unidirectional or twill?

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#1

Hi guys,

i have a question, I have been working on making a set of door sills and i have found them to come out somewhat flimsy. I am using 1 layer of 5.7 oz twill followed by 3 layers of 5.7oz glass. I’m using polyester at the moment for testing, but they keep coming out flimsy (i.e I can easily bend them in a twisting mostion). Can this be rectified by using unidirection Cf/glass rather than the twill? any ideas?

Thanks,
Harv

I know they aren’t great, but I’m working on it!

#2

The only way to prevent that shape from twisting would be to use more layers, or, a core.

#3

Thanks Jason,

I’ll be sure to add more layers.
Harv

#4

are you using chop mat fiberglass?

#5
  1. Don’t use fiberglass. Or use a lot more layers of it.
  2. You need to change the direction of each layer, and mirror the layup from the middle… (0/90, -45/+45, 0/90,[middle] 0/90, -45/+45, 0/90)
  3. Why is the surface so rough on those?
#6

Yup, as with everyone else. More layers of CF will make it stronger. A balanced layup like TET said helps.

But, at the same time, how flexible are the originals? They are just cosmetic right?
If so, as long as they are buttoned up in place in the car, they might still be ok, even with a warp. Test it out in the car.

Remember, glass is only going to weight it down.
Glass is good for prototyping though, since it is cheap!

#7

Thanks guys, actually this is a prototype so it doesn’t surprise me too much that it would be flexible, but the amount of flex did surprise me.

The gelcoat warped a bit in the mold, the next sets came out perfect.

I’ll post the next round soon.

Harv