I’m definitely getting into the fun part of the project. I spent part of the evening trying to add a servo to the front holo projector. It was a little more tricky than I thought it was going to be. I’d seen photos and vaguely remember a setup on one of the tables at C4, but until tonight I didn’t understood the nuances of the angles and forces need to move something with a servo, so it was frustrating and fun at the same time.

Most people seem to use the same basic method to move pie panels, doors, holo projectors etc. And that’s to convert servo rotation into a linear movement using a push rod attached to the servo horn.

I’d bought some random mini servos from Tower Hobbies a while ago (Hi-Tec HS-55), and a push rod/linkage assembly from ebay. Problem was the servo was too small to fit the rod attachments. I managed to improvise and this is what I finally came up with

Please ignore the kinks in the rod, it really should be straight, but I’d tried to copy what I’d seen at C4 and got it totally wrong

If I was to do this again I’d probably skip the pre-made assemble and make something in acrylic and parts from the local hardware store.

I also created a short video to summaries and demo the new setup.

As I explain in the video it’s not perfect, and I need to affix the servo more permantely to the dome rather than using velcro and I’m not entirely confident the linkage to the back of the HP will last very long.

The good news the Hi-Tec servo is definitely powerful enough to move the HP and will probably work for the pie panels as well.

I also need to decide if I’m going to add some code to my micro-controller to automate random movement.

See Also:

• Slip Ring Servo Test

I wanted to report that the new method of attaching the JAG legs and ankles worked. I didn’t have any problem with screws working loose while at WonderCon, unlike at C4, where I had to constantly tighten them up - and had two screws sheer on me.

Back in December of last year I’d decided to use pan head screws with a combination of fender and lock washers , instead of the recommended countersunk machine screws.

They’re do stand out a little but, but once I’d painted them up nobody really noticed them.

Related Posts:

• Finishing Battery Boxes and Feet

I’ve worked on a bunch of things the last few days, the simplest is probably getting my shoulder hubs finally installed.

I borrowed another idea from Victor and used rare earth magnets fix the hubs in place.

I started off by marking and drilling the holes. The magnets I used are 3/8″ x 1/8″ thick from MagCraft. There’s two magnets per hub, and two matching magnets inside the leg.

I’ve been doing a lot of drilling the last few days, and I’ve been extra careful to secure everything before I drill - even when I’m pressed for time or tired of doing it. You can never be too careful.

I then checked the polarity/orientation of the magnets to make sure they’d not repel another magnet. Otherwise I’d be in trouble when they’re presented to the magnets in the legs. Sounds simple but I almost got it wrong at least twice.
I roughed up the back of the magnets and epoxy’d them into place

I took two more magnets and epoxy’d them inside the leg stacked on top of small nuts.

Here’s a short video demonstrating the new magnetized hubs

I’ll try and post some more updates on new things in the next day or so.

More re-assembling tonight after painting last week. I did a mix of things from the feet to working on some skin panels.

I got the feet and ankles back together, and using the hex bolts worked out great. It was a breeze installing the ankle details.

With everything R2, there’s always a few steps back with a dozen forward. Today it was the braided hoses. I’d planned on using these expanding rubber plugs to hold the cables in place, but they didn’t quite work as I’d hoped. For some reason rather than bunching up and expanding the nut inside just moved/ripped up the rubber with minimum expansion as shown. The ‘bulge’ at the top being the maximum width.

Back to the drawing board and Ace Hardware tomorrow to look for an alternative. I was tempted to try Douglas Olson’s KHF System again, but space is very tight and they’ll not work for me with the JAG feet and drive system.

The other problem I had was once I tried to install the battery boxes they wouldn’t fit over the NPC motors. All the test fittings I did while filing down the tops of the motors was done without the ankle on the foot, so now I have less room to bend the box over and down onto the motors. An easy fix, but I was hoping to get the feet, ankles and legs back together tonight and now I can’t.

I also worked a little bit more on the frame and got the front vents installed and attached to the frame at last. Not sure how I’m going to fix in the blue surround at this point. Maybe silicon, but I want to be able to remove it easily with the skins. The fit is tight and I can see when removing the skins that it may get pulled off with little effort.

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.

Do yourself a huge favor and throw away the bolts that come with most of the ankle detail parts. It’s virtually impossible to quickly assemble the ankle with them. I have small hands, but even I had a problem getting in there. Instead use hex head cap bolts in place of the Philip heads.

Like an idiot late one night I suffered through putting my ankles together before C4 with the original bolts. I even bought one of those fancy right angled screwdrivers - it did the job but it’s still incredible frustrating to use. It’s funny how sometimes you’re so close to a problem that you’ll go down the totally wrong and longer path for a solution. In this case the right bolts and a small wrench did the job so much better.

I’ve also swapped out a bunch of bolts that came with the JAG drive system. The originals work fine, but again it’s hard to get into the tight space to adjust things.

I finally finished drilling the holes for the Under Shoulder Detail after procrastinating for a while.

When I ordered the parts there were two options, short and stubby for surface mounting or long to extend into the leg. I opted for the longer version thinking they’d be more secure. What’s strange now is I was convinced at the time that the uber ILM droid was also made this way, but now looking back at my reference photos I can’t see any of the screen used droids this way. oh! well. Here’s the real ILM droid -

[Edit - I knew I wasn't going crazy here's a photo of the Magic of Myth R2 with drilled holes]

The job is pretty simple given the right tools. I’d originally tried to quickly Dremel out the holes right before C4, but realized it wasn’t the right tool for the job so I gave up. Someone told me to get a ‘rats’ tail file and they were right, it make quick work of making the hole the right size after the initial hole.

Marked and center punch ready for drilling

Then enlarge the holes using the ‘rats tail’

I think if I had to do this again I’d get the stubby variant

Next I need to decide if I’m going to just silicon them in place or tap/drill the back side of the barrel to secure it to the leg.