I was going to add a few more coats of paint to the skins today, but on close inspection in the daylight they looked fine. A lot of the dust spots I was seeing yesterday just rubbed off with my finger now that the paint has had time to dry. I’m going to leave it a few more days before I attempt to remove the masking tape, as it’s been pretty cold and I’m not sure how the paint cures in this sort of weather.

I’ve decided to re-assembling R2. Started off with something easy – the center ankle as it’s relatively simple and self contained. I need to get him back on 3 legs to start laying out the electronics again. I’m probably going to move things around a bit, for example I know the speed controller can’t stay where I had it on the back mounting plate as it now hits the skins. It may end up on the back side of the plate or somewhere else internally. I also want to build in some sort of switch and circuit to allow me to charge the batteries in place rather than having to remove the cables each time to clip the charger on.

I’ve been paranoid all week that I’m going to ding or mark the paint, and tonight I had to moved passed that. Right off the bat there was no avoiding dirty fingerprint from the grease when handling the new white paint, plus I scratched a some paint off trying to get the ankle to fit back in the foot shell slot. I really should have filed down the metal parts a long time ago to compensate for the added paint – but I didn’t. I’m sure it going to wear off in this spot anyway, but don’t ya hate it when something like this happens?

I’m glad now that I didn’t get things powder-coated and at least I can touch it things up myself if I need to.

I’m going to have to keep an eye on the foot shells as they’re steel and prone to rust, especially where I live on the coast. It’s ironic that one of the reasons I went with an aluminum droid was because wood warps so easily here, even when sealed, and now here I am worrying about rust from the salt air. I may just grease up this area when I get around to weathering him.

I also noticed that nearly all of my ankle cylinders are scratched up and should really be repainted, but I’m not going to do it this time around.

I used silicon to attach the foot strips to the foot shell. I should probably tap and screw them on, but I’m feeling lazy and really want to see this done. I roughed up the two surfaces and taped on the strip. I’ll probably know tomorrow if it works.

I think it looks pretty cool all put together don’t you think?

One last thing while I remember, don’t forget to use screw Loctite or something similar. I missed a few screws in the feet before C4 and lost nearly all of them by the end of the week.

I’ve had an incredible busy weekend working on R2. I’m getting close to re-assembling him with all the skins and parts bolted on and everything painted.

If you’re browsing the gallery for new photos you’ve probably spot a lot of new work over the weekend. I tend to upload photos quicker than I can blog them here 🙂

Throughout the 4 day holiday weekend I’ve been slowly prepping and painting everything that I could, including the legs, feet, ankles etc. Every time there was some downtime I’d turn around pick something up of my paint table, take it outside and give it another coat. I must have applied 3 or 4 coats of the white by now. The paint job isn’t perfect but it’ll do for now, plus I’ll probably be weathering him at some point soon.

I also finished painting all the remaining blue pieces, mostly body detail parts like the octagon ports, power couplers and vents . Once the skins are done and fixed to the frame I’ll be in good shape to start mounting the parts.

I started to use a self etching primer on some of the latest alu parts. I’d been looking for a self etching primer locally for a while and I finally found some in stock at Kragen’s. The problem with the small local auto places is that they seem to only carry one can of some paints, and refuse to special order – so each time I looked they were out. Anyway, it got lucky this time and I picked up the Duplicolor primer (olive green top.) You can see the olive colored parts in the first photo.

I guess my new hypo blue formula is

Duplicolor Self Etching Primer – wait 30
Rustoleum White Primer – wait 30 (maybe apply 2nd coat after 15 mins)
Rustoleum Purple – wait 30-45
Duplicolor – wait 30-45
Rustoleum Clear Coat (maybe two coats)

The biggest thing I probably worked on was gluing the skins together. I’d flip flopped a few times on how how I was going to do this. I really like how Victor has left the inner skins unpainted to show off the panel detail. But having an aluminum frame makes it a lot harder to mount the skins separately, so I’d probably need to paint them in one go. I’d considered using silicon to bond things together, but from some tests I’d done with some of the doors panels, it delaminates at the edges too easily. Cleanup is also hard and it’s difficult to remove all the excess silicon. If you’ve ever tried to paint over silicon you’ll know how bad that can be. The door panels I’d glued together had small fish-eye marks once I painted them. I think I can work around it, but all the other panels will be epoxied I think.

After a bunch of emails back and forth with friends, and a phone call or two – In the end I opted to use a cheap home-brand 60 minute epoxy from Ace Hardware. It’s supposed to setup in 60 minute, hard to the touch/movable in 4 hours and sets fully in 24, but even after 2 hours it was still very soft. Which was good news as it allowed me plenty of time to clean up the excess that squished out. I only had enough clamps for one half of the skins so I tackled the back set first. I’m hoping to get to the front set tonight then on to mounting them on the frame.

I think in the end there was over 60 clamps, paper snaps and clothes pegs stuck to the frame.

