# Stabilizing blanks



## Quickstep (Apr 10, 2012)

I'm going to have a go at stabilizing a turning blank using Cactus Juice. 

I've got a rig using a small pressure cooker and a hand vacuum pump. With the pressure cooker empty, I was able to achieve 22Hg vacuum using the hand pump. I'm wondering if that's enough to fully saturate the blank which is about 1-1/2" thick. The Harbor Freight Venturi pump claims 28Hg, but that sounds optimistic. I'm not eager to spend over $100 for a "real" vacuum pump since this may very well be a one-shot deal. 

I've never done any stabilizing before, so any guidance is appreciated.


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## epicfail48 (Mar 27, 2014)

Speaking from experience, skip the hand pump. It is not worth the cramps to keep pumping that thing... You can find a decent vacuum pump on eBay for ~$30, grab one of those. Even if it ends up being a one-off stabilization for you, its still not a chunk of change to loose


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## 44260 (Aug 29, 2013)

Watch this video

https://www.youtube.com/watch?v=qLdfR8g59gY


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## Bill Boehme (Feb 9, 2014)

Quickstep said:


> I'm going to have a go at stabilizing a turning blank using Cactus Juice.
> 
> I've got a rig using a small pressure cooker and a hand vacuum pump. With the pressure cooker empty, I was able to achieve 22Hg vacuum using the hand pump. I'm wondering if that's enough to fully saturate the blank which is about 1-1/2" thick. The Harbor Freight Venturi pump claims 28Hg, but that sounds optimistic. I'm not eager to spend over $100 for a "real" vacuum pump since this may very well be a one-shot deal.
> 
> I've never done any stabilizing before, so any guidance is appreciated.



No, using a hand vacuum test is far from being adequate. According to Curtis Seebeck when I attended his program at SWAT a couple years ago, your vacuum pump needs to be able to pull a hard vacuum, meaning over 29.5 inches of mercury at standard day conditions (mean sea level altitude and 59° F temperature). If you are at higher altitudes then pull a vacuum that is within about a half inch of mercury of current barometric pressure.

The problem with your pressure cooker is that you need to be able to see what is going on inside of the chamber. You could use a half inch thick sheet of Lucite for the top and a tight sealing silicone rubber gasket. Besides your hose fittings, you will need a bleed valve to very gradually increase the vacuum level. You need to watch this very closely or else the foaming will get out of control and sucked into your vacuum pump. Your pump doesn't have to be a high open-port flow rate ... probably something like two CFM is more than sufficient. Even though the HF venturi pump is cheap, you are just wasting money without a real vacuum pump. HF has some real vacuum pumps for less than about $150 if my memory is correct. Don't forget that the Cactus Juice isn't cheap and you will need a large enough volume to completely submerge the blanks PLUS additional Cactus Juice to completely fill the blank and still ensure that the blank completely submerged. Finally, don't forget that you need an oven ... NOT your kitchen oven, but a toaster oven will work if it has good temperature control and large enough to hold the pieces. Either a meat cooking thermometer or a digital oven thermometer is essential. Don't be too surprised if your initial cast outlay is at least $250.

What is it that you want to do?


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## epicfail48 (Mar 27, 2014)

Bill Boehme said:


> Don't be too surprised if your initial cast outlay is at least $250.


Okay, I have to disagree with that. My I itial setup cost was less than $100, probably closer to $70 if I were to add everything up


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## Quickstep (Apr 10, 2012)

Bill Boehme said:


> Finally, don't forget that you need an oven ... NOT your kitchen oven, but a toaster oven will work if it has good temperature control. What is it that you want to do?


I'm hoping to stabilize that punky piece of spalted wood that I posted about earlier. It gets much more solid past the surface and I haven't been able to find another piece like it, so I figure what the hell...

I sort of thought that since the hand pump creates vacuum slowly that the foaming might not be as much of an issue, but I also know that 29Hg ain't happening with the hand pump. Looks like 22Hg is about the max. 

I figure this is a bit of a long shot, so not eager to dump a lot of cash into it. Could the same vacuum pump be used for vacuum bagging? That might spur me to reach deeper into my pocket. 

Tell me more about the oven and the issue with using a kitchen oven. I have a convection oven that's very even and accurate (and a very understanding wife .


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## epicfail48 (Mar 27, 2014)

Quickstep said:


> I'm hoping to stabilize that punky piece of spalted wood that I posted about earlier. It gets much more solid past the surface and I haven't been able to find another piece like it, so I figure what the hell...
> 
> I sort of thought that since the hand pump creates vacuum slowly that the foaming might not be as much of an issue, but I also know that 29Hg ain't happening with the hand pump. Looks like 22Hg is about the max.
> 
> ...


