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prepreg carbon..any advantage?

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NYKiter
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prepreg carbon..any advantage?

Postby NYKiter » Fri Jun 02, 2017 2:21 pm

sounds like virgin fabric.....
anyone use this?

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Re: prepreg carbon..any advantage?

Postby Blackrat » Fri Jun 02, 2017 4:44 pm

No need for it for DIY applications

It's has it's advantages and disadvantages

It's great as the fiber to resin ratio is pretty much spot on.
It has an expiry date that isn't very long, has to be kept at low temps (freezer)
Most prepreg an autoclave is needed for decent results , but you do get out of oven versions

Normal carbon and epoxy is much cheaper

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Re: prepreg carbon..any advantage?

Postby Lokihel » Fri Jun 02, 2017 5:30 pm

Prepreg carbon usually gives a better quality product because the resin to carbon ratio is exactly what it should be and perfectly distributed.
The better quality is also due to the better manufacturing techniques used, such as proper aluminium moulds, vacuum bags or bladders, and the use of an autoclave.

Prepreg carbon comes in rolls and must be kept at a low temperature. The resin usually requires cooking at a precise temperature to cure. When the resin cures it releases heat, but you still want to get it to about 110°C if I remember correctly. At 120°C your carbon composite will get heat damage, so you need to remember to switch off your source of heat before reaching temperature, but not too soon, else you don't cure perfectly.

Also, prepreg carbon is very expensive; it makes dry laminate carbon seem cheap.


Basically prepreg carbon is for professional use as it requires more equipment and more control.

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Re: prepreg carbon..any advantage?

Postby rynhardt » Fri Jun 02, 2017 5:45 pm

Yeah you get to use the word PRE-PREG in all your marketing material, as in

Our space age PRE-PREG carbon ensures optimal strength at a featherlite 2.5 lbs (*terms and conditions apply) that will pop you to the moon with pillow soft landings.

And you can write the word PRE-PREG in large lettering all over the board too, which looks kinda cool.

Ideally you should get a spread tow version with some aramid. Imagine the possible gems of marketing that could then ensue... Bulletproof... Cartan.. Triax..

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Re: prepreg carbon..any advantage?

Postby TomW » Fri Jun 02, 2017 7:24 pm

I use cheap-peg. Which means : table covered in plastic sheet, dry carbon laid out and weighed, epoxy mixed and weighed. Wet out cf on the table with squeegie. Roll up wetted out cf onto a plastic tube, roll it out onto core / mold.
I made 16,5 foot SUP this way. first time I tried it. Works great.

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Re: prepreg carbon..any advantage?

Postby plummet » Fri Jun 02, 2017 8:36 pm

As others has said. you get the perfect resin/fibre ratio which is really hard to do with a hand lay up. So you get the lightest part with no resin rich areas. Ultimately its a lighter and stronger. You also have the advantage to take your time on the lay up as you need heat to cure the resin. But you need the freezer and the oven so its just too hard for home builders who only do occasional builds.

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Re: prepreg carbon..any advantage?

Postby Mossy 757 » Fri Jun 02, 2017 8:38 pm

Talking to George at Delta Hydrofoil, he said it doesn't really matter that the pre-preg is just easier for manufacturers who have a full industrial production line and go through enough material to never worry about long term storage issues. It might offer a slight advantage in terms of resin saturation, but anyone who really knows what they're doing with composites and has appropriate equipment to get a desired saturation shouldn't struggle with this issue through other manufacturing means (i.e. not homebuilt but for other mass producers)

The Sword2 was a prepreg foil and the greatest advantage that foil had for its time is that they all came out essentially identical with great build quality, so from Taaroa's perspective it was a huge win in terms of quality control. Spotz did not use prepreg and a bunch of their early Spotz2's had quality/strength issues...not necessarily from the lack of prepreg, but possibly because making a standardized uniform product at scale was not as easy without it. Removes a variable from the equation at the expense of increased cost and handling issues.

Either way, the term has been entirely co-opted by the marketing department...

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Re: prepreg carbon..any advantage?

Postby socommk23 » Fri Jun 02, 2017 9:48 pm

Did anyone mention how easy it is to cut prepreg?
Cutting dry carbon.....just dont.
Wet carbon needs to be sandwiched between melonex to keep it together.

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Re: prepreg carbon..any advantage?

Postby Lokihel » Sat Jun 03, 2017 5:34 am

Prepreg rolls come sandwiched between two films of plastic-like material, which you only peel off when you lay it out.

As usual with carbon, you need a sharp cutting edge which will have to be replaced/sharpened on a regular basis.
Cutting prepreg is relatively easy with the right tools. Where I worked we had a cutting table to cut long strips of prepreg. Basically the roll was cut as it was being unrolled onto the table. The machine used normal Stanley knife blades to cut the carbon.


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