As an engineer and aviation fan, I want to thank you a thousand times for sharing that knowledge with us! Very interesting and informative video - why aren't more videos on youtube like yours...? Thumbs up!!
At 05:30 these coils are torque motors using eddy currents. They are connected to the mercury tilt switches we can see at 07:49. This permits to keep the gyro rotor vertical.
Probably the only way to do it at the time, and it is pretty well contained - maybe the reason for covering it in that black goop was so nobody spotted it...!
Hey mike, thanks for sharing this. It's a great way for some of us to visualize what's inside instead of imagining all the time. I don't know if someone else has already shared this but I want to write anyway: That "Fast Erect" button works in that there is an additional pair of contactors added to the tilt switch, one at each end of the mercury tube. These contactors are connected via a button to power supply; this supply is at a higher voltage than the normal erection system. That way, if the gyro is seriously misaligned, the pilot can choose the press the fast erect button and connect power to the relevant torque motor. Since it is at a higher voltage than the normal erection system, the gyro will erect rapidly enabling the attitude indicator's gyro to realign to its vertically tied position.
I've never seen "Fast Erection" on a gyro before, I'm guessing its the same as "Quick Erect" or the common "PULL TO CAGE" which allows the pilot to quickly re-calibrate zero. I've got a 70s or 80s attitude indicator in the same state of disrepair as yours. Mine has a slight drift which i suspect is a bad bearing. Its too nice of a instrument to bring myself to try to repair it, yet its likely no longer worth the cost of a professional re-build. Amazing craftsmanship inside these things! -sj
Lovely piece of engineering. It's amazing to think that all this work went into producing similar devices for WWII aircraft, for them to be blown out of the sky after 1 or 2 flights. For the 3 phase supply, could you not use a car alternator (being spun with a electric drill, wheelchair motor, etc) with its regulator pack taken off, and then run the phases out into a transformer? If it works, could be simpler than re purposing an Amp. Love to see the Gyro in action!
Wow, fantastic piece of kit! The quick erection is probably indeed using the coils that you pointed out - the quick erection function becomes necessary if you manage to topple the gyro with some reckless maneuvering or if power is lost long enough for the gyro to spin down and lose alignment.
The Erect button is basically a reset switch to center the gyro. When the gyro is started while the aircraft is still on the ground it will be at some arbitrary position and pushing the button will move the artificial horizon to the wings level, horizontal flight position. As mechanical gyros like this one will drift over time they have to be reset once in a while. This has to be done in level flight otherwise an error is introduced to the indication.
Mike, with this gyro, did you pick if the rotating mechanism actually was jeweled - ie, has a synthetic ruby at the pivot point? Have you got a tear down of an optical gyro?
BTW the spinner at the end of the gyro might be the equivalent of a plumb line. From the video it seems to be just slightly unbalanced. So in a straight flight it will settle toward the vector of gravity (sorry if this is not the correct english word) and with the pickups the gyro can then compensate for any drifts around the roll axis. Of course this bias needs to be very small to not disturb the indications while the aircraft is turning and pitching (where the g's might be all over the place)
Hello, I got a few aircraft attitude indicator gyros, one of them is a sperry MK1 witch internals are pretty much similar to the ones you show on your video. The coils you named 'synchro resolvers' are actually 2 motors, one for pitch and another for roll. This motors are used to center the horizon on startup and on fast erect button when pressed. When doing extremely maneuvers the gyro can block itself and therefor show a fake horizon, then you'll use the fast erect button.
my faith in humanity is quite often tested and sometimes I feel as though I will never claw it back, but when I see the insides of things like this and electronics in general I realize how an amazing a species we are - well some of us anyway.
+Dr Tune yeah, he's really clever at these on-the-fly things like that which come from remembering ALL your electronics training really well and great brainstorming power.
Hey there. I'm a pilot and I found your video very interesting. I think it's good to know a little more on how my equipment works. The fast erect basically aligns the attitude indications by centering the gyro and the components. The only time I use it is right after I start the engine on the airplane. This is because this instrument is vacuum powered. It takes a while to build 4.5 to 5.5 psi in the system. So.at low psi I like to pull the erect to get my insinuations while on the ground.
I would say get a 120v VFD, like one used to run on US current for running 3 phase motors. Or a VFD with adjustable output voltage. Set it to 115v 400hz and there you go. Using audio amplifiers for this like you said is touchy, much better to have a real variable frequency drive that is designed to run motors.
