Build Day 45

Boy, it’s been a while since I made an update. But a lot has happened.

A lot of time was spent finishing the drive system. We finished machining down the wheel hubs, then stuck the hub and the axle in the milling machine to drill through them both. We then tapped one end of the hole for an 8-32 screw, and screwed them together. This is a nice, tight fit, better than you could get with a set screw. Then as for the motor shaft, we drilled a 6mm hole in the end of the shaft and stuck it back in the milling machine to mill for a set screw. Because the motor shaft has a flat, the set screw would work for this. Finally, I drilled in the other end of the shaft and tapped it for an 8-32 screw. This was my dad’s brilliant idea, and in retrospect, it really was a great idea. Basically, for dis-assembly, I can thread a screw into that hole and pull the shaft out. Otherwise, there’s no way I’d get it out.

So that was all assembled, and the bearing block plates were glued in place. In the end, we doubled them up for strength, and because of their relative position with the opening in the bottom of the foot.

I decided then was a good time to put R5 together, even with the shoulder hub positioning problem. So I ran wires to the motors, but not as a final assembly. I see now how difficult it’ll be to run the wires through the slots in the foot/ankle, so I’ll wait until final assembly. But I had those run, made up the jumpers to go from my receiver to the Pololu TReX Jr, and brought everything upstairs. I get it all together, hook up the electronics, and it works!! Almost. I hadn’t bothered to make the ankle lock pieces. Apparently, those are kinda important, because R5’s feet would flop around when he would roll.

So the next day, I made them. When I screwed them in place, I accounted for the thickness of the .04″ skins that would go in place, even though I haven’t dome anything with them yet. For now, I’m using simple shim pieces. So I get those in place, and this time he actually works!! R5 could drive around!! I was thrilled. I was only annoyed with the speed. He didn’t seem to be going as fast as he should have. One test with the meter, and I see the motors are only getting 8.5 volts at full power. I run a simple calibration of my TReX Jr, and now they run at full voltage. He will go a little faster than he does now, but that’s because my battery is weak.

I thought this was a pretty good milestone. I was satisfied with this. Of course, I don’t have the wheel for the dome motor yet. If I had that in place, that would be even better. Especially considering that the TRex Jr has a third motor output.

Okay, almost caught up here. So after all that, it was time to break R5 down to fix the shoulder hub problem. I got the body up, and had a surprise about the glue I used. It’s strong!! After trying to pry apart the body, I can appreciate just how well that glue works. But I got it apart.

After some careful-ish measuring/guesstimating, I found that I needed to shim the pieces .22″. This was achieved by gluing layers of thin scraps I had from cutting everything. So I glued in the wad of scraps, then glued the hub mounts back in place. I was not entirely sure about their parallel-ness, but I think it’ll be fine.

Now, I could move onto the body. I taped up the inner skins, which fit well now with the shoulder hubs. They were taped, then glued from the inside. Success! Then, I spent a day or so cleaning up the outer skins. From cutting out the pieces, the inside corners all ended up rounded because of the cutter I used and because of limitations of the software. I made them nice and square. I then glued them on. It looks fantastic!! I have some gaps at the seams, but that was to be expected. It will be fixed later on when I prep for paint. Then this morning, I began cleaning and gluing a couple of the inset panels.

That is where I am now. I have exactly a week until I go back to college, so progress will be slowing. It’s unavoidable, and I knew this when I jumped into this project. But all in all, this was a good way to spend my summer.

Build Day 34

So, I did a dumb. I had not moved ahead with the body skins, because I thought the arm boxes had to go in first because of the geometry of that space. Whoops. Apparently they don’t, which is good news for me since I don’t have the plastic to make them yet. So I decided to move ahead with skinning the body. I had cut the back outer piece earlier, so I next cut the inner pieces; front and back. I removed the door spaces for the four doors in front which I will have open.
Next, I went about cleaning up the frame. There were a couple high spots where the uprights met the rings, so they were trimmed and sanded. Additionally, the two front uprights (surrounding the vents) were a little out of position, so they interfered with the doors on either side. So I pulled them out, and will glue them in place when I glue the skins. I then worked out the hinges. I drilled and tapped holes for the large left hand door, where the hinges are actually inside the space. This way, they don’t interfere with the tall door right next to it. As for the small right hand door, I didn’t do anything with the hinge. I will probably use the identical setup, but I will make a separate mount piece and glue it in afterwards.
After that, everything seemed to line up well. Almost. I get the front and back inner pieces all taped in place. I knew there would be a bit of a gap; I evenly put a 3/32″ gap on each side. But I then noticed a problem with the shoulder hubs. On both sides, the hubs seem to be too far forward, meaning that the front skin hits the hubs on both sides. And there is a big gap between the hub and the back skin on both sides. Now, I haven’t skinned the hubs yet, which means they probably wouldn’t even fit then. It looks like my only solution will be to remove the shoulder hub mount plates and shift them back.

