Experimenting with an Inexpensive Vacuum Chamber for Casting
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- เผยแพร่เมื่อ 4 มิ.ย. 2024
- In this video I'm testing out an inexpensive method of vacuum degassing castable materials using a jar and a food vacuum sealer. Let's see how it works and to see if it's transferable from casting resins to urethane!
Here's the original video from Jasper Sikken on the technique:
• Removed bubbles from e...
This is the pump I used:
www.amazon.com/gp/product/B08...
And this is the Jar:
www.amazon.com/gp/product/B00...
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I love the simplicity to this! Thank you for the idea
I used to work on CRT TVs. A vacuum implosion is a lot more violent than you think, especially if you use a high vacuum. Especially dangerous with glass, as pieces will bounce off each other or fly past each other and shower the room with high velocity shards of glass. I saw a chunk that had flown 20ft and embedded itself in a wood bench leg.
Absolutely awesome stuff 👊
I use flex it 90 as well, when I was testing I had the same issues as you until I made some changes, What changed for me was reducing the amount of hardener which gave me an extra couple minutes and working in a colder environment. It takes a minutes to get right because reducing too much completely changes the shore hardness. Also when testing in cups like you are, my pot life was shorter than when I was mixing and pouring into an actual mold, with thinner cavities it seems to take a little longer; just long enough to degas bubbles pulled upwards from a vacuum.
EXCELLENT!!!
THANKS FOR SHARING!
CHEERS!
You can make a pretty good vacuum pump reversing a foot pump or 12v car pump. VOG veg oil guy made a pretty good chamber and pump for around the same price. Really enjoying the content, I'm trying to cover some old aluminium skate wheels with a layer of urethane. Thanks for sharing all the cool content about wheels and bushings etc.
Oh I had seen those pumps and was thinking about trying them out, I didn't know VOG had already done a setup, I watch his stuff all the time. I'll check it out! Thanks for the tip!
I would suggest using a hand vacuum pump with a gauge most commonly used for bleeding brake systems. Or if you're willing to spend a little bit more get a used medical suction pump. The vacuum level that can be achieved with both of those I would say will work better for you.
cheap too - just bought a brake bleed pump
The bubbles have to get large enough to pop. That food "vacuum" just doesn't pull enough of a vacuum.
Interesting vid mate. I thought you use the vacuum for the silicone mold and pressure for the resin, cheers Graham
Harbor Freight sells a 2.5 CFM vacuum pump that will pull a 75 micron vacuum for less than $90. I have one that I used for vacuum degassing urethane resins when I was into casting model car parts.
I found one that was a return for (I think) 30% off, only problem was it didn't have the oil with it. Not expensive.
I know this is pretty dated, but one thing you could do is to take up a bunch of the unused airspace with something. The vacuum can evacuate much faster. (I've been using old cans of food. Sometimes their tops pull up, but so far none have opened.) I actually made a vacuum chamber basically exactly like this -- same type of chamber except the bottom vessel was stainless (top still transparent plastic), and I put a fitting on it to go to my full vacuum pump. Unfortunately, the seal shape on mine was not proper for this and the strength of the full vacuum would pull it in, breaking the air seal. Anyway. :)
Keep going bro one day you will be a famous TH-camr
Thanks dude!
Not before I ask him to vacuum isopropyl alcohol LOL
First improvement: turn the jar upside down so that you place the object to be degassed on a flat plate and the jar over it. Much less clumsy operation.
Put a wooden stick with flat end on a drill and mix the urethane/epoxy with that.
Should be pretty easy to 3D print a mixing blade that fits your container instead of a stick.
That would basically be a bell jar right? That's a cool idea!
Second improvement, ditch the wooden stirrer as they introduce extra bubbles!
Longer pot life, torch and a silicone cup would be best. Once you do your vacuum, pull out the silicone cup with ur resin and do a quick sweep of the torch over the surface will remove all of the surface bubbles.
I have a couple silicone mixing cups, I'll have to give this a shot
I have to wonder if the pump from king of random would be of more use here, as it would very quickly pull out lots of air from a smaller container and if the same one way valve is used the pump can be momentarily attached, pump out the air, and then sealed.
Along with the fact that manufactures often use resins that they cure in the oven I wonder if there might be a possibility of using a mold made of like ABS and then using in an oven set to ~ 70-90*C
I did this with a mason jar vacuum sealing pump ($20) and a 16oz mason jar. The sealer for sure works (the lids were un-popped, and you released the vacuum when opening the jar inner lid) but my resin (Shabebe brand) is maybe too thick. I ended up with tons of micro bubbles.
I'm going to build a pressure pot, as I can use a bicycle pump and simple cheap parts.
