AV Geeks Lunch 7-12-2022

[Music] um [Music] ah [Music] so [Music] so [Music] the term hardness has a specific meaning in engineering it is the resistance to permanent penetration a steel ball pressed into a piece of lead produces a spherical indentation a specific amount of force is used resistance to penetration is measured either by the depth of penetration or by the residual area of the indentation such measurements combined with the magnitude of the contact force can be used to calculate a hardness number two common tests for quantitatively evaluating resistance to penetration will be examined next the brunel hardness tester uses a specified load to force part of the lower surface of the 10 millimeter diameter hardened steel ball into the test material the penetrator is brought into contact with the specimen the load is applied hydraulically held for 30 seconds and then released a spherical indentation results a special microscope is used to measure the diameter across the top of the indentation the brunel hardness number is then calculated by dividing the applied load three thousand kilograms in the standard brunel test by the spherical area of the residual indentation this area can be determined from the diameter of the indentation small d and the diameter of the steel ball capital d commonly however the area is not calculated instead charts are used to go directly from a measured diameter to the corresponding brunel hardness number brunel hardness numbers have the same units as stress load divided by area for metals the brunel hardness number ranges from about 100 to 600. the conventional rockwell hardness tester indicates resistance to penetration directly on a dial gauge which measures the depth of penetration of a specially shaped penetrators when pressed into the test material under a particular load depending on the resistance of the material to be tested forces of 60 and 100 kilograms are used with a 1 16 inch diameter hardened steel ball penetrator affording rockwell b readings and for harder materials 150 kilograms of load with a diamond tipped conical penetrator affording rockwell c readings we shall determine the rockwell hardness of certain steels the diamond tipped cone penetrator is inserted into the machine a small cylindrical specimen of astm 1045 steel with a carbon content of 0.45 will be tested first the specimen is brought into contact with the penetrator a 10 kilogram minor load is applied to hold the material and penetrator in contact this is accomplished by tightening a hand wheel until the dial indicator reaches the set mark the major load of 150 kilograms is applied when the load lever is tripped the dial gauge is marked to subtract the depth of penetration from an arbitrary value so that a softer material yields a lower reading than a harder one when the load is removed the dial gives the reading directly in this case c13 the specimen has been indented by the cone the indentation is quite small a similar test is performed on astm 1095 steel which contains 0.95 percent carbon here the hardness number is c30 for a softer material the diamond cone would penetrate beyond the reading capability of the instrument hence the 1 16 inch diameter ball tipped penetrator is used analogously with a 100 kilogram load the hardness of this astm 1020 steel specimen with a 0.2 percent carbon content will be read on the b scale its rockwell hardness number is b eighty we see from these tests that higher carbon content is associated with greater hardness the tensile strength of these materials have also been observed to increase with carbon content grinnell and rockwell readings may be compared on a chart these hardness numbers are different and are not linearly related readings on the rockwell b and c scales may also be compared to each other it is seen that a hardness of 100 on the b scale would correspond to a hardness number of 20 on the c scale materials with a greater tensile strength also exhibit greater hardness domer has found that the tensile strength of materials is approximately 500 times their bernal hardness number hence a hardness measurement can be used as a rough estimate of tensile strength there are several other hardness testing methods among them the mohs hardness test for minerals is based on a scratch test the harder material in this case diamond is able to scratch a softer glass plate though glass is a comparatively hard material on the mohs hardness scale the softest material is talc number one and the hardest diamond is number ten the mohs scale may also be compared to the other measurements the scratch test measures abrasive hardness in addition to indentation hardness and hence another non-linear relation between hardness numbers results another mechanical property frequently measured is ductility which is defined as percent elongation to fracture some materials are ductile when pulled slowly but brittle under a dynamic load furthermore a material that is ductile at one temperature may become brittle when it is cooled to the temperature of liquid nitrogen in a static tension test toughness was measured by the modulus of toughness the area under the stress strain curve it indicated the amount of energy absorbed in deformation and fracture for materials of comparable strength toughness and ductility are closely related dynamic toughness is measured in impact testing machines a heavy pendulum has potential energy proportional to the height to which it is raised when allowed to swing potential energy changes to kinetic and back to potential energy if the pendulum rises to its initial height there is no loss of potential energy energy loss is measured on this dial when a piece