FTL writes "While in orbit a metal knob floated between a window and the dashboard of Atlantis. Once back on Earth, the shuttle contracted, wedging the knob firmly in place and damaging the window. Initial attempts to free the knob have failed and engineers may need six months to disassemble that section of the orbiter. Given that the shuttle program will probably end next year anyway, such a delay might mean scrapping Atlantis early rather than repairing it. Efforts to remove the knob using less invasive techniques continue."
The article neglects to mention the extreme disappointment of John M. Grunsfeld who spent the majority of Mission STS-125 photographing a strange phenomenon he could witness through his window but could not detect on radar. A large knob-shaped object would move about above the atmosphere with an almost supernatural fluidity and change of speeds relative to the Earth. He neglected to mention it to his crewmates hoping that he had stumbled upon either the first contact with alien life or observed a new phenomenon he dubbed in his journal "Grunsfeld's Effect." Unfortunately the engineers at NASA have immortalized his name by calling the stuck debris "Grunsfeld's Knob" or "Grunsfeld's God." The engineers have also started referring to being duped as "being grunsfelded." Example: "I called up to order some of those damn Video Professor instructional DVDs and ended up with 8 of the stupid things. Man did I get Grunsfelded!"
Or is that only an outer protective layer? I know I've seen pictures of the pitting that micrometeors and paint flecks have caused on the Shuttles while in orbit, I just assumed they were made to be easily replaced.
Or is that only an outer protective layer? I know I've seen pictures of the pitting that micrometeors and paint flecks have caused on the Shuttles while in orbit, I just assumed they were made to be easily replaced.
The article isn't wholly clear, but implies that there are three layers of glass, only the outer one gets replaced. The inner ones have never been replaced on any shuttle. The innermost one is the most important for retaining the internal pressure, and is the one that has sustained damage.
And to be clear, if you read the article, it's obvious that the engineers working on this are SERIOUS and have thought of just about anything that slashdot readers have come up with. Drill/cut? Too high risk because of (a) vibrations transmitted to the window and microgrinding of the knob against the window and (b) metallic dust it will generate. Pressurize orbiter? Yep. For some reason, they think they can only get it to +3 PSI. Might help. Apply cold to the knob to shrink it? Yep. They tried dry ice. Didn't work. (My guess is that they'll try liquid nitrogen, too at some point.) They're planning on trying dry ice and pressurization at the same time. Apply downward pressure to the dash with a crobar? Probably very risky because of unknown damage it might cause to dash.
Once the knob is out, they'll make visual inspection of the remaining surface, including taking microscopic moldings to assess the damage. The pane is tempered, so scratches are a big problem, as they can lead to spontaneous, catastrophic failure.
... the engineers working on this... have thought of just about anything... Drill/cut?... Pressurize orbiter?... Apply cold to the knob to shrink it?
How about tying a string to the knob (so it doesn't get away), reheating the orbiter, and pressurizing it - recreating the situation (except for zero G) that let it float in in the first place?
Why not spray a sealant around the surrounding materials, lay in an extraction nozzle attached to a pump, pour a mold around it then use a chemical to dissolve the metal, at least the edges of the metal, enough to remove it? No vibrations, no pressure, no crazy coolant or heating solutions. You can pick a site to work on that is least risk, such as the area in contact with the glass (assuming the glass isn't affected by the chemicals dissolving the metal).
I for one am completely comfortable with calling in a local contractor and installing some new money-saving vinyl windows which will be the only thing between me and seventeen thousand mile per hour wind.
Excellent and informed analysis. However, I think it is unlikely that "metal" knob could scratch glass. See the Moh hardness scale.
Hmm. You're saying you know what the knob is made of, and what the surface treatment of that material is? If, for example, it's aluminum with an anodization (as it looks to be in the photo), it may well scratch the glass. Scratching isn't the only issue, though, as if sufficient pressure has been applied, localized microscopic deformation might have occurred as well. If the compression layer of the tempered glass has been breached, the glass will fail. If it has been damaged beyond the stated engineering guidelines, as described in the article, the window will need to be replaced. The close up image in the article shows what appears to be damage to the glass at two points where the glass contacts the knob.
