Why Paper Jams Persist
newyorker.com
newyorker.com
In general the rolling mills call it a "cobble" when a whole or partial bit of steel escapes the rolling mill. Lots of exciting videos.
I remember years ago hearing about how the US mint misprinted over a million and had to destroy it (and on the Colbert Report, he joked about how them destroy it by burning it in front of poor people). We were talking about it at a party and someone asked, "surely they noticed? Why didn't they shut it down?" An engineer in our group said, "Have you ever been in a factory? It's so fast!" He worked in a toothpaste tube factory where you'd see hundreds of tubes come out every minute. If something went wrong, you'd have to wait for the whole pipeline to clear. Fab shops in China are even more insane.
I wonder if the mill would just sell those sheets at a reduced price as low grade/for non-visible construction or if they re-melt them down and run them again.
They weren't wildly misaligned, but far enough from true that we had to wash them off and run them through the line again. Took a couple of us most of an afternoon to sort it out.
I worked at a bar during university during a time where the popular beer sale would be "28 bottles for the price of 24". The bar owner would send me and a few guys in a truck to a beer store in another town to buy as many cases as the truck could handle. This was illegal as we would sell it at the licensed bar (all liquor was supposed to be purchased with the license, for which the sale wasn't applicable too). So the owner was willing to risk legal action for 4 free beers (x50 cases or whatever).
The point is... restaurant owners sometimes go to great lengths to save a few dollars.
Love that New Yorker article, though. I grew up reading this magazine in the 80s but drifted away. These great articles straddling tech and culture became too few and far between.
The historical perspective, in particular, was great. But what took this to another level was detailing just how big the challenges are, and how enthusiastic the engineers are in trying to solve them. Even giving a sense of vicarious excitement from the descriptions of their attempts at problem-solving.
I do realize this article is different; there is a lot of historical fact and context which helps create a narrative. It has its advantages. Maybe I'm just getting old. I read a lot of novels and I'd rather spend the time on that type of narrative in a novel or even a non-fiction book than a news article.
People may criticize the YouTube generation, but it has helped in content creators who get a lot of information over in a very concise way (Kurzgesagt In a Nutshell, Smarter Every Day and Wendover Productions come to mind).
I think the opening of the historic paper jam made me want to fall asleep. The later office space references and Xerox design became more relevant. Even then, I feel like I don't read these articles the way I did back when I bought a physical Harpers from the book store. It's a lot of content, and in the scrollable world we just end up skimming more these days.
Reading the same info (in a non-narrated way) would be much faster. Also it's often concise over exactitude or neutrality. I can't sit through these videos, boring or caricatural. At least the New Yorker is sold as an enjoyable distraction, and I find great pleasure in reading nice writing.
This isn't a news article. Perhaps it would help if you thought of it as a freely available, very short non-ficton book.
To this day I never just bang a fresh stack of paper in the printer tray. The full gymnastics of airing, flexing, feeling, airing and flexing again. I'm often laughed at. But my papers never jam!
The surprise isn't that they jam occasionally, it's that we ever get anything printed at all!
It's about the size of a 1980's copy machine, but my department easily prints a minimum of 5,000 color pages with it each day. Some days it's double or triple that. Sometimes with staples.
We go through five massive toner carts each week. They're about the size of a fire extinguisher.
In six months, I've seen exactly ONE paper jam.
I told her I thought maybe they'd figured out this whole printing thing finally. But I guess TFA says I'm wrong.
It's part of their excellent "Beginner's Guide to Aerodynamics" site: https://www.grc.nasa.gov/www/k-12/airplane/bga.html
Making it asymmetrical merely makes it more efficient to generate lift in one particular direction (similar to how glasses lenses are asymmetrical to reduce distortion).
