate sizing.Sorry having trouble linking.
The other link I left has a picture of a huge E/G machine.What is it? I will try a direct link.www.moldmakingtechnology.com/articles/040401
Larry
Woops that almost worked.use search in the top right type in 040401 If that does not work search Google"moldmaking technology secrets to hard milling