May 2007 Summary

Here’s an update of active for May 2007

Posted by Chris on May 31st, 2007 in Update | No Comments


Major Setback – Dome screwed

I’ve not posted in a few days – Been feverishly working on R2 for C4. Hoping once I get back I’ll go through my photos and post some retro updates.

Unfortunately a few days ago I could have almost cried. I’ve spent months nurturing my dome and just as I was setting him down on the table after applying the Silicon to bond the two layers together he slipped out of my hands and hit the floor hard. This was the result :(

IMG_5925

I almost gave up at this point, but I’ve muddled through the best I can and finished the dome and I will have an fully operational R2 at C4.

I can see me buying another one to do it all over again.

Posted by Chris on May 21st, 2007 in Dome | 1 Comment

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All Parts Received

Big milestone today. I received my last major part, an aluminum skirt from a fellow builder who offered to help me out for C4 – Thanks Allen :)

I still have a long way to go, and I’m sure there will be more countless trips to the hardware store to buy bits and I’ll most likely be upgrading some components along the way.

Posted by Chris on May 16th, 2007 in General, Parts | No Comments


Holo Projector LED Setup

A few weeks ago I ordered some 3000mcd LEDs from ebay for the holo projectors. I thought I was getting regular round LEDs but what showed up was these.

Square LEDs

At first I thought I’d have to go buy a round set, but then I had the idea that I could simply solder them in a 2×2 square and hot glue them to a piece of plastic for easy mounting.

2x2 LEDs

I then mounted them at a 90 degree angle on the rear cap of the holo projector, so as not to face directly forward and cause hot spots.

Rear HP Cap with LEDs

All I had to do then was screw it into the holo projector

R2 Holo Projector LED Setup

Posted by Chris on May 16th, 2007 in General | No Comments


Dome Internal Mounting Plates

Lots more dome work in the last few days. Focus was to get all the internal stuff mounted – Holo Projectors, PSI and Front and Rear Logics.

I wasn’t very happy with my previous attempt of drilling holes through the inner dome and using counter sunk screws. By the time I’d counter sunk them enough the holes had gotten so big that the screws could pull through easily. Attempts to JB Weld the screws on the inside of the dome didn’t work so well either.

Here’s what my old mounting system looked like

Didn't work so well

It really looked like I may have to do what most other builders do and that’s goop the crap out of each part – Locking them in place for good.

But a quick visit to see my friend Richard resulted in a cool solution that I’d not seen done before. He came up with the idea of having a single mounting plate for each side of the dome which would hold everything and be easily removed if need be.

After a bunch of prototypes this is what we came up with. Just 3 screws holds everything in place. I can’t believe how simple the design is.

New Dome Mounting Plate

The PSI’s are inserted into a cut down pipe fitting secured with a screw, the HP’s just press fit to the dome by the plate and the logics are held on using the bracket/box.

PSI

We still needed to secure the plate in place, and the only good way to do it was to bolt it to the inner dome – which hadn’t worked too well previously. We tried JB Welding the screws to the surface of the dome but they came off easy.

Richard remember the trick of pulling aluminum into a cone/dimple like on the side of a home made Luke Graflex lightsaber – the tool used to be called a “Shoulder Puller” back in the day when people still made their own Graflex’s. Here’s what Richard used.

Dome Hole Puller

Simply drill a hole in the dome and insert the screw and tighten down on the collar which is on the inside of the dome. I think we started it off with a thinner screw then switched to the final size. I should name it the Dome Hole Puller.

In the end we used 1/2″ 10-32 screws which are much bigger than what was originally holding things in place a few months ago. No chance of things pulling through now.

Plate is somewhat flexible, so if someone pushes on things then it’ll give a bit rather than failing or things popping out of place.

I also decided to switch back to the old style logic surrounds. Not having the front outer plate on the new version was bugging me. I’m hoping to get the panels cleanup and painted tomorrow.

