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Pressure Casting Equipment

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Re: Pressure Casting Equipment

Postby Magnetic Duckling » Fri Mar 02, 2012 1:43 am

Thanks guys (and girl xD). Things are slowly getting clearer ^^
I guess I don't need a nuclear plant, just a smaller machine could do. I heard that just a 9ltr compressor could do for a 10 ltr pot, I always assumed I needed a bigger tank than the pot.
I can't get around the quiet machine, I don't mind paying a bit more so I don 't have to deal with angry neighbors. I found 40db compressors that are looking at me like pink ponies for little girls "buy me, I am so pretty and quiet".

Fleafa : I never thought of searching as "Spray Gun" but hey, not a bad idea!

Any 25L compressor will have no trouble at all filling a paint pot, timings are only important when you start messing with vacuum!

Sadly timing do matter with my resin that cures in like 0.0001 sec. Ok I exaggerate but you get the idea. After pouring it into the mold sometimes it starts to harden even before I am done pouring.

I can't reach your ebay link Anvils Hammer. It says "Unfortunately, access to this particular item has been blocked due to legal restrictions in some countries (...)" but it is ebay UK so that doesn't make much sense.

It only takes me about 10-15 seconds to fill a 10 L pressure pot from my 40L compressor tank.

Cool O_O What is its cfm (or ltr/min) ?

I still am unsure which minimal cfm I need. Can you enlighten me ?
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Re: Pressure Casting Equipment

Postby Deadmeat30 » Fri Mar 02, 2012 2:22 am

CFM means cubic feet per minute, it's basically the air displacement the pump can remove within that time. Around 6-9cfm is good to look for. :)
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Re: Pressure Casting Equipment

Postby Magnetic Duckling » Fri Mar 02, 2012 2:56 am

Deadmeat30 wrote:CFM means cubic feet per minute, it's basically the air displacement the pump can remove within that time. Around 6-9cfm is good to look for. :)


Oh dear, thing is for quiet machines it goes like :
2.15cfm 24 ltr £526
4.5cfm 25 ltr £886
6.5cfm 100ltr £1426
so, errr, yea... but.... how can I say....
I am not that rich ? XD

Would something around 2.15 or 4.5cfm do or am I just cursed and have to move to a house or win the lottery ? :cry:
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Re: Pressure Casting Equipment

Postby Deadmeat30 » Fri Mar 02, 2012 3:02 am

depends on the size of your vacuum chamber and how quickly you need to get it to a vacuum (faster the better ;) )
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Re: Pressure Casting Equipment

Postby mangozac » Fri Mar 02, 2012 8:03 am

Isn't Duckling talking about pressure casting only? In that case the CFM isn't all that important - it will only change the amount of time it takes the compressor to fill its own tank (how long it makes a noise for). I would want the compressor tank to be at least double the size of the pressure pot - the larger it is the quicker your pressure pot fill time will be (as the compressor tank empties the flow rate drops).

Either way I think you're really going to have to find a slower curing resin - you want at least 3 minutes of work time to get it mixed, poured, in the pot and up to pressure. I prefer 5 minutes!
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Re: Pressure Casting Equipment

Postby Magnetic Duckling » Fri Mar 02, 2012 8:17 am

Yup Duckling talks about pressure only.

Well the resin I use is cool, I like it (and I don't know any other one... oops), it starts to harden fast but has a texture close to silicon (high viscosity ?) for a long while after it starts so I should be fine.

So basically mangozac, between those two 8 bar machines :
2.15cfm / 24 ltr
4.5cfm / 25 ltr
both would do the job ?... I'd rather buy the cheaper, if you see what I mean =p
I thought cfm was the time it took to transfer the air from 1 tank to the other ?

