HF pressure pot for vacuum?

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gketell

gketell

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Can the Harbor Freight pressure pot be used for vacuum too? I would guess so since it can handle the pressure and all its curves would make it even stronger for vacuum but I am just guessing.

Does anyone know?

GK
 
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I use the HF pressure paint pot for both vacuum and pressure and have had no problems.
Do a good turn daily!
Don
Originally posted by gketell
<br />Can the Harbor Freight pressure pot be used for vacuum too? I would guess so since it can handle the pressure and all its curves would make it even stronger for vacuum but I am just guessing.

Does anyone know?

GK
Click to expand...
 
I sure hope 3/4" plexi is stronger than 1/2" corian. After my corian failure I calculated the load on the corian lid to be somewhere close to 1600 lbs(should have done it before the failure). That's why I started using the pot lid. I had watched what the resin was doing and no longer needed to watch it. Be safe....
Do a good turn daily!
Don
Originally posted by Russb
<br />I use mine for both but replaced the original lid with 3/4" plexi so I could see what was happening when using vacuum.
Click to expand...
 
Which pressure pot are we talking about? The one for painting, or the one that looks like it belongs in the kitchen?
 
This one: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93119 for paint (originally, now for pen making)...

GK
 
what are you guys using to create the vacuum. I imagine you are just using an air compressor for the pressure casting, but what about the vacuum casting.

Thanks

Scott
 
Don, I was using 3/8 plexi I had on hand but to watch it flex when applying vacuum I quit using it. Probably after seeing your corian failure. I compared plexi and lexan for characteristics and decided on plexi. Price is also a big factor. I get no flex with the plexi and have had days of vacuum on the plexi and has not failed. No idea of how long you had used your corian.

Scott, most of us are using Gast brand vacuum pumps. Some purchased through American Surplus. They sell a 220v unit. Mine was purchased through Grainger, full price, ouch. Today I would watch Ebay for a good unit.

200612192106_Vacuum%20Setup,%20web.jpg
 
I'm using a vacuum pump used by air conditioner service technicians which I picked up (new) at a fleamarket for $40. A lucky but great find. It was new and in the box and probably stolen. There is a picture of the pump and the pressure pot and the failed corian lid in my snake skin tutorial.
Do a good turn daily!
Don
Originally posted by seht
<br />what are you guys using to create the vacuum. I imagine you are just using an air compressor for the pressure casting, but what about the vacuum casting.

Thanks

Scott
Click to expand...
 
Originally posted by Russb
<br />Don, I was using 3/8 plexi I had on hand but to watch it flex when applying vacuum I quit using it. Probably after seeing your corian failure. I compared plexi and lexan for characteristics and decided on plexi. Price is also a big factor. I get no flex with the plexi and have had days of vacuum on the plexi and has not failed. No idea of how long you had used your corian.

Scott, most of us are using Gast brand vacuum pumps. Some purchased through American Surplus. They sell a 220v unit. Mine was purchased through Grainger, full price, ouch. Today I would watch Ebay for a good unit.
200612192106_Vacuum%20Setup,%20web.jpg
Click to expand...

I don't know who"most of us" are, but I have been using this from Harbor freight for 2 years.
What at least ONE of us uses.[^]
 
I used the corian lid for about 8 or 10 times before it failed. After watching the resin in it large glass container and it never bubbled over or even got close, I'm comfortable in just using the lid that came with the pressure pot. If I were stabilizing I would make a clear lid like you did. Aren't we having fun!!
Do a good turn daily!
Don
Originally posted by Russb
<br />Don, I was using 3/8 plexi I had on hand but to watch it flex when applying vacuum I quit using it. Probably after seeing your corian failure. I compared plexi and lexan for characteristics and decided on plexi. Price is also a big factor. I get no flex with the plexi and have had days of vacuum on the plexi and has not failed. No idea of how long you had used your corian.
Click to expand...
 
Originally posted by Russb
<br />I guess "most of us" is me.....
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must admit a d Ghast vac would be more convenient, but the Venturi for $10.00 does the job.
If I were to upgrade I would adapt it to an automatic one from Joes Workshop like the home made ones that people who use veneers use.
The conversion is about $25.00.
 
Originally posted by gketell
<br />Eagle, can you expand on that for us newbies? "Joe's workshop"?

