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Massimiliano
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+xI would take a new mould from the existing part. After removing the chips, some sanding and polishing it should be fine to take a new mould from. Thank you!
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oekmont
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I would take a new mould from the existing part. After removing the chips, some sanding and polishing it should be fine to take a new mould from.
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Massimiliano
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+xThis is not a undercured mould issue. You can clearly see how bad the tool edges look around the chipping. You can see al lot of defects where the white gelcoat broke off with the mould. And there a white lines wich look like there were still marks of goarse grit sand paper. There was a lot of small scale interlocking, and this caused the mould edges to chip off. If you did not sand the mould, you plug was clearly not ready to take a propper mould from. Take more care finishing your plug. Thank you, I will! Now I have the dilemma: should I try to fix the mold, build a new mould from the part (after a lot of fixes...) or start over from the plug (need to find someone able to machine mdf... I am done with xps) What would you do?
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oekmont
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Group: Forum Members
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This is not a undercured mould issue. You can clearly see how bad the tool edges look around the chipping. You can see al lot of defects where the white gelcoat broke off with the mould. And there a white lines wich look like there were still marks of goarse grit sand paper. There was a lot of small scale interlocking, and this caused the mould edges to chip off. If you did not sand the mould, you plug was clearly not ready to take a propper mould from. Take more care finishing your plug.
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Massimiliano
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+xtypically light weight woven fabrics for the surface and heavy weight fabrics for bulking. Light weight fabrics give a better surface with less print. For example if you are making a carbon tool you can use 3k 200gsm for surface followed by 12k 600gsm for bulking. Some might suggest using veils for the surface but I m not a big fan of that as they typically have a microporosity issue. Be warned you wont get the same gloss level as gel coat, but you will get a tool surface that is way more durable Thanks for the suggestions!
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Hojo
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typically light weight woven fabrics for the surface and heavy weight fabrics for bulking. Light weight fabrics give a better surface with less print. For example if you are making a carbon tool you can use 3k 200gsm for surface followed by 12k 600gsm for bulking. Some might suggest using veils for the surface but I m not a big fan of that as they typically have a microporosity issue. Be warned you wont get the same gloss level as gel coat, but you will get a tool surface that is way more durable
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Massimiliano
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+x+x+x+xI think the problem was not the little porosity a mould sealer would be able to seal. Your mould is full of small open air pockets. The closeups show many white pieces of gelcoat stuck in the tooling gelcoat, as well as goosebumps on your final part. The edge of your mould doesn't look good either. There were a lot of mechanical loking points. Some of them were too much for the tooling gelcoat. My guess is that you moulded from a bad plug und sanded the mould a lot, right? If so, always try to make the plug as perfect as possible. Sanding the mould too much is always the risk of opening some air bubbles in the tooling gelcoat. A good point, its probably a void under the gelcoat. Often when you hand laminate without vacuum you will get a void from the material bending around a corner. You can add a mix of resin and cabosil and put this around the edge to help avoid these types of voids. You can also do a thin fiberglass skin on the gelcoat and inspect for voids after it cures. If you see any voids you can cut them open with a knife and they will fill with the second round of lamination. This is why I prefer infusion or prepreg/autoclave for tools. Quality is superior in so many ways to hand lamination. You mean applying by hand the tooling gelcoat and then infuse the reinforcement? Will not the vacuum deform the thin gelcoat where the plug is filleted with the filleting wax? no, when I do infusion tools I do not use gelcoat. If you want to use gelcoat and infuse, typically you need to put down a skin layer down, typically fiberglass so you can see air bubbles Ok, so what do you use to infuse a tool? Directly reinforcement and resin?
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Hojo
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+x+x+xI think the problem was not the little porosity a mould sealer would be able to seal. Your mould is full of small open air pockets. The closeups show many white pieces of gelcoat stuck in the tooling gelcoat, as well as goosebumps on your final part. The edge of your mould doesn't look good either. There were a lot of mechanical loking points. Some of them were too much for the tooling gelcoat. My guess is that you moulded from a bad plug und sanded the mould a lot, right? If so, always try to make the plug as perfect as possible. Sanding the mould too much is always the risk of opening some air bubbles in the tooling gelcoat. A good point, its probably a void under the gelcoat. Often when you hand laminate without vacuum you will get a void from the material bending around a corner. You can add a mix of resin and cabosil and put this around the edge to help avoid these types of voids. You can also do a thin fiberglass skin on the gelcoat and inspect for voids after it cures. If you see any voids you can cut them open with a knife and they will fill with the second round of lamination. This is why I prefer infusion or prepreg/autoclave for tools. Quality is superior in so many ways to hand lamination. You mean applying by hand the tooling gelcoat and then infuse the reinforcement? Will not the vacuum deform the thin gelcoat where the plug is filleted with the filleting wax? no, when I do infusion tools I do not use gelcoat. If you want to use gelcoat and infuse, typically you need to put down a skin layer down, typically fiberglass so you can see air bubbles
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Massimiliano
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Group: Forum Members
Posts: 167,
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+x+xI think the problem was not the little porosity a mould sealer would be able to seal. Your mould is full of small open air pockets. The closeups show many white pieces of gelcoat stuck in the tooling gelcoat, as well as goosebumps on your final part. The edge of your mould doesn't look good either. There were a lot of mechanical loking points. Some of them were too much for the tooling gelcoat. My guess is that you moulded from a bad plug und sanded the mould a lot, right? If so, always try to make the plug as perfect as possible. Sanding the mould too much is always the risk of opening some air bubbles in the tooling gelcoat. A good point, its probably a void under the gelcoat. Often when you hand laminate without vacuum you will get a void from the material bending around a corner. You can add a mix of resin and cabosil and put this around the edge to help avoid these types of voids. You can also do a thin fiberglass skin on the gelcoat and inspect for voids after it cures. If you see any voids you can cut them open with a knife and they will fill with the second round of lamination. This is why I prefer infusion or prepreg/autoclave for tools. Quality is superior in so many ways to hand lamination. You mean applying by hand the tooling gelcoat and then infuse the reinforcement? Will not the vacuum deform the thin gelcoat where the plug is filleted with the filleting wax?
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Massimiliano
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Group: Forum Members
Posts: 167,
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+xI think the problem was not the little porosity a mould sealer would be able to seal. Your mould is full of small open air pockets. The closeups show many white pieces of gelcoat stuck in the tooling gelcoat, as well as goosebumps on your final part. The edge of your mould doesn't look good either. There were a lot of mechanical loking points. Some of them were too much for the tooling gelcoat. My guess is that you moulded from a bad plug und sanded the mould a lot, right? If so, always try to make the plug as perfect as possible. Sanding the mould too much is always the risk of opening some air bubbles in the tooling gelcoat. You have acute and expert eyes! Yes my plug was not prefect and when I covered it with tooling gelcoat, probably some micro cracks in the hi gloss pattern coat let styrene eat a little of the xps foam, this led to an irregular border in some spots. I did not sand the mould at all. The chipping occurred on smooth corners, I think this is due to not fully cured mold... When I removed the tooling gelcoat spots from the part with a small blade, it came off almost perfectly but very tiny spots where instead it was welded. Probably as Hojo suggested I should have waited more before using it, or put it in a oven to reach full properties... or both!
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