The hand pump is entirely useless for anything beyond bleeding brakes. Seriously, look into a pump on eBay. Mine was $30 with $10 shipping if memory serves. As far as the issue with the kitchen oven, the fumes from the resin aren't exactly food safe, or plesamt smelling


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## Bill Boehme (Feb 9, 2014)

epicfail48 said:


> Okay, I have to disagree with that. My I itial setup cost was less than $100, probably closer to $70 if I were to add everything up


I suspect that this isn't something that everybody would be able to do for $70. You got a super deal on the vacuum pump. How about the vacuum chamber? I'm not convinced that everybody would be able to do this for $70. At one time several years ago I believe that Curtis only sold the Cactus Juice in gallon jugs for a bit under $100. I see that it is now available in smaller quantities, but you still need enough to totally submerge the piece plus an amount that is equal to the volume of the wood if it is very punky. If you need to buy a vacuum pump, it is best to get a piston type that can pull a hard vacuum as opposed to the rotary vane type that are best for vacuum chucking that pull a softer vacuum, but have a high flow capacity. So, while you were able to do this for $70 for your needs, some people would have to pay much more. I'm a good scrounger so I also might be able to assemble a system for $70, but I suspect that wouldn't include the Cactus Juice. Back when Curtis did his program at SWAT and was still making his own rectangular chambers, his stated turnkey price was a lot more than $250.



epicfail48 said:


> The hand pump is entirely useless for anything beyond bleeding brakes. Seriously, look into a pump on eBay. Mine was $30 with $10 shipping if memory serves. As far as the issue with the kitchen oven, the fumes from the resin aren't exactly food safe, or plesamt smelling


I wouldn't want to find out how well this would go over in the kitchen. I already catch enough heck for kitchen messes even though I haven't topped her setting the french fries on fire ... yet. :laughing:


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## hwebb99 (Nov 27, 2012)

epicfail48 said:


> Okay, I have to disagree with that. My I itial setup cost was less than $100, probably closer to $70 if I were to add everything up


 What if we want to do something bigger than a knife blank? That means we can't use a mason jar, and needing a bigger vacuum chamber greatly increases the cost.


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## epicfail48 (Mar 27, 2014)

hwebb99 said:


> What if we want to do something bigger than a knife blank? That means we can't use a mason jar, and needing a bigger vacuum chamber greatly increases the cost.


That would be when you step up to a pressure cooker with a sheet of acrylic to replace the lid for something like bowl blanks, or a half gallon mason jar for longer, thinner pen blanks, either of which would bump the total cost up to maybe $100. Shockingly, I do consider thanpt not everybody solely makes knives and adjust my advise to suit


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## hwebb99 (Nov 27, 2012)

You will be lucky to find a pressure cooker and a piece of plastic for $30. I have enough stuff laying around to do this for less than $10 plus the cactus juice, but it wouldn't be very accurate to go telling people look you can do this for $10. A quart jar works fine, but you are pushing your luck with a 1/2 gallon.


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## Gary Beasley (Jan 21, 2009)

I saw that a glass cookie jar was tried with great success and found one at a Goodwill store. Replaced the lid with a dense wood slab grooved with a silicon seal so I could easily mount the hose fixtures. Works great to the max vacuum.
On a side not if you are short on juice a bag of marbles poured on top of the blank will help keep the level up.


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## Quickstep (Apr 10, 2012)

I was thinking of drilling a 2" hole in the lid of my pressure cooker and covering it with a piece of plexi to give a look in. Thoughts?


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## epicfail48 (Mar 27, 2014)

Quickstep said:


> I was thinking of drilling a 2" hole in the lid of my pressure cooker and covering it with a piece of plexi to give a look in. Thoughts?


I dunno how much I'd trust the lid on the pressure cooked to keep a good seal without flexing under vacuum, but other than that it should work fine


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## hwebb99 (Nov 27, 2012)

The pressure cooker lid will be fine. The hard part will be making a good seal with the pressure cooker lid with the plastic because the lid isn't flat.


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## Quickstep (Apr 10, 2012)

If I make a round window about 2" in diameter, how think do you think the plexi needs to be? I have some 1/8", 1/4" is harder to find in small pieces. 

I plan to put it on the lid and soften it using a heat gun to make it conform to the arc of the lid.


