FIRST Robotics 2017 - Build Season Week Three

Week Three.  So, how's it going?

That's actually a tricky question.  Do we compare ourselves to our Rookie selves of last year? To other second year teams?  To the "elite" teams that we have become aware of after leaping head FIRST into the world of competitive robotics?   

Build and Software teams continue to work on parallel tracks.  I understand from speaking with the "Softies" that they have many things working but that other functions are proving to be tricky.  Our job on Build team is to have a robot ready when they want to transfer the competition control system over.  I figure we will be there early next week.

Although we have effectively all of last year's team back again, it is actually a very different group this year.  Veteran members now have more demands on their time from jobs and such. A few who had a clear niche last year don't have such obvious assignments this year, what with a very different kind of machine under construction.  Oddly, or perhaps not so oddly, our younger and newer members have in some ways been carrying a lot of the work load.  And doing well with it.

Example one.  We actually have two middle schoolers on the team.  With the collective student brains making little headway on a mechanism for our winch to engage the climbing rope I sat the two young cubs down at our battered shop desk and told them to come up with something.

What they drew up - then cut and welded - was a remarkably effective bit of engineering whose only downside was that in its initial version it bore a creepy resemblence to an iron swastika! With the edges smoothed down and the dimensions modified it will be perfect.

Hmmm, lets work on that a bit.

Example two.  Our device for releasing the gear onto the target spike was mediocre in its first wooden incarnation.  Feeling a bit guilty about being in charge of a gang of blacksmiths (instead of doing all of this in computer modeling as is common in FIRST) I drew up a list of specs. Where the gear had to start, how far it had to drop, suggestions on mechanical simplicity, etc.

Working in variously sized groups they produced four proposals in addition to our earlier one. Two looked very promising.  One was a bit dubious due to complexity.  And one simply ignored my specifications and solved the problem a different way.

I did not like this last plan very much.  I had them rough it out in wood and put it through vigorous testing, trying to make it fail.  I could not.

So we are building it.  It will be less complex than what the "elite" teams are doing but with the added advantage of early completion and lots of practice time I think it will serve with distinction.

Some week three pics..

With bemused admiration for those teams who create their robot entirely on a computer then send the files off to be professionally cut, I prefer our way.  Cutting and grinding in our welding area.  

It looks as if we will have the time, weight and space allotments to attempt a ball shooter as our third priority system.  The team likes to play around with the launching mechanism.  I only let them do so when other, higher priority work is complete.  It sure launches that wiffle ball...but the trajectory is unpredictable. 

Our rope climbing mechanism was a bit over engineered....it was a boat winch capable of handling 500 pounds mated to a converted CNC tool changing gearbox.  So obviously the solution was.....even more over engineering.  We actually do have some mechanical engineers helping coach the team, and in consultation with our build kids a remarkable gearbox was located.  Made of aluminum it is fairly light, well within our weight constraints.  And it takes things to ridiculous levels...

  
There are two options for a whiffle ball shooter, high and low. Of course the points are different and sentiment on the team is to "aim high". But in the meantime experiments go on with a low target shooter.  We needed a regulation dimension target, one we can move around easily. The first version was sloppy work, heavy and poorly made.  Somebody threw a ball at it, it tipped over and broke.  Version 2.0 is simply clamped onto our solid steel robot transport cart.

At roughly the half way point in build season we have our primary and practice robots both looking like this:

The earlier plywood front has been replaced with beautiful clear quarter inch polycarbonate. The gear collecting system is flawless.  We have some tinkering to do with the gear release, maybe another day or two.  I am advised that the completed lift winch is maybe two days off. Some sort of ball shooter that can be effective at point blank range looks to be seven to ten days away.

So.......doing OK.

The Bicycles in the Cave

Nothing like a bit of larceny to spice up a brewery cave story.  But first some history.

When Neuffer and Becker started their brewery in Winona, Minnesota in 1863 they were coming into an already crowded market with two substantial competitors.  I have featured the Gillmore Valley and Peter Bub breweries in earlier installments of Forgotten Brewery Caves.

