Gauge Blocks (Van der Waals forces) - Sixty Symbols
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- čas přidán 25. 07. 2017
- Professor Phil Moriarty struggles with gauge blocks.
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manual of instruction, page 1, paragraph 1:
Do not drop the blocks.
And don’t let them rust😂
Do the technicians know that you dropped the blocks ?
They do now !
That made me cringe so hard when he dropped it. Might as well throw them out and buy a new set now lol. I figure that's why they weren't sticking together too well; cause they've been really beaten up.
There is a reason they gave the theorist the set covered in rust. You remember how he said the machine shop had multiple sets, right?
Yup. I've got a high quality set, and they're super easy to wring together, and you could probably hang a 10kg weight from them, they stick so well
@@lifeteen2 i know a guy who owns an original johansson set from 1911 in pristine condition, he actually tested the force and they held a little under 120 kg when wrung together properly.
@@rockets4kids yup, that is also the reason he’s having difficulty wringing them together, they aren’t all that precise anymore
That statement at 5:55 sounds wrong. This might be partially due to the diagram, but his explanation is also vague and misleading. The pits and valleys of rough surfaces don't cause the forces to "not add up right", it simply causes there to be an incredibly low probability of surface area overlap. Since the Van der Waalls force only operates at extremely close distances, this results in a cumulative force too small to hold them together. Consider two equally sized, but differently rough surfaces that have any arbitrary amount of surface area interface when put together. Each side will always have the exact same amount of its own surface area touching the other's.
They should pin this comment. It's the amount of surface area contact that increases the amount of force, not the bonds being out of wack or something weird.
I agree with you. The smoother the surfaces, the better the more molecules are in close contact with each other, giving a greater overall effect. Van der Waal's forces are extremely distance-critical, so with a rough surfaces, most molecules are too far apart to "switch on" the attraction.
@@joeblogs8589 There are no molecules. Steel is a metal. Hence a Body Centered Cubic metallic bonded structure.
@@locktite401 Yes, but my statement is for surfaces in general looking at V.D. Walls forces in all friction.
This is more a matter of semantics, of course the amount of surface area where the distance is small enough to cause Van der Waals forces will determine the total amount of force. So these VdW forces do have to add up.
On the other hand, one could interpret "not add up right" as some forces being repulsive and some attractive, which is definitely not true, all VdW forces are attractive.
Btw, the layer of water also acts as a glue through VdW forces, it works through Keesom and Debye forces. The explanation given in this video actually concentrates on the most interesting of the 3 Van der Waals forces: the London dispersion force.
"Why don't you and I stick together?" Awwww
Brady Haran: King of "that's a great question!"
In the last "why do they have to be so smooth" part, I think the piece missing is that otherwise there would just not be enough electrons near to each other because all the surface scratches will lead to only a surprisingly low amount of points where the distance is really small.
They have to be FLAT. Smoothness is a side effect of lapping them FLAT.
Van Der Waal by Oasis
Today is gonna be the day
That they're gonna -throw it back- glue it all to you
Broken soffa Someone needs to make this parody. @acapellascience perhaps?
Lauri
+Leopoldo Aranha But there's no glue... and there's none of that jiggery-pokery either.
If they were my gauge blocks I would be mad at you for dropping them on the floor.
If they were YOUR gauge blocks, YOU would be the moron for loaning them out to anyone but your doppelganger.
Yeah, that was super cringey. If I had dropped the gauge blocks at my old job, they probably would have fired me lol.
Every block that drops to the floor I cringe, if the techs see this video they will never loan the professor another tool. Wear is a real concern for standards like these, regular calibration re-certification is needed and many owners actually pay triple the price just to get extra wear resistant ceramic blocks. Even the thermal expansion coefficients are specified by the manufacturers.
Then again that may have been their apprentice-grade set.(even at that each block is still $20, higher grades or ceramic and your talking $100 each)
(there are about five or six grades depending on the local standards organization, top one or two grades are for controlled environment lab calibration checks of other blocks and measurement devices; middle grades are for a company/shop in house reference; and the bottom two are intended for use out on the production line)
wolfedog99 Evidently Moriarty handles highly precise equations exactly the same as he handles the highly precise equipment. Garbage measurements for input equals garbage solutions for output. He doesn't get it though. He's too busy being impressed with himself.
wolfedog99 ya, seeing how rusty they were I think he got loaned the junk set, lol.
I doubt he would be dropping them if they were brand new. They're probably old and already worn out
You do get it, though. You seem to be fun.