In your opinion, do you think sliding connectors are usable for this? the issue was that theese connectors have an non neglectable contact potential. the instrument will measure e-fields in the order of ~some V/m in a very hostile enviroment, (charge buildup, solar radiation of 14kW/m thermal fluctuations, ionizing rad. and so on)
I wonder how long it takes to assemble a mechanical beast like this. There's alot of individual pieces in there. Very interesting to see the insides of it for sure.
in your opinion , how does the gyro compensate for the curve of the earth? Does a plane not always have to fly in a downward incline, yet a gyro indicates flat. I don't seem to understand how drift with a compass can compensate . My understanding is that every six hours this is needed as a gyro is not accurate over long periods of time. When flying around the earth I would think the gyro would max out as you went in a constant downward trajectory. Is the mechanism mechanical or electrical?You seem like the type that would know how this might work. -thanx, just curious.
+Robert Gelinas " Does a plane not always have to fly in a downward incline" No. Planes don't have to fly down. A plane can take off, fly level, and land without its nose ever going below its tail. In fact, when flying at a constant altitude, the plane (or at least its wings) is pointing "up" to counter the gravity pulling it down.
thank you for answering my question. I was concerned about the planes ability to compensate for the curve of the earth. If the plane always flew at a level flight path would it eventually fly up of the earth becuase of the curve? I understand the need to point up to avoid going down, however, a gyro keeps the plane flying flat. I am trying to understand if the gyro can somehow compensate for the earths curve and not fly flat. My understanding is that a gyro is independent of gravity. Is this true?
believe it or not but some people believe the earth is flat and a gyro is evidence of "no curve" in the earth or the earth not being a ball since if it was, when you stay flying flat you will "rise" away from the ball earth.
+Robert Gelinas Flat-earthers do not understand how attitude indicators work and they assume that the fact that those instruments actually follow an airplane's path around the globe "proves" that the world is flat. What they don't know (or pretend not to know) is that attitude indicators have erection mechanisms that continuously torque the instrumento to the local vertical and it is this constant torque that makes the gyro know in the long term which way is "up". This is a very small force and takes a long time (order of minutes) to act on the gyroscope, but enough to overcome the gyro's precession as the airplane travels around the world. In short, airplane atitude indicators have erection mechanisms that continuously adjust it to the local vertical wherever it is on the globe.
interesting. I've never heard of this erection mechanism. After reading about it , this makes sense. It checks for plum periodically and adjusts the gyro by means of an air pressured and vacuumed balance,. accordingly. Thanx for the info.
Fascinating. What a quality piece of engineering. I really wonder whether anyone could design one of those today.... It is also amazing to consider that this bulky thing's function can be performed by a small chip in my phone now...!
it would be cool to have instruments like this. Would be extra fun if it was actully posible to hook them up to an flight sim. Allthough most older ones that are mecalincal thats kinda inpossible. But i love the engeering that gone into making something like this!!!
they work via a vacuum running off a pump..............The best programme to watch is "A Plane Is Born" gives you alot of info on electronics and avionics of the aircraft :) This type of Avionics gives you the angle of bank of the wings and tells you the pitch of the aircraft
ok, it's most likely synchronous, so some "BLDC controller" would be best. a slow ramp-up can do too, but your best guess would be the HDD board. PM me if you want my help in figuring it out, I don't want to fill mike's video with a lot of chat. Do tell if you figure out the motor.
that "fine wired thing" on the end looks like a resolver for position feedback, KUKA robots use similar things as an encoder on their motor. It's only my guess....
the construction goes to a great length to avoid sliding connectors making it increadebly complicated. the design was decided a long time ago, maybe sliding connector performance has been improved by now.
There could be a common system called ARINC that put specific voltages that indicate pitch and roll that are universally accepted. They usually work in tantum with a flux which is a faceless compos that indicate voltages corresponding to compos headings. It auto-corrects the gyro to the compos headings
Extremely interesting video thanks. I have an old bronze gyro and have been trying to get it running for years now! I was told by Sperry Rand in the 70s that the specs were still classified although it's obviously 1930-1940 era. Lately no one will tell me what voltage or hertz but I did think 400hz 80-150 volts. Fascinating electro mechanical engineering. Cheers for your insights
Looking forward to seeing it spin up to full speed, always been fascinated by gyroscopes. (Need a chrome plugin that can auto thumbs up/like your videos ;)
in this video some sliding connectors are shown, I work as a mechanical engineer with a pice of mechanics (a satellite E-field sensor) that works by winding out a couple of sensor probes ~15m in opposite directions,
You can drive that thing smooth as butter with an Avanced Motion Controls S16A8B sinusoidal servo driver. They don't have a lot of "smarts" in them, so you can just feed them two differential sine waves 120 degrees apart from your function generator. Easy way to make a very controlled 3 phase power supply. Also, very cheap on ebay.
