I have a pressure pot I need a perfectly level bottom on. My plan is to flood the bottom with some epoxy resin and let it settle to give me a flat, level, bottom. I don't have much experience with pressure vessels, however and I'm FAIRLY sure the reason the bottom is concave is to prevent pressure building up at 90* corners. If I flood the bottom with epoxy, will that mess up the integrity of the pot? This pot is rated for 80 psi and I want to take it to 70 so there isn't a ton of safety margin here. Also, is there a smarter way for me to get a really level bottom on this pot without having to constantly re-level it every time I do another batch of casting?
I think acrylic casting resin would settle better than epoxy. Scale model guys use it for underwater dioramas. All the epoxies I've worked with were goopy and left an uneven surface. Another thing you could try if you don't need the flat surface attached to the pot is to get a cutoff chunk of stone countertop and place it inside. They grind those really flat, like to the ten thousandth of an inch
Why do you need to level the bottom of the pot? Also, why not just get a platform that fits in the pot with adjustable legs? Don't make this harder than it needs to be.
I'm casting clear resin screens for restoring small electronic toys. LONG STORY but I need to be able to make part of it convex and part of it perfectly level. I figure I can make the molds flat, but when I put them in the bottom of the pressure pot I need them to be level so the backs of the screens are level too.
My worry with using a platform is how easily it can end up uneven by a couple of degrees and end up messing up a whole batch. I will also have to check if it shifted between each batch.
And that's somehow more work than re-leveling with epoxy every time? With a platform with adjustable legs, you can re-level it more easily. As long as your platform is made of a stable material that won't warp it should be fine. Resin 3D printers require a perfectly flat bed as well, and they get plenty of use. Honestly you couldn't probably skip all of this shit and use a resin 3d printer, but you do you.
I think you are missing my goal. I want to pore this stuff in there, let it set and FOREVER MORE have a perfectly flat and level work surface that, so long as I don't take my pressure vessel somewhere else, will always be as flat as I can get. Adjustable legs will need adjusting if the rig gets bumped. Inserts that are perfectly circular and match the size of the vessel well could work now that I think about it but would require me to go get more materials and probably some fiddling.
My first post was mainly asking if my plan would reduce the structural integrity of the pressure pot. Does anyone know?
it would be a pain in the ass to get all the air out or leave a sprue that I would have to sand down. I want to avoid making more work as I plan to produce a whole bunch of these little screens.
I want to so this a whole bunch of times. If I was only doing this once or twice I would go with a plan like this, but I want to do it maybe 100 times.
>FOREVER MORE
And if your table moves slightly then your flat, level surface is no longer level because it's only going to be as level as the pot itself, while something adjustable can be changed to fit the new orientation. That being IF the epoxy is perfectly level once it dries and isn't slightly curved, necessitating flattening and leveling anyways. Again, you're making this harder than it needs to be.
>I want to do it maybe 100 times.
see
>use a resin 3d printer
>it would be too much work to spend an extra 5 minutes taking off a sprue
>than it would be to fiddle with the system until you get perfectly level pours that require absolutely zero touching up
Idk why people come here, ask for advice, then ignore all the advice. Google an engineering text or go to PrepHole if you can’t do the math.
Alright so the advice I've gotten has been;
>Just get a stand with adjustable legs
I mentioned I wanted something more permanent.
>Just get a circular stand
I mentioned it seems like it might be a better answer, but I'm trying to work with what I ave (/diy/) rather than go out and buy shit (/reddit/)
>Just buy a 3d resin printer
I don't want to make 100 different things quickly, I want to make 100 of the same thing quickly. Also technically a good solution but I'm trying to avoid having 2 3d printers and I'm already going to have a more traditonal one for making cases.
>Just grind the sprues bro
Just grind your boipussy on my wiener bro
but seriously if I can spend 20 minuets once to save 2 min 100 times I end up with a net positive.
>Just google it bro
IF YOU WOULD READ MY GOD DAMN OP you would see I'm asking about the safety of my idea as I don't know much on pressure vessels with a small side request for other answers. I've got other answers. Cool. Now can someone tell me anything about what happens if you fill in the bottom of a concave pressure vessel?