The location was alongside Sugar Loaf bluff just outside of town.  In fact they set up shop only a few hundred yards away from the Bub brewery.  The history of the Neuffer and Becker brewery is a familiar one, frequent ownership changes and at least one damaging fire. It was eventually acquired by a man named Schellhas, a former brewer for Peter Bub.  Prohibition had its usual effect on the business, and when sale of non alcoholic products proved insufficient the brewery went out of business in 1931.

Eight years later the Winona Republican-Herald had this in its January 18th edition:

ABANDONED BEER TUNNEL USED FOR STOLEN BICYCLES

Youths Put to Work Reassembling Parts found at Sugar Loaf

"Three youths, alleged members of a bicycle theft ring with a "base of operations" in a bat infested and long abandoned beer storage cave at Sugar Loaf were put to work today by police reassembling bicycles from "scrambled parts".

From 15 to 17 years old, the boys recently started riding bicycles from Winona to Sugar Loaf to a long and deep tunnel leading to a sandstone cliff cave where lager beer of the old William Schellhas brewery was stored, police said.

Tunnel and cave have been unused for nearly 40 years for the purpose for which they were intended, but in it Detective Albert Winkels and Traffic Policeman August Bingold yesterday found evidence that bicycle thieves had been stripping accessories from stolen bicycles there.  

Following the arrest of the three, police recovered two bicycles which they could not identify at first as any that had been stolen in Winona recently, but the boys admitted switching parts from their own and stolen bicycles until only they could tell which part belonged to which bicycle.  

Work at Station

So the boys got jobs at the police station Tuesday afternoon and today taking the bicycles apart and restoring them to their original condition as far as possible.  They were working today on a girls red bicycle and a man's cream and black colored bicycle.........

The mouth of the tunnel is down hill, or on the east side of the old Schellhas brewery, which stands between Highway 61 and the brick hill road which extends from the south end of Mankato avenue.  

The tunnel runs fairly deep underground through sandstone formations, under the old brewery and ends under the brick road......."

Alas, I have given the area a fairly good looking over and can see no trace of the Schellhas cave surviving to the modern era.  The best I can offer is an image from a 1908 post card.  Sugar Loaf in the back ground, the red buildings are the Peter Bub Brewery.  Schellhas would be somewhere off to the left.

Another Great Surplus Store Gone - Farewell Amble's

Amble's Metals.  It was never on my A-List of places to visit but that was just because it was in such an inconvenient location.  It was once on a proper street, just off of Franklin Avenue in South Minneapolis, but various freeway projects chopped the neighborhood up into isolated pockets, and it took some effort to even get to the place.  

Ah, but it was usually worth it.  Amble's was a complex of 19th century buildings jammed to the rafters with anything metal you could imagine.  Pipes, gears, bolts, sheets of stuff.  Pulleys, chains, drill bits, saw blades, as well as many objects that I could not identify at all.

Amble's was the kind of store where you never paid a normal price for anything.  The owner, an irascible autocrat named Jim, had peculiar ideas on what things were worth.  A beat up, vintage bit of machinery that would cost you a small fortune to resurrect might have a lofty and non negotiable price tag.  A box of odd metal parts that were perfect for your latest robotics project might get a glance, a shrug, and "Three bucks" as an answer.

Sometimes I would stop in just for the entertainment value of wandering through thousands of square feet of dusty merchandise....just marveling at mysterious stuff pushed far back and high up onto endless tiers of rickety shelves.  It had a very post apocalypse feel to it and I regret to say I have no pictures of this.

Because, when I swung by recently with a bit of time and a few vague shopping targets I found this:

Closed.  The lights were off inside.  Peering into a dusty window with security bars it looked as if the place still contained odds and ends, but there was no life left in it.

Looking down the row of miscellaneous buildings that were cobbled together to make this Surplus Emporium;

So what happened? 

No doubt there was a lot of simple economics involved.  Metal prices have plunged in recent years and to have your massive inventory suddenly be worth half as much is not a good thing. For the basic stuff people could just go to the local Big Box building supply store and get the item cheaper.  And with negligible risk of tetanus.  Also, this warren of junk filled buildings can't have been cheap to heat or to keep a functional roof over.

