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centrifugal switches (spin activated yoyo electronics)

October 13, 2011 nouyang

doing some research for 2.008 instead of freaking out over 6.131 lab

Edit 10/17/2011: Found it! Thanks to Charles.

See explanation of “tilt sensors,” which include both mercury and rolling-ball type ones, here: http://www.ladyada.net/learn/sensors/tilt.html

http://www.adafruit.com/products/173

Cost: $2.00.
(octopart search: http://octopart.com/partsearch/#search/requestData&q=tilt+switch&rangedfilters%5Bavg_price%5D%5Bmin%5D=0.54&rangedfilters%5Bavg_price%5D%5Bmax%5D=2 can maybe get it for $1)
http://smparts.com/-Switches-Rolling-ball-switches-%28AT%29/c0_2_561/index.html — but no prices listed, hah.

Hmm. So I know there was at least one previous design in 2.008 that used these switches. They put two on each side (top and bottom), facing outwards. Then, when the yo-yo spun, both switches would contact (and presumably switch on LEDs). Apparently they had issues with the thermoform shrinking and squeezing the ball switch and preventing it from switching though. All in all, I’m a bit iffy about these rolling ball switches. There’s no way to adjust their sensitivity (although I guess regardless PoV yoyo requires a microcontroller anyway, but the less pin-count the better), so what if it switches on when the the switches are rotated to (left right) and the yo-yo is slightly tilted? We’d be stuck with 100 useless switches.

I like Paulina Mustafa’s design of a flexure switch, she was prototyping this at MITERS (but I can’t find a blog for her). Looks sort of a like a ying-yang design, and the tips are flung outward and make contact with the sides when the yo-yo is spun. She’s using copper-tape, but I think something like conductive glue would be easier to apply.
http://www.instructables.com/id/Conductive-Glue-And-Conductive-Thread-Make-an-LED/step1/Make-Conductive-Glue-Conductive-Paint-and-Conduc/

=====
Earlier Research

via
http://www.helifreak.com/showthread.php?t=33567 “DIY Night Blades”

centrifugal switches:
http://www.atomicmods.com/Categories/Tutorial-1-28-Mini-Z-Rim-Light-Installation.aspx
(spring inside a brass tube)

The batteries are wired in series with the LED and the centrifugal switch. The centrifugal switch is simply a tiny spring inside a brass tube. When you accelerate, the spring swings to the outside and makes contact with the brass tube turning on the lights. It is really quite simple and very reliable. This also makes the batteries last a long time since they are only on while you are driving and you will never forget to turn them off.

types of switches and design of switch contacts (including mercury switch aka “tilt switch”): http://www.allaboutcircuits.com/vol_4/chpt_4/1.html

quora question
http://www.quora.com/Mechanical-Engineering/What-centrifugal-switches-are-suitable-for-use-in-a-yo-yo

still failing to find suppliers o.o

mercury switch:
http://mondo-technology.com/yoyo.html

paperclip style:
http://www.make-digital.com/make/vol22?pg=115#pg117

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abusing CNC mills for internet memes

October 11, 2011 nouyang

It’s official. CNC mills are sexy. Even decades-old bridgeport model ones that take giant floppies.

So a while back I was all like “I’mma mill me some nyancat for my 2.008 paperweight.” (http://www.orangenarwhals.com/?p=187)

Oh yea, my partner for this lab is the awesome Cappie Pomeroy. He did all the lathe work o.o so don’t ask me about that.

So I got around to milling it.

look, nyancat got fatter so that you can fit a 1/16” end mill between it’s crevices!

(The way I did it is I did a Tools>Sketch Tools>Sketch Picture, then resized that reference nyancat picture until it looked appropriate. I then put a Tools>Options>Grid>Major Grid 0.07 / minor grid off. System Snaps>check Grid. Also, make sure Units>IPS, InchPoundSomething. Then just trace it with lines).

