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ahender
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I have read many threads and posts on resin infusion. Still not 100% certain I can pull it off. My project is a 12 foot canoe. As with most any canoe, the width in the center is the widest. In my case, there will be 60 inches of resin travel (30 inches on each side of center). Of course this will narrow from bow to stern.
1) Would one resin line (3/8" inner diameter) be adequate to cover the entire mold (resin line running from bow to stern)? Would it make sense to have two parallel lines next to each other - each line supporting one half of the mold? Or more than two lines, each with equal separation?
2) With a full vacuum and two layers of 9 oz. plain weave S-2 glass, does anyone have a projection on how long it might take to infuse? I will be using resin flow media. I plan to heat the mold some and use Easy Composites infusion resin, which I might heat a little also. The entire area is about 3.5 sq. meters.
Thank you.
Alan
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Hanaldo
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1. Yes, because you are not actually infusing a very great distance if you are feeding from the centre. You will find it probably infuses quite quickly. No, using parallel lines wouldn't help, because again you are infusing across the short dimension and using the feed line to spread resin across the long dimension.
If it were me, I would do a staged infusion with 3 feed points all placed along the one central feed spiral. This isn't as difficult as it sounds, but you do want to set it up carefully to not trap voids. Personally, I would place a central feed point in the very middle of the bow-to-stern and start the infusion from here. Then have 2 feed points at roughly 1/3 of the way each side of that central feed, and leave these clamped until just before the resin from the central feed reaches them. This will ensure that you keep the resin moving across the length, as with only one feed point you may find the resin slows quite dramatically after about 1m, even with a feed spiral. If you can reduce that distance by having multiple feeds, then the whole infusion will go much faster.
The trick to it is making sure your feed lines are equal length and the entry ports are evenly spaced. And then you have to get the timing right. If you unclamp those secondary feed ports too early, you may end up with voids as you cancel out the vacuum front between the ports. If you unclamp too late, the air you let in from the secondary ports may not have a chance to escape at it will again cause voids. But realistically, this just means paying attention and watching the infusion. It doesn't happen so fast that you will be scrambling, it is relatively slow. Just be methodical and have everything organised before you open that primary feed.
2. With just a single feed, I'd estimate probably around an hour. Lots of variables, so its hard to guess - but an hour is reasonable. With the staged setup, I'd wager closer to half an hour. Just do your resin in batches regardless. Don't mix up all your resin in one batch, it will gel in 10 minutes. Stick to batches around 1kg. If you're feeling brave, you can make your first batch a bit bigger as the infusion always starts off faster. At 3.5sqm with 2 layers of 250g glass and flow mesh, I calculate you would need about 4kg of resin including a wastage factor. So I would do 4x 1kg batches. Have them all measured out in separate pots so that you can mix as you need them, and allow yourself 5 minutes of mixing time for each one. Pour each into one main feed pot, don't try to change feed pots.
Are you sure 2 layers of 250g glass is enough? S-Glass is tough stuff, but that is quite light weight. I havent done any canoes myself, and I know they are often very flimsy, but I would still be nervous about a 0.5mm thick laminate keeping me afloat!
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ahender
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+x1. Yes, because you are not actually infusing a very great distance if you are feeding from the centre. You will find it probably infuses quite quickly. No, using parallel lines wouldn't help, because again you are infusing across the short dimension and using the feed line to spread resin across the long dimension. If it were me, I would do a staged infusion with 3 feed points all placed along the one central feed spiral. This isn't as difficult as it sounds, but you do want to set it up carefully to not trap voids. Personally, I would place a central feed point in the very middle of the bow-to-stern and start the infusion from here. Then have 2 feed points at roughly 1/3 of the way each side of that central feed, and leave these clamped until just before the resin from the central feed reaches them. This will ensure that you keep the resin moving across the length, as with only one feed point you may find the resin slows quite dramatically after about 1m, even with a feed spiral. If you can reduce that distance by having multiple feeds, then the whole infusion will go much faster. The trick to it is making sure your feed lines are equal length and the entry ports are evenly spaced. And then you have to get the timing right. If you unclamp those secondary feed ports too early, you may end up with voids as you cancel out the vacuum front between the ports. If you unclamp too late, the air you let in from the secondary ports may not have a chance to escape at it will again cause voids. But realistically, this just means paying attention and watching the infusion. It doesn't happen so fast that you will be scrambling, it is relatively slow. Just be methodical and have everything organised before you open that primary feed. 2. With just a single feed, I'd estimate probably around an hour. Lots of variables, so its hard to guess - but an hour is reasonable. With the staged setup, I'd wager closer to half an hour. Just do your resin in batches regardless. Don't mix up all your resin in one batch, it will gel in 10 minutes. Stick to batches around 1kg. If you're feeling brave, you can make your first batch a bit bigger as the infusion always starts off faster. At 3.5sqm with 2 layers of 250g glass and flow