External diameter 80mm, diameter 23mm, length 500mm, want to use iron pipe to do external mold, internal mold with iron pipe or solid iron rod processing into taper column (and spray boron nitride release agent), do not know such a practice, OK? In this mode with the taper approach in the aluminum liquid after solidification can easily remove aluminum (because the coefficient of thermal expansion than iron, I am afraid after cooling tubes will (lock core) trouble experienced teacher for advice! Thank you！ StopWell, I'll make a small tube of plaster. If the inner mold is not working, will it be stuck together with the aluminum parts? It's not good to clean it
A drill bit that is not so long can be welded longer.Or you can't buy this round bar.
I think this kind of thing, buy a diameter of 80mm long 500mm aluminum bar, directly drilling a 23mm hole is not good? Aluminum soft, drilling is very easy.
Where do you put a solid round bar and drill it?.What the middle of the hole diameter of 23 long 500, do much to the taper, also can not play what role of draft.