It's a simple problem that many of us have faced in one situation or another where something small has managed to get wedged where it shouldn't, and requires extraction. The difference here is that there are serious, and potentially highly costly, either in dollars or in human life, or both, potential ramifications to performing the extraction badly.
pencils contain graphite. graphite conducts electricity. graphite powder is generated when you rub it up against paper to write stuff. graphite powder gets everywhere in microgravity, including behind control panels, into switches, and sensitive electrical components.
i'm glad you're not in charge of so much of a paperclip at NASA.
Fisher developed the pen at their own expense NASA only had to buy the pens, at the same price the general public could I might add.
You know, just a little research would keep you from looking quite so stupid. As a personal note you might try not being an ass, just for fun.
re: http://en.wikipedia.org/wiki/Space_Pen [wikipedia.org] NASA never approached Paul Fisher to develop a pen, nor did Fisher receive any government funding for the pen's development. Fisher invented it independently, and then asked NASA to try it. After the introduction of the AG7 Space Pen, both the American and Soviet (later Russian) space agencies adopted it. Previously both the Russian and American astronauts used grease pencils and plastic slates
Cutting would obviously be done by hand, or with a very slow speed reciprocating saw, which produce minimal vibration. They'd probably encase the whole thing in epoxy first to further reduce vibration.
Movement of the knob against the glass, no matter how slow, is potentially going to grind the glass away. Encasing the knob in epoxy isn't going to help unless the epoxy is also adhering to the glass to prevent relative motion between the knob and glass. And, in that case, there's the difficulty of removing the epoxy afterward. Could be done, but probably not a very good approach, and certainly not without risk.
If scratches can lead to "spontaneous catastrophic failure" in the window material then obviously there is zero risk because the window must have a strong scratch-proof covering, probably a thin layer of plexiglas or similar. Otherwise trivial incidents over the course of the shuttle's working life would pose an unacceptable risk--anything breaking loose on re-entry, in particular, could scratch the surface if it was not heavily protected.
The article (you did read the article before spouting off, right?) does not describe any coati
and is underfunded and ending soon anyways, give atlantis the same proper ghetto treatment a contemporary of its time would receive, like 25 year old plymouth horizon: plastic sheeting and duct tape
also knock out a back tail light and finger daub "wash me" in the cosmic dust on its hood
They need to call one of those chip-and-crack auto glass replacement people that I hear on the radio all the time. They come out to your workplace to do the job, and best of all, you only pay the insurance deductible!
I know how they feel: Toyota's quoting me $400 to fix a loose sun visor because they have to take the entire @&%#! side of the car apart to get to it.
Try replacing a heater core in a modern car - usually the entire dash assembly has to be removed to get it out. Figure out how much a factory shop is going to charge you for that.
Better than the Chevy 2.8L transverse V6 I suppose. The section of the shop manual for replacing spark plugs starts with: "Unbolt the dogbone and engine mounts and rotate the eng
...you read that as "Stuck Know Causes Serious Windows Damage To Atlantis", and think "How the hell do they know what OS they were using on that sunken island?"
I just know realized, that even my question does not make any sense...
why not just put it in a vacuum chamber, warm it up, and slide it on out?
What, you mean like they discussed in the article? They even came up with a better idea: instead of heating up the whole vessel, just freeze the knob with dry ice!
The options relating to the application of dry ice to shrink the knob have already been attempted, and failed. However, the same method, along with a pressurization of the Crew Module, may be enough to free the knob from its lodged position.
The only problem is the amount of pressurization that can be conducted in the OPF is far less than the pressure that played a part in allowing the knob to become embedded in the first place.