+a name a name You sound like you have a problem within yourself
I experienced this on "air bearings", used for a linear motor system. They are so smooth that you can always demonstrate these forces
Please have some of Ed Copeland too sometime soon.
This, so much THIS! I loved Ed Copeland and would like to see him again!
Also This
Seconded. Love Ed!
AvE where you at?
0dWHOHWb0
Skookum as frig
Uncle bumblefuck left us at a wee cliff hanger.
Oh come on AvE! He's even wearing a Rush t shart! That makes him an honourary citizen of Canuckistan!
0dWHOHWb0 email him on the gargler
I haven't had a chance to watch yet.
In the machine shop, we call it 'wringing, its a pretty common word, people talk about wringing two slips together all the time'. And usually we call them slips, rather than gauge blocks. Someone probably already said this...!!
No one calls them slips any more!
That's likely because a "slip" is also a type of sharpening/honing stone meant for concave surfaces, and that name was around for a few centuries before gauge blocks were invented - it avoids confusion. Gauge blocks or "Jo blocks" in the US (for Carl Edvard Johansson, their inventor) are the common shop terms.
OMG You were dropping STANDARDS on the FLOOR?!?
Yeah, that made me cringe lol.
Cody's Lab has a great video on this.
He was testing this but he didn't know why it happens
I haven't checked his channel in a little while, but wasn't it Cold Welding he was doing? Not this? It is a similar in the sense that no heat is needed but the reasons they bond are different. But I haven't checked his channel so he may have...
He did that with gauge blocks as well Chirs, testing in a vacuum chamber if dropping them on each-other would produce the same effect.
Ye, he even went as far as putting them in a vacuum.
Like it every time when it fails to stick together he goes "oh f..." hahaha!!!
More on this please! Very cool.
I've used gauge blocks many times in my career. The act of joining them together is called "wringing" them together. And you do indeed twist them to ring them. It is the best way to push the air out from between them. A very well wrung pair of blocks can be very difficult to get apart. The higher grade ones they use in places like national standards metrology laboratories wring together even better.
Wringing.
Wringing.
2:26 Gravity send their regards
Can remember when I was 16 and starting my apprenticeship being shown these and it was like magic.
Very well explained, thanks.
Its fun to watch guys first attempt at wringing gauge blocks together. So in my experience, the best way to consistently wring blocks together is to clean them with acetone, then swipe the contact edge along your inside wrist. Then you position them 90 degrees apart and twist them together. Also I've seen it spelled Gage as well as Gauge and I'm not sure. Gauge blocks and a surface plate are the standards in a metrology lab.
Also time to recertify those blocks. It looked like they had some rust on them, which destroys their ability to wring as well as their accuracy. Steel blocks should be stored with a coating of light oil. Not sure about ceramic block care.
Whats the point with the acetone if you are gonna rub your skin oil all over the surface anyway?
To get the last guys skin oil off! Well gauge blocks have to be coated with light oil when stored, so the acetone gets that protective coating off. Just to be clear, you can wring gauge blocks together without wiping them on your wrists, it just takes longer. Maybe the wrist wipe pre-charges the blocks... I don't know why it works so well, but I know it does work. Gauge blocks won't wring if there's any kind of oil, dirt, dust... so trying to wring the blocks with the protective oil will result in frustration, and inaccurate measurements.
They've chosen the low grade ("workshop grade" not laboratory) blocks, rusted and worn out. That's why there is a problem with wringing...
SJWs & Betas Killer Even low grade gauge block wring together perfectly fine. The issue was that he's never done it before that day, and they were corroded. And since they were corroded, they were probably not treated well, and may have deep scratches, dings, dents, etc.
Never run on your skin as your sweat can be acidic and cause corrosion. Use wringing fluid.
Van der Waals forces are what let geckos walk on walls and ceilings. Their feet have pads that greatly increase the area of contact with surfaces, maximizing the Van der Waals forces they produce.
Fascinating stuff. Thanks for posting.
The effect is really pronounced when the blocks are new. Even fingerprints on the blocks will reduce the effect.
We used standard rectangular and cylindrical jo block sets in one tooling position for years, we'd wipe the wd40 off used to preserve them with a clean rag and then to make them stick you would rub both sides with your fingers to get your oils on it (even after brake cleaner), then you push them together making an X, and while pushing you twist to align them. Fingerprints work Brian.
Oil helps them stick with surface tension.