>I mentioned I wanted something more permanent.
If you want to doggedly ignore the downsides and pursue the worst option, then shut the frick up and do it, and don't b***h about it when it doesn't work.
You THINK you want something more permanent, just like some morons on PrepHole think they want an underground shipping container bunker. There are many downsides to this approach that many people are informing you of because no, you would not actually want this if you tried it, and you refuse to listen to them.
To answer your question: The differential temperature expansion of infill and the metal walls will lead to cracking, voids, both, or neither depending on the expansion coefficients of the materials, total temperature change, and (most likely) material breakdown effects from cycling under pressure and vapor conditions of your manufacturing process.
If the metal vessel cools faster than the epoxy, resin, or other infill you have the potential to create an explosion. If the pressure vessel is sealed and the epoxy or resin off-gases under increased temperature (they do), you have created a potential explosion. You should consider safety precautions.
Continuing on, "crushing air bubbles" is the opposite of how more common manufacturing deals with this, by increasing temperature and vibration to shake the bubbles out. Trapping stress in the crystalline (or amorphous) form of your cast material will likely lead to brittleness and cracking in the finished product.
I have answered you respectfully OP, researching the specific construction and materials used in construction of the pressure vessel is a task best left to you, as only you can be responsible for your safety.
>I think you are missing the point
No, we get it. It just doesn’t make sense. Trying to get a perfectly level surface… that will frick up your pressure cooker if you mess it up… that won’t be level the second you move the cooker or the surface it’s sitting on… just doesn’t seem like a good plan. They already make adjustable inserts for pressure cookers that people use for canning or other stuff. You’d just have to maybe modify one of those.
But even that is a suspect plan. There’s a reason when people pour a mold they rarely if ever leave one side open, it just doesn’t work well and leaves massive opportunities for error. Just make the mold have a front and back and put the sprue on the side, then you just clip it off and polish the screen to your desired clarity (if it needs it)
Re: casting something in the bottom of the pressure vessel: yes it will affect the integrity. Anything that creates stress risers at a sharp angle will affect the integrity. Is the pressure vessel going to explode? Well it depends. Is it a presto? Do you have a pressure relief valve? Then I doubt it could blow up. Products are often rated to a much lower value than what they can actually safely handle.
If the pot is heated at the bottom then you are creating danger. The epoxy will superheat. May melt or behave badly. Consider casting molten aluminum into bottom of pot instead.
Yea other guy is completely correct, just get one of the inserts for canning, and reinforce it a little if you need but start with that. The thing you’re looking for is already made… so it’s gonna be easier to adapt than build from scratch
Also why would you not just make the mold front AND back? Or plan on grinding the flat side down and resurfacing it? I feel like there are better ways to go about this
Could you not use a bubble level and some shims underneath the mold to level it? You can probably even use the level app on your phone
How do you cure the resin that you want to cast? Do you just need 70 psi of over pressure, or would you also need to heat the vessel? If heat is required I would be careful since the epoxy likely expands much more than steel when heated, which could cause the vessel to burst. If no heating is involved it won’t matter what objects you put in the vessel. I also don’t get why you don’t just use a resin with different crosslinker so it will cure with just uv exposure or heat for example (rather than require a pressurised vessel), but I’m sure you have your reasons.
I don't get how the platform could get crooked between two batches. Attach the pot to the hot plate, spike down the location of the hotplate and make a little insert inside the pot that guarantee that the platform always gets placed in the same spot. Use some bolts as levelers and once adjusted, lock them in place with a set screw.
I leveled the bottom of mine with silicone
they are probably round on the corners because they are formed over a die which would frick shit up if it had sharp edges
Why not put a put inside the cooker? It will have a flat bottom. The All American electric autoclaves come with inserts like this.