I have mentioned that the owner was something of a character.  Although the internet oddly seems to contain no definitive history of Amble's Metals I have been able to glean a few details from sites and conversations devoted (slavishly devoted I might add) to vintage machinery.  The most recent owner appears to have been a second generation Amble, so it seems likely that the enterprise was started back when this neighborhood contained many small factories and a big rail yard.  These are mostly gone now, in the case of the factories they have fled to the suburbs, or to foreign shores.

 Perhaps this comment summed it up best:

Jim always walks around with a wad of cash that would choke a horse. He needs the money - his wife is about 20 years younger and really stacked. He has a wide collection of hardware that he sells very cheaply by the pound depending on what they're made of. I think Jim must buy and sell stuff that never shows up in his store inventory. Jim can be crusty at times but I always enjoy seeing that big stogie stuck in his ugly mug. He's his own man and one of a vanishing breed.

Another commenter said that a friend of his would bring along a cute college aged female friend and that it seemed to allow for more latitude on negotiations.  Machinery guys being relatively humor free I suspect his use of the term "wiggle room" was an inadvertent pun.  But maybe not.

My first thought on discovering that the business was closed was "Damn, and I missed the sale!!"  Indeed.  It happened in May of 2016 when I was overseas.  Jim Amble was said to be retiring after 42 years in the business.  I wish him all the best, and can say that my interactions with him were always enjoyable.  He was indeed "his own man".  (Note, the founding Amble, his father, was also named Jim, and appears to have been even more of a character!)

And the site?  A few months ago it was announced that it had been acquired by the Red Lake Band of Chippewa Indians.  They are going to demolish what is harshly but accurately described as a group of "blighted buildings" and put up a very 21st century development. Mixed use as they say in chirpy ads.  Apartments, a health care clinic and most interestingly their "Minneapolis Embassy".  Native American tribes have a sort of quasi independent status in our legal system.

It all seems pretty slick, and if you look at the pretty pictures and read how it is adjacent to the new transit train station and a bike trail that is reportedly going in somewhere it sounds like progress.  Of course the neighborhood that currently exists just beyond the boundaries of this little island is one of the worst in the city, but things change over time.

If change is a constant I think we are allowed our own opinions as to whether some aspects of it are good or bad.  The clinic/residence/Embassy seen above will certainly have positive features. But our cities are full of complexes that look just like it.  While places like Amble's are becoming rare treasures.  

Maybe Jim Amble had it right when he argued for prices higher than some would prefer.

I have not seen any time line on when development will actually start.  But when the bulldozers finally roll I have no doubt they will be unearthing odd bits of scrap metal everywhere.  I also would like to imagine that years from now when everything is new and shiny, that you will still be able to detect the occasional faint whiff of cigar smoke.

FIRST Robotics 2017 - Build Season Week Two

So what do you do when you lose two precious, irreplaceable work days to bad weather?

You get a bigger whiteboard for the jobs list!

Although this sort of thing can be anticipated in winter time Wisconsin it is of course quite annoying.  I take consolation in the fact that most of the teams we will be competing against regionally have experienced the identical weather and probably lost the same work time. Also, it was Final's week for the kids and we were anticipating light turnout anyway.  

The hand writing on the board is mine at this point.  Some parts of the team, software for instance, are very "self propelled" and they just do their thing.  But the build team has many separate tasks to juggle and is dependent on arrival of ordered parts, so somebody has to line up the many necessary jobs in a logical order.  As the season progresses I will turn the marker over to the kids.

At the point recorded above we had a basic frame set on top of last year's chassis.  We had the new drive frame (competition machine) partly assembled.  There will also be a practice robot, the frame for that is still in the box.  We have working prototypes for all of our priority systems and are toying with the idea of adding a ball shooter device.  It is not critical to our perceived game strategy but A: it would be cool, and B: we appear to have space, weight and battery power to add this feature.  Also, C: the game may play out in ways we have not anticipated.

