Mould for casting intricate parts

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#1

Hello guys,

I’ve recently made a mould to make a bonnet for myself, but am stumped as to even how to begin to make a mould for the vents which go with it. The originals are made from aluminium and are quite intricate, they are not just for show and do actually work. You can’t get them anymore.

Can anyone help or maybe just point me in the direction of something I can read or whatever? They don’t need to have the tapped fixing holes in them, I can just bond them in.

They certainly look tricky!

Top view of the full set:

Bottom views:

#2

are you wanting to cast in metal ??

#3

No, sorry I should have said, I’m hoping I can cast them in resin maybe?

#4

well, you could make a silicone mold…easier to demold too…

#5

Hmmm, I think I need some sort of two part silicone mould - something like this: http://www.cfsnet.co.uk/methods-silicone.html

I’ll see if I can get some material and a book to read…

#6

How much weight savings are you thinking by making them out of resin?

#7

65-70 % i bet

#8

i’ve done some searching on mold making with silicone… here’s how it would work for your parts:

first, you flange it and cover the holes etc, like you would with a fiberglass mold.

then, mix silicone with the hardener, and apply a thin layer with a brush to take all the details. leave this to dry.

then, you add a bit of a thickening agent to the silicone. you add another layer and build up thickness, untill it’s nice and fat (lol)

when its dry, you apply a release agent on the back of the mold ,some use vaseline, liquid wax, or just some tin foil, and on that, 2-3 layers of chopped strand mat. this is used to keep the shape of the mold.

when everything is dry, remove the fiberglass part, and then the silicone mold.

put the silicone mold in the fiberglass again, apply release agent (if needed) and off you go. you can either pour resin or whatever, or fiberglass…

(this method is used for building truck bumpers here)

#9

I was thinking silicone as well. But for that large part(s), it would be very expensive. But it would work well. Even if there are some negative draft angles, since the silicone is soft, it will pull out.
I would suggest a harder silicone for that size, and yes, with a fiberglass shell, or even layers in the mold for strength, else it might tear.

#10

Well none, that’s not the idea behind them, I’m making them to go with the bonnets I can now make. The panels I do for this car are not always for weight saving, but simply because you cannot get the originals anymore. It is a very limited market though as it’s a rare car and most are not used as 'daily drivers.

#11

can you add pics of your work ???

#12

Thanks Aga for your guide and others for your thoughts, when I give it a go, I’ll take some pics and post up - if it’s successful!
I’ll start with one of the small ones and see how it goes.

#13

Of the bonnet vent silicone moulds? Sure.

Out of interest, where is SoIN??