One definition of stupidity is repeating a set of actions and expecting a different outcome.
Well, after my partly successful first molten metal pour, I repeated the same steps, (with some minor corrections), and hoping for a more successful result.
The day was entertaining, with one of my daughters videoing the exercise. But this was the result…..
So, I am considering how to change the process.
I believe that I need to increase the filling pressure in the upper half of the flasks.
- Install a vacuum system for the melt pour
- Use a vertical extension for the melt funnel, to increase the height of the column
- Increase the diameter of the funnel tube
- Increase the number of the funnel tubes
- Don’t place tree branches close to the funnel
I had previously considered 1. as recommended on YouTube by several contributors.
The investment powder is a significant cost, so I would prefer to use as much of the volume of the flask as possible, which makes 5. an unattractive proposition.
There are difficulties with instituting 2. but I am thinking about this one.
And possibility 6, is to try bronze or brass, which has a much greater density, and probably less viscosity than aluminium. I am waiting for some more furnace graphite crucibles to arrive before I can try this one.
Meanwhile I have to 3D print some more PLA parts.
Hello John, The position of the defects suggest trapped air, if so a vent made by adding a PLA rod to the top patterns should fix it.
Thanks Rob. I will try that. John