Pressurize crew module and dry ice on knob to TBD (To Be Determined) pressure. Pro's: Could allow for uniform structural deflection to increase gap between pressure pane and dashboard; enough to free up the knob non-destructively. Less potential for inducing further damage to the pane.
**UPDATE: The above option was selected on Thursday as the opening process for an attempt to remove the knob. The cabin will be pressurized to 3 psid, before an engineer will apply dry ice to the knob. This option is not deemed to be a likely solution, but more so the opening option that avoids additional damage to the window.**
Although it's lengthy, you should try reading the article next time. The guys at NASA are pretty clever.
Yeah this was my thought too as soon as I read "dry ice". Just freeze it and smack it. I'm sure the reason why not is because the fragments will only cause more damage once in space.
Try this, for educational purposes:
Drop a piece of aluminum or steel into a bucket of liquid nitrogen. Now take it out and drop it on the ground from a height of 6 feet, or hit it with a hammer. Notice it not shattering.
The first time I dropped a 10 pound block of aluminum while taking it out of a nitrogen bucket I expected it to shatter, too. Then I realized I thought that because of hollywood.
In my case it was soaking the steel in liquid nitrogen for 15 minutes, then hitting it with a whopping big hammer with a knife edge at the end of a three foot long pendulum that had swung through 120 degrees or so. With most steels a 10mm cross section won't even break all of the way through under such treatment. Those that do are usually rubbish in any sort of cold weather. The "Hollywood style" liquid nitrogen brittleness is best seen with some plastics and rubbers - there is a glass transition temperature below which the material is very brittle. You can do the rick of smashing a rubber dog toy into fragments with a hammer after soaking it in liquid nitrogen for a few minutes. Polyethylene as in cling wrap doesn't do this (which is dissappointing. Anything with a lot of water (eg. a banana) will of course freeze and smash just like ice. An important safety tip is to wait some time before placing the frozen banana in your mouth or it will burn your tongue (my classmate that did that now works in an explosives factory but is still intact last I heard).
Well, since everyone else is throwing in their idea, here's mine.
How about a very low-speed, low pressure diamond wire-saw?
For example: SXJ-2 Precision Endless Wire Saw - 840 mm long, 0.35 mm dia. Diamond Loop Wire (that's a continuous loop - they'd need to cut it, and re-attach it after wrapping it around the knob).
They could feed the flexible saw wire around around the knob and adjust the cutting pressure to keep it as safe as they want to be. If it's just a wire coated in diamond dust or the like, it wil
Why not just apply extremely localised extreme heat to critical areas on the knob, collapse it and remove the new shape?
Why not just pull it really hard?
Why not chisel it really hard...etc.
You and me could think of a bunch of stuff; NASA could think of a bunch of stuff and properly assess how likely it is to work vs how likely it is to damage the shuttle vs how much it will cost and so on.
FAO any other Monday morning quarterbacks, armchair rocket scientists, and other self-appointed experts and "why don't they just" merchants out there who never seem to consider that the people working on the thing might actually have thought about what they are doing, quoth TFA:
"Induced damage of the knob being wedged between the glass and the dashboard closeout panel structure, or from removal of the knob could result in unacceptable damage.
"Consequences of unacceptable damage to the glass pane: Replacing the pressure pane would result in a significant impact to ground schedule (potential 6+ month impact). Requires de-configuring dashboard structure and instrumentation to remove window assembly for refurbishment. Windshield pressure pane removal has never been performed at KSC.
"Knob removal must be performed carefully; exhausting all risk free options first, then attempting more intrusive (higher risk) options, if others fail."