of steel is inserted into the path of the pendulum the energy required to break it will be registered as a loss of potential energy and the pendulum will rise to a diminished height this energy loss as indicated by the dial is measured directly in foot pounds the energy loss like the modulus of toughness is related to ductility some materials such as this sae 4140 steel do not break under a single impact in an impact test the total energy absorbed to fracture is desired but this specimen did not break specimens are therefore notched in addition to producing a stress razor the notch concentrates the energy at a narrow region a notched 4140 specimen does break bending impact specimens may be either simply supported as in the sharpie test or cantilevered in izod machines the size of the specimen as well as notch geometry are standardized a notched sae 4140 steel specimen when tested in the sharpie configuration breaks the energy absorbed to fracture is eight foot pounds the fracture surface is rough and relatively flat typical of brittle failures steel is a material whose toughness may be improved with certain types of heat treatment the fracture surface of the heat treated 4140 steel exhibits sheer lips on the sides and a rough horizontal fracture region in the middle shear lips are a sign of high ductility ductility and toughness are temperature dependent properties we shall retest our heat treated 4140 material at various temperatures a thermocouple is attached to the specimen in order to measure its temperature after a liquid nitrogen immersion the specimen is inserted into the impact testing machine and its temperature is allowed to rise when the temperature reaches a specified level minus 170 degrees fahrenheit in this case the pendulum is released and the energy absorbed 20 foot-pounds is recorded at minus 250 degrees fahrenheit the energy absorbed is still lower 12 foot pounds the absorbed energy can be plotted against the test temperature it is low for low temperatures but eventually a sudden increase is observed beyond which the curve flattens out again the behavior of the material has changed from brittle low energy absorption to ductile high energy absorption the temperature at which this change takes place is called the ductal brittle transition temperature hardness and impact test because of their simplicity and because specimens for them are relatively inexpensive are frequently used for the purposes of quick comparison of materials and for quality control procedures [Music] hmm [Music] [Laughter] [Music] oh man oh man that was awesome um sometimes i start the show with a film that i think is a little too niche a little too esoteric a little too procedural but uh i love nonetheless i mean there's so much to love about this film and you know not to mention the giggling the uh immature giggling with load uh penetrator um etc and all the devices and all the the scales oh man this is why i collect films really um watching some of these really just you know if you're mechanical engineer this is great but or a chemical engineer but you know the average layman will never ever ever think about these although it's interesting to see how some of these tests have made their way to youtube in things like will it blend and like we take this object and we put it in a in one of these vices um how that has become like a thing a genre so here it is back 1975. um i'm skip alzheimer and welcome to the av geeks lunchtime streaming show where we watch old 16 millimeter films and this was something that we actually had on 16 millimeter uh everything almost everything we show we have on 16 millimeter some of them we've already pre-scanned some of them we scan on demand and you get to see it live it goes straight from this machine right here and then it makes its way through a series of tubes into your eyes um and your ears um so thank you to all the technology that lets us uh dabble and things like that all right well now it's time uh speaking of tubes to learn about brass choirs enjoy [Music] so [Music] no symphony orchestra would be complete without all of its choirs in the broad sweep of emotions the versatile strings are indispensable the woodwinds among other contributions are unexcelled in portraying the pastoral and so too the brass instruments have a major function that of assisting in the sweep up to great climaxes and crowning them as was demonstrated in the selection you have just heard as is the case with all other choirs of the symphony orchestra the brasses are represented by soprano alto tunnel and base i will now introduce the trumpets the sopranos of the symphony brasses [Music] the trumpets are brilliant military and dramatic [Music] ah [Music] [Music] ah [Music] ah [Music] uh [Music] foreign [Music] the alto of the brass choir is the french horn [Music] the tone quality of the french horn is mysterious and romantic [Music] foreign [Music] [Music] foreign [Music] so [Music] the trombone [Music] the trombones are usually the tenors of the brass choir but there is also a bass trombone the trombones are powerful noble and scenarios [Music] wow [Music] oh [Music] [Applause] [Music] and now the base of the brass choir the tuber the tuba represents massiveness and power [Music] um [Music] two three the brass choir will now play for you the march from town hoiser foreign [Music] [Applause] [Music] um so that film uh was from the mogul brothers collection it was an early irpe film and uh which eventually got purchased by encyclopedia britannica and so then they re-released it but what's interesting is uh the mobile brothers collection was a library film library in new york city and sometimes they would just tap