Re: Aluminium cast Clone Trooper Helmet
hallo again,
the oven is running now an i have some "free" days until the cast on wednesday or tuesday next week. so, what have i done last week? first i made the 2 more wax helmets at the weekend. than i had to retouch them all, what was taking a lot of time, because i had to fill up every little hole in the wax (the little air bubbles which came in through the wax brushing). i also cut of the wax were the 2 pieces were put together and resculpted this area. and i finished the interior neckring...
next i cut in 2 little holes in the "ears". for the normal 501 helmet these will be filled with black polyester later and so after sanding there will be just black dots. i think this will be better than paint it on. the 2 other helmets will get some small microphones there, so i can hear whats going on outside.
i also had to cut off and rebuild the mictips on these 2 helmets, so that the speakers can be build in later.
all 3 finished helmets...
well, from now on, its just a technical description of how lost wax casting works. i have to say, that every foundry do this a little bit different, but the principal is generally the same since the antique… at first i hat to make the core. i used a mix of plaster, recycled material from old molds and grog for the whole form building. because i had several holes in the helmet, i had to close these with clay.
than i filled in the liquid plaster-grog mix and while its hardening, i put on a plate so i ve a good, solid base later.
i also had to put an iron into it… after it hardened out, i can take of the clay. you can see the core very good now.
after that, i build the casting system out of wax tubes where the aluminum can be filled in later on. you can see the funnel on the top. for the lower part i let the metal fall in. for the upper parts, you can see the system hits the surface also uprising. this way the metal can fill up the mold nice and without turbulences from bottom to the top. at the top there are 2 tubes not connecting to the system but leading to the funnels side. one of these is for the air to come out. the other is, in this case just for safety, because i have enough holes in my model. but normally its for the core air. you can see the little copper tube. this will connect the core with the outside. when hot metal will be filled into a form, the air in the core will extract immediately, so you have to take it away. otherwise you will have big bubbles in your metal sculpt later on.
the nails you see connect the core to the rest of the mold and fix it. the holes will be weld later on.
than i started to make the casting mold. first i sprayed the whole thing with a the same mix like i used for the core, but with finer material and without the recycled stuff in it to get a better surface.
than i threw on some the normal mix, just with a little bit better grog in it. so i got a nice little cocoon.
this one is set than into a cylindric form and than filled it up with the moldmix.
so you get a nice cylindric form. after burning, the mold is very soft so you have to pack it in some fresh plaster fabric so they won't crack when heavy metal is cast in. the cylindric form helps to hold the pressure in it.
at least we put all the forms into a big ceramic oven where the wax will be burned out for the next few days at around 600 degrees celsius.
well, thats it. next will be the casting itself an the finishing of the aluminum, which means: sanding sanding sanding. it will take also a lot of time/ work. but for now i hope the cast will be fine.
i also have to regret my not so good english right now. sorry if i just wrote some confusing things here. if you have any questions feel free to ask.
you will see more photos next week than.
best greets, hinrich
