Rolling Chassis

Been working the last few weeks on figuring out the center casters. None of the previous 2.5 - 3 inch casters seemed to be working for me. A couple builders, mainly the R2.0 guys, had mentioned trying a beefy 3.25 inch Gladiator Caster from McMaster. After a lot of staring at the issues with every two wheel combo I could find, I finally decided to go ahead and get the Gladiator. 

I'd hoped that the holes in the Gladiator Caster would line up with the JAG mounting plate, it was a little hard to tell based off the CAD drawing alone. Once I got it in hand, it was obvious it would be way off the mark. So the next phase of deciding how to mount the thing began. I didn't really want to modify the bottom flat JAG plate, which I would have to since the taller caster would need to sit higher up in the foot that the standard plate allowed. So I went looking at Lowe's and found a 4x12 inch piece of 1/4 inch steel. It was a little thicker than the JAG plate, but I figured its better to try cutting an off the shelf $10 piece than a hard to replace custom part.

I tried a couple methods to cutting this thing, but once I got a hard metal Jigsaw blade, it went pretty smooth, and cutting it exactly in half would be just the right size. I laid the JAG plate over the now 4x6 inch piece, centered it and marked hole locations. Then used a drill press to both drill and counter sink the holes where the plate would attach to the angled half of the JAG mounting system. I had figured out earlier that mounting the Gladiator Caster flush with one side of the new plate would put it almost exactly centered in the foot when moving forward, perhaps just dumb luck. So I marked the holes of the Caster and drilled those out next.

The biggest problem was that the caster would sit on top of the screws that mounted the plate to the angled piece via standoff couplers. I'd originally thought I'd just lock the caster screws in with nuts on the bottom side, screw in the plate, then place the caster over the caster screw nuts and get them to fit inside the rather large mounting holes of the caster itself. But, my Dad has a neighbor that can do Tig welding, so we gave him the plate to weld nuts onto the top side of the plate, thereby allowing a rather easy install of the caster itself.

Once I got the piece back, it was time to see if this plan was going to work out. I found some 7/8th inch standoffs at Lowe's, thinking that I'd try it with those first and then order whatever length I'd really need later. They ended up being the exact length I needed, another stroke of dumb luck. I also found a handy right angle ratchet driver set for $20 bucks that worked perfectly for attaching the JAG angled piece to the Center Foot.

The new custom plate went on with ease, and then the Gladiator Caster screwed in tight with some washers helping to span the rather wide holes it has. The great thing about this caster, other than being nice and heavy duty, is that it perfectly swivels 360º without hitting the side of the Foot. Its like it was made for this exact use.

So once I got the Center Foot all together, it was time to get R2 somewhat back together again. I put the Outer Feet complete with JAG Drive System installed back onto the legs. The now quite heavy legs went back on the frame, and the pretty hefty Center Foot went on as well. I immediately realized I'll have to lock the Center Ankle before I'll be able to see the whole thing in action, but holding the Center Foot down I moved R2 around with relative ease.

The other thing that became apparent was that I will have to cut a hole in the bottom of the frame and use the COM-8B adapter plate for the center leg. The Center Foot is still not sitting level, just like before I had the wheels installed. But all-in-all, I think the Gladiator Caster will work out well. It really makes me want to get the motors, batteries and RC elements in ASAP and get R2 rolling around on his own power.

Chrome Dome

Well, the long, long effort to shine the dome is complete. I've been working on and off at sanding the outer dome over the last year. With so much elbow grease involved, it's not something I cared to do all in one shot, but rather whenever I got an itch to. My goal was to get out the spin lines and have a nice dull shine, similar to the medal ceremony scene at the end of Episode 4.

I initially attempted to get the spin lines out by hand, but soon realized that it was probably too big an undertaking without getting carpal tunnel. So I broke down and bought a Black & Decker Mouse Sander at Lowe's. The reviews were mediocre, and had many reports of breaking rather fast. I can vouch that within a few minutes, my first one broke while using the attachment piece. Luckily Lowe's took it back no questions asked and I got a second. I didn't bother with the attachments and it ended up doing a great job. Over the period of a few weeks I used the 80 grit to get out all the spin lines in both the Inner and Outer Dome. Then I used 120 & 220 grits to get the dome to the point you see here:

From that point I resorted to hand sanding using two 3M sponge sanding blocks at 100 and 180 grit. These can be found in the painting department at any Lowe's Walmart, etc. I really liked these since they were able to bend to the shape of the dome and made it a little easier on the hands. I went over the whole dome using vertical motions from top to bottom several times with the 100 grit until I was satisfied that most of the pitting from the mouse sander was gone. Then I used the 180 grit sponge several times as well.

