Pressure Pot Modifications Question(s)

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SALKBL

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Jan 24, 2019
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I am a new member and new to pen turning. I have turned one(1) slimline pen and that’s it! I am relatively pleased with it, but realize it is no great piece of work.
I just joined the IAP and this is my first post. I have a question (maybe more than one).
I am considering trying to mold my own pen blanks. I have watched several videos on how to go about modifying a Harbor Freight paint pressure pot for pen blank casting. Putting aside a general distrust in the quality of HF tools, I cannot figure out why everyone (at least the ones I watched) made so many modifications. I understand the removal of the paint uptake pipe. Then folks remove the pressure relief valve and later reinstalled it on the output side of the pressure regulator. [In one video, the person boogered the threads and had to re-tap the hole. In another, the valve assembly was destroyed in the removal operation]. What’s wrong with leaving it where it is? For almost all the modifications, I see a shopping list of elbows, reducers, couplings, nipples, etc. It looks to me like all I need is a cap for the air outlet on the pressure regulator, a cap for the paint outlet, a ¼” ball valve and air quick-connect on the inlet to the pressure regulator. What am I missing here?
I would be grateful for any advice and/or clarifications of my misunderstanding of the need for many changes. I hope to be a contributor to this organization and share what I can.
SALKBL
 
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MDWine

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1. welcome aboard, you'll find this is a great lil' forum!
2. Pressure pot, I built one, changed some of the things along with some of those suggestions, some I did not. It holds pressure very well, and works just fine. IMHO, if it doesn't NEED to be changed, and/or you don't want to change it... don't!

I think most of those suggestions are for "convenience"... I did replace the valve for a better quality, and pointed it in a different direction for convenience.

I wouldn't change it for changes sake. The most important thing is that it holds the pressure reliable without exploding! (j/k.. kinda)
 

magpens

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Hi Steve !! . Welcome to IAP !! . Thanks for starting this tread about Pressure Pots. . I will follow with interest.

You will get more satisfaction from your early days of pen turning if you save the slimlines for later. . In particular, give the 30 Caliber Bolt Action pen kit a try. . It is an easier start for beginners, although the kit is considerably more expensive than the slimline. . Also good is a Sierra, or Wall Street ... made with straight sides at first and then, after you have done a few, go for slightly bulged sides.

You will find everything you want for penturning at ExoticBlanks.com. . You will get fast shipping and outstanding service, plus you can rely on the advice you are freely offered by the proprietors who will talk to you by phone on any issues you may have ... they have the greatest selection of stuff and have the greatest experience with pens of anyone I know.
 

Dehn0045

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You are correct. I think a lot of guys will swap out the pressure relief valve with one that is slightly higher quality - these cheapies are notorious for relieving early (or late). As to the quality of the HF tanks, it is pretty clear that they're not the best. There are plenty of threads on IAP the discuss the details, so won't get too far into it here. A couple of things to watch for are: don't modify the clamping devices or lid, watch the clamps and lid for damage and stop using if you see any, be cautious about pressure "ratings" they don't really mean much for the HF or similar tanks - the higher you go the more risk of failure, lastly stay out of the 'line of fire" when pressuring up (if it blows and you are behind a barrier, you stand a better chance of avoiding injury).

Welcome to IAP!
 

More4dan

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You are correct. I think a lot of guys will swap out the pressure relief valve with one that is slightly higher quality - these cheapies are notorious for relieving early (or late). As to the quality of the HF tanks, it is pretty clear that they're not the best. There are plenty of threads on IAP the discuss the details, so won't get too far into it here. A couple of things to watch for are: don't modify the clamping devices or lid, watch the clamps and lid for damage and stop using if you see any, be cautious about pressure "ratings" they don't really mean much for the HF or similar tanks - the higher you go the more risk of failure, lastly stay out of the 'line of fire" when pressuring up (if it blows and you are behind a barrier, you stand a better chance of avoiding injury).

