Evolution of a Gear-Clock

News Flash: I love to make things.

The explosion of home use fabrication technologies has given modern humans powers, god-like powers that we could only dream of even 10 years ago.  Digital design and fabrication are now accessible to practically everyone.   Those that do not have fabrication facilities at home can use services like Shapeways, 3D hubs, Oshpark, and Ponoko. to fill the gap and create practically whatever they can dream up.  What are you doing with your god-like powers?

I’ve been asking myself this same question lately and it turns out that I use them to make clocks.  Funny thing is I’m not really a clock person, but I know that I need to learn how to use these tools: 3D printing, laser cutting, circuits, and clocks seem to be the go-to target for my aspirations.

This led to ClockTHREE and ClockTHREEjr word clocks and also a Kandy, a two-sided race timer.  But none of these clocks have moving parts.  I figure I need to understand mechanical issues to really employ my god-like powers when inspiration hits.

Motivated by clocks like this one from Brian Wagner I set out to design my own version of the gear clock.  GearClock1.

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Like Brian’s clock, the hour wheel rotates indicating the hour at the top.  Unlike Brian’s clock, and others, this clock uses a idler gear to push hour ring out to the radius of the minute hand.  The parts are a made with laser-cut acrylic and 3D printed PLA.  A single hand is attached to the drive axle to indicate the minute on a stationary disk, concentric with the hour ring.  AlaMode, which comes with a DS3231 real time clock, was used in conjunction with the Adafruit motor shield to control movement.  Blue accents really make this clock pop.  But the clock had mechanical issues and would bind up frequently.

I realized that if I replaced the idler gear with a planetary gear, It could drag an hour hand along for the ride like a normal clock.  GearClock2.

GearClock2

GearClock2

After first getting the gear ratio wrong (how many hours in the day are there again?) I got it right.  Kevin Osborn jazzed up the design with some sick filigree hands and taught me how to draw in InkScape and import into OpenSCAD.  He also printed all of the many iterations of gears on this and previous clocks.  Thanks Kevin!

The clock looks pretty basic, and it is, but remember my goal is to learn mechanics and I learned a lot with this clock.  Form follows function.  I take that to mean, first make it work, then worry about how it looks.  It can also mean: make it work really well, and its shape will appeal.  We are getting there.  The good news is this clock really works.  We have it set up on a hutch in our kitchen and use it every day.  But I have to admit, the shape is a little awkward and the electronics are unsightly.  The cheap 48-step motors tick every 75 seconds, which is more than frequent enough for a wall clock, but we can do better.

GearClock3 is the same basic mechanical design with a 200 step pancake motor and electronics housed in a separate box.

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An Arduino pro-mini, a Pololu stepper driver, and a Chonodot make up the electronics package.  I really like this stepper driver.  It is very easy to use: set the step pin to HIGH to move forward one step.  No complex driver software is required.

Aesthetically, this clock has many of the right elements although a flash of colored acrylic would really make the numbers pop.  Everyone loves GearClock3, but the first thing they ask is: can you do seconds?

GearClock4 adds a second hand.GearClock4

I’ve come to appreciate the difficulty of the standard hour, minute second clocks: Three concentric hands driven at three rates with a ratio of 3600:1 between the hour and second hands.  A 12:1 ratio was already working with the planetary gear.  The 60:1 ratio was solved by using two reduction stages that take the motion off center, then back on.  After several experiments with the gear lash settings, I finally found a combination that works well and makes a pleasant tick (not too loud).  One issue is setting this clock.  You have to fast forward the second hand, which means you’d like to move the seconds hand as fast as possible.  This second hand can turn a complete revolution in 0.2 seconds which means it can fast forward though twelve hours in less than two and a half minutes.  A sealed bearing on the reduction gear allows this and should work for years to come.

What’s next?  Anool is working on a custom circular PCB that will that will bring the electrics up to par with the mechanics.   The PCB will host the real time clock, an Arduino compatible ATMEGA328, hall effect sensors to detect hand position, and a DS3231 real time clock, and GPS unit for time synchronization.  Stay tuned to our GitHub repo for updates….