Prof. Moriarty always with the best rock n roll t-shirts
I really dig the Rush shirt! Thumbs up for the professor!
I finally know! Great to see that. I managed to notice this with two very smooth Tourmalines.
Prof, thanks for that you are a genius! been looking for the reason & you found it in a way I understand it. Cheers Prof.
Really like the new style!
You’re supposed to be careful with those things!! So I heard from AvE..
Nice T-Shirt, Professor!
Denis Goddard I'm Canadian and I approve this message.
I was just going to say the same thing!
The Camera Eye caught it!
will two smooth surfaces made of different materials stick together like this?
Yes. But you need really flat (gauge block level) surfaces.
Matt indeed. You can do this with a ceramic and a steel block
Yes. Buy a brand new aluminium pan with a machined bottom and put it on your ceramic halogen/induction hob. You'll feel the attraction.
I do believe this works with HDD platters as well. I've noted a similar attractive force when playing around with two of them, and given that they have to be so smooth for operation, I can see this being the case.
@sixty Harddrive platters also work very well.Never tried removing the magnetic layer but the degauser should make it nonmagnetic as those gauge blocks.
What did you use for that crumbly sort of bass rumble at 4:20? Was wearing headphones and I thought it was something outside. Could use something like that for my music =3
Great animations. They fit the feel Phis has.
Super fun edit Mr. Haran!
Lee Stuurmans That's Dr Heron to you.
Haha, of course, my mistake.
does this kind of attraction work even in vacuum chamber? If yes it is the vanderwaal forces. If not it is the air. I am not sure but I have a feeling it is the air pressure that is keeping them together. Like when you glaze them on each other you remove most of the boundary layer and accidentally put some microbumps on the first layer into the microvalleys of the other. So their mating makes a low pressure zone as there's far lesser air molecules between them this means the outside air will keep thek stuck and if we put these things in vaccuum that effect will disappear. If it is indeed vanderwaal thats's the dominating force then vacuum wony affect it so this can be used to distinguish between the two proposed solutions
Always thought it was some tiny tiny pit of cold welding that made them stick, with surfaces so smooth, "pushing" out the atmosphere between the steel is semi possible causing the stickyness, guess i was wrong but wow you learn new cool stuff everyday :D
I actually have experience with this from my PhD research, this also works for glass slides, just a little cleaning with ethanol is enough.
Dropped?!!! You owe your machinist a new set of Josephson Blocks.
I can tell you, working in metrology, our steel XX grade blocks ring together really well, our tungsten carbide blocks will not ring together at all, or will very weakly. Not sure why that is.
Tungsten is brittle, maybe it is less inclined to be as smooth as steel when polished up...just a guess
The tungsten carbide blocks are polished to a mirror finish for one, and the silicon wafers in this video are also very brittle. Still a mystery.
Have you been able to measure accumulative error with steel vs. tungsten carbide?
It might be because steel is body centered, and tungsten is face centered. Like it might affect where the electronegatives overlap.
Maybe they're worn out (more than steel ones)?
He dropped a gauge block. Better not let the shop guys down stairs see this video.
Judging by the reluctance of the blocks to wring together I suspect the machine shop people gave them a worn out shop floor grade set to play with.
Now this is a great video.
If you press together two truly ideal smooth surfaces of the same pure substance in a vacuum, they will simply fuse. Forget about van der waals forces, they will bond on contact in a process called cold welding. As Feynman put it, the atoms in contact at the surface don't "know" they are on different blocks; it is just a continuous lattice of atoms from one block to the next.
You guys are the best! I was wondering it you could make a video about Maxwell’s demon and the relationship between information and entropy, thank you !!!!
People who use gage (acceptable alternate spelling) blocks, refer to "wringing" blocks together.
That is a known, undesired effect of metals clean of oxide layer. A problem in space technology, were contacting metall surfaces stick together. There just metall layers fuse coldly together, as if molten
I would eb}njoy drinking a grand beer with prof and talking about rush and science
Wow that's smooth!
Academia meets blue collar shop floor workers ! Thank you scientist for enlightening us machinist & the mechanically inclined.
Fascinating !
Have you covered a similar sounding topic. Cold welding in space?
Johnny Ball showed me this phenomena on his tv show back in the '70's. It's nice to know now what the physics is to explain it.
Awesome t-shirt!
smooth means there is more contact surface area that is close enough. Rough surfaces have surfaces that are further away and a few that are close.
First of all FLAT is what you need. "Shine" is a side effect of lapping blocks flat.
