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quinn
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I'm about to start machining my mold but I have a few concerns. The composite part is an 800m long tapered tube. 46mm diameter at one end, 30mm at other end. The closed mold is 75mm square by 800mm long. This means the mold walls will be as thin as 15mm at one end and as thick as 22mm at other end. One concern is the time it takes for this big chunk of aluminum to heat up, the other concern is uneven heating, thinner walled end heating up first. How should I approach this with my ramp cycles? Just go slower in general? Hold temps longer? I'm really not sure what to expect for how long it's gonna take for it to heat up. If the varying wall thickness is gonna be a big problem, I can do some machining on the outside to even it out, but would rather not if it isn't needed. First few parts will be done with vacuum bag so the laminate will be exposed to the heated air but later on I'll be trying silicone expanding plug so I'm sure that will change things as far as heating. Any advice on how to approach this? Thanks
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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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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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+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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Steve Broad
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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? When we made a hockey stick out of a carbon/aramid mix, we just used a balloon lightly coated with a release agent and connected to a pressure pump, no bagging required. This way you can improve on 1 atmosphere if you so desire :-)  
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quinn
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Group: Forum Members
Posts: 155,
Visits: 992
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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? When we made a hockey stick out of a carbon/aramid mix, we just used a balloon lightly coated with a release agent and connected to a pressure pump, no bagging required. This way you can improve on 1 atmosphere if you so desire :-) Good to know. Sounds like balloons work fine as a bladder. Just curious, did you paint the name on afterwards, or did you do that in the mold before lay up?
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Steve Broad
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Group: Forum Members
Posts: 408,
Visits: 4.1K
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+x+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? When we made a hockey stick out of a carbon/aramid mix, we just used a balloon lightly coated with a release agent and connected to a pressure pump, no bagging required. This way you can improve on 1 atmosphere if you so desire :-) Good to know. Sounds like balloons work fine as a bladder. Just curious, did you paint the name on afterwards, or did you do that in the mold before lay up? Heavy duty party balloons from eBay. Name is a transfer. added afterwards
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