Welcome to IAP!


Best to first test with water, it won’t kill you like compressed gas will. I definitely changed out the pressure relief vale to a better quality one. It is all that is between you and an ugly explosion if you over pressure the pot or your regulator fails.

Danny


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leehljp

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Welcome Steve. Enjoy the fun here at IAP!


As to your question as to why so many modifications - I have learned through watching, listening and studying people is that each one sees things though his own minds eye. Some of the modifications, I just did not understand but it worked for them, and that was the way they saw it.

I have one inlet/outlet on mine with a T on top with one side being vacuum and the other side being pressure and each able to be turned on or off as needed. I did not use the fittings that came with it, instead upgrading to known/better fittings and equipment.

Another often stated truth here Ask 10 people and get 12 different answers that work. What that means is there are a lot of variables as to what works . . . and don't work. :biggrin:
 

Dr_N

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Welcome Steve. Enjoy the fun here at IAP!





As to your question as to why so many modifications - I have learned through watching, listening and studying people is that each one sees things though his own minds eye. Some of the modifications, I just did not understand but it worked for them, and that was the way they saw it.



I have one inlet/outlet on mine with a T on top with one side being vacuum and the other side being pressure and each able to be turned on or off as needed. I did not use the fittings that came with it, instead upgrading to known/better fittings and equipment.



Another often stated truth here Ask 10 people and get 12 different answers that work. What that means is there are a lot of variables as to what works . . . and don't work.
I'm preparing to set up my pressure pot and have wondered about a pressure/vacuum set up. How does your set up work? I like the idea of being able to do either in the same tank.
 

MRDucks2

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I have 2 pressure pots. The first is a 5 gallon I set up for pressure with everything ready to add vacuum. Added a regulator to the pot itself and added an elbow to diffuse air from blowing on liquid resin inside the pot. Upgrade the valves, gauges and set it up to run multiple pots off one air line the future. All in all, about $100 in brass fittings.

Then I bought a used 2.5 gallon pot with 1 valve and a gauge. Also acquired a small vacuum chamber at the same time.

I use them all equally. Sometimes both pressure pots at once. Never hooked them up parallel and haven’t yet used the big one for vacuum.

Both the big pot with all the valves and fitting and regulators and gauges and the small pot with 1 fitting and a cheap Gauge work equally well.


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chartle

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Some people have posted that the pressure regulator has leaked. Its not needed and its not even really designed for this use.

Its to regulate the pressure of the continuous air flow going into the pot as paint as pushed out and it's not needed for just filling the pot.

Some site safety but other stuff you pressurize like your tires don't have a regulator. I don't even regulate the air coming out of the compressor, its cranked all the way up. Just like if I'm filling my tires.
 

leehljp

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Welcome Steve.
I have one inlet/outlet on mine with a T on top with one side being vacuum and the other side being pressure and each able to be turned on or off as needed. I did not use the fittings that came with it, instead upgrading to known/better fittings and equipment.
]
I'm preparing to set up my pressure pot and have wondered about a pressure/vacuum set up. How does your set up work? I like the idea of being able to do either in the same tank.
I have a T on mine. On both sides (R&L) of the T, I have a cutoff valve; Next to the cutoff valves, on one side I have a vacuum gauge; ON the other side of the T next to the cutoff valve I have a pressure gauge. On both sides, to the outside of the gauge, I have another cutoff valve; then on each side of the outside cutoff valves, I have quick release fittings for vacuum or pressure.

THIS IS THE SEQUENCE THAT I USE:

QR FITTINGS\CutOff valve\Vacuum Gauge\CutOff Valve | T |CutOff Valve/Pressure gauge/CutOff Valve/QR Fittings
(QR=Quick Release)

With this setup I can isolate either side and under pressure OR under a vacuum, with the outer cutoff valves off I can see how much pressure or vacuum I have at all times. I tested mine and tested mine until I had no leaks and can hold a vacuum or pressure for days without a leak. It took me about 3 days to isolate and stop all leaks. BTW, I unhook my vacuum or pressure after getting it to where I want it and let the cutoff valves do their work in holding the pressure or vac.

