beautiful!
20_rc51_00, you have uncanny timing! Well I suppose this thread is now the best place to announce the newest feature, Youtube embing in the forum. More info in the announcements forum.
Very nice part! Shows what high quality composites really cost. This is why real race bikes cost easily over 100k.
I’d pick one up if I still had Ducatis! Shaving weight makes a huge difference, my magnesium wheels felt like a different bike.
How is it that a part like this is made? is it several pieces that are bonded together or is it all one piece, and if so how is it made?
I had the same question when I saw a part with similar geometry being made. It was an aircraft duct similar to the one below.
A kit cutter would cut all the layers out of prepreg and they would all be complex shapes. The way it cut though each layer wouldn’t have a seam in the same place and the computer program also accounted for the thickness of the that would be layer underneath it in the layup. After that some extremely skilled fabricators put it together. The mold itself was basically a puzzle, you put it together and took it apart in a certain combination. So basically when the part was done a few long slices of mold would come out and then the rest would collapse and be removed.
It could be ether one piece or post bonded. It depends on which works out the most cost effective and strongest. If I was making it in one piece I would use a female mould with prepreg, I would have internal bags which come out where the aluminium bearing cups are post bonded in.
would something like this be possible for a hobbyist? I’ve always been a dreamer lol!
when working with prepreg can one use vacuum for consolidation or does one need an autoclave with high pressures?
You can use a vacuum for consolidation, you will need an oven though to fully cure the material. You could definitely build something like that, especially if you simply the geometry. If you take Hojo’s approach and some patience and hard work it should be possible.
Im certain that part is autoclaved, anything that structral needs to be. As for a hobbyist, prepreg is possible. Spend some time on building a good oven that circulates well and has a good temp control system that can be programed for ramps and soaks. Even better look for a used oven if you have some money to kill. The prepreg will be a decent intial investment but it is worth it in my opinion. Prepregs require high temp tooling which can be expensive. Your standard fiberglass/polyester mold will not cut it.
when one lays prepreg obviously there are air voids between the plys of reinforcement, how are the bubbles removed or are they just consolidated much smaller with very high pressure? Wouldn’t vacuum infusion be superior in this regard? Prepreg is saturated with the ideal amount of resin to begin with so how does one ensure that there are no voids?
RC51… Hi bro, long time no see 
How was school, did you complete or are you on break?
Funny i came across this thread because i had some prepreg questions myself. I found a supplier website where they say you can use sheet epoxy to bond laminates together. Although I’m not sure if they meant post-bonding. Example… you have a part that is just 4 layers of 3K cf… it is already cured but it has a peel ply surface. You leave the part in the mold, lay down some of this sheet epoxy, then more layers of prepreg… vacuum and bake. That is the “thin” epoxy sheet film they sell. They also have a thicker epoxy film that I think ( think ) is for a surface coat on the mold surface, then you lay down your laminates and vacuum, bake.
I found some bidirectional 3K twill prepreg for $96 a yard
http://mycarbonexpress.com/contactus.html
Is this a good price? I’m asuming it IS two layers of 3K twill?
prepreg I would think would be stronger than a vacuum infused part.
The bag is vented to outside the autoclave or under vacuum as well so any air escapes out of the bag thru a hose or two.
school is not done yet, just trolling around in my spare moments here. I have some CF ambitions and future proj that I’m trying to gain some insight on is all.
Hope all is well with your endeavours.
http://carbonsales.com/Carbon-fabrics-Prepreg/ $60.50 for twill and $73 for plain. I’ve never bought anything from them, but it’s right next to carbonexpress in my favorites file for composite suppliers.
Film epoxy is for bonding mostly. In parts were you have multiple pieces, you can use the film epoxy as a way to control the amount of adhesive. Good for large surface areas, like honeycomb and 2 fce sheets. Or, you can use it to glue a flange together, and add more pre-preg around the seam, bag it, and cook again. Obviously matching all pre-preg and epoxies so nothing burns
bi-directional twill is redundant. It’s like saying a 2 way clear glass. No crap. They just trying to make it sound better or something. It’s a twill weave…of course it’s bi-directional!!! Else it would be uni! So no, it’s not 2 layers…it’s just…a twill weave.
It’s like when I was working my grocery store job in high school when the Atkins diet was all the rage. They started advertising “0g of carbs” on the steaks and other meat in the meat department. Thank you, grocery store marketing department…
Thank you for clearing up that “bidirectional” thing… what a lowsy way to make people think they are getting two layers of 3K. and for $95 a yard.
How about this stuff mentioned above… 3K prepreg but it says not for high temp end use. I wonder what service temperature it’s good to? It says high temperature capabilities are not required?? means you don’t need an oven to cure it?
I want to get into making molds (frp) epoxy molds that can be baked in an oven at 350F. for some parts. Would this prepreg be good for this?
http://carbonsales.com/Carbon-fabrics-Prepreg/
You’ll have to ask for the data sheet on what service temp it is good for. I think knowing the Tg also helps, you want to stay below that temp. NORMALLY, you can use the same resin at the same temp it was cured at. So if you cure at 350f, you can use at or below 350f. There might be issues with degradation at that temp…but check with the manufacturer…