Month: August 2012

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Skycam debugging II, first test movements

I tested each drawbot separately with the new skycam drivers and – after several hours – found a one letter typo that was messing everything up. Then I decided to re-read the critical sections and found two more. A-ha!

Once each Drawbot was moving correctly in their planes, I reconnected them and began moving in all three dimensions.

I added a way to invert the rotation of a single motor because I wound the string backward and it was easier to flip the code than rewind the bobbin.

Right now it’s convinced that 12:00 is X+ and 3:00 is Y+. Not fatal but not what I expect.

Here is a model for a plotter you can use to safely attach a camera to your Skycam. If anyone buys a skycam in a kit I’ll be sure to send one of these along.

Here is some early video.

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Skycam assembly gallery and robot debugging

I sold a record number of Drawbots today. Awesome possum! To celebrate, here’s a little bit more about the Skycam I’m going to be bringing to the Vancouver 2012 New Forms Festival, September 13-16. The Drawbot will also be there.

I assembled the Skycam a few days ago. It’s two Drawbots put together with a bit of modified software on top. I assumed I would set up four steppers around a clock face. Each stepper would be at 1:30, 4:30, 7:30, and 10:30. An X+ movement should be towards 3:00 (Berlin), a +Y towards 12:00, and a +Z towards the ceiling. Sounds do-able, but it’s a whole new world of problem solving.

I knew from the start the steppers would be mounted backwards or something. I wrote some code to “jog” just one motor so I can identify which is which and then switch their positions in software. Each motor gets assigned an XYZ coordinate. When my Java program says “Go to XYZ” the Drawbots can figure out the rest on their own.

I also knew that I had to wait for a movement to complete before starting another or accuracy would suffer. That was challenging, and the first time I wrote Listener pattern in Java. Thank you to everyone in freenode#java for their help!

Re-centering a four-string device is a lot harder than a two-string device. I put the origin in the middle of the floor. I still have to manually turn the bobbins which is my least favorite part.

I broke the strings three times already. Lesson learned: run the Skycam with the emergency stop in my lap. Also, disconnect three of the four strings when I’m done with the robot for the day so people can’t get snagged on it by mistake.

So how’s the actual movement, when everything else is said and done? Well…so far the results I get are really confusing. They have to be seen to be described. Anyone interested in a video? Comment now or forever hold your peace.

For a complete description of the build process, read the descriptions and titles of each picture in the gallery. I make no apologies: I have Burning Man on the brain.

If you’d like to build one of these Skycams, let me know. I can package up all the parts if you can get the 2x4s and the drywall/wood screws.

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CNC Life Tree Work Finished, Drawbot disappointment

I spent the last three days in the garage using the CNC machine and a couple of jigsaws to make 100 cut wood patterns for a burning man project. They swear up and down they’re going to tell everybody about my service so I hope that will translate into paid work. (@$60/h+setup consultation)

We got a really good Kanban rhythym going with the jigsaws. Teams of two on a temporary table made out of sawhorses. One would hold the wood, the other would hold the jigsaw. The wood stays as still as possible and the jigsaw turns. When the jigsaw gets to a wierd angle for one user, we’d switch. Each team would do one type of cut (like the exteriors, or just one of the inside cuts) so we’d have to cut the same board two or three times but the speed we were cutting was really great, we could finish a complicated piece in about 2 minutes each, total. Compare that to CNC machining a part that took 40 minutes and left the mill bits covered in blackened glue and gum. Yuck!

I added a few parts to the CNC and it’s running very reliably now. It’s almost enjoyable to use! A proper dust shoe and a good vacuum would really make a world of difference. Before that I’m going to get a fire extinguisher, just in case. Wood table, lots of friction…

Talking with a teacher yesterday I found out their entire annual budget for new class stuff is $100 CDN. No wonder nobody buys a Drawbot or a Cando! I said send home a note with each kid asking for $5 and you’ll have enough for two Candos. The kids who finish work first get to put it together. I don’t think I won her over. So… great product, broke target audience. I’m told if a product can teach enough of the required subjects for a given class year the province will buy that product for every school. I have to think bigger and talk to the school board. Have you got a contact? Are you a teacher? Let’s make this work.

The rest of the day will probably be spent on home renovations. Mudding drywall is my least favorite part. Tonight I’m at the VHS signing a contract and (probably) installing a new eyewash station. Wednesday nights are Kaizen nights at the VHS, when members are encouraged to make a small improvement to the space.