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misc. updates: horrible epoxy rash, rudder, volvo ocean race, sewing machines

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volvo ocean race updates twice a day on their youtube channel, & the short legs are pretty engaging, well, probably mostly team SCA is in the lead right now so I’m more interested than usually 🙂

~~RUDDER~~
re: rudder construction, have not had a chance to sit down & upload/document/write-up everything,

but in brief —

Solid bronze inside. We did CNC foam on a shopboat, laid down fiberglass, the rudder post & pre-stressed the trailing rods[1] , closed the mold and poured 2-part foam-it! 15lb urethane foam, de-molded, three more glass layers to connect the two halves, then gelcoat, install, and antifoul coat.

We also have a nice 3d model of outside of our rudder now (and a renewed complaint list against solidworks):
https://github.com/nouyang/scienceboat/blob/master/boatrudder.STL
& the mold:

https://github.com/nouyang/scienceboat/blob/master/rudder-mold-bottom.STL

[1]  (glassed some GPO3 blocks down, after tack/cure time we tightened some bronze nuts against the gpo3 blocks, checked that the rods were stressed by
i added two pictures to the end of the “rudder skeleton” album
https://picasaweb.google.com/113942194695013581888/SailBoatMay2015?authuser=0&feat=directlink

~~INSTALL~~

the details i left out are: we put so much “gelcoat” (just epoxy layers since our rudder is unlikely to be flexing a lot) on that it we lost clearance on the back edge (oops), so after installing we found it didn’t turn well put rather “popped” to rotate fully since it was catching where it rotated against the keel.

we sawed & scraped until we had clearance and now the rudder turns like a dream now (we can do a sweet 180 turn now) — it’s a little “less waterproof” on that backedge since we had to take off most of the gelcoat layers, but worst case seawater finds its way to the foam, which can sit in water for up to 2 yrs before deteriorating — realistically it has so much glass still that it should be fine.

~~EPOXY~~
also, my face/arms rash is still itchy 1 week from last exposure (which did not even involve mixing epoxy –I was just cleaning up). Do not f*** with mixed / uncured epoxy, folks, and also do NOT use acetone to wash epoxy off your skin.
Displaying FB_IMG_1433071049494.jpg
Displaying FB_IMG_1433071056398.jpg
i’m using dipenhydramine (over-athe-counter skin numbing agent) & seeing a dr. on wed, but for the record:

5: Do not under any circumstances use acetone to clean up. This is the very quickest way to become sensitised. The acetone will immediately remove any natural protective oils in your skin and take anything it has dissolved, that is ANYTHING it has dissolved straight into your body. If you are going to use acetone to clean up your skin, you may as well just grab yourself a syringe and wack the crap up your arm and be done with it because it is much the same deal.

Inline image 1

~~singer sewing machine, 7442 disassembly / troubleshooting (bobbin did not wind, all lights blink & beeps) ~~

btw if you’re curious this is what the singer 7442 looks like inside when it’s operating, pretty interesting set of cams and mechanisms
https://youtu.be/RASgDLSg3Xw?t=24s

(pt 3 shows the “lights blinking” error https://www.youtube.com/watch?v=P4Cqt1lBxLY)

(pt 1 points out the things we fixed https://www.youtube.com/watch?v=T47fLW1PscE)

Crafts, Short Posts

telephone hold music: analog generator

Recently a friend recounted to me a visit to a cool museum which had, in one exhibit, a “hold music” generator (you know, elevator muzak… here have some Cisco sound samples).

That is, before there was digital recording and playback, telephone switchboard operators wanted to play soothing music to callers while connecting their calls. To do so, they used little analog electromechanical playback devices — what we now think of as those cute music box toys

440px-Music_box_elements

but which included very serious and complex devices once-upon-a-time.

Source: http://en.wikipedia.org/wiki/Music_box#/media/File:Baud_museum_mg_8548.jpg
Source: http://en.wikipedia.org/wiki/Music_box#/media/File:Baud_museum_mg_8548.jpg

Anyway, so it turns out it was the Museum Speelklok (“Musical Museum”) in Utrecht, the Netherlands:

http://en.wikipedia.org/wiki/Museum_Speelklok
https://www.museumspeelklok.nl/lang/en/

From Zoz comes this photo of the infamous Japanese telephone exchange hold music generator: (original content ahead! whoo)

Electromechanical telephone hold music generator. Photo credit: Zoz at MIT.
Electromechanical telephone hold music generator. Photo credit: Zoz at MIT.

[the end.]

