Summary for December 2006
Tonight has been a night of gaps, both good and bad.
It’s New Years Eve and what have I been doing? Sanding Aluminum for the last 4 hours in a cold garage.
The good news is that I was able to get the inner dome to fit over the dome ring tonight with the correct gap at the bottom.
All it took was lots of Dremel work with the mini sanding disks. I bought a new box of 60 grit drums for the Dremel and they seemed to last a bit longer than the one’s that come in the original kit. I did try the grinding disk attachment too, but it was slow going and it seems to be polishing more than removing stuff, so I gave up and went back to the sandpaper drums.
I had considered running the dome against my bench sander, but decided not to after a small slip and I touched a shiny part of the ring that really didn’t need sanding. No biggy and lesson learned.
I continued to sand, test fit, rotate and mark spots that were touching, followed by more sanding, test fits, rotate …. repeat for 2 hours.
I’d been working so intently on the inner dome I’d clean forgot to check the fit with the outer dome attached. What I’d forgotten was that the inner dome is not as deep as the outer and sits up in the outer dome a bit. So I really didn’t need to get the inner dome to go all the way down on the lip. Luckily I stopped sanding the ring in time and a quick check showed that I was very close to the correct gap at the bottom when I had the two domes and the ring together. But I did panic for a moment.
On the last lap around the ring I ran a hand electric sander around with some 100 grit paper. Both inside the dome and the ring. It smoothed things out and was the last step needed to get things to snuggly fit together. I may go back and polish it later.
I’d also made a start on sanding the inner dome and test fitting it with the outer. I even went as far as removing some of the pie panels, but I’ll blog about it tomorrow and post some pictures.
I finally got my hands dirty for real today. Made a start on fitting the inner dome to the ring.
The R&J Domes are great and for the outer dome not much work is needed as all the hard work of marking/cutting has already been done by laser. However, as some of you may know the inner dome and ring need some work. I think everyone I’ve spoken to has had to tweak, cajole and/or modify the inner dome to fit the outer dome snuggly, and for some, myself included, trying to get the inner dome to fit over the dome ring can be an issue too. All this is due to the the variable nature of the manufacturing process of spinning the domes – or so I’m told. Plus the thickness of the wall on the ring varied.
I got my Dremel out and tackled fitting the ring to the dome. I’d read a lot on the builders forum as well as various builders blogs, but nobody seems to agree on the best way forward. Some suggested in no particular order –
- Cut the ring lip down in height and sand to a point until the dome fits.
- Simply sand the inside of the dome AND the ring lip.
- Take it to a machine show to get them to do it.
- Cut slots in the ring and tweak/bend it to make it smaller so the dome fits over.
- Heat dome up in hot water, cool down ring in ice – resulting in a change in size and easier fitting.
Someone also recommend that I do not cut the ring lip down in size as it may cause problems further down the road.
Well I chose option 2 for now, as it seemed the easiest and least destructive – and I was able to at least get the dome to fit over the ring proper. It doesn’t go down all the way yet, but it’s a good start and I’m relieved that it looks like this method may work.
I just took my Dremel and slowly went around both the ring and the inside of the inner dome. I focused more on the ring as it’s thicker and had some spots where it was obvious where I could remove more material.
More photos in the gallery.
That’s it for now. I’ll probably finish this up tomorrow with a bit of luck and can start fitting the outer dome.
I also got a chance to work/think on the rear logic display some today.
Here’s a quick picture. Again I was lucky to pick this up pre-assembled (thanks Tom).
It works great and once I put it in the dome this will help bring R2 to life.
It’s not as fancy or as elegant as the front logic displays. There’s 108 LEDs on a bread-board sequenced by a PIC Flasher. The PIC requires 9 volts, and the LEDs 24 volts. So it requires multiple connections and difference batteries.
My original plan for the dome was to have a self contained rechargeable power source, preferably 12 volt. But the 24 volt requirement throws a spanner in the works.
It would be great if I could up-convert the 12v to 24v. It can be done I’m told by some friends who know a lot more than me, but it maybe expensive or wasteful on the battery. So I need to figure out the power requirements of the LEDs and calculate the size of the DC to DC
The simple solution would be to have 2 x 12v batteries in series in the dome, but again I’d rather avoid the extra weight.
Front logic electronics arrived today. What a cool thing these are – the wife wasn’t as easily impressed as me though.
I was lucky that the boards I ordered came pre-assembled so I avoided soldering 80 tiny LED into a super small space.
They also came with Damien black bezels – yet another great product.
One gotcha that caught me when wiring up the red connectors provided, don’t wire up based on the numbers on the connectors. Follow the tutorial as the boards pin outs are the opposite. My heart sank for a moment, but I soon realized what I’d done.
A few more parts arrived today: Rear Logic Electronics, Aluminum Front Logic Sorrounds , Aluminum Feet Half Moons.
I also placed an order with Jerry for a Center Ankle. It’s in stock so should ship soon.
Someone posted on the builders list about Radio Shack discontinuing the Vex Robotic/Radio Controller Kit. They have the starter kit on sale for $99, down from $299. Comes with a transmitter, receiver, a programmable brain and enough bits like wheels, small motors and servos, switches etc. to make a small robot.
It’s way early in my build to start thinking about this, but I thought for $99 I can’t really go wrong. It would allow me to play with RC bits which I’ve never done before at a very low cost.
Setup only allows 6 channels, so just enough to cover basic R2 functions like, Drive Motors, Dome Rotation, Periscope, Utility Arms and few more bits.
Calvin has had a lot of luck integrating the Vex into his R2 system, and even uses the small Vex motors to turn the dome, and has a prototype periscope lift done.
There’s also talk of using the programmable function of the Vex to allow more than 6 functions via multiplexing the channels.
It feels like it’s been a long wait, but the R&J dome finally arrived today.
Couldn’t wait to get it out of the box and do a quick test fit of all the pieces.
This thing is sweet. I even stuck in one of my new aluminum holo projectors. How cool is that?
It definitely needs some tweaking to get the inner and outer domes to fit snuggly over the ring.
I’m excited to get to work on it over the holidays starting next week.