Cost effective bonnet/hood molds

General Composites Discussions Products Talk
#1

Hi, what is the most cost effective method for making car bonnets/hoods moulds. At the minute its only cost effective if i can get a few wanting a bonnet made from the same car but want to be able to make on request for any car and this will mean making good quality but cheap moulds of the bonnet so i can lay with cf or infuse.

thanks
gareth:)

#2

I’d say polyester resin with a chopping gun, just spray yourself some gelcoat and then later go nuts with a gun till it’s thick enough to where you like it…

#3

Yep he’s right i think. If you don’t have a chopper gun just use some csm (chopped strand mat). you can buy it in various thickness/weights .75, 1.0, 1.5, 2.0 maybe heavier but i doubt you need it heavier than 2.0.

to give you an idea on polyester resin and csm; 4 layers of 1.5oz csm will be about 3/16 inch thick. I don’t know how thick you want to make your mold.

#4

Thanks for the replies, as long as the mould is thick enough to hold together under infusion. Is polyester resin cheaper than epoxy resin? polyester would not be used for a finished product just mould making then?

Thanks

#5

yes, polyester resin is used for mold making and in combination with fiberglass cloth or fiberglass csm (chopped strand mat).

There are two main types of polyester resin…ortho and isopthalic… use isopthalic for mold making, unless your going to just make one or two bonnets. Isopthalic is harder and better for mold making.

Also use polyester tooling gel coat as the surface coat for your mold… 25 mils thick on the tool surface.

#6

i didnt know there existed 2 types of poly. how can you distinguish them? color? thickness? (i think thickness is dependant on shelf life too)

#7

infusion doesn’t stress the molds, unless you place the bag awkwardly and it stretches. the bag is pressed by the atmospheric pressure, not pulled down…

#8

i use both resins as well. My supplier just calls them gernal poly or tooling poly. Anyone using orca resin? When I bought this company it came with about 40 gallons of orca infusable resin but I been using the rest of my valspar resin I have first. Just seeing if anyone had any issues with it.