A pressure pot company told me 3 cfm would take a few minutes to get the pressure pot under pressure but maybe the person considered the time to fill the compressor tank in the equation... how could I guess that though ><;
So I put my trust in you guys (because people who likes miniatures has to be good people ;)).
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Re: Pressure Casting Equipment

Postby Deadmeat30 » Fri Mar 02, 2012 8:28 am

Ok, i mis-understood, Ignore everything to do wtih CFM's if your only needing to pressure, for pressure you want PSI (pound per square inch). Aslong as you have a good size tank attached to the compressor, your dont really have to worry about how quickly it'll transfer to the pressure pot. The compressor will have a regulator on it, just set this to the PSI required and then open the valve. The 2 tanks will equalise to the regulators setting.

that any clearer?

regards,

Alan
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Re: Pressure Casting Equipment

Postby mangozac » Fri Mar 02, 2012 8:34 am

Magnetic Duckling wrote:because people who likes miniatures has to be good people ;).

Now you're just sweet-talking us :P

CFM is purely the rate at which the compressor fills its own tank.

OK so I assume the 2.5CFM one is cheaper? 2.15 CFM = 60.88 litres per minute. I did some quick sums (the time to fill the tank is not simply the tank size divided by litres per minute) and came up with about 3 minutes to fill the tank (guessing that the tank will run to a pressure of about 120 PSI). That's slow, yes, but if it's a quiet motor it doesn't matter - you make sure the compressor has filled its tank before you do the cast. The 24L tank should fill the 10L pressure pot in a short enough amount of time.
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Re: Pressure Casting Equipment

Postby Magnetic Duckling » Fri Mar 02, 2012 10:31 am

deadmeat (that is the most peculiar nickname xD), it IS clearer thanks!

mangozac, you assume correctly!
Thanks for making a calculation too.

I just registered myself, ask for help and you all help me, that is really sweet so you see, I am right about people who likes miniatures =p
I hope I can be of help in return. If anyone here wants information about 3D prints that is more my area of expertise.

I guess it is set then, I'll most likely get the 2.15cfm / 24 ltr compressor and this baby http://www.axminster.co.uk/axminster-10 ... prod21334/
The dual hose kinda confuse me though. Can I close one valve and use only the other or something ?
(Once I got those I'll probably whine around while batting my eyelashes to get them to work ><; ).
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Re: Pressure Casting Equipment

Postby blind pig » Fri Mar 02, 2012 11:49 am

Magnetic Duckling wrote:I guess it is set then, I'll most likely get the 2.15cfm / 24 ltr compressor and this baby http://www.axminster.co.uk/axminster-10 ... prod21334/
The dual hose kinda confuse me though. Can I close one valve and use only the other or something ?


Put a valve on on each threaded hole (they will probably be different size threads unfortunately) and attach a hose to one and the other end of that hose to the compressor tank to fill the pot. The other tap, use it to empty the pot when under pressure and finishde curing the resin.

Re: quick setting resin. Have you tried cooling it in the fridge to extend the curing/working time?
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Re: Pressure Casting Equipment

Postby mangozac » Fri Mar 02, 2012 5:00 pm

Hey Duckling, Fleafa some fantastic drawings showing how he set up his pressure pot, along with some alternative configurations here. Have a read of that and hopefully it will give you a good understanding of how you need to modify the pressure pot.

One other thing too: the pressure pot will come with an emergency release valve. It's to protect you in case you decide to stick a million PSI (well maybe not quite that much...) into the pot - the valve will "pop" open and release all of the air in a very loud manner. Generally these pots are rated to operate at well over 100PSI, however they are fitted with pressure relief valves set much lower - around 40PSI. Ideally you want to be casting at 60+ PSI so you will need to replace the relief valve with one rated at say 70 PSI. Air tool stores should sell them - I would expect to pay around 10-15 pounds.

Oh and also, you need to make sure that you use either some thread sealing tape or some kind of thread sealant compound from a tube (like thick glue) on the fittings when you screw them together. They are not designed to be airtight without some kind of sealing technique.

One day we should all get together and compile a exhaustive tutorial on the best way to convert a pressure pot and all of the parts needed...
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Re: Pressure Casting Equipment

Postby Magnetic Duckling » Fri Mar 02, 2012 10:20 pm

blind pig wrote:Re: quick setting resin. Have you tried cooling it in the fridge to extend the curing/working time?

The lady at the store mentioned that yes but I haven't tried yet since I never casted under pressure so I had enough time to do my business before it cures. Good thing to keep in mind though.

mangozac : that topic is awesome. And you are damn right about making a tutorial. It is incredible that there is so few information online.