I used a good bit of teflon tape on the fittings.

Some people simplify this by getting a combination vacuum/pressure gauge. It does simplify things considerably but in my first pressure tank, I could not get a good gauge. So the most simple for me was two gauges.
 
Last edited:

More4dan

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Some people have posted that the pressure regulator has leaked. Its not needed and its not even really designed for this use.

Its to regulate the pressure of the continuous air flow going into the pot as paint as pushed out and it's not needed for just filling the pot.

Some site safety but other stuff you pressurize like your tires don't have a regulator. I don't even regulate the air coming out of the compressor, its cranked all the way up. Just like if I'm filling my tires.


I incorporated a pressure regulator to ensure I hold pressure in case of a tiny leak where I’m using Liquid Diamonds that needs to be under pressure for 24 hours. If the pot holds pressure this long w/o make up pressure it will still act as a safety to keep me from over pressuring the pot.

Danny


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chartle

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Mar 13, 2015
Messages
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Pgh, PA
Some people have posted that the pressure regulator has leaked. Its not needed and its not even really designed for this use.

Its to regulate the pressure of the continuous air flow going into the pot as paint as pushed out and it's not needed for just filling the pot.

Some site safety but other stuff you pressurize like your tires don't have a regulator. I don't even regulate the air coming out of the compressor, its cranked all the way up. Just like if I'm filling my tires.


I incorporated a pressure regulator to ensure I hold pressure in case of a tiny leak where I’m using Liquid Diamonds that needs to be under pressure for 24 hours. If the pot holds pressure this long w/o make up pressure it will still act as a safety to keep me from over pressuring the pot.

Danny


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I have done this but just use the regulator on the compressor. I dial it down and keep the fill valve open. I also turnoff it off. There is plenty of reserve in the small pancake tank. Last time I did this overnight it still has some reserve left.

I do this so the compressor doesn't kick on in the middle of the night. I cast in my basement and you can hear the compressor all through the house.
 

Dr_N

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St. Charles, MO
Welcome Steve.
I have one inlet/outlet on mine with a T on top with one side being vacuum and the other side being pressure and each able to be turned on or off as needed. I did not use the fittings that came with it, instead upgrading to known/better fittings and equipment.
]
I'm preparing to set up my pressure pot and have wondered about a pressure/vacuum set up. How does your set up work? I like the idea of being able to do either in the same tank.
I have a T on mine. On both sides (R&L) of the T, I have a cutoff valve; Next to the cutoff valves, on one side I have a vacuum gauge; ON the other side of the T next to the cutoff valve I have a pressure gauge. On both sides, to the outside of the gauge, I have another cutoff valve; then on each side of the outside cutoff valves, I have quick release fittings for vacuum or pressure.

THIS IS THE SEQUENCE THAT I USE:

QR FITTINGS\CutOff valve\Vacuum Gauge\CutOff Valve | T |CutOff Valve/Pressure gauge/CutOff Valve/QR Fittings
(QR=Quick Release)

With this setup I can isolate either side and under pressure OR under a vacuum, with the outer cutoff valves off I can see how much pressure or vacuum I have at all times. I tested mine and tested mine until I had no leaks and can hold a vacuum or pressure for days without a leak. It took me about 3 days to isolate and stop all leaks. BTW, I unhook my vacuum or pressure after getting it to where I want it and let the cutoff valves do their work in holding the pressure or vac.

I used a good bit of teflon tape on the fittings.

