Active Cooling for Power Tools

[nbk2000]

While using a cut-off wheel on an angle-grinder for penetration testing, I noticed that the majority of the noise comes from the tool motor, not from the cutting wheel, during actual cutting.

The idea of silencing the tool by encasing it in some material occured to me, but the problem with this would be that the motor would very rapidly overheat and fail without the cooling airflow.

How to solve this in a manner that is efficient, simple, and non-conductive (for obvious reasons) as well as totally silent?

The use of dry ice seems to be the solution.

It's cheap, disposable, readily available, non-conductive, and silent.

By making the case silent, you're also making it almost airtight, as well as insulated.

The idea I'm having is to drop chunks of dry ice into the silencing case just prior to use, sealing it up, and then using the tool.

As the tool heats up, it vaporizes the dry ice, keeping the tool cooled, and creating gaseous CO2.

The CO2 gas is then vented out.

While this could be expended as waste gas, there's another idea I had that could use it to increase the stealthiness of the tool.

When you use a cut-off wheel, it creates a visible spray of sparks, which can draw attention to your activities in the dark. BAD!

But, if the tool is operating in a non-oxygen atmosphere, the metal particles won't ignite and burn, thus no visible sparks. GOOD!

So, by directing the CO2 exhaust in line with the angle of debris ejection, you should be able to shield the hot particles from the oxygen in the air long enough for them to cool to below their ignition temperature, preventing the creation of sparks.

:)

This would depend on the tool generating enough heat to vaporize the dry ice rapidly enough to create sufficient CO2 to shield with. If the tool doesn't generate enough heat as-is, it could be modified to run hotter, or electric resistance elements could be added to provide the extra heat.

While plug-in grinders are good, there are battery powered angle-grinders which are very useful for B&E work. Especially at remote construction sites or other places with no mains power.

[nbk2000]

While using a cut-off wheel on an angle-grinder for penetration testing, I noticed that the majority of the noise comes from the tool motor, not from the cutting wheel, during actual cutting.

The idea of silencing the tool by encasing it in some material occured to me, but the problem with this would be that the motor would very rapidly overheat and fail without the cooling airflow.

How to solve this in a manner that is efficient, simple, and non-conductive (for obvious reasons) as well as totally silent?

The use of dry ice seems to be the solution.

It's cheap, disposable, readily available, non-conductive, and silent.

By making the case silent, you're also making it almost airtight, as well as insulated.

The idea I'm having is to drop chunks of dry ice into the silencing case just prior to use, sealing it up, and then using the tool.

As the tool heats up, it vaporizes the dry ice, keeping the tool cooled, and creating gaseous CO2.

The CO2 gas is then vented out.

While this could be expended as waste gas, there's another idea I had that could use it to increase the stealthiness of the tool.

When you use a cut-off wheel, it creates a visible spray of sparks, which can draw attention to your activities in the dark. BAD!

But, if the tool is operating in a non-oxygen atmosphere, the metal particles won't ignite and burn, thus no visible sparks. GOOD!

So, by directing the CO2 exhaust in line with the angle of debris ejection, you should be able to shield the hot particles from the oxygen in the air long enough for them to cool to below their ignition temperature, preventing the creation of sparks.

:)

This would depend on the tool generating enough heat to vaporize the dry ice rapidly enough to create sufficient CO2 to shield with. If the tool doesn't generate enough heat as-is, it could be modified to run hotter, or electric resistance elements could be added to provide the extra heat.

While plug-in grinders are good, there are battery powered angle-grinders which are very useful for B&E work. Especially at remote construction sites or other places with no mains power.

[Jacks Complete]

Now that's a neat idea.

If you have a small directional jet that you can point right at the contact point, it would reduce the volume of gas needed. You might find that the cutting rate is somewhat slower without the oxidisation of the steel.

A quiet cutter would be very useful for not disturbing the neighbours.

You might also be able to extend this idea of active thermal sheilding to things like car engines and gun barrels, too.

[Jacks Complete]

Now that's a neat idea.

If you have a small directional jet that you can point right at the contact point, it would reduce the volume of gas needed. You might find that the cutting rate is somewhat slower without the oxidisation of the steel.

A quiet cutter would be very useful for not disturbing the neighbours.

You might also be able to extend this idea of active thermal sheilding to things like car engines and gun barrels, too.

[sdjsdj]

Perhaps something like the Argon system used when welding could be adapted?

[sdjsdj]

Perhaps something like the Argon system used when welding could be adapted?

[sdjsdj]

There's a good point point - generally speaking, automatic weapons like the LSW can't be fired for a sustained period of time becaus the barrel starts to distort due to the heat. A relatively simple gas - cooling system around the barrel could effectively remove this problem. Could be a bit heavy though.