Furthermore, pretty much no airfoils have flat sides, in nature or in engineering[1]
The wing, when placed in airflow, disturbs the air in such a way that the pressure on top of the wing is lower than the pressure below the wing, generating net lift. This isn't a very satisfying description of lift, since it just begs the question of "how/why does it disturb the airflow in such a manner" and the short answer is "we put different shapes in a wind tunnel and measured" with the longer answer being "you don't know enough math to get a good intuition of that"
[edit]
After reading the article, the article did get lift right for the case of the paper though. Jets of air behave exactly as they say, and you can feel something similar by touching the back of a spoon to the stream of water from a sink; it will get pulled towards the stream of water (or just put a piece of paper on a table and blow over it). A few planes use blown flaps[2] to help get a similar effect (the introduction of a jet of air, which "hugs" the wing helps direct the airflow of the larger mass in the direction you want).
1: https://en.wikipedia.org/wiki/Airfoil#/media/File:Examples_o...
The total effects of newton's laws and bernoullis law on pressure differences need to. Be combined but the gist is that you create a force difference using the shape and angle of attack of the airfoil.
The use of this is really quite neat especially in a printer!
That's what the article says, but it's usually the underside that is flat and the top is curved.
The air speed is not necessarily different. Lift is generated because air is deflected from moving over the top of the wing and thus reduces the air pressure. You can create flat winged aircraft with careful orientation of the wings.
Air flow is not like say a spinning disk, where the solid state of the matter forces the outer edge of the disk to move faster in order to maintain relative position.
- First, put your hand parallel to the ground, and see what the wind does to it.
- Then, incline your hand so you raise your fingers, and see what the wind does to it.
Lifting has no relation to the wind being flat or curved. It's the overall shape (the one you change once you incline your had) that causes it.
This seems quite clever:
'Corrugating is when we put an intentional wave in the sheet, like in a piece of corrugated cardboard,” Vicki Warner explained. “It adds stiffness.” The plan was to corrugate the sheet lengthwise by running it over a line of rollers turning at variable speeds before “flying it” into the stacker. If a physical fix was necessary, a part might be 3-D-printed and installed, on-site, by one of the engineers.'
The "stub point" is a common thing, and can be very, very difficult to pinpoint. They had one specific finisher that kept jamming when you printed to the top tray. It didn't jam 100%, it was pretty intermittent. Well, this finisher had been in another lab for a few weeks or so and they couldn't find the source of the jams or a pattern to them. I had the finisher installed on one of my machines in the 3 days I'd solved it. There was a small stub of plastic on a flag for a sensor. The flag sits in the paper path, and when its moved, the sensor changes state. So this flag has an pretty smooth surface so as to not catch the paper, but somehow this one got a little nick in it. Enough to cause a jam when a sheet ran right into the nick. I filed it down and the machine never jammed again.
We had another issue with a printer at a customer site and the issue dealt with static electricty. a 30kv ESD gun and the inside of a printer.. we still never solved the issue.
River transportation of lumber kept going long after railroads came along. Jam would be broken using dynamite sticks.
Here's a movie on the driving of logs on a river in the 1950s: https://www.nfb.ca/film/drave/ Driving only stopped in the 1980s on that river.
It seems really helpful, but I'm not sure which problems discussed it would actually solve.
There'd also be cases where it kept pulling on the holes but those separated and got gummed up really badly.
When you try and tug the pages out they're all perforated so you get, at best, a single page. It can be a lot of work to clear a jam.
Most people think of dot matrix printers as slow, lumbering things that would take measurable time to print a single line. The industrial ones, enterprise grade, made by companies like IBM were dizzyingly fast, pages per minute, so if a jam happened it was usually severe. Most had multiple print heads to speed up printing.
These also used much wider paper than normal for things like accounting reports. When they jammed, they jammed.
People were also really rough on those things. Yanking at the paper to tear it as the printer was just finishing it up.
I honestly don't remember printing anything but A4 for the last 20 years. We printed some labels in the 90s, that was the only diversion...
If I don't want to read the thing on a screen, then doubling its size is often useful.
But, for metric sizes, two consecutive sizes could be supported. A4 would print landscape, and A3 portrait. The large photocopier-like printer at work does this.
One of the jobs our operator had was to constantly clean, dry, and dust off the rollers that went in to those little holes on our high-speed line printer - the amount of paper dust produced by a few boxes of paper was astounding.