Some people simplify this by getting a combination vacuum/pressure gauge. It does simplify things considerably but in my first pressure tank, I could not get a good gauge. So the most simple for me was two gauges.
Thank you! That sounds like a great setup, and it's nice to know someone has done it and had success. I think I have a new item on the to do list for this weekend or next now!
 

leehljp

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Thank you! That sounds like a great setup, and it's nice to know someone has done it and had success. I think I have a new item on the to do list for this weekend or next now!
One thing to watch for: get a good solid T and good solid fittings. Get 3/8 fittings all the way if possible - because there is weight and leverage on both sides of the T. 3/8s will allow them to be beefier and withstand the unexpected bump that might damage 1/4 inch fittings. 5/16 might do, but I preferred the beefier ones.

I am not an engineer and don't know how to calculate the numbers or forces on fittings, so I tend to always overbuild, which doesn't hurt anything but my wallet.
 

SALKBL

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Thank you to all who have so generously responded with their wisdom and advice. Many configurations have been tried and all seem to work. I was particularly struck by the notion that I really do’t need the pressure regulator, that the pot will work easily as well as a vacuum chamber, and the idea of an initial pressure test with the tank full of water. Again, many thanks to all.
 

Curly

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Our pot is of unknown origin that I got decades ago. It didn't have a regulator on it but I did put one of a short hose with quick disconnects on it. The reason being the air compressor (5hp, 80 gal) system I have is set for 90 PSI so I can use it for air grinders, sanders, brad nailers etc. With the pot having its own regulator there was no chance of accidental overpressure of the pot and I can still use the air tools while the pot is in use by Marla. While you may not "need" the regulator it is a good safety measure to have in place.
 

More4dan

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Our pot is of unknown origin that I got decades ago. It didn't have a regulator on it but I did put one of a short hose with quick disconnects on it. The reason being the air compressor (5hp, 80 gal) system I have is set for 90 PSI so I can use it for air grinders, sanders, brad nailers etc. With the pot having its own regulator there was no chance of accidental overpressure of the pot and I can still use the air tools while the pot is in use by Marla. While you may not "need" the regulator it is a good safety measure to have in place.


The regulator is a good way to help us from over pressurizing but the only real safety device is the pressure relief valve. Every vessel that holds pressure needs to have a tested and working relief valve without a valve between it and the pot. Regulators can and do fail open allowing over pressurization.

Off my safety soapbox.

Danny


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Curly

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I'm not telling anyone to bypass, disable, to remove the safety valve in any way shape or form.

I do think it is unwise to rely on the compressor regulator especially if there is any possibility of multiple users. It only take one time plugging a pot into the compressor and applying 90+psi to it blowing the resin all over the pot to make that apparent. John did it recently so it can happen to anyone. http://www.penturners.org/forum/f43/tinting-liquid-diamonds-158342/#post2010814

You can do what you feel is safe but I want to isolate the casting system from the rest of the compressed air system because it is used at much lower pressures than the main system. Not everyone uses the air for one thing only. Besides I don't want to be sanding something in the shop when Marla needs to turn the air way down to cast in the garage. I sit there staring at my sander wondering what happened. :confused:
 

leehljp

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More4dan

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I'm not telling anyone to bypass, disable, to remove the safety valve in any way shape or form.



I do think it is unwise to rely on the compressor regulator especially if there is any possibility of multiple users. It only take one time plugging a pot into the compressor and applying 90+psi to it blowing the resin all over the pot to make that apparent. John did it recently so it can happen to anyone. http://www.penturners.org/forum/f43/tinting-liquid-diamonds-158342/#post2010814



You can do what you feel is safe but I want to isolate the casting system from the rest of the compressed air system because it is used at much lower pressures than the main system. Not everyone uses the air for one thing only. Besides I don't want to be sanding something in the shop when Marla needs to turn the air way down to cast in the garage. I sit there staring at my sander wondering what happened. :confused:


I did the same thing. Regulator on the pot set and locked with an ASME approved relief valve. I do have a small leak I’ve not tracked down and the regulator keeps the pressure constant.


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