On to Week Two work.

Software is making steady progress on the targeting system that looks for reflected light and steers the robot to it.  Evidently it is just a matter of pattern recognition.  Here the camera is "reading" the two upright reflector targets as those tall rectangles.  There is some scatter from the white plastic tip of the spike that will have to be dealt with.

This is our "practice" frame set up with our home brew batch of electronics.  This suffices to let the build team drive the machine around and test basic mechanisms.  Some of these components are over a decade old but they just keep working.  

Parts being turned on the lathe.

With what we consider our "basic" mechanisms well along in development and fabrication the team has taken on the "stretch goal" of a ball shooter.  Here one of the coaches is working with the team on calculating trajectories.  Actual engineering going on!

End of the day.  Final calculations for the ball shooter are up for display.  The job board is set for Monday, with most of the entries now done by the team.  The board now has a count down on it as well.  Right now it reads 30 days to deadline.  On the table next to the job board is a basket of safety glasses.

With about 30% of the build season done we are feeling good about the "hardware" side of things.  Software is also making strides but in their case they can keep tinkering right up to the moment of competition.  Stay tuned for updates.

Tree Shaped Tombstones - Construction Details

Stone masonry.  It is an arcane skill and I know nothing about it.  So when I am out looking at Tree Shaped Tombstones I am also searching for clues.  How these things were made, customized and installed interests me.  

Here is one of the twelve foot tall versions you occasionally run across in fancier cemeteries. Note the "seam"in mid picture.  These were assembled in two or three segments that were set one atop another.  Since all the lines of the bark are true I have to assume it was carved as a single unit then taken apart for shipping purposes.

Here a marker is tipped over, showing us the base.  It is rough carved either because it would not be seen or perhaps to hold mortar for secure installation.  I refuse to believe that the base seen here - an earlier grave marker - was original.  That seems most disrespectful and besides the older stones are pristine.  I think this one was put on its side not by nature or by vandals but in preparation of having a new, secure base installed.  

Note also the central hole in the stone.  I suspect these were drilled in to provide a convenient place for a lifting device, something like a set of large tongs.   

In support of this theory I have seen a handful of examples where you can see the hole in the top of one of these segments.  Here I think is one where the upper half fell off - and probably broke - so long ago that the exposed surface of the lower segment is moss encrusted.

Is this another temporary base?  It looks a bit more long standing but really is parking your monument on some loosely assembled bricks sensible?

This one has me thinking.  In the above photo you can see the classic "feet" that represent tree roots.  I have always assumed they were features of the original carving.  But in this specimen there is a chiseled slot with a metal pin right at the bottom of a "tree".  Again you can see the rough surface for mortar although no trace of it can be seen.  Perhaps this was how various standard features such as flower pots or doves were attached?  Note in this case a solid, plausible looking stone foundation.

Blizzard Etiquette

(This post is dedicated to my current and former neighbors who flee all this for sunny climes either short term or for good.  You know who you are.)

Wisconsin.  January.  Periodically the Elements conspire against you.  One week it is bitter cold.  The next week a thick blanket of snow.  Some weeks both.  

We are not as tough as the pioneers who settled the frontier.  They were enduring all this in log cabins and while wearing itchy woolen garments that probably did not get washed until Spring. But a bit of the pioneer spirit lingers on; in this place, and at this time of year neighbors have to help each other out.

There are of course Unwritten Rules.  As a retired guy with a snowblower I have the ability to get out and clear snow on a very flexible schedule.  My own does not take long.  But what about Other People's Snow?

The sidewalk that runs the length of the block is fair game.  We all want the postman to be able to get through.  Here is "Boreas" my faithful machine, having just cleared it down to a slip free cement surface.

On the other hand, plowing from that sidewalk up to people's front doors would seem a bit presumptuous....that is their individual property, not the collective Commons.

But what to do about this situation?

Here a homesteader's earlier snow removal efforts have been foiled by the city snow plows which go along and, in the necessary task of clearing the roads, throw up big ramparts of ice and chunky style snow.  As  you can see, people's recycling bins get entombed.  So do the entrances to drive ways and the place where sidewalks meet the street.  The etiquette here is a little trickier.

