L3-G0's Frame Test Run!

Warning:  Reader Discretion Advised.  This post contains discussion, photos and video of the naked interior of a Lego model as filmed by my wife.  (People who searched for some of those keywords may be disappointed by this post.)

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This part has been a bit tricky, so it's been a while since I posted.  But it's starting to get there.

For Brickcon we pretty much had L3-G0's entire body built and ready, head moving, computers making noise, etc.  All that is pretty cool, but he was just sitting on a table, and we want him to move, run around the room, scare the cats, and all that.

To do that, we need some sort of "frame" to hold all the Lego together.  Something that won't shake apart on a rough sidewalk.  We investigated using Lego, like Technic bricks, but L3-G0 is pretty big and heavy.  The original model had a single Technic pin connecting the ankles, which clearly wouldn't work.  So we settled on wood and aluminum.



This is from a test run of the frame.  He's jury-rigged to move so that I can test how sound the design of the frame is.  Hopefully I'll shake out any structural issues before he gets his skin on.

He's RC controlled, like a model airplane, with 2 channels being mixed using the radio's v-tail mode to control the left & right motors.  So he ends up driving like a tank, though the control is with a single stick.

The motors are like what you'd use in a kid's electric scooter, and he's 8 wheel drive!!! (which actually isn't great).  The RC receiver outputs for 2 & 4 go to the motor controllers, which can be configured by computer.  There's a tiny acceleration/deceleration delay so that he doesn't slam the chains, which seems about right.  The motor controllers are also throttled at about 1/2 power because I didn't want to have a short or something and have the frame got out of control.  That'll have to be increased for real.  The speed's about right on smooth floor, but on carpet it's a bit slow, and it'll be even slower with another 30 pounds of Lego bricks on it!

Gory Details

The frame is mostly aluminum t-slot, with some brackets and stuff to help out.  I want him to eventually do "2-3-2", which is going from two legged mode to three legged mode and back.  Because of that his shoulders have a round bearing.  The insides are connected to a huge t-slot beam, and the outside edges have a smaller bar connecting them (to keep them in sync - theoretically).

Along with that theme, the center leg would need to retract, so the center foot is on a single t-slot rail, hooked up to a linear bearing (above the middle plate, behind the battery in the video).  At that point there are two fixed rails that go up (the ones sticking out the top).  The center foot bearing can slide all the way to the top.

However, I've put a stop on the center leg for now, and the bottom ankle hinge is fixed.  The outside legs are hinged in the middle, but they've got lots of wheels, unlike the front foot.  With the current single wheel, the front foot would fall over if the ankle wasn't rigid.

The single foot was really loud when I hooked it directly up to the battery, but the noise on the frame isn't bad at all with both motors regulated and running more slowly.

The ankles are currently 3 layers of plywood glued together.  Originally the front ankle was a single layer, but that snapped pretty quickly and I rebuilt it.  There's a brass collar through the wood where the ankle pivots on the foot.

With the flexible ankles I figured I needed front & rear wheels, and for various reasons I chose 3" roller blade wheels. Of course, it's more stable if the foot has 4 wheels, so I did that too. And then I powered both axles. The chain runs under the foot, so I probably don't want to get on very rough or dirty surfaces.

What I realized a bit belatedly is that with 4 wheels in the corner of the foot, it's kind of "hard" to make him turn like a tank. Quite a few wheels have to slip sideways for a tank turn to work. It seems "good enough" for now though, and isn't too bad if I make wide turns. OTOH, if I rapidly switch directions, he wiggles like when Kenny Baker throws R2 around.

Test Results

I took it to work twice to see where the problems were.  Astromechs have a terrible problem with the front foot and bumps.  He did OK at first, but the impact seemed to weaken the joints, so he started folding up the legs.  If the front wheel stops, the power of the side legs is pretty impressive, they try to keep pushing. 

The first day, I'd zip-tied the beam connecting the outer hubs together to the top, so that he'd be stuck in three legged position.  However the beam is actually 3 parts because it has to avoid the center mount for the center foot.  Those joints proved weak on repeated banging into sidewalk cracks, and eventually the legs started folding up. 

In the car I'd tied him down with bungies to a tie point in the middle, which worked going to work, but on the way back I basically (gently) turned a corner and the bungies pulled all the feet together, his legs folded up and he fell over.

That also knocked the battery loose and trying to get him back upright I bumped one of the wires into the other terminal.  Fortunately it was only a momentary contact (melting the wire helped), but I probably want to do something about capping the terminals.  I'll have a better mount when I do it "for real", but better safe than sorry (it's an 18 Ah 12V lithium iron phosphate battery, like Tesla uses, but tinier).

2nd Test

I drilled a hole in the shoulder hubs and bolted them together to keep the feet from rotating.  Because the hubs are currently wood, it didn't work too well, but it helped my zip-tie thing.