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Låda, a custom project box system

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HALO is an EL-Wire night light. Photo by Emily Shaw

Project boxes can be a real pain. You can get a standard size box from a place like Radio Shack or you can make your own custom box. If you have access to a laser cutter, you can make yourself t-slotted boxes.  While the t-slotted boxes do the trick, the open slots leave an unfinished look to projects.

I wanted a more polished look for my latest clock, so I set out designing Låda.  The Låda (or Lada) Sytem, based on standardized 3D printed corner and edge pieces and custom laser cut face pieces, allows you to define a box of any size bigger than about an inch and a half on a side.  A program written in Python does all of the tedious calculations for you and spits out a PDF file.  Custom openings can be added with InkScape to accommodate stand-offs, buttons, cords an sensors.

The edge and corner pieces have mounting holes 0.4″ from the inside face.  They have an elevated platform to cradle your project.  Hex cutouts captivate a M3 nut so that once installed, they remain in place and the box allowing the final face to be screwed into place.  +Kevin Osborn has been keeping our 3D printing non-stop so that now I have plenty of Lada pieces to play with.

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HALO consists of an AlaMode, a Grove Shield, and an EL-inverter. Photo by Emily Shaw

The Lada system works fine for small projects like the EL-Wire night light seen above.  It also works with larger projects, like the Kandinsky Klock (or Kandy) for short.

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About the projects:

Halo is an EL-Wire night light configured to outline a doorway.  It helps to prevent falls by both providing light, and creating a frame of reference to orient you if you need to be up in the middle of the night.  I made it for my father who could use a little assistance getting to the bathroom in the middle of the night.  The idea comes from a story I heard on NPR.

Halo was easily assembled from: an AlaMode,the Grove Starter Kit, and a USB based EL-Wire inverter.

A special thanks to +Kevin Osborn who lined me out on what I needed to drive EL-Wire and pointed that the Grove Started Kit had everything I needed aside from the inverter.

Kandy is a two-sided mountain bike race timer that I’d promised to build for my collage roommate two years ago.  It is 4 TiM boards with c prototype LED controller called TiNA.  It is bluetooth controlled (thanks to the FTDI compatible BlueFruit module).  I think it is worth the wait.

None of these projects would be possible without Anool’s tireless work designing amazingly flexible circuit boards.

Reserve BADGEr_v4 available in our shop

Rather than pay the huge shipping costs to send the remaining 19 BADGErs back to Seeed Studio, Amy volunteered to ship them from our house.  You can pick them up in our reserve shop.  Thanks!

Justin

http://wyolum.com/shop/28-ohs-badger.html

 

http://wyolum.com/shop/28-ohs-badger.html

Open Hardware Summit 2013: Success!

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We did it.  We did it just in the nick of time.  We produced and delivered the hardware and software for 500 e-paper badges which were the hit of the summit. Flooding in Shen Zhen, where our Seeed Studio partners are located, delayed parcel pickup and nearly scuttled the whole affair. Frantic calls and emails on both sides of the Pacific only managed to confuse the situation. When seven of the eight boxes arrived in Washington DC we had them held for pickup and were greatly relieved to actually get the stinking badges in hand.

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We were able to distribute all of the boxed among all of our WyoLum passengers to get them from Washington to Boston without paying extra baggage.

Registration CrushWe received the final registration list after the doors were opened to the conference center.  Needless to say, there was much to be desired in cross referencing the final list to the badges, but we managed to get most of the people in there seats with a 30 minute delay.  For the most part the OHS participants were friendly and understanding.

Anool, Kevin and I presented a talk on #BADGEr directly after the keynote.  Video pending.

Several people managed to customize there BADGEr using wifit.py.

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When we weren’t attending the summit, we got to hang out at an amazing home in Milton about 20 minutes South of Boston.  Every room was filled with beautiful original artwork and there were a lot of rooms and hallways, enough to get lost in and we did.

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With Amy, Munmun, and Samata cooking we did not go hungry.

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To top it off we had a brunch on Saturday after the summit.

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On Saturday night, we overcame our urge to go to bed early.  Jimmie invited the OHS volunteers for beers at Artisans Gallery.  The SKUL biker gang affiliated with the Asylum was out in full force.

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