Thanks!
GK
Click to expand...
Mebad, it took a minute for me to find it on Google.
Rummage around the site.
He has 2 plans for a vacuum pump that is said to be as good as a ghast at a fraction of the price and the best part is you get the satisfaction of making it yourself.
JOe woodworker
 
well that vacuum pump certainly is cheaper than buying an air compressor, and from reading another post, vacuum casting is safer than pressure casting.

Sounds like a deal.

Is there any converting that needs to be done or will it hook right up to the HF pressure pot?

Thanks

Scott
 
Eagle,
Would you give us (or me) a brief rundown on how this HF vacuum thing works. I know it is a venturi system and uses a compressor, but could you tell us exactly how much air is required (pressure and or volume)...must it be a steady flow of air at a particular pressure....there are no instructions in the box and i've heard several takes on it. you use one so could you be our reference source on them. Thanks.
Do a good turn daily!
Don

Originally posted by ctEaglesc
I don't know who"most of us" are, but I have been using this from Harbor freight for 2 years.
What at least ONE of us uses.[^]
Click to expand...
 
Eagle,
Would you give us (or me) a brief rundown on how this HF vacuum thing works.
Click to expand...

The first thing necessary is to change a fitting(easy) to a pipe thread on the suction side.
I added a ball valve on the supply side(from the compressor).
I installed another ball valve and a gauge on the vacuum side(why does the word vacuum need two "U's"?)
Open up the valve on the Vac. side(that solved the problem of the "U's)
OPen up the valve on the supply side and keep an eye on the gague to start and then the chamber.
If the needle shoots up fast there is a good vac.
The contents of the container will tell you when to shut off the vac. valve.
It is necessary to monitor both valves at the same time but it is no big deal.
I can do it while smoking a cigarette at the same time.
It sometimes feels like you are patting your head and stomach at the same time but I have gotten used to it.
 
Eagle, when using the HF vac pump like you describe, does it use a constant 4.2 CFM to keep the vac? Or are you closing the valves and holding the vac in the tank with the pump shut down?

Just wondering, I only have a pancake compressor and 4.2 is too much draw for more the a few minutes.

Scott
 
I recently bought the HF Venturi on the advice of Eagle. It works well and is easy to use. Like Eagle metioned, the fittings needed to be changed at the tune of about 4 bucks. The pancake you have should run it fine. Once under the vacuum, I removed my pot and it holds fine. Remember though that quick disconnect will not work under a vacuum. They are designed for pressure. As long as you shutoff valve is before the quick connect (From the pot), you will be fine.

Cheers,

Fangar
 
Fangar, Since Eagle is not here or no email address do you have a picture of your setup[?]. I recently purchased the hf venturri but only have a small compressor also and it pulls fine at first but then the compressor does not keep up enough pressure. Suggestions or pics of yours or Eagles setup would be greatly appreciated.[:p]

Bob
 
Is there a cood pictorial out there that shows the setup and use of one of these vacuum systems? I get the vacuum and the pressure pot but how do you prepare the materials that go in the pot? what do you use to cast the particular objects in?
 
I can answer your questions (I think...although I don't use the venturi vacuum pump from HF but I use a real pump like HVAC guys use). I'm not sure what you are asking. How do you prepare the materials? What do you use to cast the particular objects in? Are you asking about resin or molds? Ask your questions again and be a little more specific. I'm sure several of us will offer up some answers. Have you read my turotial on casting snake skin blanks? Try again and we'll get them answered and have you casting your blanks in no time.
do a good turn daily!
Don
Originally posted by latech15
<br />Is there a cood pictorial out there that shows the setup and use of one of these vacuum systems? I get the vacuum and the pressure pot but how do you prepare the materials that go in the pot? what do you use to cast the particular objects in?
Click to expand...
 
Here comes another [:o)][:I] question. Ready? I read least night the tutorials on the 2005 library about PR casting and there is no metion about pressure or vacums to cast PR. I'm already making a list of things I need to casting PR and I keep on seeing this pressure/vacum topics. What am I missing?
BTW I do have a 30 Gal compresor as well as a pancake and not that I have all kinds of $$$ to spend but when it comes to this I get it. So what is the ideal set up (ideal without going extravagant money wise) pressure or vacum and why do I need any to start with? I am really craving [:p] to start doing it but I'm trully confused [:(].
Thanks
 
I started casting PR colored blanks a few months ago and can say that the short answer is you may or may not need pressure/vacuum if that's all you're going to do(in other words, you're not going to be "embedding" anything in the PR, like snake skins). I found that no matter how careful I am at mixing and pouring, I will occasionally have very tiny bubbles in the finished product(even after gentle agitation), and invariably, one or more will end up on the surface of the finished pen (it shows up as a small "crater" on the surface). For me, pressure was the solution.