Smooth?... I just watched a Breaking Taps video of a gauge block under an AFM... they're full of gouges and furrows at nanometer scale. :)
I love it when Phil nearly says "f...".
Love the shirt!
I would like to mention that this is how cold welding works, for engineers out there.
My understanding is that it is primarily 'stiction' that does this to gauge blocks? Despite the finish of the block they will both have peaks on the surface and the flatter the average surface is the higher the probability of numerous peaks nano-welding to each other under the force and friction of rubbing them together?
Stiction doesn't apply when you pull them apart.
althought van der walls may be the most significant force, isnt there also a suction effect? Since the surfaces are soo smooth there is very little air between it ( and very little area for new air to enter) since they are such stiff objects that when trying to pull them apart it creates a vacuum in the middle of the 2 surfaces.
love the t-shirt man
Are these specific type of van der waals forces (temporary dipole interactions) not usually called London Dispersion Forces?
I would be pissed if someone dropped any of my gauge blocks. Cheers SS!
At that point they've immediately purchased a set of "only dropped once" gage blocks and I'll have a brand new set. Yes, "gage' , cause 'merican.
I thought it was possibly the Casimir effect. Super interesting!
Love when Prof. M has time to do some Sixty Symbols!
If you want to try this you can do it with hardrive platters, they're also precision machined.
No wonder I can not shuffling a deck of cards because the law of van der waals forces.
Well this is A Level Physics. Finally something I was familiar with beforehand on this channel. At first I thought it was cold welding, but I was wrong apparently.
We were told to never leave them stuck together because they would ultimately bond together in places and the surface would be damaged in breaking them apart. Maybe this is really just a precaution against corrosion since it sounds like there's no exchange of electrons going on. I suppose this could be proved by leaving them together for an extended period in a vacuum.
the same advice was given about the anvils of a micrometer.
extra points for the RUSH t-shirt MAN!!!
Could cold welding be involved with this as well, it seems like the conditions (maximum contact, removing the oxide layer, scraping of the metal together.) for getting it to stick would also apply to cold welding.
Though Id then wonder if that would do notably different damage to the surfaces if viewed through a powerful enough microscope.
As far as I know they are similar, but not the same. In wringing, also called optical contact bonding, the two bodies are extremely close, but are still separate. All that is keeping them together are the intermolecular forces like the van der waals forces as explained, (disregarding the water effect.) In cold welding greater pressure is applied to force the bodies closer together, so much so that the atomic lattices of the two materials can become one with one another, e.g. in metals usually creating chemical bonds, sharing electrons between neighboring atoms.
@Steve Mould Actually it is quite know why gauge blocks lock on each other. The perfection of the surface is to amazing that the iron atoms from both surface exchange electrons. Well, they always do on each contact, but with the gauges the amount of atoms doing that interaction is astronomical. The resulting adhesion is strong enough to hold its own weight and far more. If you let them REALLY degreased and let it rest for a while, some weeks, once you break the connection you rip out atoms and you kay even damage the surface to a point where no adhesion more is achieved and in worst scenario the precision of the gauge is compromised (I worked with 1 micron gauges in a laboratory long ago, 1,000mm; 1,001mm; 1,002mm.... amazing stuff). In high graded blocks ( metrological calibration ones for instance) even a few days. If you let them for really long time (this one I never did) they begin to exchange atoms and get fused. This is based on the atomic diffusion law, that can predict how long it will take, I do not remember more that deeply this stuff.
But it is in the structure of steel, Iron atoms do exchange atoms in a soup of electrons. THAT is the may reason metals are conductors...
So hope to have solved the microscopic enigma :o)
I've had this happen to me and thought it was a thin layer of oil or something. Now I know. Cool vid
Wait till the machinist sees this video and how nonchalantly you where handling their precision instruments.
They gave him the worst (worn out) set, look closely. They knew, he will screw up.
So I suppose the mono-layer of water on a sufficiently smooth surface can fill in the gaps enough to make the surface almost perfectly flat. Is that right?
Tiny layer acts as glue and helps flat surface to be more smooth.
Rush t-shirt FTW!!!
Guilherme I've been looking for you!
Very good video, Phil Moriarty is really good at explaining things.
So is it basically based on the position of the electrons, a tiny magnetic force on the atomic level?
Maybe. It could be the Casimir effect too. Odd that this guy didn't mention it.
I wonder if this effect happens with glass since one of the molecular definitions of glass is being an amorphous solid, i.e. it's atomic structure has local order but no long-range order is present?
