Please help me chosse my first pressure pot

[Nick Rocco]

I am in the market for my first pressure pot to start casting my own turning blanks.

I have come up with the following options and would like some input from everyone on what might be my best option:

1. Harbor freight pressure paint pot. I have ready a lot about this one on the forum; both good and bad. This is the least expensive option.

2. Grizzly pressure paint pot. This is almost twice the price of the HF pot but looks a little more heavy duty. I like the lid clamps better.

3. A used DeVilbiss pressure pot. This can be had for a little less than the Grizzly but will need some work from the looks of it.

Any and all thoughts are welcome and appreciated.

Thanks!

 

[Edgar]

Lots of folks here have the HF pressure pot. It should work just fine for you, just be sure not to over pressure it. Up to 50 or 60 psi should be ok, and it's a good idea to have a regulator on your compressor as well as one on the pot.

Some folks like to pressure up to 80 psi or more for some of their castings, especially worthless wood casting. If you want to do higher pressure work, you might want to look at a better quality pot.

 

[mark james]

Hi Nick.

If you want, you can wander to Medina and try out my Harbor Freight set up just to try it out? It's in the garage, so a nicer temp day would be the most comfortable.

I cast with Alumilite and have all you could want to try.

 

[BSea]

My 1st question is what type of resin do you want to cast. If it's PR (Castin Craft, Silmar 41, also called Poly Resin or Polyester Resin), then you can start without pressure. I only use pressure for clear blanks like stamp blanks. However, if you want to use Alumilite, then a pressure pot is required.

I have a pressure relief valve on my pressure pot. But another regulator isn't a bad idea too.

And I'd take Mark up on his offer.

 

[MesquiteMan]

I would buy the Devilbiss hands down, no questions asked. It is the only US made pot on your list and will most likely be ASME certified.

 

[Nick Rocco]

Thanks to all for the input! Thanks for the offer Mark!

I am planning to use Alumilite for my blanks and I will probably take Mark up his offer. I would also like to make some silicone molds which will have to be made under pressure as well.

I may also try to take a ride and see the DeVilbiss in person before making a final decision.

Thanks again!

 

[BSea]

Thanks to all for the input! Thanks for the offer Mark!

I am planning to use Alumilite for my blanks and I will probably take Mark up his offer. I would also like to make some silicone molds which will have to be made under pressure as well.

I may also try to take a ride and see the DeVilbiss in person before making a final decision.

Thanks again!

I'm not an expert, but I think silicone molds require vacuum not pressure. At least that's what I've seen on YouTube videos. Not that you can't use a pressure pot for vacuum, but you would need to be able to see inside to make sure the silicone doesn't overflow the container.

And I 2nd the DeVilbiss pot.

 

[Edgar]

Curtis (Mesquiteman) is an expert on Alumilite casting & pressure pots, so I would give his advice strong consideration. Be sure to check out some of the videos on his website also - you can learn a lot there.

 

[Nick Rocco]

I was considering using the High Strength 2 mold making silicone from Alumilite to make some molds. I spoke with the folks at Alumilite and they said that the silicone mold would need to be made under 45 - 50 psi of pressure to ensure that they did not shrink or deform when casting Alumilite pen planks also at 45 - 50 PSI.

 

[BSea]

I was considering using the High Strength 2 mold making silicone from Alumilite to make some molds. I spoke with the folks at Alumilite and they said that the silicone mold would need to be made under 45 - 50 psi of pressure to ensure that they did not shrink or deform when casting Alumilite pen planks also at 45 - 50 PSI.

Did they say anything about de-gassing the mold material? But that does make sense.

 

[EdGallop41]

I had an old canning pressure cooker in the basement. Cut a viewing hole in the top and bolted down heavy plexiglass, actually a much stronger polyglass I got from a glass shop. I used cement and bolts with a sheet on the inside and outside. I put a fitting in the top steam hole to fit an air hose fitting. Works great on pressure. The gasket was an expanding type for pressure to seal it. I wanted a vacuum pot also so I bought another gasket and filled the hollow with a non-hardening caulking and it worked great. I use it for both pressure and vacuum by having two valves and switching the gasket. I tested it at double the pressure, also more than enough vacuum. I did this outside to make sure it was safe. This entire pot cost me less than $10.00 (glass, gasket, and caulking). You might find a pressure cooker in a thrift store.