I know it's an old comment, but I've seen a lot of aircraft instrumentation, and practically all of it, military or civilian, has the "Handle like eggs" text on it. Maybe it started as a joke long long ago, but it's definitely the standard now. It makes sense - many of these devices are very intolerant to high-G shocks and knocks.
Does modern aircraft say Boeing 747 uses electromechanical gyros or the MEMS type? BTW, this tear down is awesome, something, that I always wanted to see in real.
I think those coils are no synchro-resolver because the stator coil is missing. I think those are "torquer" or "torquer motors" in order to align the virtual horizon in the roll an pitch axis. Therefore the only feedback you get is from the potentiometer mounted on the roll axis. Check out this video of a Boeing 737 gyro: th-cam.com/video/lWeQsYbQ8pI/w-d-xo.html You can see the difference between the resolver and torquer for each axis very clear. Therefore I think your gyro has no resolver at all.
Is "handle like eggs" a real phrase used on military hardware? I know it was on a bomb in a Bond movie, and figured it was a wacky joke. But here it is stenciled on cockpit gear?
Regarding the phase shift network. The cap's cause a 90degree phase shift, and by adding the resistor you can tweak the phase shift so it will become 120degerees? I'm trying to get an old 3phase harddrive running. And i like the simplicity of this way of generating the signal. Does anyone have a good schematic of this?
The only question is, will he sew a screw and wear it on his pants? I guess it's too thick to work properly as a 'fly' button... (pun unintended) But if it works its FTW! Oh My, the pun potential of this thing is quite phenomenal!
As an engineer and aviation fan, I want to thank you a thousand times for sharing that knowledge with us! Very interesting and informative video - why aren't more videos on youtube like yours...? Thumbs up!!
I've seen it on a few gyro type instruments. Probably the easiest way to quantify how fragile something is to miltiary techs.
At 05:30 these coils are torque motors using eddy currents. They are connected to the mercury tilt switches we can see at 07:49. This permits to keep the gyro rotor vertical.
Mike, I like the use of the audio amps to power the motor! It's really amazing to see what could be done with machinery in decades past.
I didn't know much about gyroscopes before, but after I studied, I chose ERICCO gyroscopes, and the working ability is very good
Incredible precision. Very interesting thanks for showing us the detail of the pots !
Probably the only way to do it at the time, and it is pretty well contained - maybe the reason for covering it in that black goop was so nobody spotted it...!
I am glad that you decided not to tear-down the gyro any further than that. Excellent video.
amazing instrument! thanks for the look inside it!
Like sculpture. Gorgeous mechanics.
Hey mike, thanks for sharing this. It's a great way for some of us to visualize what's inside instead of imagining all the time.
I don't know if someone else has already shared this but I want to write anyway:
That "Fast Erect" button works in that there is an additional pair of contactors added to the tilt switch, one at each end of the mercury tube. These contactors are connected via a button to power supply; this supply is at a higher voltage than the normal erection system. That way, if the gyro is seriously misaligned, the pilot can choose the press the fast erect button and connect power to the relevant torque motor. Since it is at a higher voltage than the normal erection system, the gyro will erect rapidly enabling the attitude indicator's gyro to realign to its vertically tied position.
I've never seen "Fast Erection" on a gyro before, I'm guessing its the same as "Quick Erect" or the common "PULL TO CAGE" which allows the pilot to quickly re-calibrate zero.
I've got a 70s or 80s attitude indicator in the same state of disrepair as yours. Mine has a slight drift which i suspect is a bad bearing. Its too nice of a instrument to bring myself to try to repair it, yet its likely no longer worth the cost of a professional re-build.
Amazing craftsmanship inside these things!
-sj
Lovely piece of engineering. It's amazing to think that all this work went into producing similar devices for WWII aircraft, for them to be blown out of the sky after 1 or 2 flights.