As someone else earlier suggested, why not dissolve it? There are acids with high enough electronegativity differences to dissolve just about anything. If the acid were brushed on to the a sufficiently narrow part of the knot, and all collected as it dripped down, it would in time etch that part of the metal away enough to break it and hence dislodge the knob. Of course, it would have to be secured first so it doesn't collapse when it shouldn't. But that seems less invasive if more time-consuming. However,
If the acid were brushed on to the a sufficiently narrow part of the knot, and all collected as it dripped down
We've used a similar technique in one of our workshops, but there's no need to brush and collect - you use an inert sponge and/or capillary tube to circulate the etchant. Likewise, you don't need to use acids which produce potentially corrosive fumes and aerosols. A solution of copper sulphate and sodium chloride will do the job nicely with less risk.
Knobs do not belong in vacuum cleaners. And once it warms up, there's no pulling it out of anything. There was one bad evening I did get my knob suck it something. Don't mix up lube and super glue.
I have found the that the main difference between a $20K car and a $50K car is that the $0.20 parts get replaced with $0.50 parts. Not shaving every possible penny on every possible part seems to help a lot quality-wise. I just wish I could buy the $21K car with just those parts upgrades!
The radio that came with my 99 Grand Am has an incandescent bulb to light up the display. No way to easily replace it, in order to fix it I had to pull the whole radio apart. Tell me that's not planned obsolescence. Oh and if I ever find the guy that designed the headlights I'm going to kick him square in the nuts.
The Inanimate Carbon Knob! (Score:5, Funny)
Re: (Score:3, Funny)
Did he have a sex change?
Aren't the windshields replaced all the time? (Score:5, Interesting)
Re:Aren't the windshields replaced all the time? (Score:5, Informative)
Or is that only an outer protective layer? I know I've seen pictures of the pitting that micrometeors and paint flecks have caused on the Shuttles while in orbit, I just assumed they were made to be easily replaced.
The article isn't wholly clear, but implies that there are three layers of glass, only the outer one gets replaced. The inner ones have never been replaced on any shuttle. The innermost one is the most important for retaining the internal pressure, and is the one that has sustained damage.
And to be clear, if you read the article, it's obvious that the engineers working on this are SERIOUS and have thought of just about anything that slashdot readers have come up with. Drill/cut? Too high risk because of (a) vibrations transmitted to the window and microgrinding of the knob against the window and (b) metallic dust it will generate. Pressurize orbiter? Yep. For some reason, they think they can only get it to +3 PSI. Might help. Apply cold to the knob to shrink it? Yep. They tried dry ice. Didn't work. (My guess is that they'll try liquid nitrogen, too at some point.) They're planning on trying dry ice and pressurization at the same time. Apply downward pressure to the dash with a crobar? Probably very risky because of unknown damage it might cause to dash.
Once the knob is out, they'll make visual inspection of the remaining surface, including taking microscopic moldings to assess the damage. The pane is tempered, so scratches are a big problem, as they can lead to spontaneous, catastrophic failure.
Parent
How about reheating the orbiter to expand it again (Score:4, Funny)
... the engineers working on this ... have thought of just about anything ... Drill/cut? ... Pressurize orbiter? ... Apply cold to the knob to shrink it?
How about tying a string to the knob (so it doesn't get away), reheating the orbiter, and pressurizing it - recreating the situation (except for zero G) that let it float in in the first place?
Parent
Re:Aren't the windshields replaced all the time? (Score:5, Interesting)
Why not spray a sealant around the surrounding materials, lay in an extraction nozzle attached to a pump, pour a mold around it then use a chemical to dissolve the metal, at least the edges of the metal, enough to remove it? No vibrations, no pressure, no crazy coolant or heating solutions. You can pick a site to work on that is least risk, such as the area in contact with the glass (assuming the glass isn't affected by the chemicals dissolving the metal).
Parent
Re:Aren't the windshields replaced all the time? (Score:5, Funny)
Parent
Re:Aren't the windshields replaced all the time? (Score:5, Insightful)
Excellent and informed analysis. However, I think it is unlikely that "metal" knob could scratch glass. See the Moh hardness scale.
