I’ve almost finished the electronics and programming to control the new hinged pie panels. I’m using a small 18X PICAXE micro-controller coupled with a few buttons on the RF remote.
Check out the video of the panels in action.
I’m also in the process of replacing the veclro that attaches the servos to the dome with something a bit more permanent. The brackets are made from aluminum angle (1.5″x1.5″ and 1/16″ thick).
They’re attached to the top of the hinge and the bolts from the mounting plate that already fix to the dome.
As a side note, if I was doing this again I’d adjust the hinge position a tad. The pies open to the vertical position, but it would have been nice if they’d open a little further, and I figured out (too late) that the lower the hinge is on the pie panel the further it will open – but too far and the hinge will not clear the dome properly.
Adding hinges to anything on Artoo is tricky, with so many curves and often located in tight spaces it’s really hard to get things just right. I’d bought a bunch of the Robart “350” bomber door hinges a long time ago, and successfully added some to the power charging panel. They’re not cheap, but if you shop around you can find them for around $7 a pair.
There are other options that are cheaper, like the McMaster Carr steal hinges or the plastic one’s Calvin found for 30c. But the consensus seems to be that the Robart hinges are the way to go.
Some builders have had to reverse and trim part of the hinge to get them to work, but I’m not convinced it’s necessary for the dome pie panels. Here’s Keith’s explanation on how he uses them.
Most people seem to use epoxy to secure the hinges, but I also like how Calvin uses nuts and bolts for easy removal.
For my experiments I temporarily used adhesive foam tape, and played with several configurations.
I started off with Keith’s method of trimming and doubling up the hinges. I also added back the cut out from the inner dome to the pie panel to give it more weight and substance.
I found that by reversing and trimming the hinge, it has to sit right on the edge of the dome cut out – making it really easy to align – this is probably the only advantage I can see for flipping the mounting.
But I’m not crazy about how it look so close to the edge.
I also had to slightly file the inside bottom edge of the pie panel to get it to open cleanly.
For my next test I went the minimalistic route, and used a single hinge, configured the ‘correct’ way with it extending further into the dome. I also did not attach the extra cut out to the pie panel.
It was a snap to align and worked surprisingly well and opened just as easy as the first, if not easier. I suspect a servo would like the setup a bit better, being lighter and only having to move one joint. However, it felt more flimsy (obviously) and it would be super important to keep the single screw tight – which is hard to do on anything Artoo.
In summary – I like the heavy feel of the first option and how it sounds when it closes, but I also like the simplicity and cost saving of the second. I’m going to sleep on it tonite and get a second opinion tomorrow before permanently affixing anything to the dome.
I’ve been busy most evenings this month getting ready for WonderCon, but thought I’d stop and post this new addition which I’ve been working on and off for a while now.
I’ve expanded my battery charging port to include some LEDs. The flashing pattern is based on the scene in ESB where Luke and Artoo meet Yoda for the first time.
The whole thing is driven by a 18X Picaxe board with some custom code. I’d originally planned on using some simple timer IC’s, but thought this would be a good project to experiment with Picaxe.
I’ve tried to capture the LED sequence the best I could, but it’s only shown straight on for 10 seconds, and even then it’s obscured by the door some of the time.
To get to this point I had to create a new acrylic mounting plate. I still need to wire in the new charging circuit Bob helped me redesign, but this was the first step in the process.
I went through several iterations and prototypes to get it to fit and work around the Robart hinges. Hence the slots on the left hand side.
I’m hoping to fix it to the 12V charging socket and use it to mount to the metal bracket I made a few weeks ago as part of the original charging circuit.
It’s also been a steep learning curve the as I’ve not really done any major thinking about complicated electronics in a very long time.
I’ll try and post more details in a few weeks, but here’s the completed circuit after a few late nights. I may switch to a smaller Picaxe, like the 08M, as the 18X is a little bit of an overkill for this project. But the price is negotiable in the grand scheme of building a droid. I’d have to guess the whole circuit costs less $35, but in the process I had to buy a bunch of stuff to figure out how to get it to work.
Here’s a a close up of the LED matrix connected to the PICAXE board.
I also had to create a voltage regulator circuit to power everything directly from the batteries as the main power distribution board will be isolated/turned off when the batteries are charging – and the whole point is for R2 to show some bling while he’s charging right?
I ended up using a LM7805 which will step down the 12V supply to the require 5V.
When I get a chance, the plan is to eventually make the LED’s display the current battery voltage when I press a button as the Picaxe 18X has a built in voltage reader.
Believe it or not I am still alive and working on Artoo. I’ve had an incredibly hectic couple of weeks, but I’ve still been able to fit in some building here and there. Unfortunately, I’ve not had time to blog the progress, the good news is I have been taking photos so hopefully I can go back and post what I’ve missed later. WonderCon is also coming up in two weeks and I’m rushing to get Artoo back together and presentable.
Most of the work this last week has been working on the electronics and finishing the skins, like attaching the small detail pieces, doors, panels etc. I’ve only got a few more bits to go and he’s looking really good.
The panels and inserts I simply attached with silicon. Nothing fancy, just held in place with tape while it dried over night.
Some people use epoxy to fix the rear panels just in case they decide to collect signatures, but I really don’t care for signatures (nor epoxy) and this is a much cleaner/quicker method for me at least.
I did get one door hinged, the one I’ll be using to access the on/off switch and charging port. Like a lot of builders, I had a lot trouble getting the Robart to work correctly. In the end I left the hinge in the default setup as suggested by the manufacturer, but ended up using some spacers to lift the hinge away from the skin/door slightly. I’ll try and take some better pictures and detail how I add hinges to the remaining doors.
To secure the door closed I attached a magnet and metal stop for it to hold on to.
I also added a small warning sign to the inside of the door. It’s my interpretation of the one seen in ROTJ where Artoo helps free Leia from the chains.
One of the issues I’ve had is that the back door doesn’t fit well. I’ve been avoiding it, but I would like to have it attached for WonderCon. The problem is the skins don’t quite wrap around the frame snuggly, which leaves the back opening wider than it should be and the door has more of a gap around it than I’d like. I’ve still going some tweaking but I think I may have to live with it for now.
This is the correct gap at the top of the door
I now need to remove the skirt and bottom ring to drill and tap some holes to attach the octagon ports and power couplers. Hopefully this will be the last time I have to disassemble the frame for a while.
I’ve started to peel away the masking on the skins over the weekend and mounting the various body detail pieces.
I even temporarily mounted a door to see how well the hinges work.
Overall, I’m very happy with the finish and how the aluminum shows through from the inner skin layer. The only real clean up I had to do was on some of the green self etching primer that had leaked underneath the tape, but it was easy to remove with some acetone and a q-tip. I did spot one place on the rear skin that I may sand down and give it one more coat.
I also started to mount the detail pieces to the skin and frame. For the octagon ports and power couplers I plan on permanently attaching them to the frame and have the skins press up against them.
I took some 1″ x 1/16″ alu stock bar and made some slotted L brackets. The aluminum is easily bent in a vice.
I ended up elongated the holes to make them adjustable.