The rear feet frames are also laser cut, and seem OK that way. The Lego brick shell fits nicely over the frames, almost perfect on the first try (close enough I'm not going to fix it). The wood's a tiny bit flexible, but way lighter than aluminum.  I put one of the Lego foot shells on for the second test to make sure that the Lego didn't vibrate apart.

I zipped by the company store to our makerspace to show off the parts I'd made on the laser cutter.  Even when he's just a bare frame people stop and gawk, and most recognize what he'll eventually be when he gets his skin on!

The second test seemed to go way better, but I noticed that the legs "wander" in and out a little (toward and away from the body). 

I'm not quite sure what happened, but on the way back to the car, one of the outer shoulder hubs cracked and he started doing the splits.  That was sort of expected, we've planned to replace the plywood with aluminum there, but it wasn't great timing, he was in the driveway, and a delivery truck chose that instant to start "beep beep beep" backing up.

I didn't really want the frame run over, so I picked him up to carry to the sidewalk, and the other leg fell off!  The four bolts near the hub had worked themselves loose a tad apparently.  That's not really a problem, but I'm clearly going to have to find a better way to secure it.  I'd noticed that several other bolts seem to have vibrated themselves a tad looser.

At home I took a closer look, and the brass inserts in the ankles are also working their way loose in the wood.  I'd already thought about making the ankles out of aluminum, but that seems more likely. 

I don't quite get chills watching the naked frame run around, but my wife thinks he's already getting a personality.

I can't wait to get the bricks on and get him back together. I sure hope I can make ECCC in March.

L3-G0 is Ready for Brickcon!

Yippee!  All ready for Brickcon 2013 (October 5-6 at the Seattle Center)  He's not going to have feet at Brickcon because that's going to be another very huge undertaking.

 

I didn't have a ton of time to post, so a lot happened.  The dome sits on a bearing, so that had to be mounted and bolted on.  The dome also basically fell apart and had to be rebuilt... better... stronger... faster... (yes faster, and it didn't even cost me Six Million Dollars).

 

Nikita helped test the dome:



 

The bearing and dome base rest on a support that is made from the hinges that hold the panels together.  There are two motors for the Lego EV3 Mindstorms (this is the largest Mindstorms robot I've built by far).  Two because they push a lot better than they pull.  The wheels will rest on the inside of the bearing, attached to the dome of L3-G0.  On the right, near L3-G0's blue front you can see a color/light sensor.  The light sensor is used so the EV3 knows when he's facing forward.

 



And here it is with the dome base on.  You can see that the plates on the base of the dome ring are bolted to the aluminum bearing.  The bearing has a plastic support ring on top of it, also to keep it from dragging the dome bottom on the static side of the bearing.

 

The bottom of the bearing is mounted to 1/4" plywood, seen here from inside the body, before the dome ring was installed on top. 

 

 The dome itself has been strengthened, and stays together much better now.

 

Also finally got the shoulders finished.  Lots of bits weren't perfectly aligned in the Lego Digital Designer (LDD), and LDD also doesn't show you how to attach 12 pieces from different directions at the same time!  Getting everything to snap together right was a bit challenging.



I like the detail on the shoulders, and also I like the "Under Shoulder Detail" (R2 Builders Club Lingo):

 

Timelapse Video on YouTube

 

I show his dome spinning at the end.  I'll have a better video of that later, but here's what I have so far:

Building the 2nd Dome Panel Row

Hosik, a Korean foreign exchange student helped out this time, thanks Hosik!



Hosik and Darius also helped make sure the cat (devil cat?) got some cameos.

It's sort-of days 11-12. Sort of because sometimes I only get an hour or two, so I try to get those into a "day" unit, whatever that is. This part of the dome's being really hard because of the multiple curves. At least the plan is mostly working, however the incomplete sections are fairly fragile. I also took time to build up some plates where the dome will rest on the Lazy Suzan bearing. Since the dome was already partially built, I did that from the bottom.

Also got the eye done!  The eye was challenging because the shapes don't align very well to actual brick sizes and shapes.

 

The logic display also looks particularly nice with a flashlight behind it.  This was fairly challenging to get all of the panels to fit next to each other and provide enough structure for the panels above and below.  It was rebuilt several times.

 

Its starting to get there.  I'm so focused on the detail that I miss the big picture sometimes.  A few times L3-G0's gotten my skin crawling when I walk into the room after stepping away.  Then it's like "who put that R2-D2 in my kitchen?"



Time Lapse Video for the Middle Dome Layer

 

Building on Day 4 - Starting the Body!

The parts we needed for the body arrived!!!  We're still waiting on ~1500 of the original ordered parts (a little bit of rework has caused us to order a little more since then).  So there're still some gaps for parts.  Considering it's 15K+ parts, we've done great missing 10% of the bricks!

The body is 12 panels, and I started on six of the easiest.  Mostly because they're either identical pairs or mirrors.  So that's about half of the body!  (just the easy half).  3 of them are contiguous, the next two holes in this photo need an additional panel, and the last two go next to each other (despite the gap in the photo).  You can see the missing bricks :(

 



Three are next to each other, so we can see how they fit.  If you can get over the missing bricks, you can get an idea of the 3-D detail.  I'll probably take some close ups when we get the other bricks filled in.