mesh, I calculate you would need about 4kg of resin including a wastage factor. So I would do 4x 1kg batches. Have them all measured out in separate pots so that you can mix as you need them, and allow yourself 5 minutes of mixing time for each one. Pour each into one main feed pot, don't try to change feed pots. Are you sure 2 layers of 250g glass is enough? S-Glass is tough stuff, but that is quite light weight. I havent done any canoes myself, and I know they are often very flimsy, but I would still be nervous about a 0.5mm thick laminate keeping me afloat! Thank you very much for your reply. Very informative. As for the secondary feed points, I watched an Airtech video and it shows the primary feed line being clamped off when the resin was a couple of inches from the secondary line. Then as soon as the resin meets the secondary line, the secondary line was un-clamped. I assume the resin has to be at, or past, the secondary line at all points before it is un-clamped. As for the 2 layers of s-glass, I should have been more clear. These are the bottom layers. I will then add a core and two more layers of glass. My goal is a canoe less than 20 pounds. This includes the gunwales. It will be close. Again, thank you for sharing your experience. Alan
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Hanaldo
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Group: Forum Members
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+xAs for the 2 layers of s-glass, I should have been more clear. These are the bottom layers. I will then add a core and two more layers of glass. My goal is a canoe less than 20 pounds. This includes the gunwales. It will be close. I see, this should be fine then! I thought it may be the case, but figured I'd ask. And yes, you want the resin to be very close to the secondary feed point before you unclamp it - but not past it. If you open the feed line after resin has passed, then you will introduce air into that resin that will struggle to escape again. In theory theres a chance that air could happily travel along with the resin and then end up on the outside of the laminate and not cause any issues. However in my experience, it will likely get trapped in the laminate. How big an issue this is depends on how much air is let in and how critical you are of void content. But considering it is not hard to avoid, and 0% void content is desirable (if not realistically achievable), it is best to just try to avoid it. Really it is ok and probably better to unclamp a little bit early. The closer the resin is to the feed line, the less disrupting the flow front vacuum will matter. If you unclamp too early, the two flow fronts won't want to flow towards each other. But resin will happily penetrate an inch or two without the high vacuum flow front. So I would start unclamping when the resin is about an inch away from the secondary feeds. It also isn't completely necessary to clamp the primary feed - I would use your intuition here. If the resin has reached or nearly reached the perimeter of the layup, then I would probably clamp it for a bit simply not to waste resin. If it still has a way to go before reaching the perimeter, then leave it open. Or close it for a bit to let the secondary feeds somewhat catch up, and then open it again to complete the infusion. There's lots of ways to do it. Likely none of them are very critical. You won't ruin the infusion because you clamped or didn't clamp the primary feed. But you may speed things up or saves a fraction of weight if you get it all correct. So do what you feel is right based on how your infusion is going.
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ahender
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Group: Forum Members
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+x+xAs for the 2 layers of s-glass, I should have been more clear. These are the bottom layers. I will then add a core and two more layers of glass. My goal is a canoe less than 20 pounds. This includes the gunwales. It will be close. I see, this should be fine then! I thought it may be the case, but figured I'd ask. And yes, you want the resin to be very close to the secondary feed point before you unclamp it - but not past it. If you open the feed line after resin has passed, then you will introduce air into that resin that will struggle to escape again. In theory theres a chance that air could happily travel along with the resin and then end up on the outside of the laminate and not cause any issues. However in my experience, it will likely get trapped in the laminate. How big an issue this is depends on how much air is let in and how critical you are of void content. But considering it is not hard to avoid, and 0% void content is desirable (if not realistically achievable), it is best to just try to avoid it. Really it is ok and probably better to unclamp a little bit early. The closer the resin is to the feed line, the less disrupting the flow front vacuum will matter. If you unclamp too early, the two flow fronts won't want to flow towards each other. But resin will happily penetrate an inch or two without the high vacuum flow front. So I would start unclamping when the resin is about an inch away from the secondary feeds. It also isn't completely necessary to clamp the primary feed - I would use your intuition here. If the resin has reached or nearly reached the perimeter of the layup, then I would probably clamp it for a bit simply not to waste resin. If it still has a way to go before reaching the perimeter, then leave it open. Or close it for a bit to let the secondary feeds somewhat catch up, and then open it again to complete the infusion. There's lots of ways to do it. Likely none of them are very critical. You won't ruin the infusion because you clamped or didn't clamp the primary feed. But you may speed things up or saves a fraction of weight if you get it all correct. So do what you feel is right based on how your infusion is going. Thank you again. I have asked in different forums the importance of where the resin bucket is in relation to the part being infused. I would say the majority opinion is to have the bucket below the resin infusion inlet. The opinion is having it higher will lead to resin pooling in the part. I had much prefer to have the bucket next to the inlet to reduce waste. My question is how does resin pool in a part under a complete vacuum when the resin inlet area is already saturated? Also, in one Easy Composite document I read it states the resin line should be clamped off when the resin front in 2/3 of the way across the part. Others say clamp off when the resin is a few inches from the end of the part. What would be your recommendation? Alan