Hmm. You're saying you know what the knob is made of, and what the surface treatment of that material is? If, for example, it's aluminum with an anodization (as it looks to be in the photo), it may well scratch the glass. Scratching isn't the only issue, though, as if sufficient pressure has been applied, localized microscopic deformation might have occurred as well. If the compression layer of the tempered glass has been breached, the glass will fail. If it has been damaged beyond the stated engineering guidelines, as described in the article, the window will need to be replaced. The close up image in the article shows what appears to be damage to the glass at two points where the glass contacts the knob.
It's a simple problem that many of us have faced in one situation or another where something small has managed to get wedged where it shouldn't, and requires extraction. The difference here is that there are serious, and potentially highly costly, either in dollars or in human life, or both, potential ramifications to performing the extraction badly.
Parent
Re:Scrap it! (Score:4, Informative)
pencils contain graphite. graphite conducts electricity. graphite powder is generated when you rub it up against paper to write stuff. graphite powder gets everywhere in microgravity, including behind control panels, into switches, and sensitive electrical components.
i'm glad you're not in charge of so much of a paperclip at NASA.
Parent
Re:Scrap it! (Score:5, Informative)
Parent
Re:Scrap it! (Score:5, Informative)
Nope sorry p51d007
Fisher developed the pen at their own expense NASA only had to buy the pens, at the same price the general public could I might add.
You know, just a little research would keep you from looking quite so stupid.
As a personal note you might try not being an ass, just for fun.
re: http://en.wikipedia.org/wiki/Space_Pen [wikipedia.org]
NASA never approached Paul Fisher to develop a pen, nor did Fisher receive any government funding for the pen's development. Fisher invented it independently, and then asked NASA to try it. After the introduction of the AG7 Space Pen, both the American and Soviet (later Russian) space agencies adopted it. Previously both the Russian and American astronauts used grease pencils and plastic slates
Parent
Re: (Score:3, Insightful)
Cutting would obviously be done by hand, or with a very slow speed reciprocating saw, which produce minimal vibration. They'd probably encase the whole thing in epoxy first to further reduce vibration.
Movement of the knob against the glass, no matter how slow, is potentially going to grind the glass away. Encasing the knob in epoxy isn't going to help unless the epoxy is also adhering to the glass to prevent relative motion between the knob and glass. And, in that case, there's the difficulty of removing the epoxy afterward. Could be done, but probably not a very good approach, and certainly not without risk.
If scratches can lead to "spontaneous catastrophic failure" in the window material then obviously there is zero risk because the window must have a strong scratch-proof covering, probably a thin layer of plexiglas or similar. Otherwise trivial incidents over the course of the shuttle's working life would pose an unacceptable risk--anything breaking loose on re-entry, in particular, could scratch the surface if it was not heavily protected.
The article (you did read the article before spouting off, right?) does not describe any coati
Re: (Score:3, Funny)
They are easy to replace FOR A SPACE SHIP.
finally, a use for a dremel tool (Score:2, Funny)
they can borrow mine. I never use it.
Re:finally, a use for a dremel tool (Score:5, Funny)
they can borrow mine. I never use it.
I read your comment before reading your title and assumed you meant your knob.
Parent
Re: (Score:3, Funny)
belly lol.. me too ;o)
NASA forgot low tech approaches? (Score:2)
Saw. The one in the form of elastic cutting "wire".
Re: (Score:3, Funny)
Yeah, why didn't those rocket scientists think of using a magnet to clean up aluminum dust - what losers!
Re: (Score:3, Insightful)
Magnets for aluminum. Sure.
missed opportunity (Score:4, Funny)
Title suggestion: "Shuttle has a Wedgie"
Well, it works with dogs... (Score:3, Funny)
Throw a bucket of cold water on it and the knob should slip right out.
Re:Well, it works with dogs... (Score:4, Funny)
How did you get a knob stuck in a dog?
