Project Tank Cover

General Composites Discussions Composites Talk
#1

For the past month or so i’ve been working on a mold for a motorcycle fuel tank cover. The mold leaves MUCH to be desired. This is the first mold i’ve made that is this complex of a shape.

So i go to infuse the first part in this new mold today… darn mold partially folded in on itself under vacuum. Mold is too too thin for this type of part. I just wanted/needed to get a part made so i thought i’d give it a go before i added more layers of fiberglass and resin to the mold. I can honestly say by looking at things now…the mold should have been at least 1/4" thick with an “exo-skeleton” crating on the backside.

Another rookie move i made is I forgot to lay down the flow medium before bagging the mold. The infusion went ok, considering the lack of flow medium :o I may be able to re-infuse the part to cover the dry areas. Tips or suggestions on this would be useful.

What is an easy and effective way to egg crate the backside of a mold?

I may be able to salvage this part after reinfusing it. To get the mold back into shape i released the vacuum pressure after 5 hours, wedged a wood stir stick into the mold to flex it back out to the proper shape. The part in the mold is epoxy resin/cf/fg and the resin remains very flexible for 8 -10 hours.

#2

If you put a bit of pleating even with the stretch stuff you will not need a thicker mold. Only when there is stress caused by the bagging material needing to stretch does the mold come under twisting forces. You can have the thinnest mold in the world, pressure is always the same on both sides (it’s the atmosphere thats doing all the work for us).

try to go thinner with the number of layers of reinforcement, I went with only 3 layers in mine and it had the same flex as teh stock plastic one, but weighed only about a third, it will aslo infuse faster and use less materials. There is no need to make a ridgid/structural part of a thnig if it does not have to serve that purpose (I don’t actually know how many layers you used, but I’m just saying for simplicity and practicality.)

any pics of it and what happened?

#3

yeah i wondered about that… the bag film flexing caused mold flex:o

This work is sure not easy.

Camera batteries are dead like usuall. sorry.

edit: well it definately came out like crud. has about 4 long edges bridge with the c/f. Waisted part all in all, but it’s ok i learned something from it.

#4

I know what it’s like, it took me a few tries for the tank cover before I started getting it right… not easy, it’s a very intricate part with compound curves and a strange shape…

#5

very tricky part for me.