The mechanism known formally as the Trammel of Archimedes (Wikipedia) has practical application, when fitted with a drawing or cutting tool, as an ellipsograph. Otherwise it is fascinating but generally useless, and these qualities have earned it a variety of approximately affectionate epithets: “do nothing machine,” “nothing grinder,” “BS grinder,” and “Kentucky do-nothing” are a […]
Dug North spotted this gem in a recent (and now unfortunately closed) eBay listing. Would love to hear what it sounds like when you pull the lever.
EdenTXlocation.jpgBack in 2008, I wrote a series of posts about Alvin E. Gandy’s 1965 patent “Gandy Slide-A-Way” mechanical gate opener, which uses the weight of an approaching vehicle to automatically open and close a remote vehicle gate without electrical power. The story has apparently gotten back around to Mr. Gandy’s surviving family. His niece Annie just commented:
If you’ve been around long enough to have ever actually blown out your flip-flop, stepped on a pop top, you’ve already got one great reason to appreciate the 1975 introduction of the stay-on tab or stay tab: No more little metal razors littering the beaches.
Now, “Engineer Guy” Bill Hammack helps us appreciate the stay tab for another reason: It’s a little gem of mechanical poetry. There’s a lot going on when you pull that little ring. Bill’s video exegesis of that action, like all Bill’s videos, is a little piece of poetry unto itself. I can’t get enough of ’em. [Thanks, Bill!]
This mechanical model of a comet’s orbit, based on the action of elliptical gears, is dated to 1766, and is housed at Harvard’s Putnam Gallery. From which:
This apparatus was designed to demonstrate how the speed of a comet varies in its orbit according to Kepler’s law of equal areas. The comet Benjamin Martin chose for this instrument is Halley’s Comet, which goes around the Sun every 75 1/2 years. Martin began producing cometaria before Halley’s Comet made its predicted return, and so was betting that Halley would prove correct in his theory.
Interestingly, the device turns out to be not an entirely accurate demonstration of Kepler’s second law. Physicist Martin Beech of the University of Regina has studied the history and mechanics of cometaria at great length. His clearinghouse page is an excellent source of detailed information.
A “whiffletree” is a mechanical digital-to-analog converter. Brilliant science-and-technology documentarian Bill Hammack, professor of Chemical and Biochemical Engineering at the University of Illinois, has produced this fascinating video anatomy of IBM’s classic Selectric typewriter, in which a 7-bit whiffletree is employed to convert keypresses (digital) to precisely coordinated tugs (analog) on the control cables that rotate and tilt the type ball. Doubly awesome is the fact that the video features an appendix (yes, a video appendix) which focuses exclusively on the whiffletree itself, closely illustrating its operation with a simple 2-bit case.
Very cool design from Thingiverse user msruggles, printed as shown above by user Linkreincarnate, who reports some reification issues with the model requiring hand finishing. Gonna keep an eye on this as it develops.