Footnotes

Some wikipedia articles of interest:

  • http://en.wikipedia.org/wiki/Music_on_hold
    Which contains this “lolwut” anecdote:

    > For those still uncertain of the difference between “song title” and “mechanical” copyrights, consider the Capitol Records lawsuit for copyright infringement against Nike some 20 years ago. Nike legally obtained permission to use the Beatles song title “Revolution” from the title’s owner, Michael Jackson. They used the Capitol Records owned recording of the Beatles’ performance, but failed to obtain and pay for permission and use. Capitol Records sued and prevailed because Nike ONLY had a license to use the title and did not have a license to use the mechanical recording

  • http://en.wikipedia.org/wiki/Elevator_music
  • http://en.wikipedia.org/wiki/Sound_recording_and_reproduction
  • http://en.wikipedia.org/wiki/History_of_sound_recording
  • http://en.wikipedia.org/wiki/Music_box
  • http://en.wikipedia.org/wiki/Museum_Speelklok
  • http://en.wikipedia.org/wiki/Telephone_exchange#Sounds

Other interesting links I dug up while hunting for this museum before giving up and emailing Zoz:

  • http://www.telephonetribute.com/pdf/telephone_history_series_rev1.pdf
  • http://www.slate.com/articles/arts/culturebox/2014/09/history_of_hold_music_how_did_we_end_up_with_handel_tinkling_through_the.html
Sunday Silly Papers

Sun Paper: why do abandoned bikes get their rims all bent? is it snow plows?

tl;dr “it’s like bird spotting but for bike tacos”

It has come to my attention recently (on facebook) that with respect to the question

why do abandoned bikes get their rims all bent?

http://www.bostonglobe.com/metro/2015/03/30/wreckage-bikes-racks-emerges-from-melting-snow/TW21NuCmtCrNbSSM4o0q0I/story.html
Source: http://www.bostonglobe.com/metro/2015/03/30/wreckage-bikes-racks-emerges-from-melting-snow/TW21NuCmtCrNbSSM4o0q0I/story.html

there is a lot of pseudoscience, rumors, speculation, passionate eyewitness accounts, and vague theories. take this forum thread: http://boards.straightdope.com/sdmb/showthread.php?t=606670

I notice the same thing a lot on College Campuses and assume its drunk college students limping home after the bars close and deciding to indulge in some low-grade vandalism. Presumably they don’t really need a vice to get it to bend like that though, I think they just brace the wheel against whatever the bikes chained to and then kick/jump on the edges

wild speculation

Unlikely Scenario D: People carry a bent wheel with them and mount that on the bike when chained, and carry the good wheel with them to prevent bike theft.

even some mechanical engineering insight

Bicycle wheels are very strong vertically, and fairly weak horizontally.

here’s a friend of a friend’s thoughts on the matter

Reason I think it’s the snow is the bikes are usually parked a little away from the road. The weight of snow falling plus the weight of snow being pushed into them with plows== all bent up… 

okay, so it _is_ plows, but not that plows are directly touching bikes, they’re pushing ice rocks into the bike? that’s the winner?

but then someone chimes in from Florida

Right, I imagine there’s lots of people kicking bikes or hitting them with cars in florida (people can’t drive in Miami. I’m serious. They’re insanely bad drivers. And this is coming from someone who considers himself a fairly bad driver). This is about why virtually _all_ of the bikes are suddenly completely destroyed after the snow melts. Semi-abandoned bikes that are just left at a pole for a month or so during the summer in Boston may have their wheels stolen (or just be totally stolen), but they don’t get destroyed like this.

As you can see, despite all these rumors go around, there is no actual science on the matter.

We must address this issue with scientific rigor if we want to prove that everyone in the world can be a citizen scientist. I suspect the state of the universal “bike taco” phenomenon may be similar to the “same symptom but vastly different underlying causes” scenario.

The solution is to create a crowdsourced science application. Just like you can participate in science  by reporting sighting of banded birds, or by putting a feeder up and counting birds,

Source: http://feederwatch.org/about/how-to-participate/
Source: http://feederwatch.org/about/how-to-participate/

You should be able to report on how, exactly, bikes are getting “taco’d”.

Everyday scientists can

  • submit pictures of an abandoned bike over time
  • reports of what state the bike was in
  • see a timeline of related weather phenomena in that state
  • and submit eyewitness videos of bikes getting taco’d

We must get to the heart of this matter. Our bikes are at stake.

I’m too lazy so just use reddit: https://www.reddit.com/r/AskReddit/comments/32ta2a/why_do_abandoned_bikes_get_their_rims_all_bent_is/

projects blog (nouyang)