Adding lightness.
April 8, 2010 10:32 AM   Subscribe

Machinist's cubes (or turner's cubes) are a traditional test of skill for aspiring machinists.
posted by 1f2frfbf (35 comments total) 36 users marked this as a favorite

 
Doesn't Vonnegut describe something like this in Player Piano?

This reminds me of the whittler's equivalent: The ball in a cage, which some take to excesses.
posted by Ogre Lawless at 10:39 AM on April 8, 2010 [5 favorites]


So, I'm a little confused. Are the inner cubes connected to the outer ones? Or are they free floating in there?
posted by DoublePlus at 10:39 AM on April 8, 2010


They're supposed to be free floating.
posted by Jairus at 10:43 AM on April 8, 2010


Like the intricate carved ivory or jade balls within balls
posted by infini at 10:57 AM on April 8, 2010


Ah, that's what thing is on our chief engineer's desk!
posted by infinitewindow at 11:01 AM on April 8, 2010


Pshaw, cubes are easy. The Romans did it with 12 sides. Not really.
posted by Nelson at 11:03 AM on April 8, 2010


Pinhead: Ah, no more boxes, Kirsty?
Female Cenobite: No more teasing, Kirsty, it's time to play.
Pinhead: Time to play...
posted by FatherDagon at 11:16 AM on April 8, 2010


When my grandfather was alive, he had his own machine shop. I grew up behind it....it was a fascinating place, with all sorts of machinery and things inside...I will never forget the smell of that place, metallic and oily and mysterious.

He and dad didn't get along that well, and dad declined to go work for him, instead going into electronics. But he'd have been good at it.
posted by St. Alia of the Bunnies at 11:18 AM on April 8, 2010


You know,

Almost ten years ago, when they were teaching all of us young engineers how to machine things, we were told that we were lucky we weren't in Germany, where the first lesson in machining was:

"Here is a file. Come back with a perfect cube."

I always wondered if that was actually true.

(We did, however, have to prove that we could make floating cubes before we were allowed to weld things on our own.)
posted by Comrade_robot at 11:38 AM on April 8, 2010


What fun to be able to make things like that!
posted by Cranberry at 11:43 AM on April 8, 2010


So, where can I buy one of these things?
posted by Cool Papa Bell at 11:45 AM on April 8, 2010


Beautiful objects... the jewelry is lovely.

My father sold tool and specialty steel and often came home with beautiful machined objects. He claimed that many machinists were frustrated artists, and this is elegant proof.
posted by kinnakeet at 11:47 AM on April 8, 2010


"Here is a file. Come back with a perfect cube."

I always wondered if that was actually true.


I wouldn't be surprised, since that's basically the first step in Gingery's classic book. Not a full perfect cube, but a flat surface parallel to another flat surface using only a file.
posted by DU at 11:47 AM on April 8, 2010


Dunno about Germany, but 25 some years ago in Bangalore U we had a separate course called "fitting" which entailed exactly what you describe comrade_robot. nothing as fancy and shiny as this example though which doesn't get into actual making of the pieces. (reminisces, then there was foundry, smithy, machine shop, sheet metal and carpentry.. but interestingly, no computers until 88 or 89)
posted by infini at 11:51 AM on April 8, 2010


Yup, what DU said (had I previewed...)
posted by infini at 11:52 AM on April 8, 2010


When I started out in the business, the foreman handed me a file, a fist size piece of neutronium and said to come back when I had turned it into a perfect cube. Unfortunately it fell from my hands and punched a hole to the center of the earth. I was fired on the spot.
posted by digsrus at 12:13 PM on April 8, 2010


"Here is a file. Come back with a perfect cube."

I heard that story from my grandfather also.
There was also a science fiction story about the sudden appearance of a Johansson block, a type of gage block that is so perfectly finished that they stick together via molecular forces (all air is excluded and vacuum holds them together)
posted by 445supermag at 12:26 PM on April 8, 2010 [2 favorites]


"here is an html file. come back with a perfect time cube."
posted by the aloha at 12:29 PM on April 8, 2010 [7 favorites]


"Here is a file. Come back with a perfect cube."

This is one of the first assignments that sophomores at RISD's industrial design program have to do. It's boggling the kind of perfection some people are able to achieve.

I once carved a length of chain from one piece of wood, but I used a dremel and it's not nearly as smooth as the ones in Ogre Lawless's second link. People are still impressed by it, though.
posted by fancyoats at 12:46 PM on April 8, 2010


our standards were charpoy legs and chakla/belans - i preferred lathework on wood than metal but there's something about the smell of the machine shop grease (as St Alia puts it so well above)
posted by infini at 12:53 PM on April 8, 2010


So, where can I buy one of these things?

I bet It's likely you can't. I doubt most folks ever make more than one, and it's either not for sale, or given to someone special. (I gave mine away.) I also gave away my captured nut, which is a similar type of object: This is the idea but this picture isn't of mine.
posted by fritley at 12:57 PM on April 8, 2010


So, where can I buy one of these things?

