I have a mold for a mast that is .75 inches/2 cm thick. It's made of PLA plastic that softens around 150 f / 70 c. I am thinking if I lay it all at once it'll exotherm and melt the plastic. Is this a valid concern?
Thanks.
I've actually got my second (failed) attempt at a fiberglass wing mold drying in the garage right now. I am trying every method I half way understand and learning as I go.thewindego wrote: ↑Sun Feb 25, 2018 11:30 pmI decided to move to the 3d printed plug and make fiberglass mold from the plug as others have suggested to avoid this issue.
I haven't figured out that part yet. Originally I tried to make the end of the mold fit a K-F box. I don't think it will, but decided to keep going, mainly to learn if a PLA mold can be made to work. Now my goal is to not destroy the mold with my first attempt.downunder wrote: The board 'plug' is, I think, almost always premade, hence you just build the straight mast and 'embed' it into a plug after. With your mold, you'll have a problem of laying a carbon around that area (at least I did).
Greetings,opie wrote: ↑Mon Feb 26, 2018 5:30 amI've actually got my second (failed) attempt at a fiberglass wing mold drying in the garage right now. I am trying every method I half way understand and learning as I go.thewindego wrote: ↑Sun Feb 25, 2018 11:30 pmI decided to move to the 3d printed plug and make fiberglass mold from the plug as others have suggested to avoid this issue.
I haven't figured out that part yet. Originally I tried to make the end of the mold fit a K-F box. I don't think it will, but decided to keep going, mainly to learn if a PLA mold can be made to work. Now my goal is to not destroy the mold with my first attempt.downunder wrote: The board 'plug' is, I think, almost always premade, hence you just build the straight mast and 'embed' it into a plug after. With your mold, you'll have a problem of laying a carbon around that area (at least I did).
To build the mold is 'easy'. To actually use it right is not so. I've got at least 4 FG molds, all discarded...opie wrote: ↑Mon Feb 26, 2018 5:30 amI've actually got my second (failed) attempt at a fiberglass wing mold drying in the garage right now. I am trying every method I half way understand and learning as I go.thewindego wrote: ↑Sun Feb 25, 2018 11:30 pmI decided to move to the 3d printed plug and make fiberglass mold from the plug as others have suggested to avoid this issue.
I haven't figured out that part yet. Originally I tried to make the end of the mold fit a K-F box. I don't think it will, but decided to keep going, mainly to learn if a PLA mold can be made to work. Now my goal is to not destroy the mold with my first attempt.downunder wrote: The board 'plug' is, I think, almost always premade, hence you just build the straight mast and 'embed' it into a plug after. With your mold, you'll have a problem of laying a carbon around that area (at least I did).
Short answer is yes, it is a valid concern. Once you start getting into the 5mm thickness range on a wet layup, it'll generate a fair amount of heat.
Mistakes were result of me
Do you mean use a core with the mold, so that I am not using so much carbon? I've considered this, do you think I could just print one? It would not help at all with strength, I think, but maybe the carbon could be enough. My other idea is to print a another complete (smaller) mold for the core and use pour foam.rynhardt wrote:Short answer is yes, it is a valid concern. Once you start getting into the 5mm thickness range on a wet layup, it'll generate a fair amount of heat.
You can mitigate this by waiting for the previous layer to get to the tacky stage before doing the next layer, but this is obviously very time consuming and you need to time the window period right. Tricky.
A better solution might be to use a core.
Yes. Use a core within the mould, with just a few layers of carbon on the outside. The core needs to handle compression and shear force and bond well with the reinforcement. A printed core might work, if it's as strong as a good foam or wood core.opie wrote: ↑Mon Feb 26, 2018 7:04 pmDo you mean use a core with the mold, so that I am not using so much carbon? I've considered this, do you think I could just print one? It would not help at all with strength, I think, but maybe the carbon could be enough. My other idea is to print a another complete (smaller) mold for the core and use pour foam.
That's a good idea. I am going to try that. Thanks.
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