Build Day 31

My motors came!! They are exactly what I needed, and they fit right in. I ran out yesterday and bought the metric screws to mount them. Other than that, I’ve been working on getting the drive train operational. I cut out bearing mount plates which will be glued in to support the axle. They were made as two half pieces just so I could use some of the piles of scrap I have left. But they fit together, and fit in, well.
Other than that, we’ve continued working on the aluminum hubs. One is done, save for the pin . Tonight, I may be able to have at least one side together!! We’ll see how it goes, though. That’s about all the progress I’ve made. Today, I may work on designing the computer system. I really don’t know much about what’s out there, but I know my system will be self-contained.
It will have motor output built in, sounds, radio control capabilities, speech recognition, obstacle avoidance, motion tracking, and more. I’m wondering if anyone would be interested in a system like this. Down the line, once I have my system dialed in, I would consider doing a run of these. Oh, and I’m going to have an IR remote link within the body, so the main computer communicates with the dome. This way, sensors, servos, and lights in the dome will be controlled by the main computer. This will give greater control than randomly flashing lights.

Build Day 29

I’m still making some headway, even though this is a secondary project. So when I realized that my R5 dome skins PDFs were squashed, I was a little bummed. I re-downloaded them, and I’ll be able to use them. I just wasted what precious little plastic I have. Anyway, the only other skin cutting I’ve done is the back half outer piece. I’m very happy with how it came out. I could (and probably will) cut all of the main body skins relatively soon. But again, I can’t glue on the fronts until I make the arm boxes, and I can’t do that until I have enough plastic.

I have however begun work on the drive system. My motors aren’t here yet, but I’ve worked on the other stuff. I’ve decided that for the foot, just using the motor shaft to support the weight would not be enough. So, I plan on using 1/2″ axle and bearings to support the outside of the axle. Shortly, I will be cutting mount support pieces that i will use to screw the bearings on.

Also, my dad graciously volunteered to turn my wheel hubs. We started with a pair of 1″x3″ round aluminum slugs. They were turned down to about 2.75″ diameter, have a 1/2″ bore, and a groove cut to accommodate the shape of the wheel. When they are done, they will taper, and use either a cold roll pin or a screw to pin them to the axle. Then the end of the axle will be drilled to 6mm, and a set screw will fix it to the motor shaft.

Oh, and I am now using different wheels. The original pair I bought off of McMaster were terrible. They weren’t even round. Probably worth the money I paid for them, but they were unusable. So instead, I’m using these I bought at Lowes. I broke them down, and found that they would work perfectly. So the hubs were made to fit these wheels. I also have my caster all mounted, but I see now I haven’t taken any pictures. I’ll get some up eventually.

And finally, here’s R5 as he stands. I’ve got the dome bearing all set, so that’s nice. So as you can see, I’m slowly making progress. I’ve got 2 1/2 weeks though, until work will have to stall. At least I’ll be able to work on the computer control while I’m at school. I’ve already mostly figured out how it will work.

Build Day 23

Another short update. I’ve got my bearing all prepped, and it fits and works well. Sorry, I see now I didn’t take a picture of R5 with the bearing in place.


Anyway, I broke R5 down, and started working on some of the pieces I have, but didn’t glue on yet. Mainly, foot pieces. Then today, I cut out a couple of motor mount plates from residual scrap pieces. Some proper drilling, and tapping, and they fit in the foot perfect. Now, I need to make my hub to mount the wheel, and I need my motors to get here. I think the estimated delivery date was within the next 7 days. I’m so excited.

