It’s been awhile since my last build log post, but I’ve covered a large milestone. See my previous posts:
Following up on my last post, my plastic pieces were ordered from Ponoko: two main plates made out of 3.2mm white Delrin plastic, and the carrier boards, motor mounds, and battery mount from 2.3mm white Delrin. I enlarged all but the motor mounts in order to scale up the size of the carrier boards to cleanly fit a Chumby Hacker Board (CHB). One addition I made to the main plates was adding a set of extra holes (inner holes) to line up with the standard power distribution board. I also used the standard 28cm by 14mm square tubes for arms.
The battery holder was enlarged in order to use the outer set of holes so that it wouldn’t get in the way of the power distribution board using the set of inner holes. I went through Hobby King’s stock of 3S 25C LiPo batteries to find approximately 5000 mAh while keeping it as light as possible. I picked out two Rhino 2350mAh 3S1P to tie in parallel for a total of 396 g. I can use only one battery if weight ends up being a problem.
The power distribution board from jDrones.com fits right in between the two main plates. As you can see from the image below, in order to make it fit I replaced the right-angled pins with a connector. I’ve read that some people have issues with the power distribution board causing interference with the compass, so this should alleviate it a bit by putting more distance and plastic between the two.
I still used a 10mm standoff from the main plate to the first carrier board to leave some clearance for Velcro. On the first carrier board lays the APM+IMU+Magnetometer and the radio Rx. I went ahead and ordered a sample of the Tempur-Pedic mattress foam and sliced it roughly 7.5 mm thick. If you haven’t found the thread on here, you cut it by freezing it and then cutting it with a bread knife. It may take a few rounds because it ‘thaws’ quickly.
The next carrier board up has the CHB, GPS, and XBee. I just completed building it so I haven’t fully tested to see if there is too much interference with it being close to the GPS unit. The CHB requires 5 volts so I use the DE-SW050 regulator tied to the distribution board. I also got the GPS connected via FTDI to the CHB for my WiFi stumbling project.
Here is an approximate weight breakdown…
ESC+Motor+Prop (x4): 332g
Total Weight without Batteries: 885g
Battery (x2): 396g
Total Weight with 2x Batteries: 1282g
Here is a zip with my EPS files I sent to Ponoko: Arducopter_XL.zip
Things I’ve learned:
One mistake I made throughout this project so far was not ordering enough parts the first go around. I eventually found that Amazon sells bags of 100 M3-.5 nylon screws and nuts that work perfectly for about $6 per bag, which is the cheapest route for hardware I’ve seen in you live in the US.
I also learned that the Deans Ultra plug connectors and I don’t get along well. I ended up going to Radio Shack in a fit of rage and bought a bunch of 2 pin Molex connectors that work really well.