I'm sure you can buy one online. Maybe a tedious job by hand, but trivial with a CNC machine. The hardest part is putting each side in the vice.
posted by digsrus at 1:02 PM on April 8, 2010


As an aside: I love the smell of gear and machine oil madly. If I could, I'd wear it as perfume and anyone who wasn't put off by the smell would immediately become my fast friend. When I come home at night from my day job, and open my door I almost always get a snoot full of it (unless it's time to take out the garbage) since my studio is on the sunny side of the house and my anvil has been soaking up the sun all afternoon. It smells like something pumped from deep out of the earth and made of dead organisms should smell. Earthy and deep and musty with a weird twinge of chemical rightness. For me it is strongly associated with many happy memories and fun stories. It's everything I squander my spare time on: from my car to my motorcycle to jewelry and sculptures. It's all business and ready to go, "Let's grab us some scraps, stock and tools and get going, man, we're gonna make us somethin'." Now I'm all ready to get there... *checks clock, sighs*
posted by 1f2frfbf at 1:03 PM on April 8, 2010 [13 favorites]


*reads and feels something visceral*
posted by infini at 1:06 PM on April 8, 2010


ever fix the gap on a spark plug and then light up a cigarette only to get a whiff of lingering smell even after scrubbing hands with detergent?
posted by infini at 1:08 PM on April 8, 2010


Yup. And a can of beer just doesn't taste right without the slight scent of synthetic 10w30 on the pull ring.
posted by 1f2frfbf at 1:13 PM on April 8, 2010


funny how that is...

(btw, anyone know if there ever been an fpp on smells evoking memories or emotions?)
posted by infini at 1:25 PM on April 8, 2010


Yup. And a can of beer just doesn't taste right without the slight scent of synthetic 10w30 on the pull ring.

Ever reminisce about the scent of your grandmother as you close your eyes and feel that warm embrace that comes after huffing gas?
posted by spikeleemajortomdickandharryconnickjrmints at 2:18 PM on April 8, 2010


I made one of these once, although it was on a CNC mill so it was definitely "cheating" compared to doing it the traditional way. Mine is made out of Delrin, which is a sort of tough plastic used for prototyping.

What makes it so difficult — the reason it's traditionally been a test for a new machinist — is that you have to make the initial cube very, very square. If the opposite faces aren't parallel and the touching faces aren't perpendicular, then it will sit differently depending on which face is up, so when you make the cuts to free the inner cube, they won't match and it won't drop free. (Or it'll drop free but be obviously flawed.)

So to do it traditionally, at least in my understanding, involves spending a lot of time getting covered in prussian blue and filing or scraping the surfaces flat, while also being careful to keep the thickness along each axis consistent. (If you file off too much to make it flat, then you have to re-work the other faces in order to get it back into a regular cube. In other words, you have to make the X, Y, and Z thicknesses the same as well as making the faces square and flat.) It's a real challenge, and I suspect it was even more of a challenge a century ago.

Anyway, they're pretty neat, and something to keep your eye open for even if you never make one yourself. Now that you know what they are, you'll almost certainly notice them sitting around as desk ornaments (at least if you work with a technically inclined crowd of a certain age). It nearly always represents a lot more than just a paperweight.
posted by Kadin2048 at 2:46 PM on April 8, 2010 [1 favorite]


Yup, I spent my first week as an apprentice Fitter and Turner in front of a bench with all the other apprentices, with five or six grades of emory paper and a piece of metal that had to be smooth and mirror-like before it was done. Wax on, wax off indeed.

~Matt
posted by mdoar at 4:32 PM on April 8, 2010


There was also a science fiction story about the sudden appearance of a Johansson block, a type of gage block that is so perfectly finished that they stick together via molecular forces (all air is excluded and vacuum holds them together)

I don't understand. Are you saying that there was a story written about gauge blocks, or that you simply perceived your grandfather's description as science fiction?

(At first I thought you had linked to a fictional object on wikipedia. But, it appears that I can buy a set of AA SAE gauge blocks for just $3960.)
posted by Netzapper at 6:46 PM on April 8, 2010 [1 favorite]


I remember my HS drafting teacher telling us about Johansson blocks sticking together. I thought he must be pulling our legs. And that everything I've heard about them since then has somehow been set up by him to keep string me along.
posted by DU at 6:53 PM on April 8, 2010 [1 favorite]


I don't understand. Are you saying that there was a story written about gauge blocks, or that you simply perceived your grandfather's description as science fiction?


Sorry if that was a bit stream of consciousness, it was really two separate comments, the first adding another anecdotal data point to the apprentice machinist and file story, and the second was adding another fictional piece (someone upthread mentioned Vonnegut).
posted by 445supermag at 8:21 PM on April 8, 2010


so perfectly finished that they stick together via molecular forces

That's the standard for planing and dressing the blank woodblocks for traditional Japanese printmaking (no sanding, only planing). Two freshly planed blocks placed together face to face simply cannot be separated again, without sliding them sideways.

But the verb tense should be 'was', I should add, because there is nobody now left who can prepare them that way.
posted by woodblock100 at 8:57 PM on April 8, 2010


well, if we're reminiscing about high school drafting teachers - or rather Tech Drawing - mine was a persnickety young man who claimed to be Bohemian (as in his parents moved to the US from the former Bohemia). He extolled the virtues of clean hands on paper ("it turns me on" I dont want to see fingerprints) and was snarkier than most Mefites I know and read (I said stud Harold not stub ;p) - but taught me more in two semesters than I learnt in the following three years of machine drawing in college
posted by infini at 10:38 PM on April 8, 2010


« Older San Francisco Vehicles Cropped to a Square...  |  The recently announced 2010 Hu... Newer »


This thread has been archived and is closed to new comments