 

[cal91666]

If you do decide to go with the HF pot. I found the supplied pressure relief valve to be junk. It leaked and popped off the first time I pressured my pot at about 20 psi. I replaced it with this and feel a lot better about it. https://www.grainger.com/product/CONRADER-Pressure-Relief-Valve-41H786

 

[79spitfire]

I use the HF pot, I replaced the Pressure relief valve and poured a gasket from silicone. It works great. Be sure not to over pressure it, what it's rated for is plenty of pressure (IMHO). Remember your millage may vary....

 

[endacoz]

I adjusted the hf stock relief valve so it goes off at 60lbs instead of 25 out of the box.

Zac higgins video explains that. Many people don't realize it is adjustable.

 

[Bob Roehrig]

Pressure Pot Failures

I to am looking to purchase my first pressure pot. After reading and viewing some of the responses to the Harbor Freight model, I have at least made a decision that my life is more important and do not want to deal with a pot failure under high pressure. As it looks now, I probably will spend the extra money and go with a CA Technologies 2.5 gallon pot. Well built and super sturdy. Just my 2¢

 

[EdGallop41]

I to am looking to purchase my first pressure pot. After reading and viewing some of the responses to the Harbor Freight model, I have at least made a decision that my life is more important and do not want to deal with a pot failure under high pressure.

I bought a Harbor Freight pot and eliminated the poor quality problems. After replacing the fitting that goes into the lid, and the "T" fitting for the regulator, it is as safe as any pot in my opinion. I also took the paint pipe out and added a pressure gauge in it's place to make sure the two readings match. It probably was not necessary but it does read actual pressure in the tank. The other gauge is on the regulator and reads the pressure going into the tank.

The fittings I replaced were of poor quality but after I replaced them the pot is as safe as any. I pump up to 60 lbs. and would be confident with a bit more if it were necessary (but it isn't). I also made it into a Vacuum pot. I bought a thick 1/2" x 12" x 12" Plexiglass like sheet and also a sheet of 1/4" rubber at Amazon. I cut out a circle in the rubber to see in the pot, glued them together. I drilled a hole to add a "T" fitting for a vacuum gauge and a short hose attached and hooked up my Harbor Freight vacuum pump. All I do it lay the 1' square plastic on the pot and it seals itself. If not all I to is tap it while the pump runs and it seals. It pulls a very good vacuum to degass bubbles out of resin or plastistone (or whatever).

I couldn't get my square mold into the pot so made a cradle to hold it sideways. Then the square mold slipped right in. Makes a nice setup.

I'm not sure you are better off spending a lot when you can fix the Harbor Freight to eliminate any problems for a small amount of money (1/4" fittings and a gauge if you want a failsafe system). I did it in less than a couple hours, not counting planning what to do and trips to the hardware store.

 

[EdGallop41]

I to am looking to purchase my first pressure pot. After reading and viewing some of the responses to the Harbor Freight model, I have at least made a decision that my life is more important and do not want to deal with a pot failure under high pressure.

I bought a Harbor Freight pot and eliminated the poor quality problems. After replacing the fitting that goes into the lid, and the "T" fitting for the regulator, it is as safe as any pot in my opinion. I also took the paint pipe out and added a pressure gauge in it's place to make sure the two readings match. It probably was not necessary but it does read actual pressure in the tank. The other gauge is on the regulator and reads the pressure going into the tank.

The fittings I replaced were of poor quality but after I replaced them the pot is as safe as any. I pump up to 60 lbs. and would be confident with a bit more if it were necessary (but it isn't). I also made it into a Vacuum pot. I bought a thick 1/2" x 12" x 12" Plexiglass like sheet and also a sheet of 1/4" rubber at Amazon. I cut out a circle in the rubber to see in the pot, glued them together. I drilled a hole to add a "T" fitting for a vacuum gauge and a short hose attached and hooked up my Harbor Freight vacuum pump. All I do it lay the 1' square plastic on the pot and it seals itself. If not all I to is tap it while the pump runs and it seals. It pulls a very good vacuum to degass bubbles out of resin or plastistone (or whatever).

I couldn't get my square mold into the pot so made a cradle to hold it sideways. Then the square mold slipped right in. Makes a nice setup.

I'm not sure you are better off spending a lot when you can fix the Harbor Freight to eliminate any problems for a small amount of money (1/4" fittings and a gauge if you want a failsafe system). I did it in less than a couple hours, not counting planning what to do and trips to the hardware store.

I forgot to add that I put 1/4" ball valves for the intake. Also replaced the unreliable pressure release valve. If you regulate the pump to the required pressure you will not need the release valve on the pot. Both the pump and pot will have a regulator.