[sdjsdj]

There's a good point point - generally speaking, automatic weapons like the LSW can't be fired for a sustained period of time becaus the barrel starts to distort due to the heat. A relatively simple gas - cooling system around the barrel could effectively remove this problem. Could be a bit heavy though.

[megalomania]

With my recent computer overheating problems I have been reading about cooling solutions. One nifty device for extreme CPU cooling is the Asetek Vapochill. This is a miniture self contained refrigerater the produces -40 C temperatures on the processor via a cable ending in a flat piece of copper.

With minor modifications a device like this could have a different cooling head for cooling other things. The tools motor could be sealed, and only the refrigeration unit would remain open to the air.

These things are not cheap... the Vapochill runs about $850. Of course it can keep a high end CPU overclocked by 50% running under heavy load chilled to -11 C. For a motor it can likely keep it much cooler, or cool a larger area.

[megalomania]

With my recent computer overheating problems I have been reading about cooling solutions. One nifty device for extreme CPU cooling is the Asetek Vapochill. This is a miniture self contained refrigerater the produces -40 C temperatures on the processor via a cable ending in a flat piece of copper.

With minor modifications a device like this could have a different cooling head for cooling other things. The tools motor could be sealed, and only the refrigeration unit would remain open to the air.

These things are not cheap... the Vapochill runs about $850. Of course it can keep a high end CPU overclocked by 50% running under heavy load chilled to -11 C. For a motor it can likely keep it much cooler, or cool a larger area.

[festergrump]

Corrugated metal structures such as some industrial walls and roofs cause alot of noise despite the quieted tools you might use to do the job.

I've been expirimenting to some success with laminating a 3/4" thick rubber pad (my foot relief at work) of aproximately 4'x 4' to one such piece of steel and grinding my way through them both. The pad seems to help buffer the noise to a pretty good degree (about 25% of noise left) but the noise increases as you get some vibration from the freed edges of the steel. Putting your body against will help to deaden the noise some more while in this stage of the cut, though.

Ultimately, if one was so inclined to penetrate a structure in this manner, I think that a collapsable tent-like "blind" might easily be reinforced inside with a sound dampening barrier (spiked foam sheets?) to hide noise and sparks from the compromised steel. This in conjunction with a sprayable foam or stick on laminate foam rubber to buffer the metal might be the trick. For rooftops a grey dome tent would be ideal since grey is easiest to blend in with shadows and dome-like silouettes are easily mistaken by the unknowing eye for an integral part of an industrial rated HVAC system.

Also, much loose weight on a rooftop would be ideal for dampening noise for cutting through the thinner barriers. Dirt in abundance could help considerably and be brought in little by little and spread about your future workplace... providing you are not pressed for time (and you shouldn't be, either, until it's "GO-TIME" else give up the mission).

From my expirience as a second rate musician, spiked foam will reduce the noise of the higher end of the sound spectrum much better than that of the bass frequencies, and that's really what we're looking at here.

I wouldn't find it too hard to imagine such a setup being stuffed in an Alice pack along with your tools and carried to your decided point of entry. :)

[festergrump]

Corrugated metal structures such as some industrial walls and roofs cause alot of noise despite the quieted tools you might use to do the job.

I've been expirimenting to some success with laminating a 3/4" thick rubber pad (my foot relief at work) of aproximately 4'x 4' to one such piece of steel and grinding my way through them both. The pad seems to help buffer the noise to a pretty good degree (about 25% of noise left) but the noise increases as you get some vibration from the freed edges of the steel. Putting your body against will help to deaden the noise some more while in this stage of the cut, though.

Ultimately, if one was so inclined to penetrate a structure in this manner, I think that a collapsable tent-like "blind" might easily be reinforced inside with a sound dampening barrier (spiked foam sheets?) to hide noise and sparks from the compromised steel. This in conjunction with a sprayable foam or stick on laminate foam rubber to buffer the metal might be the trick. For rooftops a grey dome tent would be ideal since grey is easiest to blend in with shadows and dome-like silouettes are easily mistaken by the unknowing eye for an integral part of an industrial rated HVAC system.

Also, much loose weight on a rooftop would be ideal for dampening noise for cutting through the thinner barriers. Dirt in abundance could help considerably and be brought in little by little and spread about your future workplace... providing you are not pressed for time (and you shouldn't be, either, until it's "GO-TIME" else give up the mission).

From my expirience as a second rate musician, spiked foam will reduce the noise of the higher end of the sound spectrum much better than that of the bass frequencies, and that's really what we're looking at here.

I wouldn't find it too hard to imagine such a setup being stuffed in an Alice pack along with your tools and carried to your decided point of entry. :)

[nbk2000]

I went to the grocery store and picked up some dry ice and tested the idea of spark suppresion out.