And an idea of the scale, Lara posing with the partial body.

 

Time lapse video for day 4

(All 3 cats interrupted the video, they like playing with the loose bricks.  Additionally there's.... horses?)

Building Session Three

Well, something about having to work, so I didn't get daily updates.  Instead the bits are interrupted and built over a few days.

We still don't have all of the parts, so there's a few holes to fill in the results, but there's a good start on the skirt (under the body), the very top of the dome (I thought I had all the parts, but it's missing a little gray ring), and the legs.

Worked on the skirt first (daughter realized it's his butt, what do you expect from a teenager?)  Unfortunately we're missing a bunch of the "wing" pieces to round out the edges :(

It's also a bit "wobbly" because the hinges let it bend, but that'll get fixed later.  Even so, I think it's looking pretty good.  (Photos are with the skirt upside down).



I thought I had all of the parts for the tippy top of the dome (above the pie plates), so I figured I'd whip that out in about 10 seconds.  Unfortunately I'm still waiting for a little ring on the very top.  (Hopefully tomorrow).  I was able to use the flying saucer or whatever they're called parts for this part of the dome.  The angles and sizes matched surprisingly well for that.

More successfully I worked on the legs.  Again, some parts are missing, but I got further, including some complicated stuff.  Obviously they're incomplete, but I'm reasonably happy with the detail.

 

One thing I realized looking at a photo of a real R2 is that my legs seem a bit tall.  I was expecting them to attach to the plate on top of the ankle, but the distance between the notch and the bottom seems longer than on the real photo.

 

Coincidentally, the R2 builders group had a thread today that mentioned "standard" and "extended" legs.  I wonder if I followed plans for "extended"?  Clearly there's some measuring in my future to make sure I get them the right height.

 

Top is missing some of the slopes to make the recess rounded (it's a pretty complex curve), but here's the top so far.  Hopefully the slopes come today:

Time Lapse of Phase 3 Building:

On to Day 2...

Day 2 building L3-G0.  Mostly finished the center foot, except a few parts are missing (still on order), which is part of why the corner edges don't fit as nice as they eventually will. 

Also the center ankle cylinders (back one's also missing some parts).  And a tiny bit of the dome, which was missing a lot of parts so I decided to come back to that later.  The dome edge will need a little rework, and it's got me wondering a bit about how I'm going to fit it to my bearing.

There's a Day 2 Time Lapse Video too...



We've got brick!!!!!!!!!!!

We've got brick!!!!!!!!!!!  The mailman's a bit impressed.  This is JUST ONE DAY's delivery, only 18 packages of 52.

And when you get bricks, you have to sort :(  Thanks Jaron for the sorting boxes!

 

As of today we have enough to start building, but we're still waiting on 6 packages, so available parts will guide what we start building with.

 

Also a few packages were short a couple bricks (we're still above 99.9% accuracy, but when you order 13 thousand bricks I guess a few are going to be short).  So I've updated the parts needed list if you have a few bricks in great shape to spare.

L3-G0, the full size Lego R2-D2.

We've made a few Lego models, such as the Lego Disney Wonder cruise ship and a Lego Space Needle, and it's about time to do something new, but all of our ideas were pretty lame.  So in the back of our minds there was some thinking about "what could we build next?" 

Then we went to Emerald City Comicon and saw some of the wonderful Astromechs there.  Of course I wanted to build one, but quickly realized it'd be a ton of effort, cost a lot, and I wasn't terribly familiar with the materials.

It should've been obvious, but "gee, I wanna build a droid" sat in one part of my brain while "I wonder what I'll build next in Lego" sat in another part.  Eventually we came to the obvious conclusion:  "I'll build an L3-G0".  Don't know why it took so long.

Normally I grab a bunch of bricks and start building, then get more bricks, but for various reasons I started toying around with some of the sections in Lego Digital Designer to see if some of my ideas were practical.  Of course, once I started, I forgot to stop.

Now we have a 15,000 piece model pretty much figured out, and all we need are about 12K more bricks!  (Well, and some sort of frame, and some motors, and some electronics).  We're hoping that at least part of L3-G0 will be done for BrickCon in October.  Feel free to send us your spare bricks ;-)

There are some parts that will undoubtedly need changed from the LDD model, and he's going to need an internal frame of aluminum or wood or something, but it should be do-able.

A couple more screenshots of the drawing:

The model is based on plans from the R2-D2 Builder's Club (Astromech.net)  Of course brick isn't as finely detailed as manufactured parts, but he should be "pretty close" to spec.  He'll probably be about 100 pounds.  Eventually we'd like more functionality, but for a start we're looking at getting him to move and beep in time for Emerald City Comicon (ECCC) 2014.  We'd love to take him other places too, anyone know how to get him to Celebration in one piece?

We'll post more as the project goes.

Bricks acquired so far:  15900/16000.