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quinn
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+xEasy Composites dont sell the single sided pre-preg anymore, that was the old EasyPreg system. The new X-Preg system is double sided, with no specific surface ply, and works extremely well. I dont see why you cant get their stuff because you are in the US? I'm in Aus and I use lots of pre-preg from Easy Composites. As for bagging method, you've got it sussed. Dont skimp on the bag - make it bigger than you expect you will need to. The breather will depend a bit on the pre-preg you end up using and how well it breathes. The EasyPreg system worked better with breather on both the back of the mould and over the laminate, while the X-Preg doesnt need it over the laminate. You may have to experiment if you get a less 'guided' system, however I dont think you will have too many problems by only doing breather on the outside of the mould. Ok, sounds good. I didn't actually look into ordering prepreg from easy composites, I just assumed shipping would be ridiculous cost to US and probably longer ship time than I want for prepreg that needs to stay cold, but I'll look into it. I'm sure a lot of the technique will come to me and get better with experimentation. Each part is only about 5 bucks worth of prepreg so no big deal if the first few tries aren't great. Also an added perk that it's now only a few hours for each try rather than 24 to 36 for infusion. That will be nice. I'll go for the double sided stuff and see how it works out.
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Hanaldo
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Easy Composites dont sell the single sided pre-preg anymore, that was the old EasyPreg system. The new X-Preg system is double sided, with no specific surface ply, and works extremely well. I dont see why you cant get their stuff because you are in the US? I'm in Aus and I use lots of pre-preg from Easy Composites.
As for bagging method, you've got it sussed. Dont skimp on the bag - make it bigger than you expect you will need to. The breather will depend a bit on the pre-preg you end up using and how well it breathes. The EasyPreg system worked better with breather on both the back of the mould and over the laminate, while the X-Preg doesnt need it over the laminate. You may have to experiment if you get a less 'guided' system, however I dont think you will have too many problems by only doing breather on the outside of the mould.
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quinn
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+x+x+xDepends on the pre-preg. But it should stay put well enough. Sounds good. After watching a few more videos, it looks like +/-45 is great for getting into corners so that should work to my advantage. Couple more questions before I order prepreg. I'm still a bit unclear on whether or not it's an advantage to use single sided prepreg for first layer. I see that easy composites sells a prepreg that is optimized for the surface layer and it's single sided. I'm in the US so can't order their stuff, but should I pick a single sided for my first layer, or is it gonna make much difference? The part will not be getting clear coat or paint so I want it to come out of the mold with good finish. If 2 sided is not much of a disadvantage for surface layer, I'd rather use it since I need it for other areas. My other question is the bagging technique. Eventually I want to try a silicone plug if I go into production, but for prototyping I'm just gonna vacuum bag it. I'll make a tube out of bagging material that is slightly larger than the inside of my part. This will be fed through the middle once mold is closed, then I'll bag the whole mold and seal the outside of the ends of that inner tube to the outer bag. Before closing the mold I will apply release film to the laminate, leaving a strip of laminate exposed for the overlap, then close mold and push overlaps down. Question is, do I need a breather between the release film and the bagging material? In most videos I watch, they use breather, but in the tutorial on this forum they bag straight onto the release film, only using breather on outside of mold. It will be much easier for me if I can do it the same way and only wrap breather around the outside. Will this work well in my case? If you only want to vacuum press the laminate you will need a special surface ply prepreg, or you live with the pinholes. I would just put an endcap on both sides and pressurize the inside of the mould to 3 bars and you won't have any issues. Or go the silicon core route. Depends a little on the layup thickness. But be aware that you just created a potential pipe bomb. So make sure that thing is not going to explode... Ok. Yeah I'm also considering pressurizing. I think it should be pretty tough. Minimum wall thickness of 12mm and the 2 mold halves are held together with 12 m6 bolts. Each part is only about 5 bucks worth of prepreg so not too expensive to experiment. Might try vacuum first just to see how it goes. If I end up going with pressure, what do you think is gonna be the easiest way to make a bladder? I could make the same oversized tube I planned on for vacuum, but I'm having a hard time picturing how to seal up the bag at the end with a line going in for pressure. Milling some concave caps that bolt onto the ends is no problem, but how should I handle the inlet side? And will a bladder made from bagging material and tack tape be a good method, or should I use something else? Perhaps a condom? Or maybe a length of surgical tubing? I looked around for other bladder possibilities. Found some "rocket balloons" which inflate to 3 inch diameter by 48 inch long, plenty oversize. Are latex balloons ever used for this? I imagine I would want to stretch the balloon along the length and secure at both ends before inflating.