Attached are a couple of frame captures from the video I shot of the test. I've got a video of the test that's small enough to fit on a floppy. If someone wants it, I'll e-mail it to you to upload somewhere so others can see it too.

I put a pan of hot water in a large water cooler and dropped in a bit of dry ice, waited till the vapor fog had filled the whole cooler, then conducted the test.

Target was a piece of 1040 steel round stock, tool was a 4.5" angle grinder with ALOX grinding wheel.

At first, there were no sparks, but the grinder generates such a draft that the CO2 fog was dissipated from the cooler within a a second or two. :(

But the results are encouraging.

Compare the 'with' picture against the 'without' picture. The first is barely visible, the other lights up the night like a fireworks show. The former lets you enjoy the spoils, the latter gets you an extended vacation. ;)

The green tint is from the camcorders Nightshot IR mode.

With a means of keeping the target adequately shrouded in the gas, I think total spark suppression is possible.

Something else noted was how the target steel was rusted after its brief exposure to the dry ice fog. This stock was pristine prior to the test, and a few minutes later was looking years old. I think the carbonic acid formed by the carbon dioxide reacting with the water is responsible.

This isn't going to do your tools any good. I examined my grinder and found water drops in the motor casing. I can imagine what it's doing to the windings inside the grinder motor. Must be from the water fog created by the dry ice. I wonder how long a tool could last in such a fog before shorting out...

This was ghetto style testing, of course, so problems are to be expected. A more refined method probably wouldn't affect the tooling.

Next time I'll use an electric heating element to vaporize the dry ice (no water) and an air-tight enclosure to keep the grinder draft from being a problem. :)

In the context of a job, depending on what you're attacking, it might be good to build a tent from plastic sheeting around the target and filling that with CO2 gas, using an electric heater to prevent the corrosive fog from forming.

Then you can work in the tent, using a supplied air respirator. This is easy to make, using a battery-powered air-bed inflator attached to a half-face respirator by a length of vinyl tubing. Don't knock the mask off or you'll die in one breath when your epiglotus siezes shut.

Another good thing about this may be the reduction or elimination of smoke from torch attacks.

Since smoke is the product of incomplete combustion, by eliminating ALL combustion, you should eliminate the smoke. :)

Since oxy-acetylene and exothermic torches supply their own oxygen, you can cut while shielding the surroundings from burning caused by slag splatter.

While a cylinder of carbon dioxide gas would be more controllable, it's also very heavy, bulky, and something else to be traced if found. A block of dry ice is cheap, disposable, and the perfect crime tool as it evaporates with no trace.

[nbk2000]

I went to the grocery store and picked up some dry ice and tested the idea of spark suppresion out.

Attached are a couple of frame captures from the video I shot of the test. I've got a video of the test that's small enough to fit on a floppy. If someone wants it, I'll e-mail it to you to upload somewhere so others can see it too.

I put a pan of hot water in a large water cooler and dropped in a bit of dry ice, waited till the vapor fog had filled the whole cooler, then conducted the test.

Target was a piece of 1040 steel round stock, tool was a 4.5" angle grinder with ALOX grinding wheel.

At first, there were no sparks, but the grinder generates such a draft that the CO2 fog was dissipated from the cooler within a a second or two. :(

But the results are encouraging.

Compare the 'with' picture against the 'without' picture. The first is barely visible, the other lights up the night like a fireworks show. The former lets you enjoy the spoils, the latter gets you an extended vacation. ;)

The green tint is from the camcorders Nightshot IR mode.

With a means of keeping the target adequately shrouded in the gas, I think total spark suppression is possible.

Something else noted was how the target steel was rusted after its brief exposure to the dry ice fog. This stock was pristine prior to the test, and a few minutes later was looking years old. I think the carbonic acid formed by the carbon dioxide reacting with the water is responsible.

This isn't going to do your tools any good. I examined my grinder and found water drops in the motor casing. I can imagine what it's doing to the windings inside the grinder motor. Must be from the water fog created by the dry ice. I wonder how long a tool could last in such a fog before shorting out...

This was ghetto style testing, of course, so problems are to be expected. A more refined method probably wouldn't affect the tooling.

Next time I'll use an electric heating element to vaporize the dry ice (no water) and an air-tight enclosure to keep the grinder draft from being a problem. :)

In the context of a job, depending on what you're attacking, it might be good to build a tent from plastic sheeting around the target and filling that with CO2 gas, using an electric heater to prevent the corrosive fog from forming.

Then you can work in the tent, using a supplied air respirator. This is easy to make, using a battery-powered air-bed inflator attached to a half-face respirator by a length of vinyl tubing. Don't knock the mask off or you'll die in one breath when your epiglotus siezes shut.

