Author, Publisher, Developer, Stitchcoder


Appearance In, and Report From, Beijing

Next Friday at 7PM I'll be speaking at what is described as a TED-like monthly lecture series at the Beijing Haidian Culture Treater (海淀文化小剧场). The event is open to the public, but some kind of ticket is required, which you get in some kind of complicated way that involves a lot of Chinese I don't understand. Here is a link to the event description:

In the mean time, here is a small update from Beijing. First, hotels—at lease my hotel—have robots to deliver small packages to guest rooms. I'd ordered a replacement for the Apple Pencil I forgot at home, and when I went to pick it up from the desk, the bell captain kindly agreed to send it by robot so I could follow it to my room....

When it gets on the elevator it says "I'm a little girl and I'm very nervous about getting on this elevator! Please give me the space in the middle!". There are many questions. For example, how does it push buttons on the elevator? When it got on, it asked, in its nervous-little-girl voice, for someone to please push floor 15, but no one did (including me because I wanted to see what it would do). The answer is that it is actually in telepathic communication with the elevator, because floor 15 pushed itself moments later. Perhaps it's just asking because people like to be helpful, and it's trying to endear itself to passengers (while demanding, in a cute way, that everyone get out of the way).

Second question: How is it going to knock on the door to my room? At the very end of the video you can just about hear the answer: It is also in telepathic communication with the phone system. A few seconds after arrival, the phone in my room rang. Unfortunately my room key was messed up so I couldn't get in to answer the phone, but I'm going to assume that it would have been a kindly robot mom saying "Hello nice hotel room occupant, my very nervous daughter-robot is at your door to deliver a package, could you please open the door and pat her on the head? Er, I mean, push the button on top to open the delivery compartment?"

China is very kid-friendly in many ways. For example, I had lunch outside Beijing with laser cutter engineers in a huge restaurant attached to some kind of bizarre children's paradise. You know those pretend backhoes they have in playgrounds for kids to dig with? The ones made of just a few metal bars that are entirely kid-powered? Well, here they are real power shovels with working hydraulic systems. God how I want one of these. They also have a sketchy-looking zipline and a large area that looks a lot like a paintball range, except it's a playground.

Back in town the next day, I was finally directed to the proper set of buildings for Beijing's electronic components market. (I tried to find these buildings last visit but only found nearby ones that were not quite right.) It's two buildings, one 4-story, one 6-story, filled entirely with farmer's market style vegetable stalls, except all the vegetables are capacitors, resistors, connectors (SO MANY CONNECTORS), chips, LEDs, potentiometers, heat sinks, power supplies, and so on forever. 

I had been warned by the laser cutter engineers that I would probably not find stepper motors, and we did in fact walk around for a good hour without seeing any. (I told my translator that this is what it's like when a girl takes a guy clothes shopping. It just seems like hours and hours of endlessly pointless walking around not buying anything. Actually there is a deeper logic to the activity.)

As time was running out, we finally hit the jackpot: A stepper motor vendor who had a sign saying he was closing his shop soon, everything on sale!

I didn't take a picture of them, but I got a super deal on six of exactly the stepper motors I wanted, plus over-sized drivers. I had calculated that I wanted about one Newton-meter of torque, but since my excellent translator is non-technical, this was a bit difficult to communicate. Finally I heard the guy saying "new me" and I leapt on this to ask, through the translator, how many new me's the motor had. One! Perfect. $145 for six motors, controllers, and pulleys, maybe 1/3 what I'd expect to pay from a proper supplier in the US.

Why do I need six stepper motors? Because I have a six-heddle loom that I want to automate. I'll mount them above with strings going down to lift each frame. Connor will be pressed into service to make an Arduino controller that will step through the desired pattern sequence.

Here's a couple pictures of how I was warping the loom just before leaving for China, complete with high-stakes cat:

It has what is called a sectional beam, and the thing I made to hold the yarns is called a warping rack. Combs (literal hair combs) guide the yarns to the beam. 24 yarns fill a 2-inch wide section of the beam (12 yarns-per-inch).

Here are videos of both ends of the yarn path:

24 yarns makes 2 inches, do that 12 times and you have a 288 yarns over a 24-inch width. Unfortunately I miscalculated and only had half as much yarn as I needed, so I only got half way and will have to finish with more yarn when I get home.

Theodore Gray1 Comment