For the 3 phase supply, could you not use a car alternator (being spun with a electric drill, wheelchair motor, etc) with its regulator pack taken off, and then run the phases out into a transformer? If it works, could be simpler than re purposing an Amp. Love to see the Gyro in action!
Wow, fantastic piece of kit! The quick erection is probably indeed using the coils that you pointed out - the quick erection function becomes necessary if you manage to topple the gyro with some reckless maneuvering or if power is lost long enough for the gyro to spin down and lose alignment.
There are usually several on ebay - search attitude indicator
The Erect button is basically a reset switch to center the gyro. When the gyro is started while the aircraft is still on the ground it will be at some arbitrary position and pushing the button will move the artificial horizon to the wings level, horizontal flight position.
As mechanical gyros like this one will drift over time they have to be reset once in a while. This has to be done in level flight otherwise an error is introduced to the indication.
Radio Rally (Hamfest). Ebay is your best bet - look for attitude indicator
You need to get a teardown of a Ring Laser Gyro...
Mike, with this gyro, did you pick if the rotating mechanism actually was jeweled - ie, has a synthetic ruby at the pivot point?
Have you got a tear down of an optical gyro?
BTW the spinner at the end of the gyro might be the equivalent of a plumb line. From the video it seems to be just slightly unbalanced. So in a straight flight it will settle toward the vector of gravity (sorry if this is not the correct english word) and with the pickups the gyro can then compensate for any drifts around the roll axis.
Of course this bias needs to be very small to not disturb the indications while the aircraft is turning and pitching (where the g's might be all over the place)
Needs to be underneath a nice bell-jar on the mantelpiece! Thanks for the very educational video.
... with some subtle LED lighting to highlight the mechanism...
Hello,
I got a few aircraft attitude indicator gyros, one of them is a sperry MK1 witch internals are pretty much similar to the ones you show on your video.
The coils you named 'synchro resolvers' are actually 2 motors, one for pitch and another for roll. This motors are used to center the horizon on startup and on fast erect button when pressed.
When doing extremely maneuvers the gyro can block itself and therefor show a fake horizon, then you'll use the fast erect button.
my faith in humanity is quite often tested and sometimes I feel as though I will never claw it back, but when I see the insides of things like this and electronics in general I realize how an amazing a species we are - well some of us anyway.
LOL love your homemade 3-phase 400hz power supply. Always worth keeping a couple of found-in-a-skip home stereo amps kicking around...
+Dr Tune yeah, he's really clever at these on-the-fly things like that which come from remembering ALL your electronics training really well and great brainstorming power.
Hey there. I'm a pilot and I found your video very interesting. I think it's good to know a little more on how my equipment works. The fast erect basically aligns the attitude indications by centering the gyro and the components. The only time I use it is right after I start the engine on the airplane. This is because this instrument is vacuum powered. It takes a while to build 4.5 to 5.5 psi in the system. So.at low psi I like to pull the erect to get my insinuations while on the ground.
I would say get a 120v VFD, like one used to run on US current for running 3 phase motors. Or a VFD with adjustable output voltage. Set it to 115v 400hz and there you go. Using audio amplifiers for this like you said is touchy, much better to have a real variable frequency drive that is designed to run motors.
In your opinion, do you think sliding connectors are usable for this? the issue was that theese connectors have an non neglectable contact potential. the instrument will measure e-fields in the order of ~some V/m in a very hostile enviroment, (charge buildup, solar radiation of 14kW/m thermal fluctuations, ionizing rad. and so on)
This one is not air powered - the Sperry ad at the end explains the advantages of this.
I wonder how long it takes to assemble a mechanical beast like this. There's alot of individual pieces in there. Very interesting to see the insides of it for sure.
i bet it takes long
0:54 this is a very useful button to have when you have trouble rising to the occasion.
amazing piece of engineering
Is it a 12V motor? there is a lot of 3-phase drivers (ESC) made for RC-plane/boat/car use.
amazing craftsmanship
in your opinion , how does the gyro compensate for the curve of the earth? Does a plane not always have to fly in a downward incline, yet a gyro indicates flat. I don't seem to understand how drift with a compass can compensate . My understanding is that every six hours this is needed as a gyro is not accurate over long periods of time. When flying around the earth I would think the gyro would max out as you went in a constant downward trajectory. Is the mechanism mechanical or electrical?You seem like the type that would know how this might work. -thanx, just curious.