Another good thing about this may be the reduction or elimination of smoke from torch attacks.

Since smoke is the product of incomplete combustion, by eliminating ALL combustion, you should eliminate the smoke. :)

Since oxy-acetylene and exothermic torches supply their own oxygen, you can cut while shielding the surroundings from burning caused by slag splatter.

While a cylinder of carbon dioxide gas would be more controllable, it's also very heavy, bulky, and something else to be traced if found. A block of dry ice is cheap, disposable, and the perfect crime tool as it evaporates with no trace.

[FUTI]

I'm afraid that dry ice can cause troubles NBK2000. I remember that one of the problems with it reacting in Grinard reaction is that being so cool actually spoil everything since it condense so much water from air that Grinard reagent react with water instead of CO2. Now condense water inside the motor casing isn't something I would like to see.

[FUTI]

I'm afraid that dry ice can cause troubles NBK2000. I remember that one of the problems with it reacting in Grinard reaction is that being so cool actually spoil everything since it condense so much water from air that Grinard reagent react with water instead of CO2. Now condense water inside the motor casing isn't something I would like to see.

[Skean Dhu]

What about surrounding the grinder case in a light oil and having it circulate from the motor housing through vinyl tubing around a cooling core of (dry)ice. Since the oil (unless its dirty as all get out) won't conduct the motor should still operate. You could then use the CO2 fog arround the grinder wheel to control the sparks, since its not your property your grinding away the surface rust left as a result won't matter.

just thinking out loud, elaborate, modify, tear apart.

:: Last second though I had while proof reading; you'd probably need a brushless motor for this to succeed, since the oil could prevent the brushes on a regular motor from making contact.

[Skean Dhu]

What about surrounding the grinder case in a light oil and having it circulate from the motor housing through vinyl tubing around a cooling core of (dry)ice. Since the oil (unless its dirty as all get out) won't conduct the motor should still operate. You could then use the CO2 fog arround the grinder wheel to control the sparks, since its not your property your grinding away the surface rust left as a result won't matter.

just thinking out loud, elaborate, modify, tear apart.

:: Last second though I had while proof reading; you'd probably need a brushless motor for this to succeed, since the oil could prevent the brushes on a regular motor from making contact.

[nbk2000]

I tried another test yesterday.

I took the remaining dry ice and placed it in a large plastic bag, put the test target and the grinder in, squeezed all the air out and twisted the end shut.

After the bag was suitably inflated by the subliminated dry ice, I conducted the test.

There were NO sparks. :)

The removed material collected at the bottom of the bag, unburnt, along with some of the grinder disk material. Perhaps this technique could be used to grind aluminum or magnesium for use as pyro material.

Another idea I had was to make a limpet charge out of dry ice and magnesium for attaching close to a vehicles air intake to smother it into stalling out.

I got the idea from a video clip from a science experiment on the FTP, where magnesium shavings were ignited in a block of dry ice. The magnesium burned very quickly, lighting the block up brightly from inside and, more importantly, releasing a huge amount of CO2 in just a few moments.

Experimentation would be needed to determine the best arrangement for the components, but the ideal would be to generate a constant flow of carbon dioxide, sufficient to smother a diesel engine of the type typically used for dough delivery trucks ;) for at least 2 minutes.

The charge would be constructed such that you can whip it out, slap it near the air intake, and ignite it to generate the gas, immobilizing the vehicle long enough to do what you need to do.

It'd be much lighter and more compact than a tank of the gas, in keeping with the RTPB of K.I.S.S.

A 10 pound block of dry ice will convert into over 80 cubic feet of gas. Since air contains 21% oxygen, and you only need to reduce that to 12% to stop combustion, you should have no problem creating enough carbon dioxide gas to drop the oxygen level down to that level.

Really trick would be to make the casing out of nipolite and adjusting everything so that, just as the last of the dry ice was vaporized, the last little bit of burning magnesium ignited the casing, which burns to nothing, leaving nothing but some magnesium oxide powder to blow away in the wind.

CSI that, piggies! :p

As an enhancement, chlorinated hydrocarbons, such as perchloroethylene, could be added in with the dry ice, where it would remain frozen, until vaporized. Chlorinated hydrocarbons are like poor-mans Halon, breaking the combustion cycle, thus increasing efficiency.

[nbk2000]

I tried another test yesterday.

I took the remaining dry ice and placed it in a large plastic bag, put the test target and the grinder in, squeezed all the air out and twisted the end shut.

After the bag was suitably inflated by the subliminated dry ice, I conducted the test.

There were NO sparks. :)

The removed material collected at the bottom of the bag, unburnt, along with some of the grinder disk material. Perhaps this technique could be used to grind aluminum or magnesium for use as pyro material.