Then, I started cutting some .04″ (1 mm). I did a quick test on some .02″ I had laying around, to see how well the 1/16″ cutter I used would work. It worked well. So I laid it out, and cut some dome pieces. I used a 20″ swath rather than a 24″ one, because this way I will optimize my plastic as I cut the almost 20″ body pieces. But then I ran into a snag. Somehow, the PDF I used for the toolpaths was squashed. Meaning, that the circles I cut out were actually ovals. So the two rings are pretty useless. It was a waste of plastic, and I’ll need to re-cut them. Oh well

Build Day 19

I hit a milestone last night. R5 is now standing on three feet!! Still far from done, but seeing this is very satisfying. Once my bearing gets here, either today or tomorrow, it’d be even better. Now, I can move on to some of the skins. The only problem is that I don’t have the parts to make the arm boxes yet. Meaning, I don’t think I can do the front skins yet.So for now I will be laying out how I will cut the skins. I think I may do the dome first, yet there’s plenty I can do. As for the mechanics, I am waiting on my motors (should be here in a week). But temporarily, I will be using a standard radio control system from one of my dad’s old model planes. I will pair that with a Pololu board I have that converts the PWM signal to DC out. This will at least make R5 mobile, until I design and build his main computer system. I plan on giving him the works; proximity sensors galore, PIR sensors (detect human bodies), dual microphones. Plus he will have speech recognition. In essence, R5 will function and operate like a real droid from the movies. At least that’s the plan.

I’m going back to college in four weeks, so I’m a little pressed for time now. I’ll just keep working, and see how far I can get. But I know that once I’m at college, I’ll at least have time to design the main computer. That’s something I think I can have up and running by next May at the latest. However, programming in responses to mimic an AI isn’t going to be easy. And I’m an Electrical Engineer, not a Computer Scientist.

But that’s all for now. Maybe next I’ll be cutting out some skins, or maybe then I’ll turn some of the eye details or wheel hubs on the lathe.

Build Day 18

Well, three and a half weeks in, and I’m happy with my progress. I’ve now gone through the last of my .125″ plastic. So from two sheets, I have everything except for the battery boxes, the horseshoes, and the booster covers. This is including an R5 head as well, so it’s really not bad. I at least have enough to have a structural skeleton of a droid. I will soon be moving on to the skins.

As for the other parts, I have my drive wheels and bushings. I’ve got my dome bearing from Mouser on its way, as well as my motors off of Ebay.

Build Day 15

Well, I’ve ordered my motors, so R5 might be rolling around in the near future. I went with the recommended Jaycar motors, but I got them off of Ebay. I got them for about 60% list price, with free shipping. Anyway, I’ve got a handful of parts for the dome cut, but now I’m wondering about my styrene consumption. I need to cut 5 or 6 more rings for the dome from a 48″x48″ sheet of styrene. Plus all the parts for the center ankle and the triangles and uprights for the dome. I think I can do it, but it will be close. I know I don’t have enough for the horseshoes or battery boxes though; I won’t even try to fool myself.

We have a family friend coming this weekend who happens to be a big fan of Star Wars. So my plan is to have R5 semi-presentable and standing on two feet by Friday. But with orders now coming in for my business, I’m not sure how much time I can give to R5.

Build Day 12

Another small update here. I’ve now cut into my second sheet of .125″. But I’m thinking, and the next 24″x48″ chunk should be enough to finish both feet, the following one should be good for the center ankle and some of the center foot, and the final one should get me the parts for R5’s dome. Hopefully. I know now that I don’t have enough for the booster covers, horseshoes, and other details like that. But I’m not as worried about that yet. Right now, it’s all about the structural components.

Anyway, here’s a glued up leg framework. I chose to use a channel like this, contrary to the plans, because I’m not sure about how much cabling I’m gonna have to feed to the leg. I also increased the size of the slot and hole in the ankle to possibly accommodate more cabling. One of my ideas is to use proximity sensors in the back, bottoms of the feet. This way, R5 will know if he’s about to drive backwards down the stairs.Just a safety measure.

I cut out a handful more parts, then collected them all. I left it last night with some ankle parts drying,

Build Day 8

I’ve gotten a bit more done. I cut out the rest of the leg pieces and some of the ankle pieces from another 24″x48″ piece of .125″. I’ve got the shoulder hubs done, and half of each leg done. I also started gluing the layers for the ankle pieces. This here is a good representation of what you can get out of one 4’x8′ piece of styrene. Not bad. With the exception of maybe the R5 dome, it looks like two sheets can do the whole thing. I have decided that I’m gonna wait to do the skins. I’d be more than happy with a solid, rolling body, even if he’s naked for a while! So from here, I’m gonna finish the legs, ankles, and main feet, then do the center ankle and foot, then work on the dome.