Keeping the sidewalks clear to the streets follows the same rules as above.  So I plowed out the two corners on my side.  Going around to the other two corners on the back side of the block would be showing up my neighbors, and as such a bit of bad form.  Unless of course you have elderly neighbors on the back corners.  Or you know they are out of town.  I am not the only person on the block with a snow blower and it would not do to deprive others of an opportunity for minor service to the community. 

Clearing at least one end of the alley is a high priority.  Otherwise anything short of a monster truck is not going to be able to negotiate that last crucial two feet that will get them onto the city street and off to work.

Recycling bins are a tough call.  It would not do for a person to miss the every two week opportunity to get rid of empty cans and bottles.  If you know a neighbor well enough to not be shocked or curious about how many clinking empties you have to move to get the way clear for the recycling truck, go ahead.  If you don't know them that well, best not to.

That's better.

Anthropologists could study the ways of this little snow bound tribe for quite some time.  I have for instance not addressed the touchy matter of how soon to start plowing.  You want to wait long enough for the precipitation to stop.  No sense having to plow twice.  But if you wait too long the other members of the clan might beat you to it, the whine of their motors starting up a gentle rebuke to your by-the-hearth sloth.  

Another blizzard dealt with.  One step closer to spring.  I hang up my snow dusted coveralls until the next round.

FIRST Robotics 2017 - Build Season Week One

We had a few bumps in the road but have made good progress.  Regards the former, we lost one work day due to weather, and had some of our parts go missing for a while.  But as was the case last season we get a lot done on Saturdays.  We in fact have our three main systems all working in prototype stage and have our competition drive frame and electronics partly done.

Evolution of a robot.

The game this year involves manipulating these big plastic gears around.  We have to deliver them onto this springy thing.

We also have to collect the gears.  Our system for doing this involves having them drop down between these two plastic plates.  The back plate is designed to be springy and flexible so as to encourage the gear to rebound down into the space.  Oh, that's just not true.  We did not design it that way we just built it out of scrap stuff on hand and noticed that function as a happy accident.

Another feature of the challenge involves tracking with a light sensor.  The "target" area has reflective tape on it.  I just happened to catch a good flash off it with this shot.  The on board cameras of the robot will also be looking for this.

The final version of course will have a polycarbonate front plate.  Here we were just mocking it up built on last years drive frame and using plywood.  The gear holder is also wood at present, but does function to cleanly drop the gear on cue.

Another aspect of the challenge involves, not kiddin' here, the robot scaling a rope.  So, about 120 pounds hauling itself four feet up in the air in fifteen seconds.  We actually had parts on hand that let us build this proof of concept lifting device.  

It is helpful to have great big ceiling beams when you want to test a winch.  It lifted more than the required weight and at a very brisk pace.  

Wooden prototypes are OK, but the process of converting over to nice neat finished work will take us a few weeks, even if unexpected difficulties do not arise.

They always seem to.

Forgotten Brewery Caves - Leinenkugels

Leineinkugel's Brewery has been making the residents of Chippewa Falls happy since its establishment in 1867.  It has the classic location.  On a creek, edge of town, right next to a nice hillside with a stone face.  So of course there was a brewery cave.

But this cave is elusive, the stuff of rumor and myth.

Supposedly when renovations were done on the brewery circa 2000 the cave was briefly exposed.  It was said to be in a bad state, wet and partly silted in.  I did not have a chance to see it before it was sealed off.

A while back I ran across an 1871 newspaper article that describes the cave.  It was said that it 

"..commences just back of the brewery and is one hundred feet long and twenty wide, built in the solid rock.  It is 49 feet from the cellar to the surface and through that there is an air hole of about one foot.."

It sounds like a classic brewery cave, but behind the current brewery I can see no clear evidence of it.  So my hopes were raised when I saw this going on:

No cave in sight - by my reckoning it is about 50 feet to the left.  But that "solid rock" that was described is still there.