+Robert Gelinas " Does a plane not always have to fly in a downward incline"
No. Planes don't have to fly down. A plane can take off, fly level, and land without its nose ever going below its tail. In fact, when flying at a constant altitude, the plane (or at least its wings) is pointing "up" to counter the gravity pulling it down.
thank you for answering my question. I was concerned about the planes ability to compensate for the curve of the earth. If the plane always flew at a level flight path would it eventually fly up of the earth becuase of the curve? I understand the need to point up to avoid going down, however, a gyro keeps the plane flying flat. I am trying to understand if the gyro can somehow compensate for the earths curve and not fly flat. My understanding is that a gyro is independent of gravity. Is this true?
believe it or not but some people believe the earth is flat and a gyro is evidence of "no curve" in the earth or the earth not being a ball since if it was, when you stay flying flat you will "rise" away from the ball earth.
+Robert Gelinas Flat-earthers do not understand how attitude indicators work and they assume that the fact that those instruments actually follow an airplane's path around the globe "proves" that the world is flat. What they don't know (or pretend not to know) is that attitude indicators have erection mechanisms that continuously torque the instrumento to the local vertical and it is this constant torque that makes the gyro know in the long term which way is "up". This is a very small force and takes a long time (order of minutes) to act on the gyroscope, but enough to overcome the gyro's precession as the airplane travels around the world. In short, airplane atitude indicators have erection mechanisms that continuously adjust it to the local vertical wherever it is on the globe.
interesting. I've never heard of this erection mechanism. After reading about it , this makes sense. It checks for plum periodically and adjusts the gyro by means of an air pressured and vacuumed balance,. accordingly. Thanx for the info.
Fascinating. What a quality piece of engineering. I really wonder whether anyone could design one of those today.... It is also amazing to consider that this bulky thing's function can be performed by a small chip in my phone now...!
it would be cool to have instruments like this. Would be extra fun if it was actully posible to hook them up to an flight sim. Allthough most older ones that are mecalincal thats kinda inpossible. But i love the engeering that gone into making something like this!!!
How old is this? It's beautiful looking!
First time I've ever seen "handle like eggs" on something electronic. Do you suppose they come in a giant carton with 12 compartments?
Considering it's an electric, not vacuum motor that would be rather difficult....
they work via a vacuum running off a pump..............The best programme to watch is "A Plane Is Born" gives you alot of info on electronics and avionics of the aircraft :)
This type of Avionics gives you the angle of bank of the wings and tells you the pitch of the aircraft
ok, it's most likely synchronous, so some "BLDC controller" would be best.
a slow ramp-up can do too, but your best guess would be the HDD board.
PM me if you want my help in figuring it out, I don't want to fill mike's video with a lot of chat. Do tell if you figure out the motor.
Novel way of driving the gyro using DC coupled audio amps!
that "fine wired thing" on the end looks like a resolver for position feedback, KUKA robots use similar things as an encoder on their motor.
It's only my guess....
the construction goes to a great length to avoid sliding connectors making it increadebly complicated. the design was decided a long time ago, maybe sliding connector performance has been improved by now.
the Air driven attitude indicators are real Kewl too
There could be a common system called ARINC that put specific voltages that indicate pitch and roll that are universally accepted. They usually work in tantum with a flux which is a faceless compos that indicate voltages corresponding to compos headings. It auto-corrects the gyro to the compos headings
I mean flux detector. It's a compos floating in oil.
One word springs to mind...EXPENSIVE.
i know all about fast erections, and this beautiful piece of engineering totally gave me one.
Interesting.. It's connector is the exact same as used for power supply on the swedish military radio Ra200 from 1956.
great commentary friend, your comments are as good as the exhibits
One heck of a find!
I would love to have a gyro on my workbench, they're so cool.
It is properly a 12 volt motor. The thing is i don't want to buy anything but get it working with the stuff i have laying around.
Extremely interesting video thanks. I have an old bronze gyro and have been trying to get it running for years now! I was told by Sperry Rand in the 70s that the specs were still classified although it's obviously 1930-1940 era. Lately no one will tell me what voltage or hertz but I did think 400hz 80-150 volts. Fascinating electro mechanical engineering. Cheers for your insights
Great video. Will you please show how it tumbles when you pitch or roll out of bounds and how long it takes to re-stablize again?