things off and so at the end you have that the end and it's a spider web um which is pretty great um and this was a great film anyways it's um kind of wonderful and there's i think there's three different versions of it and we've been i think we've scanned the second version of it for this uh encyclopedia britannica project we've been working on anyways this next film is uh interesting uh piece promotional piece for the army corps of engineers um and what i love about it is it's a presentation within a presentation and um so this is we were there enjoy [Music] [Music] [Applause] [Music] please be prepared on monday have a nice weekend class dismissed oh good paper very nice good luck on the game boys oh becky carlos gary and linda please stay a moment captain keenan is going to come by to help you on that special project if you want to go to the workbench you should be here anytime good afternoon great right on time this is captain keenan who's been good enough to come by today to answer your questions on the army corps of engineers and what its role has been and is in the management and development of our country's natural resources and in the protection of our national security captain this is becky carlos gary and linda mrs drake has sort of filled me in on your project which has to do with our country's 200th birthday and how the army's core of engineers has helped to develop build and protect america in these various roles well i've had to do my homework too and to help me help you i've brought some film and other pictures along by putting it all together i hope to give you an overall picture as to what the army's core of engineers has done and is doing for our country now where would you like to start well i always think of the army as marching and fighting war but engineers build things and prevent flaws from happening i read where you build dams and control our big water ports like new york but you're still soldiers i mean like back in world war ii korea and vietnam right whoa whoa yes no yes i mean you're all partially right but an army engineer military or civilian he's a special breed of cat we wear two very important hats in our jobs well just like the one you mentioned gary we do have a proud combat history going back to the revolutionary war but army engineers have also made important contributions to america's growth from helping to explore our own country to helping space exploration from building historic forts to major structures in our nation's capital we are soldiers for sure but we're also pioneers architects builders and innovators and always american citizens who care i'd like to hear the captain tell it his way like from the beginning does that turn anybody off okay let's try it that way but first i need to show you who it was that got this whole story started carlos would you put that on the projector please [Applause] none other than george washington engineer soldier statesman while still a general in charge of our continental army he was authorized by our then continental congress to set up a special department to be headed by a chief engineer and two assistants so the history of the army engineers which began the day before the battle of bunker hill is actually longer than that of our own country military engineering efforts during the revolutionary war were confined mostly to building defensive fortifications to protect our forces and garrisons against british attacks the job done was pretty good for the time and the limited experience of those involved [Music] the creation of a corps of engineers was actually accomplished by thomas jefferson who is president persuaded congress to establish military academy this country's vast interior began to excel thanks to pioneers like major loft but not for conquest an important milestone in the corps role of helping to shape america's destiny efficient as was transportation of mail and by this act army engineer officers could be used in the carrying out of work as well as civilian engineers it was this act which really established the core civil works program as we know it today it meant army engineers would have two roles of national importance one called the chesapeake end of canal beginning in what is now george bending to pittsburgh before this ambitious project was suspended but core civil works projects continued and by 1827 players would have become directly involved with another carrying assistance to help develop and build the first railroad railroads more were to become with the surge of railroad canoe horizons and opportunities passages through the delta where river opened to sea progress to make the missile sometimes failing but mostly succeeding a brilliant west point graduate robert e lee devised a system what's the river to do the job of scouring the channel clean two engineer officers named management which today is the science of river hydraulics [Music] in the great lakes region a stubborn natural rapids at a point called sioux st marie was a barrier which had to be conquered if this 1 000 mile long shipping route was to serve our expanding waterway commerce system army engineers involvement to change the great lakes into a servant for those who would sail these lakes and benefit from their man-made improvements between 1842 and 1846 the legendary explorations of lieutenant fremont and his kit carson extended into what is on area for exploration and survey so army engineers were sent west to discover what was out there what the land people living there were like among the debate in california was gold and that would immediately create a stampede to the west the pacific railroad survey fell to army engineers who recommended