This morning the skins had definitely stiffened up, and I’m glad that I’d made sure they were sitting in the correct curved shape I marked on the workbench before going to bed.

Talking of mounting the skins I’ve flip flopped on how best to do this too. Like anything to do with R2 building there always more than one way to go, and there is never a right or wrong answer. I have skin mounting systems from Daniel and Darren, both are very different with pros and cons to each. Darren’s quick snap mounts are made from plastic and allow quick and easy removal, where as Daniel’s are aluminum and require screws to hold everything together. Having experimented with both I’m opting to go with Daniel’s mounting blocks for now.

I also worked on getting the skirt finished this weekend. I didn’t quite finish it ready for painting, but I did get the strips mounted. It probably took close to 4 hours to drill and tap all the small holes.

I started off by marking up where the strips would go and drilling a series of holes.

I then clamped each strip one by one into place, center punched through where the strip needed to be drilled, tapped the hole, reattached to the skirt, repeat for the second hole. That’s a total of 48 holes and 24 taps needed. I also had to cut down each screw as they were too long!

The holes in the strips do not go all the way through, so tapping them was hard and didn’t leave much for the 4-40 screws to hold onto.

Each strip had to be tweaked and filed to get it to fit, and due to the construction of the skirt, some strips are too long and need filing down in length. I’m also going to have to bondo/fill in the gaps before painting.

I’m sure there was more done this weekend, but that seems to cover most of it for now.

I’d posted a few weeks ago that I had a problem with the bolts on the Knurled Hose Fittings (KHF) hitting the drive wheel in the foot. Well I finally got around to cutting down the nuts and at the same time making some small nuts for the battery boxes.

For the feet I simply cut the nuts in half and filed them down. Here’s a before and after shot

At first I tried to cut the nuts with a hand saw, but it was slow going so I switched to the dremel

Here they are attached to the foot with the expandable rubber plugs which hold the hose in place

I also had to adjust the holes in the feet to get the foot strip to line up properly. I just used a hand file to remove some material

For the battery boxes I had to grind down the nuts to fit into the tight space.

Nice and snug fit

[edit 12-03-07 – see the following post about the failed rubber plugs on the KHF)

Here’s a quick template I created to help mark out the hole in the battery boxes necessary to accommodate the NPC-2212 motors and the JAG/Dave Painter Foot Drive System.

Download and print the file at full size on 8.5″x11″ paper without scaling. I can’t stress enough not to scale or alter the margins.

I used a Dremel to cut out the hole and if I had this template to start with I’d probably saved myself a few hours work and a bunch of cutting wheels.

[PDF Template]

Note: Your mileage will most likely vary. This is not an official builders club document but based on my experience in cutting my JAG Battery Boxes. Everyone has a slightly different way of building a droid, so best check then double check all measurement before cutting.

Weather has turned a little cold and we’ve had some rain, so I got to work in the garage this last weekend.

It was a mix bag, from cleaning up space to work to jumping between painting some parts, cutting the skins and fitting the battery boxes and hoses. I also tried to troubleshoot some issues I’m having, like the dome speed rotation, but more of that later.

First up I really needed to make space to totally disassembled R2. I’d been dreading it and a few events throughout the summer kinda gave me an excuse to avoid it. Even though he’s not finished it’s still been fun driving him around and people love him.

So I started off by breaking him down and inspected parts for wear, missing screws etc.

I never did get a coat of undercoat on the center foot before C4, and some surface rust had set in. I was also surprised how well the omniball castor’s have held up given the terrain I’ve run him over.

A once over with some sandpaper removed the rust from all the center foot parts and I was able to give them a coat paint.

I also inspected my center ankle for any problems. George Luck broke a JAG center ankle right after C4 and I was a little worried about mine, but all the joints looked fine. I’ve heard of two ankles breaking now, and both times the droids had done a long cross country trek for C4. I’m wondering if that’s the problem rather than every day wear and tear. To be on the safe side I had ordered a spare center ankle from Jerry just in case, but hopefully I’ll not need to use it anytime soon 🙂

Next up, I finally drilled the holes in the outer feet for the Knurled Hose Fittings (KHF). I had a bit of trouble securing the the foot on my drill press, so had to use my cordless hand drill instead, problem was the drill bit would not fit. I had to use my stepping bit instead. I don’t think it like it much as the steel feet are pretty tough – but it got the job done.

The Kurled Hose Fittings only just arrived last week from Doug and they have a nice feature where the hose is easily secured with a screw-in plug.

With the KFL I also got some new braided hoses, but I wasn’t too keen on how gold they were. I much prefer the original copper one’s I got some time ago.

I had to insert some tubing into the braided hoses to make sure they held their shape and secure the hose in place inside the KHF.

