Playing Ketchup Episode I: Stinkin' Feet

Its been four months since I've posted any updates to my R2 build - mainly because I've been concentrating on actual building while letting the posts slide. But today its a balmy 20º, snowing and I'm taking a day off work after a nearly 90 hour work week. So get ready for a couple long posts of progress.

I'll start where the last post left off - getting the NPC motors finalized for installation. I ran into the same problem everyone did with the old battery boxes and had to grind the tops of the NPC motors in order for them to fit inside the boxes. I also had to modify the openings of the left box a fair amount to get it to slip all the way over the motor. Not sure why the right one didn't require it, but I'm fine with only cutting one box if the other one works.

At this point I was done with the NPCs but needed to do more work on the Battery Boxes. I wanted to make sure the Battery Harnesses were going to be secure, so I drilled a hole into the harnesses and the boxes at the bottom of the main vertical piece, where the decorative cover would eventually cover the unsightly screw. I had to do a bit of sanding on the harnesses to get them to fit in the box facade as well. My boxes are from an older run before the face of the box was CNC'd. So they are not quite exact, and you can tell just by looking at them. Eventually I'd like to replace them with the newer improved version.

At this point I was looking at the issues of securing the boxes to the feet. The curved inside panel of the feet have holes for a screw to slide into as you can see in the pic below, but after a lot of staring I realized the boxes were such a tight fit that I'd never be able to get box mounted screws to slide down in the pre-drilled foot holes. I did a little searching on the forums, and decided to drill two holes at the bottom of each box and foot that a screw could pass through and be tightened from the bottom. Drilling into several hundred dollar parts is always scary and this was no exception, especially because of the curved area where each hole needed to be.

Its a tight squeeze with the fingers, but it works quite well. In the end it turned out very good, and the boxes are rock solid on the feet.

The final piece to the feet puzzle was drilling out the holes for the Knurled Hose Fittings. After even more research I went to Harbor Freight and bought a step down drill bit. It was money well spent and made expanding the pre-drilled holes quite easy. Going from 1/4 inch to 11/16th took only a few minutes on each hole and the KNFs slid right into place.

At this point its was nearing late November and I was ready to break everything down for paint. Luckily it was an unusually warm December, and the added help of a propane heater didn't hurt either.

Rolling Chassis

Been working the last few weeks on figuring out the center casters. None of the previous 2.5 - 3 inch casters seemed to be working for me. A couple builders, mainly the R2.0 guys, had mentioned trying a beefy 3.25 inch Gladiator Caster from McMaster. After a lot of staring at the issues with every two wheel combo I could find, I finally decided to go ahead and get the Gladiator. 

I'd hoped that the holes in the Gladiator Caster would line up with the JAG mounting plate, it was a little hard to tell based off the CAD drawing alone. Once I got it in hand, it was obvious it would be way off the mark. So the next phase of deciding how to mount the thing began. I didn't really want to modify the bottom flat JAG plate, which I would have to since the taller caster would need to sit higher up in the foot that the standard plate allowed. So I went looking at Lowe's and found a 4x12 inch piece of 1/4 inch steel. It was a little thicker than the JAG plate, but I figured its better to try cutting an off the shelf $10 piece than a hard to replace custom part.

I tried a couple methods to cutting this thing, but once I got a hard metal Jigsaw blade, it went pretty smooth, and cutting it exactly in half would be just the right size. I laid the JAG plate over the now 4x6 inch piece, centered it and marked hole locations. Then used a drill press to both drill and counter sink the holes where the plate would attach to the angled half of the JAG mounting system. I had figured out earlier that mounting the Gladiator Caster flush with one side of the new plate would put it almost exactly centered in the foot when moving forward, perhaps just dumb luck. So I marked the holes of the Caster and drilled those out next.

The biggest problem was that the caster would sit on top of the screws that mounted the plate to the angled piece via standoff couplers. I'd originally thought I'd just lock the caster screws in with nuts on the bottom side, screw in the plate, then place the caster over the caster screw nuts and get them to fit inside the rather large mounting holes of the caster itself. But, my Dad has a neighbor that can do Tig welding, so we gave him the plate to weld nuts onto the top side of the plate, thereby allowing a rather easy install of the caster itself.

Once I got the piece back, it was time to see if this plan was going to work out. I found some 7/8th inch standoffs at Lowe's, thinking that I'd try it with those first and then order whatever length I'd really need later. They ended up being the exact length I needed, another stroke of dumb luck. I also found a handy right angle ratchet driver set for $20 bucks that worked perfectly for attaching the JAG angled piece to the Center Foot.

The new custom plate went on with ease, and then the Gladiator Caster screwed in tight with some washers helping to span the rather wide holes it has. The great thing about this caster, other than being nice and heavy duty, is that it perfectly swivels 360º without hitting the side of the Foot. Its like it was made for this exact use.

So once I got the Center Foot all together, it was time to get R2 somewhat back together again. I put the Outer Feet complete with JAG Drive System installed back onto the legs. The now quite heavy legs went back on the frame, and the pretty hefty Center Foot went on as well. I immediately realized I'll have to lock the Center Ankle before I'll be able to see the whole thing in action, but holding the Center Foot down I moved R2 around with relative ease.

The other thing that became apparent was that I will have to cut a hole in the bottom of the frame and use the COM-8B adapter plate for the center leg. The Center Foot is still not sitting level, just like before I had the wheels installed. But all-in-all, I think the Gladiator Caster will work out well. It really makes me want to get the motors, batteries and RC elements in ASAP and get R2 rolling around on his own power.