Today I attempted another aluminium casting session with trees that I had made 2 days ago. More wheel forks, and barrel trolley brackets. 16 parts altogether.
And this time I installed air release vents, following my previous poor results, and at the suggestion of reader Rob R.
I also made some 50mm extensions of the pouring funnel, to increase the head of melt pressure. The extensions were “add ons” rather than designed into the system, and the molten aluminium leaked between the extension and the main flask with the tree, so I doubt that they were very effective.
BUT! Of the 16 parts on the trees, 14 were good to excellent, and only 2 showed any voids, and I assess one of those as repairable. So, 15/16 is very pleasing. I feel that I am closer to getting good results every time, if I can make an effective system of increasing the delivery pressure of the molten aluminium.
And while the investment burnout and baking was proceeding, I worked on previously cast parts.
One more melt and pour, and that should be the last of the castings made for the model Armstrong cannons. It has been a challenge, and lots to learn, but very interesting and very satisfying.
Many thanks to Rob R for his spot on suggestion about the air vents.