I was taught that these forces are called London dispersion forces. When atoms are attracted to each other without there being a permanent dipole. Further, I was taught that the van Der Waal's forces also include dipole-dipole attraction from permanent dipoles. This was taught to me in IB chemistry, higher level and that quite recently as I graduated the IB earlier this year.
I don't mean to say that he is wrong, As he is correct, but I think it would be more accurate to call it London dispersion forces, which are a sub-category of van Der Waal's forces.
in short the like charges repel, and the unlike attract, so "Extropic" Charge alignment between opposite charges predominates over time organization occurs over time along the surface.
Does cold welding (in vacuum) operate on the same effect?
As far as I know they are similar, but not the same. In wringing, also called optical contact bonding, the two bodies are extremely close, but are still separate. All that is keeping them together are the intermolecular forces like the van der waals forces as explained, (disregarding the water effect.) In cold welding greater pressure is applied to force the bodies closer together, so much so that the atomic lattices of the two materials can become one with one another, e.g. in metals usually creating chemical bonds, sharing electrons between neighboring atoms.
Will extremely smooth two different materials will stick together?
Geckos use that effect to walk on the ceiling.
They have bazillions of tiny hairs under (or above, if they walk upside down?) their feet, which increases the touching surface and thus the total Van der Waals force.
That's true! To be precise, they have 4.37 bazillion on each foot on average.
There's a demonstration using Chinese Rubbing Bowls of standing waves, (equivalent to thermal excitation), and it goes with the ejection/evaporation of molecules from the surface tension boundary of a substance (and solids), so the interaction of fields of Van Der Waals forces seems to fit the story. Interesting.
Is this effect similar to the effect happening during cold welding?
As far as I know they are similar, but not the same. In wringing, also called optical contact bonding, the two bodies are extremely close, but are still separate. All that is keeping them together are the intermolecular forces like the van der waals forces as explained, (disregarding the water effect.) In cold welding greater pressure is applied to force the bodies closer together, so much so that the atomic lattices of the two materials can become one with one another, e.g. in metals usually creating chemical bonds, sharing electrons between neighboring atoms.
That's awesome :-)
So it's like the smallest Legos ever, they aren't melting together. One side happens to have a lot of stuff, and the other one happens to be a bit empty on one side... Legos for the win again!
holy cow this is the first one of these videos that i actually understand this is a weird feeling lol
Is this what's called "Cold Welding" or are they separate things?
I have heard that very clean metals under high pressure can actually stick together using metalic bonding, which can be a big problem for space probes and such.
Can anyone confirm?
Yes, that is cold welding, which is a similar but slightly different process to the wringing together of materials shown and explained in this video
At 1 atm pressure if you prevent air from getting in between two surfaces you have slightly more than 1Kg normal force per square cm, which is more than enough for some nice tricks. If you work with precision mechanics you know that very flat and smooth sufficiently large matching surfaces can cause dangerous sudden detachments...
And yet they still wring together in a vacuum.
Which is interesting, because up at the macro level, we deliberately make surfaces _rougher_ to make things like glue and paint stick better.
trejkaz Paint and glue are not hard surfaces though.
Oh my, I had no idea that paint and glue were not hard. Thanks for pointing out a totally not obvious fact!
I made a video about the cabinet makers air gap which i think is the opposite of this phenomenon. Id like to know what other people think. Are these 2 things related?
How has the drum beat analysis been going, Prof. Moriarty? Any promising results? :)
I dont think the surfaces must be absolutely flat. They just have to fit perfectly so the atoms are as close as possible.
Merto6 For Van der Waals bonding you could use surfaces with macroscopic roughness provided they conform well with eachother. However microscopically they have to be exceediingly smooth because any roughness will result in greater separation between the base surfaces. The attraction between approximately spherical irregularities and the surface they touch is pretty much negligible to surface to surface attraction. As the force drops off with the square of the separation (if what applies to sphere-sphere contacts also applies to surface-sphere contacts) A small increase in roughness results in a large decrease in attraction.
Yes, but it is fairly more practical to make very flat surface, than two custom curves that fit together that accurately as flat ones. So, if you want "wringing" effect, your only practical option is going flat!
I've always wondered how its possible to wring gauge blocks together.
I remember the Lennard-Jones approximation to the Van der Waals potential.
Perfectly clean blocks dont wring the best, we always give em a swipe on the wrist so they have a bit of something to actually seal the surfaces.