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## epicfail48 (Mar 27, 2014)

Quickstep said:


> If I make a round window about 2" in diameter, how think do you think the plexi needs to be? I have some 1/8", 1/4" is harder to find in small pieces.
> 
> I plan to put it on the lid and soften it using a heat gun to make it conform to the arc of the lid.


For a span that small you could probably get away with 1/8, but I wouldn't wanna risk something happening. I'd go with the 1/4


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## Quickstep (Apr 10, 2012)

Thanks for the advice from everyone. It's helpful as I venture into this uncharted territory. I'm hoping to go to the glass store today and get either a small piece of plexi to make a window in the pressure cooker lid, or a larger piece of 1/2" to make a new lid all together. If I end up making a new lid, how do you make the seal?


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## hwebb99 (Nov 27, 2012)

epicfail48 said:


> For a span that small you could probably get away with 1/8, but I wouldn't wanna risk something happening. I'd go with the 1/4


 1/8 probably wouldn't break,but it would flex and break the seal.


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## epicfail48 (Mar 27, 2014)

Quickstep said:


> Thanks for the advice from everyone. It's helpful as I venture into this uncharted territory. I'm hoping to go to the glass store today and get either a small piece of plexi to make a window in the pressure cooker lid, or a larger piece of 1/2" to make a new lid all together. If I end up making a new lid, how do you make the seal?


Reuse the one from the pressure cooker lid


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## hwebb99 (Nov 27, 2012)

I'd reuse the pressure cooker lid. Be aware of the forces at work here. 1/2 plywood will be not even close to strong enough.


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## Quickstep (Apr 10, 2012)

hwebb99 said:


> I'd reuse the pressure cooker lid. Be aware of the forces at work here. 1/2 plywood will be not even close to strong enough.


The forces at work are not lost on me. So much so, that I'm wondering if a hole in the pressure cooker lid to make a window could weaken it. Makes me wonder if there's a way to reliably control the foaming so the a peek inside wouldn't be necessary. 

I plan to put the 1-1/2" thick blank inside a vessel that is about 6" tall, then put that in the pressure cooker. Can I pull it off if I start slowly?


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## hwebb99 (Nov 27, 2012)

The pressure cookers I have seen are like 1/2 thick aluminum lids. I think putting in a window would be fine. The pressure cookers I have seen have an existing hole about 1/2 inch diameter for a rubber plug that serves as safety pressure release valve. You think it would be big enough for a window?


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## Quickstep (Apr 10, 2012)

hwebb99 said:


> The pressure cookers I have seen are like 1/2 thick aluminum lids. I think putting in a window would be fine. The pressure cookers I have seen have an existing hole about 1/2 inch diameter for a rubber plug that serves as safety pressure release valve. You think it would be big enough for a window?


 My cooker is all stainless steel. Looks to be about 16 gauge. 

The hole for the pressure release in mine is about 1/2"; I was going to put a vacuum gauge in it. It might be big enough for a window if I got up close, but again, given the forces at work, I'm thinking getting an eye that close might not be a good idea. Granted if it does go bad, it would be an implosion not an explosion, but for me all 'plosions are bad 

I see oil level sight glasses that are threaded; might be the ticket if they're thick enough.

Also, I'm thinking about leaving a small flashlight inside for light to see what's going on. Can it survive the vacuum?


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## Quickstep (Apr 10, 2012)

What do you guys think about this for a window. I'd cut out the baffle looking thing for a better view. It looks like the "window" part is about 1-1/4" to 1-1/2"

http://www.ebay.com/itm/Liquid-Indi...733513?hash=item33ae11ca09:g:0T0AAOSwwE5WZ4em


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## hwebb99 (Nov 27, 2012)

Isn't there a hole in the cooker for a pressure gauge and the other pressure release valve? Get a flashlight with a sealed body rated for use in a hazardous environment, and it should be fine. I thing about any sight glass would work. You are pulling about 14 psi. 14 psi isn't very much over 3/4 of a square inch. 14 psi over a square foot is a much greater force.


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## Quickstep (Apr 10, 2012)

Again, thanks for keeping in touch.

My cooker has the fitting in the center of the top where the pressure regulator valve goes. I'm re-using that like a hose barb to connect the vacuum hose. Then there's an over pressure plug that I guess blows out if you leave it on the stove too long. There's a pressure relief valve but that's integrated into the handle with an interlock which appears to prevent a user from quickly opening the lid when it's under pressure. I can't put a fitting in there, because anything other than the relief valve interferes with the interlock. I suppose I could put a tee in one of those holes to make it serve double duty.


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