Just saw a tip on another Composite forum. i havnt tried it myself, but will soon on my molds. Using Sand, Fine sand after 2 layers of fiberglass and then epoxy sand, then glass again to keep it together. heavy, keeps it in place. and mold doesnt warp as much. i will try it soon, but i have to many things on my plate as we speak =(…
i think this is my first post =) hi guys
I doubt it is sand but PUR foam dust…
trust me, its sand
It would seem to me that sand would add a ton of weight and little in strength. It would be better to use cardboard as a poor mans honeycomb layer and glass over that for light weight but extemely strong mold…
Is there any chance you can tell me or us what the forum was you saw this on?? Was it fibreglast?
cheers mike
you’ll also see some VERY useful tips in there. they also have a link on the 4th page for another method.
Still, sand is going to add a lot of weight and little stength…try moving (for storing) those large molds with sand on them…gets old but then…ok Doug, here’s your chance to chim in… :lol:
so anyone else got anything on this. the thread went in the direction i was thinking using some microballoons to keep the wieght down while minimizing resin use. I’ve been trying to come up with exactly this type of filler for about 6 months now but never was able to think it all the way out to get to the right conclusion. thanks Chelon for hooking us up with this link.
It seems to me that a
cloth
cloth
cloth
filler
cloth
cloth
cloth
would both take less time and cost less. i haven’t done the math yet, but a few poeple in that thread did and it makes sense to me. just as long as i can keep the wieght down
I don’t think the point of the sand is to keep the weight down. I think the sand is being used in place of expensive core material. It also conforms much better than cardboard.
I tried the sand buisness on a smaller mold I was doing… actually worked quite well… went to home depot and got some fine playground sand and just mixed with some resin, then put a few layers of glass over the top… worked quite well
I guess I missed this one.
I used to work for a company where we mixed a low exotherm epoxy with sand til it was just moist. we layed it on actually quite thick.
These molds were used for RTM or reaction injection molds. You’re right they were very heavy.
We also did this for vacuum form molds and the mixture was quite porous so that you only laid a surface coat, one light cloth, and then sand. all you had to do was drill through the surface caot and glass and make sure the bottom was cleared out for the vacuum.
Yes they were very heavy…we used to use concrete anchors to attach into the snad and glass. this made it safer to lift with a chain fall.
sorry, i left out the wieght savings if you were using a micro balloon, but that doesn’t seem to even out in cost for filler VS time saved.
we actually layed it on to about a 4 inch thickness and buried copper refrigeration lines in it to heat the tool for faster cycle times.