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Lester Populaire
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+x+xDepends on the pre-preg. But it should stay put well enough. Sounds good. After watching a few more videos, it looks like +/-45 is great for getting into corners so that should work to my advantage. Couple more questions before I order prepreg. I'm still a bit unclear on whether or not it's an advantage to use single sided prepreg for first layer. I see that easy composites sells a prepreg that is optimized for the surface layer and it's single sided. I'm in the US so can't order their stuff, but should I pick a single sided for my first layer, or is it gonna make much difference? The part will not be getting clear coat or paint so I want it to come out of the mold with good finish. If 2 sided is not much of a disadvantage for surface layer, I'd rather use it since I need it for other areas. My other question is the bagging technique. Eventually I want to try a silicone plug if I go into production, but for prototyping I'm just gonna vacuum bag it. I'll make a tube out of bagging material that is slightly larger than the inside of my part. This will be fed through the middle once mold is closed, then I'll bag the whole mold and seal the outside of the ends of that inner tube to the outer bag. Before closing the mold I will apply release film to the laminate, leaving a strip of laminate exposed for the overlap, then close mold and push overlaps down. Question is, do I need a breather between the release film and the bagging material? In most videos I watch, they use breather, but in the tutorial on this forum they bag straight onto the release film, only using breather on outside of mold. It will be much easier for me if I can do it the same way and only wrap breather around the outside. Will this work well in my case? If you only want to vacuum press the laminate you will need a special surface ply prepreg, or you live with the pinholes. I would just put an endcap on both sides and pressurize the inside of the mould to 3 bars and you won't have any issues. Or go the silicon core route. Depends a little on the layup thickness. But be aware that you just created a potential pipe bomb. So make sure that thing is not going to explode...
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quinn
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Group: Forum Members
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+xDepends on the pre-preg. But it should stay put well enough. Sounds good. After watching a few more videos, it looks like +/-45 is great for getting into corners so that should work to my advantage. Couple more questions before I order prepreg. I'm still a bit unclear on whether or not it's an advantage to use single sided prepreg for first layer. I see that easy composites sells a prepreg that is optimized for the surface layer and it's single sided. I'm in the US so can't order their stuff, but should I pick a single sided for my first layer, or is it gonna make much difference? The part will not be getting clear coat or paint so I want it to come out of the mold with good finish. If 2 sided is not much of a disadvantage for surface layer, I'd rather use it since I need it for other areas. My other question is the bagging technique. Eventually I want to try a silicone plug if I go into production, but for prototyping I'm just gonna vacuum bag it. I'll make a tube out of bagging material that is slightly larger than the inside of my part. This will be fed through the middle once mold is closed, then I'll bag the whole mold and seal the outside of the ends of that inner tube to the outer bag. Before closing the mold I will apply release film to the laminate, leaving a strip of laminate exposed for the overlap, then close mold and push overlaps down. Question is, do I need a breather between the release film and the bagging material? In most videos I watch, they use breather, but in the tutorial on this forum they bag straight onto the release film, only using breather on outside of mold. It will be much easier for me if I can do it the same way and only wrap breather around the outside. Will this work well in my case?
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Matthieu Libeert
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Like above, when very cold the prepreg wont stick well, what you could do is preheat your mould at around 25-30°C that way your prepreg will find an easier way to stick, or use a heatgun. Once your first ply is well against the mould all the rest should stick pretty well to each other. Ambient working temperatures are ideal between 20-25°C for prepreg lay up (at least that's what I think  )
Founder MAT2 Composites X Sports
website: www.mat2composites.com  
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Steve Broad
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A little bit of heat to make the prepreg tacky works for me on aluminium.
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Hanaldo
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Depends on the pre-preg. But it should stay put well enough.
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quinn
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 First mold section. One concern I have is those radiuses in the corners at the close end, they are 4mm. First layer going down will be 200gsm +/-45 twill so I imagine that should bend a bit easier than 0/90. After that is uni running lengthwise. Am I gonna have issues getting the prepreg to stick down in those radiuses? First time using prepreg so not sure how well it wants to stick to polished aluminum with frekote. Is it gonna stay put?
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Lester Populaire
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+x+x+xMeant 800mm long, not 800m absolutely no issue with the different wall thickness. Aluminum has a heat transfer that is really good which means that you will get a uniform temperature. I would just make the soak times longer to give it time to get to temperature. No need to get slower, if anything you might go slightly faster as the big mass will slow things down. Great thanks! I did pick up a few extra temp sensors. maybe ill bore a couple holes in tbe thickest area of the mold to insert temp sensor and monitor If you have the opportunity to do so this will give you some very valuable bits of information. just have a look at the time as well and make a graph over time to get a better feeling for the next time.
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