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Hanaldo
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Group: Forum Members
Posts: 2.5K,
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+x+x+xAs for the 2 layers of s-glass, I should have been more clear. These are the bottom layers. I will then add a core and two more layers of glass. My goal is a canoe less than 20 pounds. This includes the gunwales. It will be close. I see, this should be fine then! I thought it may be the case, but figured I'd ask. And yes, you want the resin to be very close to the secondary feed point before you unclamp it - but not past it. If you open the feed line after resin has passed, then you will introduce air into that resin that will struggle to escape again. In theory theres a chance that air could happily travel along with the resin and then end up on the outside of the laminate and not cause any issues. However in my experience, it will likely get trapped in the laminate. How big an issue this is depends on how much air is let in and how critical you are of void content. But considering it is not hard to avoid, and 0% void content is desirable (if not realistically achievable), it is best to just try to avoid it. Really it is ok and probably better to unclamp a little bit early. The closer the resin is to the feed line, the less disrupting the flow front vacuum will matter. If you unclamp too early, the two flow fronts won't want to flow towards each other. But resin will happily penetrate an inch or two without the high vacuum flow front. So I would start unclamping when the resin is about an inch away from the secondary feeds. It also isn't completely necessary to clamp the primary feed - I would use your intuition here. If the resin has reached or nearly reached the perimeter of the layup, then I would probably clamp it for a bit simply not to waste resin. If it still has a way to go before reaching the perimeter, then leave it open. Or close it for a bit to let the secondary feeds somewhat catch up, and then open it again to complete the infusion. There's lots of ways to do it. Likely none of them are very critical. You won't ruin the infusion because you clamped or didn't clamp the primary feed. But you may speed things up or saves a fraction of weight if you get it all correct. So do what you feel is right based on how your infusion is going. Thank you again. I have asked in different forums the importance of where the resin bucket is in relation to the part being infused. I would say the majority opinion is to have the bucket below the resin infusion inlet. The opinion is having it higher will lead to resin pooling in the part. I had much prefer to have the bucket next to the inlet to reduce waste. My question is how does resin pool in a part under a complete vacuum when the resin inlet area is already saturated? Also, in one Easy Composite document I read it states the resin line should be clamped off when the resin front in 2/3 of the way across the part. Others say clamp off when the resin is a few inches from the end of the part. What would be your recommendation? Alan Because as soon as you open that inlet line, the part isn't under complete vacuum anymore, it is under partial vacuum. And due to the mechanics of infusion, you have something of a 'wave' of resin moving through the part, where the laminate will be under less compaction closer to the resin inlet and more compaction closer to the vacuum outlet, leading to an uneven laminate thickness and an uneven resin content. This should balance out again as the infusion nears completion and the vacuum equalises. But sometimes, depending on your layup, it doesn't, and you end up with resin pooling around the inlet. That is because while the pressure differential is the driving force behind infusion, you still have other physics in play as well - namely friction. Both of your above questions are actually related to solutions for the same problem. By clamping early when the resin is 2/3 of the way through the part, you allow the excess resin near the inlet a chance to move through the laminate and even out. Or, by having the resin pot below the inlet, you use gravity to reduce some of the pressure on the resin to help slow how quickly the resin flows into the chamber. If you have the resin pot above the inlet then you have the opposite effect, and you increase the pressure on the resin and how quickly it can flow into the chamber. The reason you get so many varying opinions and methods is because there is no hard and fast rule - these are all things you can do to influence the mechanics of infusion, but whether you want/need to depends on what you are doing and your specific layup. Personally, I will often clamp and unclamp the feed line throughout an infusion if I notice the area close to the entry is slacking off. This is easy to monitor because you can see and feel it. If the bag is loose or you can see excess resin, clamp it off for a few minutes or until the flow front really starts to slow (DD Compound have actually invented the MTI Valve to do this for you, though I prefer to just do it as I see fit). I never clamp for the final time until the part is fully infused - you dont know how much excess resin is in the part, nor how much resin the unsaturated part of the laminate needs to fully wet out. It's all well and good to say 2/3 of the way across - what if your laminate is 2 layers for the first half of the part but 10 layers for the second half? It depends on what you are doing. So better to just regulate the flow, but always finish the infusion before shutting it off. As for pot height - I don't worry about it 99% of the time. Place it next to the resin inlet, it just works. Occasionally I have a complex infusion that I know will need to flow faster or slower and so I'll move the feed pot appropriately, but its very rare.