Parent
since the shuttle programming is so old (Score:5, Funny)
and is underfunded and ending soon anyways, give atlantis the same proper ghetto treatment a contemporary of its time would receive, like 25 year old plymouth horizon: plastic sheeting and duct tape
also knock out a back tail light and finger daub "wash me" in the cosmic dust on its hood
Well... (Score:2, Funny)
Listen to the radio ads (Score:5, Funny)
Been there done that (Score:5, Funny)
I know how they feel: Toyota's quoting me $400 to fix a loose sun visor because they have to take the entire @&%#! side of the car apart to get to it.
Re: (Score:3, Interesting)
Try replacing a heater core in a modern car - usually the entire dash assembly has to be removed to get it out. Figure out how much a factory shop is going to charge you for that.
Better than the Chevy 2.8L transverse V6 I suppose. The section of the shop manual for replacing spark plugs starts with: "Unbolt the dogbone and engine mounts and rotate the eng
Dissolve it (Score:5, Interesting)
Re:Dissolve it (Score:5, Funny)
Don't you think dissolving the space shuttle is overkill?
Parent
Re:Dissolve it (Score:5, Funny)
Look, do you want the knob back or not?
Parent
Stuck knob (Score:5, Funny)
If this condition lasts for more than 4 hours, call a doctor.
You know you should go to bed, when... (Score:5, Funny)
...you read that as "Stuck Know Causes Serious Windows Damage To Atlantis", and think "How the hell do they know what OS they were using on that sunken island?"
I just know realized, that even my question does not make any sense...
New Eternal Question. (Score:3, Funny)
I'm know I'm not smarter than nasa, but... (Score:3, Insightful)
why can't they put postive pressure inside the orbiter and pop it out?
but a better question perhaps, is why the hell is there junk rolling around inside the space shuttle?
Re:physics (Score:5, Informative)
why not just put it in a vacuum chamber, warm it up, and slide it on out?
What, you mean like they discussed in the article? They even came up with a better idea: instead of heating up the whole vessel, just freeze the knob with dry ice!
The options relating to the application of dry ice to shrink the knob have already been attempted, and failed. However, the same method, along with a pressurization of the Crew Module, may be enough to free the knob from its lodged position.
The only problem is the amount of pressurization that can be conducted in the OPF is far less than the pressure that played a part in allowing the knob to become embedded in the first place.
Pressurize crew module and dry ice on knob to TBD (To Be Determined) pressure. Pro's: Could allow for uniform structural deflection to increase gap between pressure pane and dashboard; enough to free up the knob non-destructively. Less potential for inducing further damage to the pane.
**UPDATE: The above option was selected on Thursday as the opening process for an attempt to remove the knob. The cabin will be pressurized to 3 psid, before an engineer will apply dry ice to the knob. This option is not deemed to be a likely solution, but more so the opening option that avoids additional damage to the window.**
Although it's lengthy, you should try reading the article next time. The guys at NASA are pretty clever.
Parent
Re: (Score:2)
Re:physics (Score:4, Informative)
Yeah this was my thought too as soon as I read "dry ice". Just freeze it and smack it. I'm sure the reason why not is because the fragments will only cause more damage once in space.
Try this, for educational purposes:
Drop a piece of aluminum or steel into a bucket of liquid nitrogen. Now take it out and drop it on the ground from a height of 6 feet, or hit it with a hammer. Notice it not shattering.
The first time I dropped a 10 pound block of aluminum while taking it out of a nitrogen bucket I expected it to shatter, too. Then I realized I thought that because of hollywood.
Parent
Re:physics (Score:4, Informative)
The "Hollywood style" liquid nitrogen brittleness is best seen with some plastics and rubbers - there is a glass transition temperature below which the material is very brittle. You can do the rick of smashing a rubber dog toy into fragments with a hammer after soaking it in liquid nitrogen for a few minutes. Polyethylene as in cling wrap doesn't do this (which is dissappointing. Anything with a lot of water (eg. a banana) will of course freeze and smash just like ice. An important safety tip is to wait some time before placing the frozen banana in your mouth or it will burn your tongue (my classmate that did that now works in an explosives factory but is still intact last I heard).