From there I used 400 grit paper dry, and then started a round with it wet. Being single has its advantages in that I just sat the dome hanging over the kitchen sink without anyone complaining. Plus, I was able to watch the living room TV during this phase. I spent an evening each on a grit of paper, wet sanding with 600, 800, 1000 and finally 2000, always using the same vertical motion. At this point the dome felt silky smooth but still had visible sanding lines.

That's where a little tip I picked up watching the webcast of last year's DroidCon came into play. I bought some Bombs Away Metal Polish last year after hearing about it during the Dome presentation. I'd used it a few times on some of the other parts, including the Center Vents. It seemed to do a pretty good job so I decided to go ahead and use it on the Dome as well. After seeing Lasse's results with a drill polishing attachment, I'd had my eye on one from the auto department at Walmart. I finally broke down and got it once I'd finished all the sanding on the dome. You can see the results of using the Bombs Away and polishing ball together.

One pass of the polish still left some unevenness so I worked my way around the dome with two applications to each area. I was very careful on the lower portions where the aluminum is quite thin. I kept the drill as slow as possible in those areas so I wouldn't accidentally break anything if the polishing ball caught the metal. Then I made one final application to the middle, wide section of the dome in order to get out as much of the splotchiness as I could. All-in-all I'm fairly happy with the results. It has a nice shine to it, there's no spin lines at all, and its not quite a mirror finish while still having a few very small imperfections when you look close. Its a good start before I eventually weather it down the road.

Move Along

Decided to try the captive studs on the body hinges today. I marked the holes on the outside of the Inner Skins first just to make sure they would be under the Outer Skins once they were glued together. Everything looked ok, so I drilled and bolted the hinge for one panel then placed the Outer skins back on and clamped them down. You can see below that there is a pretty good gap. So I'm nixing using the studs on the hinges altogether and will just glue them to the inside instead. Some may be able to live with that gap, but not me. I think its just because the studs are so close to the edge, in fact, they may have even stuck out a tiny amount once glued together. So lesson learned, at least I only tried it on one hinge.

Also yesterday I went to the parents house and used the drill press again. This time on the other foot drive to foot shell holes. I still had a similar problem as with the first one and had to use a larger hole and even ended up filing a little on a couple holes to get everything to line up right. I started wondering was why Jerry doesn't go ahead and have the holes drilled in the feet when they are made. Seems like a machine would be able to be exact and alleviate a problem on the builder end. The only thing I could think of was that other drive systems may not use the same holes, and you'd end up with unnecessary holes in your feet. Something I may ask one day if I ever meet him in person. I also decided not to countersink the holes. The steel is just too thin. Looks like maybe 1/8th inch think at most. I'll still use the low profile flat head screws though. I think they look a lot better than the rounded fatties and will hopefully blend in a little more when everything is painted.

Captive Audience

Finally got the captive studs from McMaster that I'd been putting off purchasing for awhile. So I bit the bullet and decided to try them on the skins first. Nobody on the forums had replied that they tried them on the skins. They were mainly used for the dome. But I figured its the same 2 layer principle with the skins, so why shouldn't they work? I'll use them on the JAG hinges for the front doors, the coin slots and of course later on the various dome pieces.

I used the coin slots as the guinea pig. After marking the holes with pencil first, I attempted drilling the first hole solely off the mark. I'm not sure if its the drill, the bits or me that suck, but every time I try to drill something, it glides off center even when I center punch a guide. I had barely started the first hole when I thought of a better idea. I clamped the coin slots in place very gently and protected the outside with a rag since they are already painted. Then I proceded to drill the holes out with a 7/64th bit using the slots themselves as a guide. I removed the slots, bore the holes out a tiny amount so the 4-40 captive studs went through the holes easily, and then sanded the slag off with some 120 grit sandpaper.

Next, I proceded to see how flush the captive studs would be. Loose they still stick out a bit. But once they are tightened from behind with a nut they pull into the aluminum a good bit, not entirely but pretty good. I countersunk the next three holes very lightly to see if it improved the flushness at all. It didn't seem to make much of a difference. These photos make it seem much worse than reality, they only stick out maybe a millimeter. I guess a good macro lens will do that.