Another idea I had was to make a limpet charge out of dry ice and magnesium for attaching close to a vehicles air intake to smother it into stalling out.

I got the idea from a video clip from a science experiment on the FTP, where magnesium shavings were ignited in a block of dry ice. The magnesium burned very quickly, lighting the block up brightly from inside and, more importantly, releasing a huge amount of CO2 in just a few moments.

Experimentation would be needed to determine the best arrangement for the components, but the ideal would be to generate a constant flow of carbon dioxide, sufficient to smother a diesel engine of the type typically used for dough delivery trucks ;) for at least 2 minutes.

The charge would be constructed such that you can whip it out, slap it near the air intake, and ignite it to generate the gas, immobilizing the vehicle long enough to do what you need to do.

It'd be much lighter and more compact than a tank of the gas, in keeping with the RTPB of K.I.S.S.

A 10 pound block of dry ice will convert into over 80 cubic feet of gas. Since air contains 21% oxygen, and you only need to reduce that to 12% to stop combustion, you should have no problem creating enough carbon dioxide gas to drop the oxygen level down to that level.

Really trick would be to make the casing out of nipolite and adjusting everything so that, just as the last of the dry ice was vaporized, the last little bit of burning magnesium ignited the casing, which burns to nothing, leaving nothing but some magnesium oxide powder to blow away in the wind.

CSI that, piggies! :p

As an enhancement, chlorinated hydrocarbons, such as perchloroethylene, could be added in with the dry ice, where it would remain frozen, until vaporized. Chlorinated hydrocarbons are like poor-mans Halon, breaking the combustion cycle, thus increasing efficiency.

[nbk2000]

A flaw in the design occured to me recently.

Since the grinder is completely enclosed in a bag, the abrasive dust is also enclosed in the bag, thus the abrasive dust will be sucked into the tool vents and into the motor. Not healthy, I'd imagine.

But, if the tool vents were open to the air, while the rest of the bag was sealed around the tool, then the dust would be contained within the bag, without affecting the tool. :)

Build the soundproof casing around the tool, feed in the CO2 from an external heater and through the airvents, venting the gas into the bag which is attached to the target. Being completely enclosed as it is, there's no dust in the air, so you don't need a respirator. Also, dust is a forensic clue that can connect you to the scene, but there's none of it on you since it's all in the bag. :p

The neat thing about using the inert gas with the grinder is that you can use an ordinary plastic bag as, being finely powdered, it cools almost instantly, and since there's no air, it doesn't burn holes in the plastic. :)

If you use a grinder in normal air, you can burn dozens of tiny holes in the same bag from several feet away.

[nbk2000]

A flaw in the design occured to me recently.

Since the grinder is completely enclosed in a bag, the abrasive dust is also enclosed in the bag, thus the abrasive dust will be sucked into the tool vents and into the motor. Not healthy, I'd imagine.

But, if the tool vents were open to the air, while the rest of the bag was sealed around the tool, then the dust would be contained within the bag, without affecting the tool. :)

Build the soundproof casing around the tool, feed in the CO2 from an external heater and through the airvents, venting the gas into the bag which is attached to the target. Being completely enclosed as it is, there's no dust in the air, so you don't need a respirator. Also, dust is a forensic clue that can connect you to the scene, but there's none of it on you since it's all in the bag. :p

The neat thing about using the inert gas with the grinder is that you can use an ordinary plastic bag as, being finely powdered, it cools almost instantly, and since there's no air, it doesn't burn holes in the plastic. :)

If you use a grinder in normal air, you can burn dozens of tiny holes in the same bag from several feet away.

[Jacks Complete]

Hang on, I'm a bit lost now.

If the tool is completely enclosed with an airtight bag, how do you get to cut the bolt which is attached to the door, without breaking open the bag?

Surely there needs to be a "first stage" bag, which then feeds to a second stage vent which blows on the working area. That working area could also be enclosed in some sort of shield to increase the CO2 pressure/concentration.

Also, as regards the CO2 stopping trucks, I know something like it was tried in WWII but wasn't quite successful. They used ozone, though. The risk with CO2 at those levels is that if there is enough to stop the truck engine, there is enough to kill those inside the truck. Since double murder is investigated far more carefully than a robbery, with higher penalties, it's worth thinking about.

Along similar lines, don't knock yourself out with CO2. It would be a case of "Americas dumbest criminals" if you were found by the vault dead, having cut through 90% of the door.

[Jacks Complete]

Hang on, I'm a bit lost now.

If the tool is completely enclosed with an airtight bag, how do you get to cut the bolt which is attached to the door, without breaking open the bag?