I mean you can also make a vacuum chamber by reversing the air on the bike pump, i'm gonna do that tomorrow I can let u know if it works well or not
What if you put the 2 parts together in the vacuum chamber without mixing, draw a vacuum, and mix them in that vacuum with one of those chemistry magnetic stir gadgets while it's under vacuum?
Sir, can you do a degassed water mixing with tallow or oil with this vacuum?
is it strong enough to boil water ?
like could you make a dry extract from a water extraction ?
For kicks, I think you should see what happens if you do use that cheap container under pressure.
Get a snap in valve stem in that hole, a bicycle pump, and see what it can take.
Though, being acrylic it will probably shatter. If there's similar polycarbonate or steel jars I think it might be workable at this small scale.
That sounds like a disaster waiting to happen, I've read to many horror stories about PVC pressure pots shattering to risk it. I also don't think the clasp and gasket on this jar would hold the kind of pressure you need to get rid of the bubbles.
Yeah, I think the clasp would probably be the weak point, even for this acrylic jar.
You need to get, what, 50-60 PSI for pressure casting? And you're looking at probably approaching 9-10 square inches on that lid so, 400+ lbs?
Clasp would fail way sooner than that.
I didn't realize PVC casting chambers were a thing.
Pressure can be pretty weird. I'm pretty sure Tom Stanton will routinely use pressures over 60PSI for his air engines with soda bottles.
You'd think that if thin walled bottles could handle 60PSI, that it would be cakewalk for massively thicker PVC, and yet I can totally understand the horror stories.
What might be interesting, though likely impractically difficult to pull off, is if you could pressurize the molds themselves rather than putting the molds in a pressure pot.
Bringing up Tom Stanton again, but his air engines are all 3D printed, and they hold up because they're small without a lot of surface area. A wheel mold might have too much surface area for a 3D print to hold up, but a bushing mold I think is small enough where it would probably be possible to design in a way where you clamp it shut, and pump air into it to pressurize it. And in this scenario the short pot life is probably a good thing as a slow leak would probably be unavoidable.
Anyway, that's neither here nor there really. You're on a vacuum project with this.
@@LongboardTechnology We used to build potato cannons out of PVC as a kid and we'd get them up to 80psi. But I've read that the problems come in from holding the material at that pressure, I don't know enough to tell if three or so hours at high pressure is a really bad idea so I don't want to risk it
Bad idea, don't eff around with pressure vessels. People don't realize how much energy is stored in a pressure tank. A plastic pressure tank is sure to explode, no joke.
You could use a smaller vacuum container, so the amount of gas you need to take out is samller, that would reduce your vacuum time.that if you want to keep the small pump. Otherwise, you would need to get a stronger pump.
Also, you could try to add a pressure release mechanism like a small valve you could open slowly in order to pressurize the chamber in a controlled way after achieving vacuum.
Would having a smaller chamber help? So that the pump has less work to do?
It would help it degas faster but I think it's a separate issue from the strength of the pump. Both things need to be addressed
Average used AC compressor works great
If u get fridge one it is slow but can work too
Big units for home AC have good liter per min. ratio
Both can achieve -0.9 so the same as vacuum pumps
U only need to change the oil or it will rust super fast
And use oil filter at the end or u will get oil vapour everywhere + it is good to make some filter at the vacuum side to protect the pump
I'd love to do an AC or fridge compressor vacuum pump if I ever tackle a vacuum table build, which is a machine that I'd definitely love to have in the shop. For this project I'm really hoping I can find something cheap and pretty pre-fab that doesn't require much tinkering. I just don't know what kind of off-the-shelf pumps are out there
Let’s do this!!!!!!!
For mircobubbles on surface use a lighter and it should clear em (also idk if its different but make dice for friends and how i avoid bubbles ot pressure pot i use a casting resin with a 45 min work time. I heat both parts separately and them mix warm. Then i let degas near a space heater (i never have problems with flash curing) and i assume if you use this with this really thin reasin the bubbles will be barely noticable ofc nothing beats a pressure pot
This is more for casters and not what you are doing but for those out there who do ther eis a skightly better version of this pump and also resinators vacuum chamber
You can maybe use this for small projects
Wonder if it will do good with silicone
this has saved me time and money. A better $50 pump is needed to burst the bubbles and collapse them in time
Have you tried using a break bleeder instead ?
But is this like, completely taking all the air out of the jar? Or just most of it?
I am your fan and subscriber
Plastic is porous.
Try the same pump on a glass jar or biscuit barrel maybe? A glass cake dome with a silicone seal?
I've seen people using the pumps used for oil changes on cars for chambers too but can't remember if it was for vaccum or pressure.
There's also a way to invert bicycle pumps to pull a vaccum.
Hope some of my ramblings help!
