What kind of pressure pot should I buy for casting resin blanks?

[ndep]

I'd like to teach myself how to cast blanks and am curious what kind of pressure pot people use or recommend. Thanks!

 

[Amanap]

I use a converted Harbor Freight paint pot but I see a lot of people posting about the California Air Tools pot. If I had to do all over again I would go with the California Air Tools and it will be my next one.

 

[jrista]

I bought a California Air Tools pot, 5gal. It worked great the first, 3 times I guess. Its a really nice unit really, and price wise...it was much better priced than many of the other popular pots I was hearing about when I was researching. I think I spent $249 on it when I bought, which was on sale. IIRC the list price is $299. A lot of the smaller pots I was looking at from...oh, now I can't remember the brand, were around $450-$600+, and generally smaller in size.

Since my third use, it seems to have developed a leak, so it can't maintain 40PSI pressure without keeping the compressor hooked up for more than about 40 minutes. So, that's thrown me a bit, but, I found some info to help identify where the leak(s) are coming from, and bought some anaerobic Loctite stuff to seal them. I am keeping the compressor hooked up, but not without some level of restricted airflow to make sure that I don't end up with high pressure whipping a hose about if anything were to fail. Hoping to have the leaks identified and fixed soon here, though. It may simply be that I'm not tightening the lid properly, or tightly enough. I'm still a beginner, so it could indeed be user error here. Anyway, just thought I'd note it.

Overall, I actually really like how the pot is designed. Its like a tank, solid, so I know it can handle the pressure (it is rated to 60psi, I never go about 50psi, and for most of the resins I use, 40psi is all that seems to be necessary to crush the bubbles). Its easy to use. It has this great handle bar that sits above the top, and is designed in such a way that it makes it easy to carry the pot around. Its large enough that I was able to purchase this HDPE caddy from PTownSubbie.com with multiple shelves, and with that, I can handle probably around 8x 4-slot pen blank silicon molds. Two per shelf, four shelves. The caddy also has this clear cover plate, which is an added bonus when filling the pot with pressure, as you don't have to worry as much about the inflow stream splashing any of your resin (still have to worry about rapid change in pressure doing that, though, but I can fill the pot faster with the caddy now, which when you are working with short open time resins (i.e. 7min alumilite) its a bonus.)

 

[SabertoothBunny]

There are various brands of paint pots you can modify and convert into a casting pressure pot. That is not my recommendation.

California Tools released a pressure pot (model 365CW) designed specifically for casting for woodworkers. This thing comes out of the box ready to use, no modifications needed. You can get it for $250-300 at most online woodworking retailers. To me, just buying the pot ready to go is ideal. I did not want to take the time and money to modify a cheap one for the purpose of casting.

 

[SabertoothBunny]

I bought a California Air Tools pot, 5gal. It worked great the first, 3 times I guess. Its a really nice unit really, and price wise...it was much better priced than many of the other popular pots I was hearing about when I was researching. I think I spent $249 on it when I bought, which was on sale. IIRC the list price is $299. A lot of the smaller pots I was looking at from...oh, now I can't remember the brand, were around $450-$600+, and generally smaller in size.

Since my third use, it seems to have developed a leak, so it can't maintain 40PSI pressure without keeping the compressor hooked up for more than about 40 minutes. So, that's thrown me a bit, but, I found some info to help identify where the leak(s) are coming from, and bought some anaerobic Loctite stuff to seal them. I am keeping the compressor hooked up, but not without some level of restricted airflow to make sure that I don't end up with high pressure whipping a hose about if anything were to fail. Hoping to have the leaks identified and fixed soon here, though. It may simply be that I'm not tightening the lid properly, or tightly enough. I'm still a beginner, so it could indeed be user error here. Anyway, just thought I'd note it.