I eventually put a one way air valve on the intake (replacing the ball valve) so I could prevent pressure from leaking out the line to the pump. I then put a ball valve where the pressure relief valve was to release the pressure from the pot. I always watch the pressure build up to 55 or 60psi and then remove the pump hose and walk away. If your pressure doesn't hold simply clean the gasket. If you use soapy water and apply with a brush to the fittings you can find a leak if it exist. Turn the pot upside down to check the lid gasket for leaks. I have tiny gasket leak but its not severe enough to be of concern. It will hold long enough to degass completely, even a lot longer.

 

[Mrs. Charlie_W]

I would buy the Devilbiss hands down, no questions asked. It is the only US made pot on your list and will most likely be ASME certified.

Curtis just talked about this at MAPG and it was very informative! Please look at his site because he has some valuable information. I so appreciate his candor. Sometime cheaper isn't always better in the long run.

 

[jttheclockman]

It all depends on what you are doing with it. No reason to go over 45lbs on pressure for what I do. Well below limits on that unit. It is good you change some of the weak points but the most weak point is point of closure. On the more expensive pots you will notice a distinct lip on the edge of the lid. This helps keep those clamps from slipping off and that is what will cause disaster. Proper tightening and even tightening will help and observe as you add pressure. Never go above 80lbs on those units and I would not even come anywhere near that either. As I said I cast alot in one of those and always keep around 45 lbs.

 

[TonyL]

One of our members graciously tested some of the HF's structurally qualities about a year or more ago by engaging an independent lab. In the spirit of learning and facilitating a decision, one may benefit from consulting the results.

 

[jttheclockman]

One of our members graciously tested some of the HF's structurally qualities about a year or more ago by engaging an independent lab. In the spirit of learning and facilitating a decision, one may benefit from consulting the results.

Do you know where to find those results???

 

[TonyL]

I remember that he posted them here.

 

[jttheclockman]

I remember that he posted them here.

Tony is this the thread you are referring to??? Someone posted this today.


www.penturners.org/forum/f97/hf-pressure-pot-108145/

 

[TonyL]

No JT; it was a post will a pretty comprehensive lab test results.

 

[jttheclockman]

No JT; it was a post will a pretty comprehensive lab test results.

Here you go Tony. It was an easy search to find. Some valuable info but nothing earth shattering that we all know already .


www.penturners.org/forum/f159/possibly-better-alternative-hf-pressure-pot-124294/


It has been brought up in that thread and is quite true from all that I read I have never heard of a catastrophic incident other than Curtis who we all know mishandled the pot which he even stated. There are far more of the HF pots being used in our hobby than the more expensive ones and you would think we would have heard of more instances of disasters.

I do believe for what we do or at least the type casting I do the HF pot is suitable. 45 to 50lbs of pressure is all I use and do not leave the pot energized for more than 2 to 3 hours and never ever leave the compressor hooked to it. I have replaced the fittings and my pot holds pressure for the time stated.

The lid and the clamps are the weak links and if inspected and properly installed they should last a long time. But as with all tools inspection and the knowledge of knowing your tools plays a huge role in successful work practices.

Using pressure for casting or even for nailing or even painting is just another tool we need to understand when we use it. Work safe and read all instructions and head all warnings. The topic of using HF pots has been discussed in length here and I believe it will continue as we get more and more Newbies joining and wanting to try their hand at casting. Lots of good info on this site so take advantage of it and get informed. Take care.

 

[TonyL]

Yes, that is it. I wasn't looking for it, but I thought the OP may benefit from reading it because the post solicited help making a decision. I know ZERO about most things and not an expert on anything, therefore I have no business sharing anything but my own personal and limited experience. Thank you for finding it. I hope it helps the OP draw his own conclusions as to what PP suits him. Good find...I searched, but could find it. Have a great one!

 

[BSea]

I forgot to add that I put 1/4" ball valves for the intake. Also replaced the unreliable pressure release valve. If you regulate the pump to the required pressure you will not need the release valve on the pot. Both the pump and pot will have a regulator.

You can do what you want, but a pressure relief valve is always going to be on my pot. After having a regulator go bad, I was really glad my pressure relief valve popped a few times to let me know something was wrong. I know you have 2 regulators, but I wonder how often you look at the 1 closest to the compressor. I did upgrade my fittings also, and mine is a Sears pot before they quit making/branding their own. My PRV is a 75psi valve. I normally cast at about 60 to 65.

EDIT: My bad regulator didn't just fail completely, it would slowly go beyond the set limit. It took about 15 seconds after I put pressure to the pot for the valve to pop. From how you describe your process, It seems like a good way to do things. But a PRV just seems like cheap insurance.