Surely there needs to be a "first stage" bag, which then feeds to a second stage vent which blows on the working area. That working area could also be enclosed in some sort of shield to increase the CO2 pressure/concentration.

Also, as regards the CO2 stopping trucks, I know something like it was tried in WWII but wasn't quite successful. They used ozone, though. The risk with CO2 at those levels is that if there is enough to stop the truck engine, there is enough to kill those inside the truck. Since double murder is investigated far more carefully than a robbery, with higher penalties, it's worth thinking about.

Along similar lines, don't knock yourself out with CO2. It would be a case of "Americas dumbest criminals" if you were found by the vault dead, having cut through 90% of the door.

[Boomer]

Totally off topic but that dry ice bag idea is THE way to grind down Mg without it igniting, plus you collect it un-oxidised in the process.

Has anyone niticed that all new cigarette machines have an EXTERNAL flat iron going around from the front door to the side and back into a lock (instead of the internal T-bar)? I watched one being filled up, and it is really the only thing holding the door closed.
A hand saw is useless as the part is hardened stainless. Even with a diamond blade it would take ages to cut. My second thought was LSC but they are not remote enough. The third thought (angle grinder) I discarded too, due to noise. But now ....

BTW when is the first k3wl going to suggest thermite? I need some cheering up right now...

[Boomer]

Totally off topic but that dry ice bag idea is THE way to grind down Mg without it igniting, plus you collect it un-oxidised in the process.

Has anyone niticed that all new cigarette machines have an EXTERNAL flat iron going around from the front door to the side and back into a lock (instead of the internal T-bar)? I watched one being filled up, and it is really the only thing holding the door closed.
A hand saw is useless as the part is hardened stainless. Even with a diamond blade it would take ages to cut. My second thought was LSC but they are not remote enough. The third thought (angle grinder) I discarded too, due to noise. But now ....

BTW when is the first k3wl going to suggest thermite? I need some cheering up right now...

[fr0sengh0st]

In regard to the silenced power tool topic - could one not use a pneumatic motor running of a small cylinder of CO2 (or another inert gas) to power the cutting blade?

I know that it has been said that gas cylinders are heavy but it’s unlikely that the building/lock you want to cut has a handy mains plug nearby ;) . Plus high drain battery powered tools tend to be expensive/heavy of don’t last very long per charge.

If the motor made too much noise then it could be silenced using conventional foam insulation and there would be no problem with overheating. The outlet of CO2 from the motor could then be easily directed to minimise sparking.

[fr0sengh0st]

In regard to the silenced power tool topic - could one not use a pneumatic motor running of a small cylinder of CO2 (or another inert gas) to power the cutting blade?

I know that it has been said that gas cylinders are heavy but it’s unlikely that the building/lock you want to cut has a handy mains plug nearby ;) . Plus high drain battery powered tools tend to be expensive/heavy of don’t last very long per charge.

If the motor made too much noise then it could be silenced using conventional foam insulation and there would be no problem with overheating. The outlet of CO2 from the motor could then be easily directed to minimise sparking.

[xyz]

Boomer, most flat sheet metal brackets that hold padlocks (I think that's what you're describing) are easy prey to a combination of bolt cutters and a shifter (Aus name for a large adjustable spanner).

Through a combination of cutting the metal with the bolt cutters and bending it out of the way with the shifter to cut more, you can get through such a bracket easily and without much noise or any need for power. Coupled with the fact that they're almost always made of very soft and crappy steel that bolt cutters will cut like butter, it's actually pretty easy.

SWIM has opened a bunch of locked shipping containers using the bolt cutters/shifter method to cut the bracket holding the lock.

[xyz]

Boomer, most flat sheet metal brackets that hold padlocks (I think that's what you're describing) are easy prey to a combination of bolt cutters and a shifter (Aus name for a large adjustable spanner).

Through a combination of cutting the metal with the bolt cutters and bending it out of the way with the shifter to cut more, you can get through such a bracket easily and without much noise or any need for power. Coupled with the fact that they're almost always made of very soft and crappy steel that bolt cutters will cut like butter, it's actually pretty easy.

SWIM has opened a bunch of locked shipping containers using the bolt cutters/shifter method to cut the bracket holding the lock.

[nbk2000]

Jack:

The bag would be attached to the target by double-sided tape, or magnetic ribbon, a ring magnet, or whatever appropriate means, and the tool then used. It's not like an angle grinder is going to be stopped by a 2 mil plastic bag. :)


Also, as regards the CO2 stopping trucks, I know something like it was tried in WWII but wasn't quite successful.


You're thinking of combustion inhibitors that the Nazis experimented with for their anti-aircraft shells.

It didn't work because they were trying to stop B-29 bombers flying at 30,000 feet and 400 MPH using stuff fired from 88mm flak guns into just the general airspace of the bombers.