Thing is my English sucks when it gets technical so I read it twice and still feel more or less in the dark.
Paulson games mentions a diverter to avoid resin mess but I fail to understand what that means.

I got it that the checklist is :
2x 1/4 inch ball valve (male to female)
1x 1/2 inch ball valve (male to female)
1x female quick connect nipple
1x 70 PSI safety release valve (male)
Silicon tape

I guess I'll get those then manage to follow the advices on the topic, once I got the parts in hand.

Could someone in the UK be the dearest and pick up a good website and give me links to all this stuff so I don't get the wrong sizes ? Sorry to be a drag but this really is not my area of expertise and I am afraid to mess up (or do I just pop at Homebase with the list and ask ? But if they are like that guys at some local computer store that were clueless about the simplest things, I am afraid xD).

Also what material do I need to get rid of the tube inside that feed the paint ?

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Re: Pressure Casting Equipment

Postby blind pig » Sat Mar 03, 2012 1:20 am

A diverter is someting that goes over the inlet pipe under the lid of the pressure pot that stops the high pressure air from blowing down onto your resin and making it splash out of the mould.

A good hardware store should be able to help you with the fittings. Take your pressure pot and the hose that fits the aircompresser you are going to buy into the hardware store and say you want valves and connectors to fit it.

Batter your eyelases and wear something with a bit of boob showing and ask if someone would mind unscrewing the pipe inside the lid when you are in the hardware store (worked for me!) :lol:

@Zac: I can't believe there is a wiki about Teflon tape!!!
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Re: Pressure Casting Equipment

Postby Magnetic Duckling » Sat Mar 03, 2012 3:04 am

blind pig wrote:Batter your eyelases and wear something with a bit of boob showing and ask if someone would mind unscrewing the pipe inside the lid when you are in the hardware store (worked for me!) :lol:


But we don't have a car ;_; (and who would want to drive on the left anyway ><;;;;; ). The boobs technique would probably have worked though ;)

Ok so here is what I found so far :
-Valve : http://www.ebay.co.uk/itm/75-PSI-AIR-CO ... 415df78b59
http://www.compressor-source.com/Compre ... 250070.htm
I can't find Valves besides in the USA, strangely.
-Nipple (wait what?) : http://uk.rs-online.com/web/p/fittings- ... e/0497946/
-1/4 inch ball valve (male to female)
http://uk.rs-online.com/web/c/?searchTe ... e+&sra=oss
-1/2 inch ball valve (male to female)
http://uk.rs-online.com/web/c/?searchTe ... e+&sra=oss
TOTALLY clueless about the valves...(inches, mm.. what ?) *tries the boobies technique* Help ? ;p
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Re: Pressure Casting Equipment

Postby mangozac » Sat Mar 03, 2012 7:22 am

For the diverter some people use a T-piece (named that because it is shaped like a "T") so that the air entering the tank is diverted sideways rather than straight down. I don't have a diverter set up because I'm hard-core (or maybe lazy I'm not sure) ;)

Before you buy the safety release valve you need to find out what your pot is actually rated to. This is very important because if the valve is rated higher than your pot then it will not protect you. The manual that comes with the pot should tell you (you want to know the maximum pot pressure, not the safety pressure), otherwise you will need to contact the manufacturer. I would then get a release valve rated at least 10PSI less than that.

Remember, compressed air can be dangerous if you do silly things. I'm the last person who will harp on about safety, but the last thing I want is one of our members hurting themselves. Don't let that put you off though - with the right advice it will be fine ;)

RS is about the most expensive place you can get these things from. Any good hardware will be much cheaper. If you don't have a car you must be used to catching public transport around? And although I'm sure most of the young people in the hardware would have no idea, an older guy should know enough about the fittings to help with what you want (I agree show some cleavage, wear your hair out and bat your eyelids).

Oh and left side of the road is the best side to drive on! What country are you from?

I'll have a chat with Fleafa about getting him to update some of those cool graphics he drew up for us to make a new tutorial...

blind pig wrote:@Zac: I can't believe there is a wiki about Teflon tape!!!

Bec I thought you had more faith in wiki than that! :P
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