Rear spoiler 3 piece mold making of

General Composites Discussions Showcase
#21

building up some volume on the center section

1st layer 100grm glass, 2nd layer 290grm twill glass, 3rd layer 380grm plain weave glass… combined with epoxy surface coat and epoxy resin, its gonna be damn strong! how much thickness you guys think i should go for? i don’t wanna waste too much materials for no reason… maybe another layer of 380grm?


oh i used some 3mm chopped glass fibers with epoxy for the corners and the tit-thingies on the flange…

#22

for hood mold I use 1x 165g glass + 5x 400g twill and it`s still litle flexible

I think you should add 2x 380grm

#23

yeah i guess i should… this damn fabric is a pain to laminate :frowning: took me 2 hours for just 1 layer of 380grm… i’m thinking of making some vertical reinforcements,to give more strength to the flanges connecting the 3 pieces together…:cool:

#24

finally completed. After a lot of kicking and pushing and shoving, mainly due to the damn clay, and some mold resin that had dripped through, the spoiler was demolded. Here it is, trimmed and drilled (but not polished or anything, it came like this out of the plug)

#25

Total cost:
1kg kit of epoxy mold resin (used about 800gr)= 30 euros
1/2 kg epoxy resin = 12 euros
various glass fabrics = 30 euros
brushes, cardboard, aluminum tape and stuff = lets say 20 euros

92 euros…could be a hundred

it better pay off! :smiley:

#26

good job aga. So you only used frekote as your release agent ?

Can you give some pics of the 3 pieces bolted together so I can see what the part line will look like where they bolt together?

#27

yeah just frekote. The parting line has some gaps, that was because of some clay pieces that were “lodged” below the gelcoat, but now are gone… nothing dramatic, but enough to say “its not perfect” :smiley: . my plan is to use some car repair putty to fill the gaps and just leave it at that. I’ll take some pics soon.

#28

How do you plan on bagging that piece? It looks like it may be difficult due to that one cut-in and a vertical edge…

#29

i dont plan on bagging it, but if i was, i would fill the gaps on the vertical flanges with sticky tape, and as for the gaps on the flanges, the gelcoat would block air coming from there…

#30

aga how many layers of the frekote did you use on the part?

#31

5, 6 layers of frekote

#32

Very good :wink:

#33

thanks george! :slight_smile:

#34

ok, it would be a shame to leave this thread without posting some finished product images… Here’s one, 1 outer layer of 100grm woven glass, 2 layers 300grm CSM, and 1 layer of 300grm woven roving

and here’s another. Clear epoxy gelcoat, 1 layer of 300grm twill carbon, 2 layers of 300grm twill glass with black epoxy. very strong and very light, but the vacuum bagging left us with voids in the carbon’s surface

i’m gonna overlay carbon on this one… but these photos show the mold’s surface (the part has not been sanded or polished, just trimmed. i’ve pulled several products already from this mold and it’s starting to show it’s age)

#35

update pics ???

#36

Good job. The parts seem to be coming out nice. But the parts really should be made with a balanced layup schedule. Also, are you using any reinforcement in the +/-45* orientation? I’ve seen A LOT of these kinds of parts warp because of that, and then obviously the don’t fit well or produce gaps after being mounted for a while.

And don’t overlay that part! Defeats the whole point of molding parts.

#37

no i havent laid ±45 degrees reinforcement, that would require me to throw a lot of material away and i’m working on a budget :frowning:

well, i am gonna overlay this part, cause its mainly cosmetic (a rear lip spoiler more like ruins aerodynamics than improves it anyway) still, it will be lighter than oem (1600gr)… this one is 800 gr, it may go up to 1200gr after the overlay.

Its such a small amount of weight, that it can be gained if i go for a dump before i drive the car…heheheh :smiley:

#38

part of the problem with the voids left in the carbon might be that the resin isn’t wetting out the glass with a similar affinity as it is the carbon. I know that I have infused with glass and with carbon and the glass never comes out as nice. Talk to the distributor/manuf and see what they say.

#39

i vacuum bagged it only with carbon. left it for a couple of days and then took out the bag and breather etc, and laid the glass with epoxy resin with black pigment. some say the voids may be caused by too much vacuum…

#40

Too much vacuum will not cause that. Seems like you just pulled too much resin out, or the surface wasn’t wet out well.
We run parts at full vacuum PLUS 100 psi in autoclave an the parts don’t come out like that.