Try attitude indicator or artificial horizon
Looking forward to seeing it spin up to full speed, always been fascinated by gyroscopes. (Need a chrome plugin that can auto thumbs up/like your videos ;)
where did you get it?
That is crazy, I was thinking of trying to make a miniature one for a hobby plane, sort of intimidating, yet beautiful. Thanks for the video. :)
Somehow never thought how that thing actually works. Very interesting vid.
How much is one of these?
Do modern aircraft still use mechanical gyroscopic instruments or is everything now digital? Drones use chips containing gyroscopic instruments
In an aircraft does the control system switch it to full power right away or ramp it up slowly to 115v?
i think it does does run off a vacuum, the modern ones do
I think you will find that those mercury switches are used for drift correction...
Hmm interesting. that connector is the same as the power connector as the Swedish military's Ra200 shortwave radio.
Would a small VFD be suitable for generating the 400Hz 115V supply? Although I guess most of them are 50Hz max output...
Very beautiful piece of kit, I hoped that you didn't tear it down and you delivered :D
I want one for flight sim :D that is amazing, I always wondered how attitude indicators work!!
I collect aircraft gauges,,what kind of gyro is this??? I'd love to have one in my collection,,,nice video by the way awesome engineering!!!!!
Artificial Horizon indicator from an RAF Buccaneer
very nice piece of kit.thanks.
The educated make the BEST vids. Keep it up.
in this video some sliding connectors are shown, I work as a mechanical engineer with a pice of mechanics (a satellite E-field sensor) that works by winding out a couple of sensor probes ~15m in opposite directions,
You can drive that thing smooth as butter with an Avanced Motion Controls S16A8B sinusoidal servo driver. They don't have a lot of "smarts" in them, so you can just feed them two differential sine waves 120 degrees apart from your function generator. Easy way to make a very controlled 3 phase power supply. Also, very cheap on ebay.
I know it's an old comment, but I've seen a lot of aircraft instrumentation, and practically all of it, military or civilian, has the "Handle like eggs" text on it. Maybe it started as a joke long long ago, but it's definitely the standard now. It makes sense - many of these devices are very intolerant to high-G shocks and knocks.
This guy is my hero.
great videos Mike,
Does modern aircraft say Boeing 747 uses electromechanical gyros or the MEMS type? BTW, this tear down is awesome, something, that I always wanted to see in real.
What a fascinating demo
I think those coils are no synchro-resolver because the stator coil is missing. I think those are "torquer" or "torquer motors" in order to align the virtual horizon in the roll an pitch axis. Therefore the only feedback you get is from the potentiometer mounted on the roll axis. Check out this video of a Boeing 737 gyro: th-cam.com/video/lWeQsYbQ8pI/w-d-xo.html You can see the difference between the resolver and torquer for each axis very clear. Therefore I think your gyro has no resolver at all.
Is "handle like eggs" a real phrase used on military hardware? I know it was on a bomb in a Bond movie, and figured it was a wacky joke. But here it is stenciled on cockpit gear?
Something like a minute each way
I love aviation instruments
a lot of these type gyros. If you got the rotor running it might take up 5 minutes to run down
totally cool bit of kit
You best be keepin that button
That button would make a great shirt button.
Wow, I want one, I'd de-case it and just put the gyro on display :o) Yes, that's far to gorgeous to destroy, it's a display piece :o)
I think it would work, but first you need to position the whole thing horizontally. The display is supposed to be facing the pilot :)
So cool. Wow!
Regarding the phase shift network. The cap's cause a 90degree phase shift, and by adding the resistor you can tweak the phase shift so it will become 120degerees?
I'm trying to get an old 3phase harddrive running. And i like the simplicity of this way of generating the signal.
Does anyone have a good schematic of this?
nice, you should have tried it with a vacuum pump! :)
had no idea it was electric...only watched 5sec of the clip without any sound, so
instead of using an amp you could get a VFD off of eBay
That's Impressive!
This is soooo cool!
I would like to have one
The only question is, will he sew a screw and wear it on his pants?
I guess it's too thick to work properly as a 'fly' button... (pun unintended)
But if it works its FTW!
Oh My, the pun potential of this thing is quite phenomenal!
Huh....I thought you were taking it down to the core, bearing replacement, etc, hmmm, good tutorial though, thanks