Monday, January 9, 2012

Stator Wrapping Complete!

It's a milestone in an engineer's life when he completes the wrapping of his first stator for a custom brushless D motor. I'm proud to announce that I have hit that milestone, and my thumbs are killing me. First step was to make a diagram for wrapping, which can be found in this post. Over the course of the next 10 hours (not consecutive), thumb and finger health decreased steadily and a few pictures were taken. To help you understand the numbers in the captions, one "Phase" consists of two pairs of two strands (four strands total) each wrapped around two teeth (four teeth total). The A phase consists of two teeth wound clockwise and two teeth wound counterclockwise. Put three of these phases together in the right order with the right orientation, and you've got yourself a motor.

1/4 of phase A wrapped
1/2 of phase A and 1/2 of B wrapped
Phases A and B complete, 1/2 of Phase C
One more tooth to go!
DONE. GORGEOUS.

Finishing this felt amazing (as I loudly proclaimed in N52 when I completed the last turn) despite my throbbing fingers. I've technically been working on this project since late August, and I'm finally getting somewhere. Shortly after I posted this photo to facebook, Shane and Charles displayed their amazement with the quality of the wraps, which is apparently pretty good. Which was what I was aiming for. The next step will be machining the endcaps and spacers to house the stator and rotor. Too bad I'm going back to school in a week and I'm helping the MIT Marine Robotics Team with some stuff until then.

Looks like it's time to get reacquainted with the machine shop. Let the hub motor season begin.

Thursday, January 5, 2012

Stator Wrapping and Xbox Case Mod Preview

I finally got off the ground with (name TBA) scooter's drive system. After many months of planning and procrastination, I began wrapping my stator... and boy do my thumbs hurt. Shane told me before I began that there is a spectrum of quality of stator wrapping from neat and meticulous to quick and dirty. I chose to pursue the neat and meticulous path because a more tightly wound stator would be a more powerful one. A side effect of this path is that my right thumb and forefinger are now throbbing from pulling as hard as I could on wire for an hour straight. I am not looking forward to wrapping another 11 teeth, but it must be done!

This just popped into my head: I might call this project Time Scooter. Because I've been working on it since August. We'll see if the name sticks.

Here are some pictures from the day:

Wrapping configuration diagram
Wrapping two strands at the same time is tough.

Another project I've been doing on the side this past week is creating a clear case for my xbox made from acrylic. Unfortunately 3-402 has been (hopefully temporarily) closed before MIT's IAP starts, at which point it will be occupied full time by a class. I haven't been able to make any new parts, but I have started to model the case in SolidWorks. So far I have taken my Xbox apart four times, designed and made a prototype of the motherboard mount... and that's about it. I was aiming to complete this project before school starts again, but that might not happen because of the fabrication delay.

Let's see what this thing looks like on the inside.


What an Xbox looks like on the inside.
Might be tough to see (it's clear!) but here we have the first version of the motherboard mounting piece.

Hard drive module, disassembled
Ideally I will buy a ~120 Gb 2.5" hard drive and format it to xbox's native system so I don't have to spend exorbitant amounts of money for a tiny amount of space. The current drive was $80 for a 20 Gb USED, which I find to be absolutely ridiculous.

ALASKA UPDATE!
I just got off the phone with Ed Moriarty, who is currently in McGrath, Alaska, and he says the Aurora Bears are a huge success! The kids up there are having a great time making the bear assemblies, and even the superintendent of schools showed up to make one!

Sunday, January 1, 2012

End Year Post: Aurora Bearealis

Happy New Year, everyone! I'll spare the little details, but boy, 2011 was quite an adventure. A year ago I would have never thought I'd be where I am now, and it's still amazing to me how lucky I've been.

Goals for 2012:

1) Create something new that has the potential to improve someone's lifestyle
2) Do something that is universally regarded as "totally awesome, dude"

(Goals may be changed, removed, or added over the course of the year)

On to the engineering part of the post:

The past week was incredibly hectic. Ed Moriarty is headed to Alaska on Tuesday to promote interest in science and engineering in young kids. To help him achieve this goal, I designed and mass-produced what he calls "Aurora Bearealis" which combines the Aurora Borealis (northern lights) with UAF's Aurora Bear logo.

Over the past 96 hours, I've spent about 50 of them at the Edgerton Center making this project come to life. I've also consumed about a pound of boneless chicken wings and a whole pizza. That's not a lot for four days of food, but then again I really didn't find time to eat. Big thanks to Ed, Tommy, Bruno, Kenny, and the several drop-ins who took an interest in the project and helped in any way they could. Here are a few shots that were taken when I wasn't CADing or eating.



A tricky part to cut efficiently.



Approximately 150 full assemblies. In a box.


video
A video of the final product. Turn down your volume; the video was taken in the laser room with ventilation going at full blast.

After several days of dreaming in vector format spending more time at MIT than at home, we cranked out over 190 full assemblies, which, as I said earlier, took about two full days' time. This includes transport, setting up parts to cut in AutoCAD, cleaning machines, preparing materials for cutting, establishing cut settings, actual cutting, taking materials out of machines, cleaning machines again, testing prototypes, sorting parts, and packing them into sets of 10 or 20. It was exhausting but extremely rewarding. As put by Ed, these bears are going to make a lot of kids in Alaska really happy because they now have a really cool night light during the darkest time of the year, and the kids can say "I made that!"

TL;DR I am now one with the laser cutters in 3-402.