However, my resizing and retracing ended up not mattering, since I decided to engrave it. This was because we had to make a 15 minute version, and no matter how I tweaked Mastercam (using 0.02” depth instead of 0.1”, using a wide endmill to clear it and then remachining with the 1/16”), there was no way the full 3D paperweight was milling out in 15 minutes.

Yea so there are really dumb ways to make a path in Mastercam.

See the X’d out paths to the left — I was tracing all the paths by hand, essentially. Then Pat, the shop instructor, came by and showed me the magic of the the “polygon” tool which will automatically apply a function (in this case, engraving) to everything within that polgyon. It created some weird paths, like you get on a lasercutter which doesn’t recognize your vector as one shape but as individual lines*, but it gets the job done. In other words, he finished in 10 minutes what was taking me hours to do… hah.

*aka it doesn’t trace them continuously but rather jumps back and forth between different lines in the drawing

See link below for g-code / mastercam / solidworks files.

The jig was made by the instructors for the class, along with the “offset” used in Mastercam to make sure the blank is positioned correctly.

gahhh technical difficulties. Yes, I used my phone to take a picture of picture on my camera. You really don’t want to know.

Nyanweight documents:
https://docs.google.com/leaf?id=0B9r0HZeoMbmgZjgzMTkyOTEtOTU4OS00MDhjLWJlMmYtNTQzMjc2YmJlMzkx&hl=en_US
where “base/lab1” docs are for the CNC lathe and “engraving” docs are for the CNC mill.

Software used: solidworks (.sldprt, exported to .dwg), mastercam

Todo next: Mill out the actual thing.

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todo, DIY vending machine (countertop and oshw)

October 5, 2011 nouyang 1 Comment

Like this, but with arduinos. and caffeine. and breadboards. and 1/64” drill bits. and nyancat-etched poptarts. Oh, and open source. And constructable for less than $600.

(I get to the whole build-my-own vending machine thing further down the page. Got a bit ADD).

Well, in other news, my 2.008 group did not fall over themselves to build a PoV yoyo. This is okay. I will just make one or two PoV (persistence of vision) yoyo’s manually then. (you, dear reader, have just been saved from a pages-long rant as I sulked over the last few days :P)

In other news, in MAS.863, it’s waterjet and shopbot week! I’m super-excited.

<3 3-axis mill. Shopbot r awesome~

(look, someone made a giant scrabble set using the media lab shopbot:

http://mako.cc/copyrighteous/20110725-00

)
Mini projects this week:

[1] Shelving. make this (playatech’s plans — rec’d by fellow classmate novysan, who had fun with these at burning man. also rec’d “nomadic architecture” which sadly did not mean nomadic furniture like Walking Hexapod Racing Chair but rather furniture suited for nomadic humans)

http://www.playatech.com/index.php?deptName=03Bare%20Necessities&prodDesc=09Gear%20Gizmo

(aka shelving made from one sheet of $8 7/16” OSB plywood,

http://www.homedepot.com/h_d1/N-5yc1v/R-100091344/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053)

Artsy furniture (metal): http://dornob.com/open-source-free-flat-pack-plans-for-laser-cut-furniture/
Styrofoam furniture: http://dornob.com/laser-cut-styrofoam-seats-solid-3d-polystyrene-chair-design/

[2] I have lots of marble leftover from our clock class, which some people took proper advantage of while I merely used lasercutter and acrylic:

classmate’s AWESOME marble koi fish clock

mmm, instant noodles. aww. I miss my old room.

Oh right, where was I?

Arduino vending machines. That’s right. Make a DIY “open-source hardware” vending machine. Not interested in the electronics of accepting money and such (although that’s what everybody leaps to help with that, despite me explicitly stating I’m more interested in the vending mechanism).

Research:
http://en.wikipedia.org/wiki/Vending_machine#Mechanism
www.discapa.com/eng/download/manualt/MTMacSpiralE — coin mechanism and spiral set? not sure what it vended
http://www.vending.com/vending_machines/combination_vending_machines/combo/manual/
So they’re called “augers.”