Overall, I actually really like how the pot is designed. Its like a tank, solid, so I know it can handle the pressure (it is rated to 60psi, I never go about 50psi, and for most of the resins I use, 40psi is all that seems to be necessary to crush the bubbles). Its easy to use. It has this great handle bar that sits above the top, and is designed in such a way that it makes it easy to carry the pot around. Its large enough that I was able to purchase this HDPE caddy from PTownSubbie.com with multiple shelves, and with that, I can handle probably around 8x 4-slot pen blank silicon molds. Two per shelf, four shelves. The caddy also has this clear cover plate, which is an added bonus when filling the pot with pressure, as you don't have to worry as much about the inflow stream splashing any of your resin (still have to worry about rapid change in pressure doing that, though, but I can fill the pot faster with the caddy now, which when you are working with short open time resins (i.e. 7min alumilite) its a bonus.)

Did you reach out to California Tools about the problem?

 

[NJturner]

I modified a Harbor Freight pot about a year ago - basic stuff, nothing crazy - and it works great. I can get the pot to 40 lbs quickly and hold pressure for over 24 hours with less than 2-3 lbs of bleed off. My suggestion if you choose this pot, be sure to mark each tightening spot and make sure you place the lid in exactly the same spot every time. Build a simple rack for the inside, or at a minimum put a plywood disk in the bottom of the pot with a bubble level on it to provide a level, smooth surface for your casting moulds.

 

[MRDucks2]

I initially bought a Brinks type pot used from a member here in the 1 gallon size and still use it. However, I found I wanted to do other casting work also and bought a California Air Tools pot in the 3 gallon size.

I use both routinely. I modified my 3 gallon pot from a paint pot to a casting pot. If you use quality fittings and valves you will spend more than the new pot from them made for casting. Plus, I was chasing leaks for at least a week.

Because of my arrangement, having both pots is ideal for me. If I were to choose one it would be the 3 gallon California Air Tools in the Casting Configuration. For $250 I do not think you can do much better.

 

[Jim Campbell]

I also use a Harbor Freight pot. I know a number of people who frown on them. The same folks tend to run 60 pounds and use a crescent wrench to tighten it down.

The above suggestion to mark the lid and pot to ensure the same alignment each time is a key one.

The second is to not over tighten. I never use a tool to tighten down the top. Doing so will warp the pot, causing the seals to leak. Hand tighten, and even then don't get all gung-ho about it.

I did replace the pressure relief valve with a better quality one from Amazon. I use a 55 pound relief valve and never run more than fifty pounds.

Once I hit fifty pounds I shutoff the intake valve, turn off and disconnect the air compressor. As mentioned earlier, I lose about 5 pounds in 24 hours.

No matter which one you go with, follow the alignment and tightening advice, and keep yourself to fifty pounds or less and you should be fine.

 

[crokett]

I don't use a pressure pot. Never have. I use a thrift store crock pot. I preheat the molds and preheat the resin before adding the catalyst. I have a meat thermometer and heat things to about 130. After I add the catalyst I pour into the molds then put in the pot until everything kicks. Then I turn off the pot and let it all start to cool down. I use Silmar 41 Polyester resin for my casting. I've never had problems with air bubbles.

 

[jrista]

Did you reach out to California Tools about the problem?

I haven't... Not sure if they would. I bought the pot a year ago, and it was a few months before I actually had a chance to use it. Its been sporadically used, and now that I'm having this issue, I believe the warranty period is over. I am pretty sure it is me not using it properly, though...I don't think I am tightening the lid enough, but, at the same time, there are so many warnings to not over-tighten the lid. So I need to figure out what the proper tightness is. People talk about number of turns of the knobs and stuff online, but, its hard to translate that virtual description into real-life tightness, so I'm experimenting. I ran out of resin with my last project, so I'm waiting on a gallon order of Alumilite to come in.

 

[MRDucks2]

David has a point, there are options for casting that do not require a pot. I do not use a pot for polyester resin or epoxy, most of the time. Urethane is a different story and is going to need a pot.