CNC cut foam to make a mold

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CNC cut foam to make a mold

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Joel Illerhag	Joel Illerhag posted 7 Years Ago HOT Topic Details
Group: Forum Members Posts: 14, Visits: 37	Hi! I will CNC cut a plug from Polystyrene foam and will buy the Easycomposites "Uni-Mould Complete Mould Making Kit " My question is: How can I get a smooth surface at the finished foam-plug before I put gelcoat on? Is there some kind of product that would be suitable for this? The plug is 1800 mm long and 600 mm wide. Have a great day! Regards. Joel Edited 7 Years Ago by Joel Illerhag
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Fasta	Fasta posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	+x Joel Illerhag - 12/2/2018 10:40:12 PM Hi! I will CNC cut a plug from Polystyrene foam and will buy the Easycomposites "Uni-Mould Complete Mould Making Kit " My question is: How can I get a smooth surface at the finished foam-plug before I put gelcoat on? Is there some kind of product that would be suitable for this? The plug is 1800 mm long and 600 mm wide. Have a great day! Regards. Joel Assuming that is a violin for this small size it would be nice to simply use the tooling board materials which can then be sealed. A foam surface would need at least some light fiberglass and a suitable paint to get your smooth pattern ready for moulding. If you try to paint directly on to a foam it can be difficult to sand as the the foam behind is soft and easily gouged etc when doing this hand sanding. You could also use a suitable timber for CNC machining like Jelutong or even just MDF boards slabbed to be thick enough. Fastacraft Facebook page
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Joel Illerhag	Joel Illerhag posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 14, Visits: 37	Hi Fasta! Thanks for your answer. It seam to be a good idea to put glassfiber on top of the foam. I saw a guy that is using "epoxy fairing compound" or putty to flatten out the glassfiber after sanding. I guess I can use that. It might be the same as "Filler" that makes the epoxy thicker with higher viscosity. It is a double bass by the way :-) Cheers! /Joel Edited 7 Years Ago by Joel Illerhag
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Fasta	Fasta posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	Ok a bit bigger then. It just seems that since you have CNC to accurately make a nice pattern that a firmer material will better replicate the CNC. With some general strength better than a typical polystyrene. Maybe urethane foams? or even PVC foam$? Then it safer and easier to do hand work on thereafter and without fibreglass even. . If you were to glass a polystrene foam you could try the really light tissue type fibreglass wet out with epoxy resin, let cure and then the epoxy fairing paste you are thinking of. There are additives to make your own fairing type paste like Q cells and microballoon powders to add but these are different to the ones that make thicker resin. A thicker resin is like making a glue and these glue additives make a resin that is denser and very hard to sand. The sanding fairing type filler must be used or you can buy epoxy faring pastes as A + B kits ready to go. Resin suppliers like easy composites could have this ? or any marine shop can be a good source for these things. Fastacraft Facebook page Edited 7 Years Ago by Fasta
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Joel Illerhag	Joel Illerhag posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 14, Visits: 37	Thanks Fasta, A very good advice about not using dens epoxy. It would be a nightmare to sand down. I will definatly go for "epoxy faring pastes". I found this at easycomposites: https://www.easycomposites.co.uk/emp60-epoxy-moulding-paste And I will go and see what kind of foams they have in the local shop. PVC or urethane foam sound like a good alternative to the standard white polystyrene Thanks a lot!
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