I was looking at those 12v pumps for fuel changes as an option. It would be a more DIY route but it's still really inexpensive if it works. The bike pump idea is really interesting too!
P.S. I've found some vaccum seal lunch boxes with the valves already installed.
They come in plastic or borosilicate glass.
Going to be testing the plastic ones.
They indicate they are at full vaccum when the clips loosen and the lid is held on by the vaccum.
They come in a range of sizes.
Fingers crossed it works.
(For polyurethane.)
P.P.S. I'm also working out a method to print on wheels which can be done at home. That is similar to professional production. Low cost.
You mean printing graphics on wheels?
When you have foam like that, you can remove it with heat. Take a blowtorch to it and it'll be gone.
Pull repeated vacuums on that plastic container and it will crack/deform.
Walmart used to sell those but for some reason stopped.
They were great for storing food in or things you want to keep dry.
A centrifuge will remove bubbles faster.
Would you really need to pour this after? What if you poured the urethane into your mold and then vacuum sealed the whole contraption?
My understanding is that when vacuum degassing works right the material can bubble up by like three times its volume, so if you had it in a mold it would overflow
Have you tried a Space Bag and a vacuum cleaner? I'm curious if that would work?
I don't see how. A vacuum cleaner is designed to pull a lot of air, not work against a closed container.
Hear me out, I know this sounds silly... but would a adult toy vacuum pump work for this in a similar way? They are usually cheaper than the food sealers at least in some countries.
Hahahaha! That's actually an interesting idea! My guess is that it would have the same drawbacks as the food sealers because I'd imagine the pumping mechanism would be the same. The problem here isn't really price, its that we need something that can pull a stronger vacuum and I think that kind of vacuum wouldn't be something you'd want to apply to what we'll call _sensitive areas_
Funny you say this because when I first saw the food sealer there was no scale to its size and that's exactly what I thought it was, just without a clear casing.
Saying that, an adult vacuum you may not even need a jar to put the cup in, just place the cup on a tile and the adult vacuum should be big enough to go over a cup and create a seal against the tile
what about the roarockit pump?
yes - you have to pump manual, but if it's sufficient for snowboards, it should also work here... Unfortunately they are not selling the valve only :-(
That's a possibility for sure
Does it work for silicone too?
You should be able to degass the 2 parts before mixing. I don't know anything about resin casting, bit just based on the physics, which are that this is not gas produced by the hardening reaction but gas already dissolved in the resin.
The bubbles are introduced by the 2 minutes of vigorous stirring required to mix parts A and B seamlessly.
Thank you Saul Goodman!
You should revisit this with a stronger pump.
That's the plan!
Could you vacuum the two before you mix them? So they wouldn't setup.
Most of the air actually gets introduced during mixing so its best to degas afterwards
@@GoodRoads so you need to like mix it in a vacuum
You should try pulling vacuum on the parts A and B separately, before mixing! Then you get the whole pot time to pour. Just take some care to mix them without introducing more air... maybe in a Ziploc, then snip off a corner to pour.
Except there is no air until you mix it.
Can you pack ice around the resin to slow the reaction?
Would also make it a lot more viscous, which might make the bubbles more stubborn.
It could also make mixing take longer.
I know temp can make a huge difference in slower set resins.
But if your pot life is only 3 minutes, that's a pretty aggressive reaction that probably won't be slowed down by much anyway.
@@LongboardTechnology I would try mixing it and then chilling, but yes, it will get properly thick. A larger vacuum pot where you can increase the surface area of the resin could slow things down a bit too.
Resins have a minimum working temperature and if you go below that they won't cure up right, for the ones I've used it's around 50 degrees Fahrenheit. There are urethane formulas out there that have longer pot lives, I've just got to get a hold of some and get testing
You need to light the bubbles.
Hey if you have a car you have a good vaccume 😉
Put resin in mold - mold in chamber , then vacuum.
Rubber seal on the end of wet-vac
That pump can not pull a vacuum. It will remove a small portion of air inside the jar, but no where near vacuum.
This pump is too weak. The best cheap (or free) solution is to scavange a refrigerator (or freezer) motor. Then you will need the proper fittings, a vacuum gauge plus in and out valves to control the vacuum. One of the biggest factors of bubbles as I understand it is atmospheric moisture. There were times that I poured perfect, bubble free resin, only to discover tiny bubbles later. Those bubbles were created during the setting reaction of the resin combined with moisture. Sometimes the resin is old and has alot of moisture trapped in. This can happen without you knowing it as some shops sell resin that was decanted from large canisters to smaller bottles. You can be sure about your resin only if its packaging is factory sealed.
Why don’t you store the vacuum in a tank and release it quickly? HVAC GUY HERE
Vacuum = heat. Heat decreases working time and Increases set up.
Great chamber. Crap pump.
jar too big