Experimenting with an Inexpensive Vacuum Chamber for Casting

[Music] hey there it's chris from goodroads a question that i get a lot on the channel is why do i use a pressure pot to cure my urethane when i'm making wheels and bushings the quick answer is it eliminates bubbles from the material it compresses any bubbles down and dissolves them leaving you a solid block of urethane that makes for a stronger more structural part but those of you who know a little something about casting might be wondering why not a vacuum chamber would a vacuum chamber work and i think it would the urethanes that i've used so far on this channel have a really short pot life which means they set up within a matter of minutes and that's why so far i've been using a pressure pot with vacuum degassing you have to mix your resin you have to put it into your vacuum chamber you have to pull a vacuum which pulls all the bubbles out and once they're out you have to take your resin back out of the vacuum chamber and pour your mold with a pressure pot you just mix your resin pour your mold put it in the pot and pressurize and you're done it's much faster and when you've only got a couple minutes of working time every second counts but pressure casting does have its downsides the tooling is expensive the cheapest way to do it is to buy a paint pressure pot and you also need a compressor and you need all of the plumbing hardware to retrofit the paint pot into the pressure pot that we can use for casting a pressure vessel is also inherently less safe than a vacuum chamber if your pressure pot fails it could burst or explode throwing shrapnel all around your shop on the other hand when a vacuum chamber fails it just collapses in on itself which still makes a really loud bang but it's much less violent and it's much less likely to throw debris around that could be dangerous a standard vacuum setup for casting isn't a whole lot cheaper than a pressure pot but what if we could get that cost down it would really lower the barrier to entry to making parts like wheels and bushings at home so in this video i'm going to experiment with a method that one of you guys sent me to try to do just that john cummings left me a comment on one of my videos he did some digging into some ways for inexpensively removing bubbles from casting materials and he sent me this really cool video by jasper sikkin i hope i'm pronouncing that right he uses a food sealing vacuum pump in order to pull bubbles out of casting resin it's an awesome technique and if we're able to transfer it over from casting resins to being able to cast urethanes then we can get a wheel and bushing casting setup for about 50 bucks so let's take a look here's the pump i chose there are a ton of these cheap vacuum food sealers available this was the least expensive one i could find that didn't have a bunch of bad reviews although in the long run i think it might be better to spring for a higher quality pump more on that later and this is the container i picked for my vacuum chamber it's plastic it's got a swing top lid a latch a gasket and that should get me a good airtight seal but in addition to being easier to open and shut i think the plastic jar is going to be safer than glass in the case of a failure since it won't shatter [Music] i used a step drill to drill a hole in the lid and well that's it our vacuum chamber is done it really couldn't be any easier to use it you simply fit the pump over the hole on the lid and turn it on after a few seconds of pressing it down into place the vacuum will seal itself and the pump will continue to pull air out of the container to release it you just tilt the pump and break the seal now that we know our pump is pulling a vacuum let's run some tests to start with i'm trying out specialty resins flex at 90 which i've successfully used under pressure to cast skateboard wheels i mixed my batch dropped it in the jar sealed and started pulling a vacuum [Music] hmm the urethane does seem to be bubbling and when i release the vacuum it does collapse back down which is part of how this is all supposed to work but this particular resin only has a three minute pot life and just like that it's already starting to set up and those bubbles are trapped in place and that obviously didn't work out so let's give it another try this time around i'm going to pull a longer single vacuum instead of a number of shorter ones i'm not sure that seems to have worked out better but it's still not really what we're looking for even though the urethane is collapsing down at the end some of the bubbles are still staying in place let's try something else this casting resin has a similarly short pot life but is far far less viscous maybe the vacuum will be able to pull the bubbles out of the thinner liquid better than it will out of the more viscous urethane mix pop seal pull [Music] oh my god that went everywhere dang i released the vacuum way too fast on that one but the way it collapses down means that something here is working right unfortunately just like the urethanes this resin set up almost immediately trapping bubbles in place this is a different casting resin that has a much longer pot life and it's also the only two part resin that i've got left in the shop so let's try it out and hope for something good i mixed up a batch and got it in the pot and again we can see that the vacuum is doing something since this resin has such a long pot life i actually left it under vacuum for about 10 minutes and when i went to crack it back open huh still some small bubbles but i came back a few minutes later and look at that that is a crystal clear bubble free puck of resin so what's going on here we've confirmed that this technique works for some casting resins but is there any hope of being able to degas urethane on the cheap well let's talk first of all i think pot life is going to make all of the difference if we can find a suitable hobby grade off-the-shelf urethane with a nice long pot life i think the food sealer method might have legs but it's really hard to tell right now because it seems like the urethane is setting up before the vacuum has a chance to pull the bubbles out all the way another stumbling block is i think this pump might just be a little bit too weak normally vacuum degassing looks a bit like the materials boiling but for this it looked a little bit more like a simmer now for my experiment i was shooting for extreme low cost which means there might be higher quality better pumps out there that allow us to pull more vacuum faster and therefore should get better results a stronger pump and a urethane with a longer pot life and we might just be in business so that's where we stand not a conclusive experiment but one that suggests that there is a solution still out there waiting to be discovered so i'm gonna do my best to hunt down some more forgiving urethanes find a stronger pump and get the cost of casting these materials way down so that you guys can get out there and start making your own wheels bushings and other parts and if you want to help me help you you can always check out the patreon the support over there is what allows me to buy materials for experiments like this and i'm so grateful to everyone who's already supporting over there you guys rock there's a link down in the description below if you want to see the next iteration of this experiment and a lot of other awesome diy board sports stuff you should go ahead and click that subscribe button because that's what we do here there's a new project every week if you got questions or comments leave them down below if grandma has the best coolest vacuum sealer you've ever seen and you want to recommend it leave it down below we'll talk you and me will talk and as always i love having you guys along for the ride so until next time i'll see you soon [Music] you

Channel: Good Roads

Views: 26,235

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Id: wOWLrNrV3Ts

Length: 8min 25sec (505 seconds)

Published: Fri Mar 05 2021