federation in surveys covered california oregon utah the rockies land which was barren unfriendly and challenging but what was learned from these early studies meant opening the west to those who would come this way in increasing numbers to settle in america's western frontier any of you have any questions or comments at this point i'm here to help you you know i'm sure gary go ahead well like you guys were building all these railroads and canals and things didn't you have to fight it off i mean like in war yes gary army engineers being soldiers know what combat is like when our country's security is in danger army engineers were there during the war with mexico among them men named beauregard mead mcclellan lee names destined to fill pages of american history during years not far away but in the war with mexico they helped prove that jefferson's vision about west point would prove to be correct they were men of exceptional engineering and soldiering ability what about the civil war did the engineers fight after which side good question becky and one which requires some explanation just before our civil war began washington dc was the scene of intense army engineer activity we were planning the completion of the washington monument beginning the dome for a capitol building planning civic improvements for our capital city president lincoln was in office hoping for a solution to the problems which were splitting north and south [Music] but as you know that was not to be and civil war resulted even our army couldn't overcome personal feelings some followed their convictions by joining the confederate army which included general beauregard and its distinguished leader robert e lee for engineers wearing both uniforms the war introduced new combat applications like the use of telegraphy for faster communications employment of aerial balloons for observation these two military experiments really helped lead to what became the army signal and air corps on land both sides used railroads to their advantage to move men and equipment where they were needed our civil war not only changed the country but also the way war would be fought in the future so it was both a trying and testing time in our history when the civil war ended washington dc needed attention population increase had made streets a nightmare conditions were so bad that some people wanted our capital site moved elsewhere but army engineers were put to work finishing what had been started laying out the grounds for arlington national cemetery paving streets and in so doing setting the stage for their future involvement in design and building which would make washington dc a national showcase [Music] as the 1800s moved on civil works projects again focused on our rivers and harbors and army engineers were at work developing navigational systems to extend our waterborne transportation routes in the west exploration was beginning to reveal the still blank spots on our country's map areas like the upper yellowstone valley the efforts of army engineers to map and bring back reports about this unknown area resulted in the creation of what is now yellowstone national park for its first 10 years this natural scenic wonder was victimized by neglect and man caused abuses aware of what man could do to destroy yellowstone the corps of engineers asked congress for authority to build roads and establish army patrols to preserve and protect the park in the mid-1880s congress authorized the request and an army engineer captain dan kingman who would later become chief of army engineers spent a three-year tour of duty in yellowstone during which he laid out a highway loop which is still a main artery in the park's roadway system the concern of army engineers about protecting and preserving land areas in our west wasn't limited to one place yosemite in california was another and it too was kept safe from exploitation and abuse by army engineers before our national park service was created and took over the job as fast as america was growing so were her transportation needs old man river the mississippi was still a stubborn challenge which required engineering work to safeguard shipping and passage along its winding course the arkansas and the missouri rivers also posed monumental problems which received army engineer attention to make them navigable and safe for the people who lived close to their banks the ohio river was yielding to navigational development and a real beginning to what would eventually mean a system of interconnecting waterways scattered throughout the country harbor improvements were continued by army engineers in our port cities to better handle ship traffic [Music] when the 20th century came along army engineers had already provided 125 years service to their nation and had been a dominant factor in its growth and protection um yeah uh so uh that film was kind of beat beat to hell um for there to be so many splice breaks in the middle of it tells me i don't know if somebody rewound it and something broke or they didn't have a good loop on it so it was just tearing sprockets periodically like it's weird normally it's at the beginning or the end that you see that uh those like multiple uh splices because of rewinding or you know whatever or they didn't thread it right but in the center is is kind of weird um so unfortunately uh yeah um sorry all right uh so behind me i have another film on the uh scanner and uh somebody asked the difference between this and the the older uh machine that i had which was the german flash transfer uh made by a company called md nwa nova uh that film that uh would only do 16 millimeter and it would only do uh sd and we had a box that