So after all four were in, I put the outer skins on loosely with binder clamps. I think with a good clamping during the gluing phase, you won't even be able to tell that the studs are under there. Again the photos make the gap look worse than real life. There is no visible bulge in the outer skins, and the coin slots will cover these seams anyway. So, I think I'll use the captive studs on all the other necessary spots. Thanks to Pangborncc & CuriosMarc for the captive stud tip. Now I just wish I hadn't already spent some money on regular 4-40 screws. Oh well.

License to Drive

Spent the weekend doing various things on Artoo. First I took him all apart, so he's not standing on his own legs anymore. I'm going to do some work on the skins again in an attempt to get some white painting done before the heat of summer gets here. So they're screwed/clamped back on the frame at the moment. 

I looked through my box of blue painted parts and wet sanded some of the ones that needed touchup. The first three pieces turned out good, then the next three looked pretty cloudy and flat, so I'm holding off till it cools down a little this evening to do anymore. It was in the low 80s this afternoon, but felt a little warmer in the garage while I was painting.

After re-reading every post I could find about center foot casters, I proceeded to order a couple sets from Lowe's website yesterday since they weren't available at any local store. Hopefully one, or a combo of these will work.

I decided to tackle the foot drives this afternoon. I followed this tutorial, so I can't take any credit for originality.

Here's the steel foot shell and foot drive.

I took the large wheel out to get access to the screw holes, then placed the mount inside the foot shell.

Then I took a blue sharpie and marked all 6 holes. I also took a pencil and circled it around the hole too. The angle makes it look like the outer marks are off center, but they are not.

I center punched the marks and then drilled a small hole first just in case.

They all lined up just fine after putting the bracket back in for a visual inspection.

So then I drilled the holes out larger. First I used a 1/4 inch bit which should be large enough. I was having a little trouble getting them all to go in with ease, so I went ahead and used a 5/16 inch bit to help loosen it up. I wish I didn't have to and that they had lined up perfectly with the 1/4 inch hole, but it should be fine. Then I put the large wheel back in the foot drive bracket and screwed the whole thing in from the top/outside with the 1/4-20 screws Jerry provided.

Like the tutorial I followed, I may end up getting the low profile flush style screws and countersinking them. The bulky screws take away a little in my opinion.

One thing I noticed after I had the drive in was that the smaller back caster wheel in the drive needed to be lowered because the foot wasn't sitting level. I figure I'll fix this one later since I'd have to remove it to do so, but I went ahead and leveled out the other foot drive. It was fairly easy. I loosened the two screws using a T-bar allen wrench through the two holes in bracket. Then I sat the whole drive upside down and put a metal ruler across both wheels. Then, I used my trusty Dollar Store level to check the position of the small caster wheel and then tightened it down.

One foot drive down, one to go. With the new center casters coming this week I'll hopefully have all the wheels figured out and done soon. Then I'll have to go ahead and order the NPC motors and get busy on some electronics side of things. Can't wait for that first test drive!

99 Problems

And Center Casters are one. Since I have the Foot Drives in now, my next plan of attack was to tackle the whole drive system and get R2 on wheels. The main problem I'm having right now is with the center caster wheels. I got these below from Rockler after reading up about how much better skate style wheels are. The issue I'm having is that they don't line up with the JAG mounting bracket very well. This is about the best way to mount them, but when you swing them both to the extreme outer position they are almost 2 inches too wide for the foot shell. I'm looking into possibly getting the post style casters that I could pop the wheels out and still use these. Its either that or devise a way to mount the casters over the plate's bolt holes after its installed. That may be what finally happens. I'm also looking at the one big McMaster caster that a couple builders have used, but it looks like it would require modifying the JAG plate a good bit.

Footlose

Finally received the infamous JAG Foot Drives! Been waiting one year, one month and 21 days on these bad boys, hopefully a record that won't be broken. They are very solid, pretty hefty and have a reputation for lasting quite a while with little issue.

Anyway, now I'll be able to get moving on getting R2 moving. I've been reading up on center casters again, just because the two I have don't fit the bracket too well, so I'll have to find different ones that I can put the skater wheels in, or something altogether different.

I guess its time to start looking into getting the speed controllers, batteries and remote control as well!