I'm thinking about this from the physics standpoint. If you increase the pressure inside the vessel it will press everywhere evenly, including the epoxy you put in the bottom, which will press against the outside, which is the part that contains all the pressure. I'd say that, effectively, there would be no change and very little difference over a wide area like that. Sounds safe to me man.If you're worried, put it in a steel cage or box if you can find one for free or have something on hand with one open part facing away from you or anything you don't want destroyed, just in case.
Agree. If it's rated for 80, it's bursting pressure is likely over 160. 80 is standard water line pressure to be expected in a domestic setting. If it's not- say it's 110 - other equipment would have problems, so pressure reducers are used in-line right after the city meter.
Cycling it 100x at 70 psi should have negligible issues regarding it's strength. Play it safe though, as the guy above describes.
See, I was wondering if the epoxy would change the pressure points, but thinking on it the epoxy wont be bonded to the edge of the vessel well enough to matter. Thanks for actually responding to my question. I might throw the whole thing in a junk microwave case I have just for added containment.
The pressure isn't needed to cure the resin per se, but after vacuuming out as much air as I can, curing under pressure squeezes any minor air bubbles I couldn't get out small enough they aren't noticeable. The project is to replace the plastic screens these little dodads came with. There won't be any real amount of heat.
Don't put it in a small space, put it in a large one. The pressure is going to reduce at 1/(x^3) so the larger the thing you put it in, the less strong it will need to be.
I'm really not sure what you are getting at. Once the vessel bursts, the pressurized air is going to go everywhere and unless my hand is on the crack while it happens there won't be enough force to hurt anyone. The thing I'm worried about is the shrapnel caused by the bursting vessel. The metal box of a microwave oven isn't all that strong but from experience it will absorb enough of the force to prevent any shrapnel form hurting anything. I don't plan on running this thing with my face right next to it either.
I actually did not know water pressure to a house ran that high, but it does make sense considering how far sprinklers can throw water.
80 is the maximum before it goes beyond Code. Some solenoid valves won't work right below, or above, certain pressures; like a fill valve on a dishwasher, or an icemaker. Even if the pipe is rated higher.
I should have said, '80psi is within the standard range of 50-80psi.'
If the vessel bursts, it is going to leak more than air, most likely. There is a higher likelihood that it will do more than rupture and let air out. The lid might fly off, or it might break into several pieces. (Shrapnel)
Are you a god damn ai?
>The thing I'm worried about is the shrapnel caused by the bursting vessel.
was in my exact post
which was in response to
>Don't put it in a small space, put it in a large one. The pressure is going to reduce at 1/(x^3) so the larger the thing you put it in, the less strong it will need to be.
which does not mention shrapnel at all but somehow is concerned about a pressure wave starting at 80 psi killing me I think?
Why are you thinking there is a hot plate involved? I'm going to pump it up with a compressor. I'm putting stuff inside so said stuff can cure in a high pressure involvement to crush air bubbles. Read the damn thread.
I've considered that and I'm probably going to go with something like it. If the plug isn't perfectly air tight (which it wont be) there will be no chance for a pressure differential to build up and it will be the same as me just having anything inside the pot. Also, the pot will be going on the same bench each time but if I ever do move it being able to make a new plug will be nice.
Hot plate, table, your mum's ass, I don't give a shit. Frick you, OP. Take your stupid thread and stuff it. I hope your Presto blows up and the shrapnel causes you blood poisoning and gangrenous neurosis. A thread died for this asinine garbage.
>curing under pressure squeezes any minor air bubbles I couldn't get out small enough they aren't noticeable.
Ohh! Okay cool.
You wouldn't want to bond anything to the bottom of the pot, period. Best case after a few cycles your resin will fatigue and crack worst case you'll rupture the vessel. Sure they can take much greater pressures than they ate rated for but thats assuming some dumbass didn't try and Black personrig the pot by say bonding a bunch of epoxy to the bottom.
If your dead set on the idea then cast a removable epoxy plug into the pot. Cover the bottom of the pot with crayon or wax before you pour so you can remove the cast after. As suggested by another anon find some way to make reference points so it always goes in level.
Have a suitable bottom insert machined from solid. Place on bottom of pot and done. Likely best to source an industrial pressure vessel instead of kitchen crap.