I got the HF pressure pot and added a few fittings, caps, and valves (so it will retain the pressure). Now when I cast, I put the mold in the pot just before it reaches the gel stage and pressurize to about 45ppi. I hold it there for about a hour or so before removing from the pot. What the pressure does is squeeze the bubbles in the resin to a microscopic size. When the resin hardens and you release the pressure, they cannot expand back to their origin size thus, for all practical purposes, eliminating them.

You could also put it under a vacuum to degas the resin (i.e. draw the bubbles out), but so far I have not found that to be necessary. Pressure does the trick.
 
Lee. Thanks for the explanation. I am dying to do embedding, so it seems that the help of pressure of vacum will be needed.
Do you need two different set ups for either pressure and vacum?
Where can I find a detail of what I need and how to do the jigs to either pressurize or vacum the PR?
Thanks for the info
 
Hello,

I would like to try my hand at stabilizing and casting soem of my own blanks. I have an idea on how I might do this, please let me know how far out in left field I am with my thinking. I am thinking of buying one of the HF paint pots, buy 2 pieces of 1/2" plexiglass, drill a small home and put a brake bleeder screw in one top, and a rubber valve stem in the other. I would then create vacuum with one of HF's hand operated brake bleeders for stabilizing, and use a tire pump to create pressure for casting. Would this work?
 
Originally posted by heineda
<br />Hello,
I would then create vacuum with one of HF's hand operated brake bleeders for stabilizing, and use a tire pump to create pressure for casting. Would this work?
Click to expand...

IF all the fixtures were air tight, no leakage and a good one way valve, it would work or more precisely, it CAN be made to work. But if you take the time to search and look back over the last two years of vac and pressure, you will find that most of those that did that - only did it a few times with the hand vac. They soon realized that there has to be a faster and better way. The HF hand vacs will require a huge amount of hand pumping to lower the pressure in the HF tank. Brake line hand vacs were not designed to remove that volume of air.

The original readings that I remember - were from using the hand vac on much smaller containers, and they were tiring. It worked fine, but it is just that the muscle required to use hand pump was quite tiring, IIRC.
 
where is Fangar or Eagle?
still wondering about pics for setup.
"Fangar, Since Eagle is not here or no email address do you have a picture of your setup. I recently purchased the hf venturri but only have a small compressor also and it pulls fine at first but then the compressor does not keep up enough pressure. Suggestions or pics of yours or Eagles setup would be greatly appreciated."
 
I am about to purchase the pressure paint tank at HF (on sale for $39.99). For those folks that are using it, did you change the pressure gauge? I read in a previuos post the gauge needs to be replaced to measure the vacuum.

Also, I have read it is critical to get to 29" of mercury at sea level for the vacuum to be effective. I have also read that some folks are using the Venturi pump from HF. But it states on the HF catalog page that it can pull to 28.3" - Those that are using this setup (Venturi pump) - is it effective? I sure would like to only have to pay $15.99 and use my air compressor versus paying $250 for a Robinair pump.

Thanks for any help in advance.

Rick
 
You will need to replace the gage to read vacuum. Combo gages are available that read both vacuum and pressure if you use the same lid for both.

http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=4512&PARTPG=N2DRVSH&PMT4NO=20128639&PMITEM=56469059&PMCTLG=00&PMT4TP=*LTIP
 
Originally posted by rickbw
<br />

Also, I have read it is critical to get to 29" of mercury at sea level for the vacuum to be effective.
Click to expand...

Be careful using 29" of Mercury on the pressure pot. I don't know what the diameter of the pot is but let's assume it is 12". At 29" hg you will have a force of over 1600 pounds of pressure on the lid of the pot. That is a dangerous amount of force. It's best to put a bleeder valve on the tank to keep the forces down. At 5" hg the force on the lid is down to about 275 pounds if it is a 12" lid.
 
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