Far removed from placing pounds of inhibitor directly in the air intake of a stationary vehicle. ;)

I got the idea from a recent patent issued to Los Alamos (or similiar) for using halons for stopping vehicle pursuits.

Their technique utilized pressurized latex bladders (AKA Water Balloons) dropped from lead vehicles or overhead passes into the path of the target vehicle and would instantly kill the combustion cycle.

Though halons are now banned by international agreement and are about as precious as black pearls.

I wonder how difficult it is to make halons?

I know that chlorinated solvents, such as carbon tetrachloride and methylene chloride have, in the past, been used as fire fighting fluids, so perhaps they'd be useable.

When CO2 displaces oxygen, it will inhibit combustion at 19% oxygen content, but humans can live for half an hour at 12% oxygen content, so there's a sufficent gap there to prevent death, as it's expected that once the vehicle has been immobilized, that the attacker will very shortly be opening it up, thus venting out the CO2.

Also, I don't think that vehicles share the engines air intake with the passenger compartment.

XYZ:

I don't think Boomer was talking about the kind of padlock hasps that you put on the garden shed. It's probably more like the ones I've tested that are 1/4" hardened boron alloy steel. You ain't even going to scratch it with a bolt clipper. :p

Boomer:

Does the hasp you're talking about have a round lock on it? Or does the lock have a rounded shield around the part the lock attaches to?

[nbk2000]

Jack:

The bag would be attached to the target by double-sided tape, or magnetic ribbon, a ring magnet, or whatever appropriate means, and the tool then used. It's not like an angle grinder is going to be stopped by a 2 mil plastic bag. :)


Also, as regards the CO2 stopping trucks, I know something like it was tried in WWII but wasn't quite successful.


You're thinking of combustion inhibitors that the Nazis experimented with for their anti-aircraft shells.

It didn't work because they were trying to stop B-29 bombers flying at 30,000 feet and 400 MPH using stuff fired from 88mm flak guns into just the general airspace of the bombers.

Far removed from placing pounds of inhibitor directly in the air intake of a stationary vehicle. ;)

I got the idea from a recent patent issued to Los Alamos (or similiar) for using halons for stopping vehicle pursuits.

Their technique utilized pressurized latex bladders (AKA Water Balloons) dropped from lead vehicles or overhead passes into the path of the target vehicle and would instantly kill the combustion cycle.

Though halons are now banned by international agreement and are about as precious as black pearls.

I wonder how difficult it is to make halons?

I know that chlorinated solvents, such as carbon tetrachloride and methylene chloride have, in the past, been used as fire fighting fluids, so perhaps they'd be useable.

When CO2 displaces oxygen, it will inhibit combustion at 19% oxygen content, but humans can live for half an hour at 12% oxygen content, so there's a sufficent gap there to prevent death, as it's expected that once the vehicle has been immobilized, that the attacker will very shortly be opening it up, thus venting out the CO2.

Also, I don't think that vehicles share the engines air intake with the passenger compartment.

XYZ:

I don't think Boomer was talking about the kind of padlock hasps that you put on the garden shed. It's probably more like the ones I've tested that are 1/4" hardened boron alloy steel. You ain't even going to scratch it with a bolt clipper. :p

Boomer:

Does the hasp you're talking about have a round lock on it? Or does the lock have a rounded shield around the part the lock attaches to?

[xyz]

I didn't mean those little garden shed hasps...

If you've ever had a look at a shipping container, the hasp is about 1/4" thick, but it's definitely not boron alloy :p

I agree that there's no way you're cutting a boron alloy hasp with bolt cutters.

Your method of making them softer... does it involve heating them?

[xyz]

I didn't mean those little garden shed hasps...

If you've ever had a look at a shipping container, the hasp is about 1/4" thick, but it's definitely not boron alloy :p

I agree that there's no way you're cutting a boron alloy hasp with bolt cutters.

Your method of making them softer... does it involve heating them?

[Jacks Complete]

You will get good results on a lot of very tough steels by heating them up to red, then cooling rapidly with water. They get so hard that they will just shatter when you put any force on them. Obviously you don't want to wreck the jaws of your bolt crops on the superhard steel, but a good lever bar (or hammer blow) will fracture them without a sound.

Just make sure you heat for long enough that the inside of the bar gets red hot, too, and you use enough water to cool rapidly for long enough. It helps if you add a detergent, as this helps wet the steel, giving even more rapid cooling.

[Jacks Complete]

You will get good results on a lot of very tough steels by heating them up to red, then cooling rapidly with water. They get so hard that they will just shatter when you put any force on them. Obviously you don't want to wreck the jaws of your bolt crops on the superhard steel, but a good lever bar (or hammer blow) will fracture them without a sound.