A couple of screw ups/lessons learned along the way. JB Weld didn’t want to hold the screws in place, even when going through the dome. So in the end I notched the underside of each screw a bunch of times and scored the hole with a dremel. As of right now things seem very solid and once the outer dome goes on there’s no way for things to move…hopefully.

Screw all JB Welded and sanded down

A big notch was also cut in the dome ring by mistake while making room for a PSI. I’ve tried to fill it with a piece of aluminum and JB Weld and I’m hoping it will not be noticeable once the outer dome goes on.

Patched Dome Ring

The marks in the top band will be covered by the blue paint, but behind that is the patch which is visible. It wouldn’t be so bad if the dome touched the dome ring at the bottom, but there needs to be a slight gap.

I also had one hole from my previous attempt of mounting things that needed fixing. It fell on a panel seam line and I ended up plugging it with a aluminum rivet I filed down. You can hardly notice it with the outer dome on.

Hole filled by rivet

And tonight I finally got all the pie panels cut out, so I’m very close to being able to glue the two domes together.

Pie Panels Cut Out

Posted by Chris on May 15th, 2007 in Dome | 2 Comments

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RoboteQ 3500 code 8 fixed

Drive system jerkiness is all fixed. The problem was the AX3500 and not a Vex compatibility issue. The board had a dry joint on the main power control tab which was causing a short. The speed controller thought the battery was low which cause the fail safes to kick in and turn everything off to avoid damaging the Mosfetts.

I’d gone back and forth on the phone with RoboteQ for a few days, and finally they just overnighted me a new board which fixed the problem instantly. While I was removing the cables to send the old board back the tab connector popped off the board totally.

In the process of troubleshooting the problem, they also convinced me to reconfigure my batteries to have a dedicated 12V supply to the board rather than using a single shared 12V supply for everything. They explained that the symptoms I was seeing were very similar to a low battery problem due to the motors drawing too much current.

I’m probably going to keep the batteries separate for now, but will have to rethink the wiring and my fuse block as I was hoping to just get away with one battery feed which also made charging easier.

The real worrisome thing is he’s way too fast and really dangerous. He can zip around at lightning speeds and can plow through most obstacles because of his weight. I may need to have a fast/slow switch.

He’s also shacking himself to pieces and has already dropped several screws.

Posted by Chris on May 13th, 2007 in Electronics, RC | 2 Comments

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Artoo’s First Steps

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.

Ground Block

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.

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.

Frame and Legs together

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.

Posted by Chris on May 13th, 2007 in Electronics, Feet, RC | No Comments

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Conquering My Fears – Front Logic Surgery

It’s been a long evening and I spent most of it working on my Front Logic Display. It’s something I’ve been putting off for months hoping it would either go away or a work around to my problem would magically come to me.

The problem is that my aluminum surround from Doug Olson does not fit the cool front logic electronics without going through some major surgery.

The surround is a one piece design and looks great, but it’s very precise in the way it fits. The more traditional two piece surrounds people had been using are more forgiving and you could angle the boards away from each other to get it things to fit.

So as I said, I’ve been avoiding taking my soldering iron to the delicate circuit boards for months, but it had to be done and tonight was the night. Without it I’m totally blocked on the dome. Luckily I only needed to separate one of the pair of boards.

I think if someone was still offering the front logic electronics then I wouldn’t have been so fearful of screwing things up, but I didn’t have the luxury of being able to fall back and simply buy a new set.

It took me hours to get it done and the good news is they still worked at the end. I’m not going to go into the hack job I did in fear that somebody may copy my method. But the tools used were soldering iron with a nice new tip, a de-soldering pump, one of those helping hand gripping thing and finally a small pair of pliers/wire-cutter.

Tomorrow I’ll get the surround fitted to the dome.

So, without further ado I present my new improved logics –

Front Logics in Doug Olson Surround

Side by side view - basically before and after

Click here for photos on Doug’s website of the logic board the surround.

Posted by Chris on May 9th, 2007 in Dome, Electronics | No Comments

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