Why do I listen to my students? It only causes me to have crazy ideas.
So here is the full story.
The student who designed the barman’s bottle opener (see a previous post) was looking at how his design would be manufactured “for real” and decided that it would probably need to be die cast… Of course we couldn’t contemplate doing that but we do have some casting facilities in school… And we have heard of “lost wax casting”, but what about “lost plastic casting” in a traditional sand mould? Errrrr?? This got me thinking, surely at the temperature that aluminium melts the plastic print from our 3D printer would just burn away to nothing. Time for a bit of testing!
With the fume extraction going full blast we placed a sample of ABS in our brazing hearth and played a flame over it… Result a black blob and lots of black smoke. But what about PLA? Tried this too… Result it completely disappeared just leaving a small stain on the fire bricks. Maybe there was some mileage in this, so time for a full test.
We unearthed all the casting boxes, crucibles, leather aprons, face masks, gaiters and other other paraphernalia, made a sand mould with petrobond (oil bound) sand with suitable runners and risers and then fired up the furnace. All very exciting stuff as we don’t get to do this sort of thing very often in school these days.
After a bit of a wait we degassed the molten aluminium and the moment of truth had arrived… Time to pour it into the mould! Everything went smoothly, we now only had to wait for the aluminium to solidify and cool down… The excitement was mounting! And the smell of scorched sand was pervading the whole department much to the disgust of my colleagues.
But now the time had come to break open the mould… Bated breath as the sand was crumbled out of the casting box….. And….. FAILURE!!!…. It hadn’t worked! The 3D printed PLA object was only slightly melted on one side, surely it couldn’t have resisted that sort of heat, but it had.
So, back to the drawing board and a bit more thinking is needed… I’m convinced that it should work but we just have to find out exactly how to do it.
On the other hand, perhaps I shouldn’t keep listening to my students.