Just make sure you heat for long enough that the inside of the bar gets red hot, too, and you use enough water to cool rapidly for long enough. It helps if you add a detergent, as this helps wet the steel, giving even more rapid cooling.

[xyz]

I know that steels can be further hardened by heating and cooling, I was wondering more along the lines of whether the boron alloy steel would be softened by heating followed by SLOW cooling.

Heating and rapid cooling followed by a hammer and chisel (remember how they used to "cut" diamonds?) sounds like an alright way to go however.

[xyz]

I know that steels can be further hardened by heating and cooling, I was wondering more along the lines of whether the boron alloy steel would be softened by heating followed by SLOW cooling.

Heating and rapid cooling followed by a hammer and chisel (remember how they used to "cut" diamonds?) sounds like an alright way to go however.

[ghill]

Here's what I would do

1st of all get a large 4500psi paintball HPA tank (high pressure air). Those of you who play paintball should know what i'm talking about.:D This will alow maximum portability and minimal wheight. Although a larger volume of CO2 can be compressed into the same sized tank you will find that rapid discharge of CO2 is very endothermic (cold) and will cause lots of water to condence on the tool you are using. If you go the CO2 route a CO2 tank will be much cheaper than a HPA tank though you will need to fully seal the tool and make sure it stays free of moisture and that it can handle the very low temperture you will encounter. This tank should work good for HPA: Crossfire Fixed High Pressure N2 Tank - 114ci 3000psil.

2nd You will also need a pressure regulator no matter what route you go. Here is the rock regulator http://www.palmer-pursuit.com/online-catalog/rock.htm you can ajust it from 0-300 pressure output to your tool.

3rd You will need a high speed die grinder around 28,000 rpm you can find the perfect one here http://www.thetoolwarehouse.net/shop/CP-876.html

4th You still need a cutting wheel. Here are the best cutting wheels around. Trust me I would know;) Gyros Precision Tools 3 1/2 in ST wheel. http://www.gyrostools.com/product.asp?table=Product&key=category&value=STFIBER&key=mfg&value=ALL&description=Fiber+Disks+%2D+Super+Tensile you will need to buy a mandrel from them also:rolleyes:

5th You will need fittings to put it all together. Your on your own there:D Try talking to the guys from palmers persuit shop they are really helpful.

Ps. The cutting wheels say max 26,000rpm but they can pull 30,000rpm without a problem at all. With my setup I run the wheels at a constant 32,500rpm and never once have had a problem.

-ghill

[Jacks Complete]

From my studies, steel generally becomes "over hard" when rapidly cooled from red heat. It becomes so hard that it is brittle as anything, and a 2mm wire which was strong and just about bendable with pliers will simply snap when force is applied.

You can sometimes soften it by red then slow cooling, but it doesn't tend to work on anything exotic, as they are designed to stay hard.

[Third_Rail]

You might also be able to extend this idea of active thermal sheilding to things like car engines and gun barrels, too.


Already covered the gun barrels. I use a CO2 discharger bought for black powder purposes rigged to disperse CO2 into the suppressor after each shot to keep everything cool and quiet.

In my dreams, of course.

[IronMongrel]

I think portable oxy/acetylene is your best bet for quietness, on a side note, if you wanted to get through sheet steel, you can get cordless nibblers, which are a pretty usefull tool all round anyway, and they can cut 1m/min.

[Jacks Complete]

Nibblers are a bit rubbish for most things, as they make lots of noise, and you need to drill a big hole to get them started. They also die a horrible death when they meet a seam or weld, and get stuck when you get to anything over 1.2mm thick.

Portable oxy/acetyl. is only relative! And there is a big flame that is nothing if not obvious, even in a CO2 atmosphere.

Those little cutting discs are going to be ok for a few jobs, but only if you only need to cut through a few mm to 10mm of metal at most. For a chain and padlock, it will work great, but for a door or a container you aren't going to get far. You want the same things, only scaled up. My dad gave me some, special import from Germany, and you should see them cut through steel! 1mm thick, doing 3000 RPM with a 4.5" disc in an angle grinder.

The other great tool, is the Rage blade for metal cutting. You run it in a special saw that does about 2200RPM, but I use a standard circular saw. It's a carbide blade that cuts through "up to 10mm of steel" - that's an underestimate! I ran it through a double thickness of fairly hard hot rolled 40 x 40 x 6mm angle iron in one go! That's 46mm of steel, and I did the cut at 45 degrees, too! Not a problem, and very little sparking. If I had to chop a safe open, I bet it would do the job. And the disc doesn't wear down, either.

[nbk2000]

http://evolutionrage.com/rage_wm.wmv