Pressure Pots for casting questions

[nick daring]

I've been thinking about building one of these and stumbled across this video where the guy has two quick disconnects so that he can have a attach a compressor and vacuum to achieve either a pressure pot or vacuum chamber with the same pot.

Bubble-Free Pressure Casting and Vaccum Chamber for Resin Games Workshop Ral Partha Miniatures - YouTube

Is this setup sound solid? I don't think I've heard anybody doing that before.

 

[Luke0312]

This is the only picture I have handy, this is the lid for one of my pots... Anyway everything was removed and all unused holes plugged... You will see a vacuum gauge on the top, and on the right you will see an on/off valve and a quick connect... And off to the side you will see my pressure dongle...

Basically when I want to pressure cast, I plug the pictured dongle into the tank and hook up the air compressor... The dongle has a pressure regulator on it and will hold the tank at whatever pressure it's set to as long as it's attached, even if it leaks it will compensate...

Also note that the quick connect on the tank lid also act as a valve, it's self shutting when nothing is plugged in, so I also use the pictured dongle as a pressure release dongle as well, basically just a way to hold the quick connect open... As long as the dongle is in place the valve to the tank is open it will return the tank to normal atmosphere for opening...

For vacuuming I simply plug my vacuum pump into the tank, and watch the vacuum gauge on the top... And to release the vacuum, like I said above I plug in the pressure dongle and open the tank valve... Originally I had a vacuum dongle just like the pressure dongle built from the cheap HF venturi pump, but that has been replaced with an electric vacuum pump...

http://rpf.exoray.com/vac01.jpg

The biggest thing to remember is to allow for a way to return the tank to normal atmosphere... Be it a secondary release valve or what not, care needs to be taken that it's at normal atmosphere prior to opening...

I've been thinking about building one of these and stumbled across this video where the guy has two quick disconnects so that he can have a attach a compressor and vacuum to achieve either a pressure pot or vacuum chamber with the same pot.

Bubble-Free Pressure Casting and Vaccum Chamber for Resin Games Workshop Ral Partha Miniatures - YouTube

Is this setup sound solid? I don't think I've heard anybody doing that before.

Nope, never done before, lol.

 

[nick daring]

Yeah I saw that but i gues I was wondering if the two nozzles set-up were nessesary or beneficial in some way that I don't understand. Can't you just attach vac or pressure to the same nozzle? It would only take a second and you'd have less hoses dangling around everywhere.

Will the same gauge work for both negative and positive pressure though?

Also if you do use two different gauges do you need to isolate the different gauges from the pressure it's it not built to measure?

Also does anybody have the usable inner dimensions of the Harbor Freight pot handy?

 

[Luke0312]

Yeah I saw that but i gues I was wondering if the two nozzles set-up were nessesary or beneficial in some way that I don't understand. Can't you just attach vac or pressure to the same nozzle? It would only take a second and you'd have less hoses dangling around everywhere.

Will the same gauge work for both negative and positive pressure though?

Also if you do use two different gauges do you need to isolate the different gauges from the pressure it's it not built to measure?

Also does anybody have the usable inner dimensions of the Harbor Freight pot handy?

I thought you were referring to that exact set-up, but I couldn't let the opportunity to pass, ha ha.

A compound gauge will work for both, never priced them though, so not sure whether it would be worth it or just buy two separate gauges.

I probably would isolate the gauges, would prevent damage to the opposite one.

The ID of the HF pot is about 9 1/4" and the depth is 8 1/2". It's actually deeper than that, but the bottom is concave, so you'll need to fill it to get a flat surface, once filled is when it hits 8 1/2".

 

[nick daring]

Thanks a million! Exactly what I wanted to know!

 

[robn1]

exoray posted a setup in another thread that uses a compound gauge, it reads vac and pressure. If you're using separate gauges you can attach them with quick connects, remove one and attach the other. I use a lot of quick connects to keep everything as modular as I can.

The HF pot is fine for vacuum but I don't recommend it for pressure, I've read too many horror stories about failures with it. I detailed my setup with a Grizzly pot here http://www.therpf.com/f9/pressure-casting-grizzly-paint-pot-conversion-184777/