Now comes the kicker with the KHF – there’s always a kicker right? They hit the main drive wheel once I got things back together

I even switched out to using regular nuts, but it looks like I’ll need to trim the KHF’s down by half

I decided to move on to cutting the back of the battery boxes to accommodated the big NPC motors. I couldn’t find a template anywhere, so it was a bit of trial and error. I started off with cutting the smallest hole I could, traced from the matching hole in the foot. It wasn’t big enough to slide down and over the motor so I gradually made things bigger until thinks worked. Once the box is in place you’ll not be able to notice the hole.

I’ll try and create a PDF template later tonight to share [update – here’s the template]

I also had to grind down the motor in three spots. In the Dave Painter tutorial it looks like you only need to grind the top sides of the motor, but I also had to grind the bottom outside edge too

So here’s the first foot assembled with the motor encased in the battery box ready for painting. Next step battery harnesses.

As I said at the start of this blog entry, I did a lot more on R2 over the weekend, but I’ll stop here for now.

As always more photos in the gallery section.

Here’s another retroactive post about something I worked on a few months ago.

One of the challenges is passing the drive wires that goes from the ankle into the foot shell. Some people use the totally hidden/invisible method where slots are cut in the side of the ankle and foot shell very close to the bolt. Here’s an example of Wayne O’s setup using this method.

Space is tight and things have to be perfectly aligned or you run the risk of chopping the wires when the ankle pivots. It’s also virtually impossible to add grommets so over time my worry is that the wire may wear. edit 9/7/07 – Wayne just informed me that his setup above has been working fine for over a year and half without any problems or wear and tear.

I was on a time crunch and not sure if I was up to marking and cutting such precise slots, so I opted for the more conventional method of drilling holes in the foot shell just behind the ankle and corresponding hole in bottom of the ankle.

My wires are pretty think and by my calculation I needed a chunky grommet, but I couldn’t find anything suitable so had to improvise. Instead I used a short length of opaque tubing which passes through from the ankle into the leg. Not only does it protecting the wires it also hide them.

This is the inside of the Ankle

And the Foot Shell

Tube passing from the ankle into the foot shell

I also used the same hose in the top of the legs/shoulder to protect the wire as it passes into the body.

I received my center foot on Friday and it was the last structural part that I needed to get R2 on all 3 feet. So, my goal for Saturday was to get him running around under his own steam by the end of the day. I still needed to wire in the RoboteQ AX3500 speed controller which controls the drive system.

I added a power strip to the inside of the back mounting plate to connect all the grounds to and set about wiring things up.

I then did some basic tests of the 3500 and noticed something strange. The motor would run for a second then stop for a split second then start again, like it had a slight tremor. Message code on the 3500 status panel flickered from motor direction information to an ‘8’ – which means under or over voltage. I suspect it’s a low battery. I hope it’s not a Vex/RoboteQ incompatibility problem. I suspect I may need to add a second battery dedicated to just controlling the 3500.

I then worked on trying to get the center foot assembled and attached to the frame. But there was a problem, I was missing the pack of hardware. A quick trip to Ace fixed it, but I couldn’t get the exact parts and had to improvise on the standoffs.

Like the outer legs and feet the new foot was a snug and it took some cajoling to get the pivot point to fit.

Now that the center foot/leg was attached I was excited to think I was close to getting him mobile.

However I really shouldn’t have rushed as much as I did. What followed was a bunch of silly mistakes which cost me a lot of time. Luckily no harm was done and I learned a lot in the process.

Even in my haste to get the legs on and the motors hooked up, I’d remembered that I needed to lock the legs somehow. I’m not going to be using the satellite motors to do 2-3-2 at this points, and one of they’re jobs in the design was to lock/hold the legs in place. So I knew I needed to figure something out, but I thought it wouldn’t hurt to skip this step just for now. Boy was I wrong!

At the same time I also had the drive wheels in the back of the feet, and they weren’t always touching the floor. I’d also forgotten to reverse the drive wires on one motor.

As you can imagine his first steps were not pretty to say the least and he jerked around because of the RoboteQ battery problem, and his legs went in opposite directions. It was a total shambles. Luckily I didn’t have the camera handy for a photo.

I also needed to tension the drive belts more which meant that I had to partially disassemble the feet again. I’m beginning to realize it’s a major pain to unscrew so many bits just to fix one thing.

After stripping him back down and fixing the problems and locking his legs back in 3 legged mode I gave him another spin and here he is. He’s super fast, but I really do need to figure out the battery/undervoltage problem that makes him stop/start/jerk.

Once I get the RoboteQ speed controller working correctly this thing is going to scream.

On a tip off from a fellow builder I bought a few of these cheap motors for $45 vs $150 for the NPC-2212’s.

I already had my NPC-2212, but thought these would make for good spares, and apart from the extra holes and a longer drive shaft they’re a perfect match.

The NPC-2212 is on the right with the long leads and the cheap OEM motor on the left. Click on the image for more photos.

They can be found here.

Your mileage may vary!