Note, I don't want anybody bothering the good folks at Leinenkugels so I set this post aside until construction was finished.  There is no point in nosing about looking for a cave.  Neither the entrance nor the vent hole are visible in 2016.

The National Enquirer Gets Real

Before Christmas I noted with bemusement that our local supermarket had stopped selling Tabloids in the checkout aisle and had been using the same racks to sell something that was at least initially labelled as "Adult Coloring Books".  Well as I suspected the tag was in error and soon replaced.  Near as I can figure these are conventional coloring books for kids.  I hope.

But the persistence of this phenomena - cheery coloring books on racks advertising lurid Celebrety Newz - continues to distract me.

Has the National Enquired been seized by a sudden fit of absolute honesty?

OK...so how do they build this?

And we have an answer.

After months of baroque speculation based on the flimsiest of hints we have received the "specs" on this year's FIRST Robotics Challenge.  The answer is below, but before we get to that I wanted to go on record with my own predictions.  Trust me, 'cause the Internet never lies, my prediction was made well before the official reveal.  I take my kudos and lumps as I earn them. Maybe I will even give my predictions a grade.

My Prediction 1/4/2017

With a theme of "Steam Punk" it is reasonable to assume lots of gears, implausible blimps, shiny brass stuff.  But the actual game has to be something that can be set up in the same venues - usually gyms and arenas - as in years past.  So no pools of water and I consider flying drones and actual blimps to be impractical.

I say there will be some kind of "coal mine" from which lumps of "fuel" are removed and put into a "boiler".  This will require some kind of grabber arms and/or conveyor belts.  I also expect there will be a series of ramps that have to be moved into position, or in the case of a defense strategy, moved out of positions that the opposing team would prefer.  The "end game" should involve placing some sort of gears onto a big peg board.  The boiler provides an amount of "energy" that varies with the amount of "coal" in it.  The gears provide some kind of multiplier of this.  The final style touch will be a fake blimp rising up a structure in the fashion of those old fashioned strength measuring games at carnivals.  You know, the ones where you swing a hammer and something scoots up to perhaps ring a bell...

The reality 1/7/2017

The Reveal Video:

I did OK on my predictions.  Fuel, gears...no ramps.  The fake blimp is stylised but the spinning rotors are certainly trying for it.   I give myself a B.

Our first (FIRST) build session was a bit chaotic but it was the chaos of many ideas flying around.  Stay tuned.

Kicking out the Elves, Bringing in the Robots

After a pre-season where we have done as much as possible to get ready, the hectic FIRST Robotics Build season begins in just a few days.  We have a fabulous work space, but it does have the minor down side of being shared with a community Christmas program that does not clear out until very late in December.  It is rather fun to be headquartered in Santa's Workshop but it means we can't really unpack everything and get ready to work until rather shortly before the 7 January Kick Off date, aka The End of the World as We Know It.  

As we will be spending a ridiculous amount of time here over the next few weeks and months it behooves us to be both comfortable and efficient.

We have as our headquarters a rather unusual space.  All the serious machines - manual and CNC mills, lathe, welding, paint and carpentry shops, are on the first floor.  Take the freight elevator (yes, really) up to the second story and there is a big open space.  This is a former warehouse. Our little stash of robot stuff was huddled off in one corner.

We expect to set up a mock playing field here.  The pillars will make for extra realism in drive practice.  The game of course changes every year, and on occasion calls for firing beach balls and such at targets higher than this ceiling.  You just never know...

On a recent night we got the team together.  As usual there was plenty to do.  Inventory parts. Dismantle last year's robot down to a drive frame for future test purposes.  Haul desks and work tables into position.  We thought we had some storage shelves but these had disappeared...I suspect the Elves nicked 'em.  So in keeping with our team philosophy a rugged storage unit was cobbled together out of pallets and scrap lumber on hand. 

A few pictures of the last "pre-season" work session.

I anticipate the fluorescent lighting, wide expanses and constant motion will continue to challenge my photographic skills..

One end of the scrap lumber storage system has a wire dispenser.  The spools are of differing wire gauges.  I think they even organized them left to right by size.