would up convert it to hd then we would broadcast it um this uh blackmagic cintel is made by uh was originally made by a company called ranks intel um but then the technology got bought by blackmagic and they set on it for like i feel like eight years to try to come up with a new machine um that used a camera instead of a flying spot uh crt to scan the film and so blackmagic was making cameras and so that's what they put in here uh and so this machine can do up to 4k uh 35 millimeter and 16 millimeter uh and it also has what we call video tap it has a hdmi out which we plug into a box which we plug into here so what we can do is i can be scanning a high quality file on this computer behind me and then i can also be pumping a video and audio out via the hdmi to for the stream so it's there's most computer most scanners can't do that and so this one is pretty great in that regard so this is why we're able to broadcast all right i geeked out pretty hard there um so anyways this next film that we have set up uh is a child development film and these uh tend to be like uh um nature documentaries in that you know let's watch the child do this and let's watch the child do that and then there's this kind of raw footage of whatever's going on so i haven't seen this one i'm not sure what uh it's gonna be in it but um i'll be standing by in case it gets crazy like too crazy uh for youtube um all right anyways here's half a year apart enjoy [Music] this short film shows two children six months apart in a concentrated 45 minutes of playing [Music] this is rachel age 2. for her plays a chance to explore through her senses [Music] hmm hmm [Music] okay [Music] oh [Music] i [Music] [Music] i [Music] um [Music] me oh um [Music] [Music] um hmm [Applause] how much [Music] this is josh age two and a half for josh plays a chance to build events so so so so lay down so so [Music] so so so um [Music] play is always a chance to explore it's only how we play the changes [Music] oh my mother me [Music] oh i uh like i said i had not seen this film before and and i had a guess that it was going to be like that um and i was not disappointed uh it's it's fascinating to see some of you in the comments embrace films like this and some of you are like even wanting to invoke a clown that's hilarious john that is so hilarious careful what you wish for um yeah so that's the one thing about av geeks i will show you stuff that you probably had no idea that you would be seeing um and so i'm happy to do that this next film is a whacked out encyclopedia britannica film about time enjoy [Music] hmm [Music] [Music] [Music] 100 million 200 million 500 million 750 a billion years a trillion 1 000 years 100 years 25 years one second [Music] a micro second [Music] no time but the present time no memory of the past no expectation of the future three dimensions in space the fourth of time not yet perceived what is time an appearance which takes the form of motion day and night of play and sleep of being of life [Music] perhaps life is time in the days the minutes fly fast unseen [Music] we move through time we live [Music] in it we say that time is money but time is precious that time is king we know what can be pressed into a week and into a busy day awareness of time experienced by the perceptions of man by the pace of events by productivity [Music] [Music] and yet what is time is time one's view of it is time what one does with it 58 seconds try today is the 17th i've got contractors on my back waiting to get into 58 and 30 seconds is time real i am and thus time is but i also wonder why the clock of life is wound but once and why no man has ever had the power to tell just when the hands will stop whether late in life or whether at an early hour now now perhaps is the only time i own to live to love and as i must to toil placing no faith in tomorrow for the clock may then be still [Music] and time flees from my hands like sand in the wind my past is what i can remember my future it defies the imagination legends and beliefs have made it simple it is said that the light was called day and the darkness night and the evening and the morning were the first day my day is but a moment in the breath of the universe [Music] still i yearn for the promise of immortality for i am i and my soul denies the timeless oblivion of death in the dark of a vast eternity [Music] is time real does it have a beginning will it ever end [Music] [Applause] [Music] i witnessed in my life the existence of [Music] i do not know what [Music] bye primitive man looked at creation and sensed the existence of time he observed and he could predict summer and winter planting and harvesting we apprehend time only when we have marked motion so aristotle said not only do we measure the movement by the time but also the time by the movement because they define each other events their duration their repeating patterns were perceived in the rhythms of the heavens rhythms time the seasons the years months the passage of centuries preserved in a few inches of sedimentary rock clocks of nature time is left behind fine traces of its passing chronicles of millenniums of seasons moisture makes the tree rings grow wider drought keeps them narrow and a calendar of events can be traced back through time a year by year countdown to date the past events recorded in sequence before or after another event reaching back past the beginning of the first calendar stonehenge years before christ perhaps among the first of the calendars man set stones in a precise order to identify the summer and winter sun and to recognize the fallen spring equinoxes all events have been observed to take place in time and all are affected