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ahender
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Group: Forum Members
Posts: 38,
Visits: 300
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+x+x+x+xAs for the 2 layers of s-glass, I should have been more clear. These are the bottom layers. I will then add a core and two more layers of glass. My goal is a canoe less than 20 pounds. This includes the gunwales. It will be close. I see, this should be fine then! I thought it may be the case, but figured I'd ask. And yes, you want the resin to be very close to the secondary feed point before you unclamp it - but not past it. If you open the feed line after resin has passed, then you will introduce air into that resin that will struggle to escape again. In theory theres a chance that air could happily travel along with the resin and then end up on the outside of the laminate and not cause any issues. However in my experience, it will likely get trapped in the laminate. How big an issue this is depends on how much air is let in and how critical you are of void content. But considering it is not hard to avoid, and 0% void content is desirable (if not realistically achievable), it is best to just try to avoid it. Really it is ok and probably better to unclamp a little bit early. The closer the resin is to the feed line, the less disrupting the flow front vacuum will matter. If you unclamp too early, the two flow fronts won't want to flow towards each other. But resin will happily penetrate an inch or two without the high vacuum flow front. So I would start unclamping when the resin is about an inch away from the secondary feeds. It also isn't completely necessary to clamp the primary feed - I would use your intuition here. If the resin has reached or nearly reached the perimeter of the layup, then I would probably clamp it for a bit simply not to waste resin. If it still has a way to go before reaching the perimeter, then leave it open. Or close it for a bit to let the secondary feeds somewhat catch up, and then open it again to complete the infusion. There's lots of ways to do it. Likely none of them are very critical. You won't ruin the infusion because you clamped or didn't clamp the primary feed. But you may speed things up or saves a fraction of weight if you get it all correct. So do what you feel is right based on how your infusion is going. Thank you again. I have asked in different forums the importance of where the resin bucket is in relation to the part being infused. I would say the majority opinion is to have the bucket below the resin infusion inlet. The opinion is having it higher will lead to resin pooling in the part. I had much prefer to have the bucket next to the inlet to reduce waste. My question is how does resin pool in a part under a complete vacuum when the resin inlet area is already saturated? Also, in one Easy Composite document I read it states the resin line should be clamped off when the resin front in 2/3 of the way across the part. Others say clamp off when the resin is a few inches from the end of the part. What would be your recommendation? Alan Because as soon as you open that inlet line, the part isn't under complete vacuum anymore, it is under partial vacuum. And due to the mechanics of infusion, you have something of a 'wave' of resin moving through the part, where the laminate will be under less compaction closer to the resin inlet and more compaction closer to the vacuum outlet, leading to an uneven laminate thickness and an uneven resin content. This should balance out again as the infusion nears completion and the vacuum equalises. But sometimes, depending on your layup, it doesn't, and you end up with resin pooling around the inlet. That is because while the pressure differential is the driving force behind infusion, you still have other physics in play as well - namely friction. Both of your above questions are actually related to solutions for the same problem. By clamping early when the resin is 2/3 of the way through the part, you allow the excess resin near the inlet a chance to move through the laminate and even out. Or, by having the resin pot below the inlet, you use gravity to reduce some of the pressure on the resin to help slow how quickly the resin flows into the chamber. If you have the resin pot above the inlet then you have the opposite effect, and you increase the pressure on the resin and how quickly it can flow into the chamber. The reason you get so many varying opinions and methods is because there is no hard and fast rule - these are all things you can do to influence the mechanics of infusion, but whether you want/need to depends on what you are doing and your specific layup. Personally, I will often clamp and unclamp the feed line throughout an infusion if I notice the area close to the entry is slacking off. This is easy to monitor because you can see and feel it. If the bag is loose or you can see excess resin, clamp it off for a few minutes or until the flow front really starts to slow (DD Compound have actually invented the MTI Valve to do this for you, though I prefer to just do it as I see fit). I never clamp for the final time until the part is fully infused - you dont know how much excess resin is in the part, nor how much resin the unsaturated part of the laminate needs to fully wet out. It's all well and good to say 2/3 of the way across - what if your laminate is 2 layers for the first half of the part but 10 layers for the second half? It depends on what you are doing. So better to just regulate the flow, but always finish the infusion before shutting it off. As for pot height - I don't worry about it 99% of the time. Place it next to the resin inlet, it just works. Occasionally I have a complex infusion that I know will need to flow faster or slower and so I'll move the feed pot appropriately, but its very rare. Again, thank you so much for taking the time to share your expertise.
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