Parent
Re: (Score:3, Funny)
The guys at NASA are pretty clever.
Oh come on - it's not like they're rocket scientists or anything! :) :) :)
Re:physics (Score:5, Funny)
I used to do tech support at Honeywell. Had real rocket scientists there. Called them my brilliant idiots.
Parent
Re: (Score:3, Interesting)
Well, since everyone else is throwing in their idea, here's mine.
How about a very low-speed, low pressure diamond wire-saw?
For example: SXJ-2 Precision Endless Wire Saw - 840 mm long, 0.35 mm dia. Diamond Loop Wire (that's a continuous loop - they'd need to cut it, and re-attach it after wrapping it around the knob).
They could feed the flexible saw wire around around the knob and adjust the cutting pressure to keep it as safe as they want to be. If it's just a wire coated in diamond dust or the like, it wil
Re: (Score:2, Insightful)
Why not just apply extremely localised extreme heat to critical areas on the knob, collapse it and remove the new shape?
Why not just pull it really hard?
Why not chisel it really hard ...etc.
You and me could think of a bunch of stuff; NASA could think of a bunch of stuff and properly assess how likely it is to work vs how likely it is to damage the shuttle vs how much it will cost and so on.
Re:physics (Score:5, Informative)
FAO any other Monday morning quarterbacks, armchair rocket scientists, and other self-appointed experts and "why don't they just" merchants out there who never seem to consider that the people working on the thing might actually have thought about what they are doing, quoth TFA:
"Induced damage of the knob being wedged between the glass and the dashboard closeout panel structure, or from removal of the knob could result in unacceptable damage.
"Consequences of unacceptable damage to the glass pane: Replacing the pressure pane would result in a significant impact to ground schedule (potential 6+ month impact). Requires de-configuring dashboard structure and instrumentation to remove window assembly for refurbishment. Windshield pressure pane removal has never been performed at KSC.
"Knob removal must be performed carefully; exhausting all risk free options first, then attempting more intrusive (higher risk) options, if others fail."
Parent
Re: (Score:3, Insightful)
As someone else earlier suggested, why not dissolve it? There are acids with high enough electronegativity differences to dissolve just about anything. If the acid were brushed on to the a sufficiently narrow part of the knot, and all collected as it dripped down, it would in time etch that part of the metal away enough to break it and hence dislodge the knob. Of course, it would have to be secured first so it doesn't collapse when it shouldn't. But that seems less invasive if more time-consuming. However,
Re:physics (Score:4, Informative)
We've used a similar technique in one of our workshops, but there's no need to brush and collect - you use an inert sponge and/or capillary tube to circulate the etchant. Likewise, you don't need to use acids which produce potentially corrosive fumes and aerosols. A solution of copper sulphate and sodium chloride will do the job nicely with less risk.
Parent
Re:physics (Score:4, Funny)
Knobs do not belong in vacuum cleaners. And once it warms up, there's no pulling it out of anything. There was one bad evening I did get my knob suck it something. Don't mix up lube and super glue.
Parent
Re: (Score:3, Insightful)
Re:pressure (Score:5, Funny)
<Slaps Head> Of course! The answer is in the article. Phone NASA and tell them to read it.
Parent
Re: (Score:3, Insightful)
I have found the that the main difference between a $20K car and a $50K car is that the $0.20 parts get replaced with $0.50 parts. Not shaving every possible penny on every possible part seems to help a lot quality-wise. I just wish I could buy the $21K car with just those parts upgrades!
Re: (Score:3, Funny)
The radio that came with my 99 Grand Am has an incandescent bulb to light up the display. No way to easily replace it, in order to fix it I had to pull the whole radio apart. Tell me that's not planned obsolescence. Oh and if I ever find the guy that designed the headlights I'm going to kick him square in the nuts.