On the back of the storage rack are slots for a couple of robot building staples.  The slotted aluminum stock is called 80/20.  It is extremely adaptable for building things.  Kind of like a giant, sturdy Erector set.  The clown colored Styrofoam tubes are "pool noodles".  Believe it or not these are standard, required elements for FIRST robotics.  Each robot has padded bumpers to prevent damage to humans or other machines when inexperienced drivers get a bit carried away.

Just tidying up.  We have the ability this year to leave work out on the benches, but have to be careful not to abuse the privilege.  Floor is clean.  Our team banner is hung from the rafters. This too is something of a "statement" of what kind of work we do.  A home made flag hanging from a century old one foot square wooden beam.  It is held on by big metal C-clamps that would easily hold several hundred pounds instead of a few ounces of red cloth!

Coinage of the Late American Empire

I had no intention of doing three straight postings that featured coins.  Its just one of those things that happens.

Appearances aside this technically is not a hoard of coins.  The strict definition of a hoard in the archeology sense is a collection of coins all intentionally buried in one location.  This agglomeration represents one calendar year's worth of picking up scruffy looking coins while out for walks.

I know that this, along with a heightened interest in all things relating to squirrels, is a warning sign of becoming An Old Guy.  But I justify it in several ways.  I need walks.  It actually is free money. And it keeps my archeology "eye" in tune year round so that when I arrive at Vindolanda for my annual dig I am all set to spot minor variations in shape, color and texture. A closer look:

There is much variation of course, not only between denominations but with different ages of coins, differing degrees of damage from the circumstances of where they ended up, and so forth. But there were a few things I noticed that had parallels to the Roman coins I find when excavating.

Here is a fairly typical late Roman coin as it comes out of the ground after 1600 years or so:

Not much to look at really.  It is copper, or an alloy of same.  Basically its the equivalent of our modern penny.  Note the greenish tint, this is copper oxide and is the natural consequence of aging copper.   Some of our pennies show a bit of this:

Notice that these are somewhat older coins.  56 years in the case of the specimen on the left.  But newer pennies...

Yuck.  They just get a sort of dirty coating on them.  In fairness I suspect some of this is from the salt we so liberally use on our roads and sidewalks in the winter.  But there is also a very different make up to modern pennies.  Lets take a closer look..

This coin is mere months old, and despite obviously living a rough life there is nary a smidge of oxidization on it.  In fact, the thin shiny coating of whatever alloy is on it simply is a thin wash covering up a core of some other cheesy stuff.  Note the beard and side burns of "Dishonest Abe". 

This process of using a thin coat of (apparently) valuable metal over a base core is as old as coinage itself, being practiced not only by counterfeiters but also by dishonest mint workers since ancient days.  In a previous post we have visited a few examples.  Here is a silver denarius with a crappy base metal surprise waiting for the outer layer to wear through.

It has of course been many years since we have had any real silver coinage in our own currency. Our financial wizards make no effort to hide the process, and the copper - more or less - inside a modern day dime can be seen just by looking at the edge.  Or wait until it wears through a bit. From my 2016 ambling I present a spiffy new dime that somebody dropped soon after it came into circulation.  Next to it is a tired and dingy specimen with its copper showing through on the lower edge.

Archaeologists are probably guilty of reading too much into coins as a barometer of societal health.  Not every devaluation of currency is another marker for Decline and Fall.  We just don't consider coins to be as important now as in times past.  There are even periodic attempts to eliminate the penny as a useless anachronism.  If you dropped a penny circa 1900 it was the equivalent of about five minutes of salary at the then typical "dollar a day" wages.  Today with the minimum wage at $7.25 an hour a penny is what you would earn every five seconds. No wonder people don't bother picking them up.

And of course we are rapidly approaching a cashless economy where physical manifestations of wealth are used less often than a swipe of the plastic or the entry of a few numbers onto a screen. 

So I can't make the devalued coinage of the current American Empire into anything profound. Money is less important than it once was, at least money as the Romans would recognize it.

Whether this is progress or not is debatable.