by it so it should be easy to measure time by units [Music] and the counting of time must thus begin at zero sand flowing at different rates begins at zero time then it marks the quarter hour the half hour the hour a 17th century pocket sundial counted the same units of time in a different way [Music] and so did years in their more controlled more precise manner zero revolutions then one two three tick by tick to the hour [Music] as inevitably the hands of the clock moved again to zero [Music] man has learned to break up the apparent flow of time with clocks each ultimate imperfection to split the seconds to count divide and conquer time still a tenth of a second has become a precious commodity [Music] in six thousand years this cesium clock will not gain or lose more than one second and that second is defined by the vibrations of atoms of cesium 133 the earth's rotation no longer serves for accuracy it loses three seconds a year some years three seconds out of 31 and one half million seconds yet man seems no closer to defining the entity that is time itself he may stop an event in each of its positions but what would happen if he were able to play with time and change the order of events to suit his own will can the clock move back let the word go forth from this time and place to friend and foe alike that the torch has been passed to a new generation of americans born in this century tempered by war disciplined by a heart and bitter peace proud of our ancient heritage and unwilling to witness or permit a small undoing of those human rights to which this nation has always been committed and of which we are committed today at home and around the world [Music] which way is time is time the tick of a clock [Laughter] is time motion does it flow like a river and if it does where does it go discuss this [Music] oh [Music] [Music] evidence of time evidence of life of a dark bygone unhuman past of struggle of survival of evolution down through time i pass through rocks of ancient deserts flood plains and oceans time probed through the mammoth units of geology 200 million years ago 300 million years ago passed by walking only a few steps i wonder what is the significance of my life in these vast stretches of time my mind can hardly comprehend the immensity of the figures i saw here a distinctive sandstone formed from sand dunes of a great desert that 250 million years ago spread over vast areas of the american west what forms of life what kinds of plants what insects could have lived in it footprints are all that remain time my narrow view of the human scene i and eternity so [Music] there were here in the grand canyon two great mountain ranges perhaps as high as the himalayas that have come and gone there were great oceans great deserts like the sahara great flood plains like the mississippi all have come and gone now the place is a high plateau through which the colorado river has cut one of the deepest gashes in the crust of the earth when the river first started cutting the age of man as an upright beast was still millions of years off it seems so small man's place in time so unimportant [Applause] near the bottom of the canyon and over a steep ledge lie rocks of shale limestone and quartzite undisturbed relative to each other for eons of time [Applause] jellyfish-like structures representing one of the oldest multi-cellular organisms known on earth 1200 million years old documents of a past of time but what is time [Music] is time life is it eons is time motion [Music] the speed of light is it relative is it absolutely the light from andromeda reaches the earth after nearly two million years of travel when it started man was just beginning to claim the earth it is very old light but it reaches me now [Music] past and present existing at the same instant in time the dimensions of time relativity the past the present the future the vastness of the universe the place of man in time there are footprints on the sands of time the future is yet unwritten what will man do with it whether he will survive or destroy himself is as awesome a question as that of time itself will time continue whoo that was i feel like i have another film about time that is also equally as just like what is going on wow this is our opportunity to take this this concept and just um thank you encyclopedia britannica for that uh and thank you for uh tuning in with us today today was um was a challenge it sounds like it based on the comments where we were going down one path where people some people were happy and we're going down another path people were like oh that's crazy um and that's kind of the way it is it's the the roller coaster for your eyeballs um and i appreciate you being there for us um one of the ways that you can help us is by smashing the like button or hitting the thumbs up button or the like or share the subscribe all those things that all those video podcasts that you watch that they talk about doing um those are things that help us as well you can also buy us coffee by going to ko-fi.com av geeks you can also go to avgeeks.com and see other things that we put online thousands of things and also you can buy dvds there um but thanks for joining us on today's bizarre adventure visual adventure and i hope to have more of these in the future because sometimes that's just the way it plays out some some days it's really basic stuff and some days it's like so thank you for being there for that um you know as always we ask people to please rewind and to take care of themselves and love each other and if they don't um there's the devil so please please rewind and we will see you again tomorrow on wednesday take care everybody bye you