I am going to be making a few molds, but I can’t decide what sort of glass to use for it. I will do a simple hand layup to make the molds but I’m not sure if I should use chopped strand or the “boat fabric” stuff? Any suggestions.
I’m leaning toward the boat glass for ease of use…
Do you guys use infusion to make your molds?
You will should need many types of FG materials from surfacing veil, mat and H.D. cloths. Built over a long time.
Best material to make moulds with very much depends on the type of mould and the sort of use you are looking to get out of them.
Small moulds are a lot easier than larger ones, but with any mould you do need to bear in mind that thicker moulds are more likely to have problems with shrinkage, and that a proper mould resin is very desirable.
I’d recommend surfacing veil, followed by a layer or 2 of 4oz, and then the heavier woven stuff.
Wouldn’t use any CSM at all, as it consumes A LOT of resin, which causes shrinking and warpage.
And yes, most of our molds are infused.
Im not sure how people infuse molds thou. like for exp: right now im using foam board + the part. now, if i infuse that, that boards going to snap in half in a matter of a sec. once the pump starts.
i was thinking of laying up the mold, then just vac bagging.
man…anyone who has the time to actually infuse the mold itself is really going for it.
I dont even use any of the tooling resin right now…I dont have problems with shrinkage but my parts are pretty complex.
To answer your question RC
I use:
3 layers of surfacing veil
3 layers of 6oz plain weave
12 layers of 3.5 oz Chopped Strand Matt <— I hate that stuff
3 layers of 6oz plain weave
2 layers of veil <------ I veil glass in a name badge on the out side of the mold.
I dont have any problems other than the chopped mat eats up resin, but it build thickness like a mother.
I dont think youll have problems with shrinkage if you do it like I do. 3-4 layers and let cure overnight and then add 3-4 layers until done.
My mold layups consist of:
1 ply .75oz CSM
8 ply 1.5oz CSM
2 ply 6oz Cloth
More or less depending on the the complexity of the part.
I will be doing a mold infusion tutorial in the following month. Keep an eye out for that.
Hybrid: Your layup must build ridiculously thick molds.
hahaha!
Youre the one who told me I shouldnt be able to flex a mold!
They are about…1/4-3/8ths thick on average.
I just try to keep them thick enough to pull as many parts as I can without cracking the mold.
EDIT* I forgot to mention that my 3.5 ounce chopped mat gets peeled into seperate plies. So its not quite as thick as youd imagine based on that.
I got the 3.5 cause it was only a fraction more expensive but it sure does suck to work with.
Im thinking of getting a chopper gun to build molds…anyone use them?
Ha!.. alright then. My mold are about the same thickness. I thought you were using 12 plies of straight 3.5oz. Thats crazy!
thanks guys,
so the surfacing veil is just for a better finish?
Surface tissue means less chance of print through, and reduces liklihood of air between gel coat and initial layers of glass.
very good thanks