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.

I'm just talkin' bout Shaft

Work commenced again yesterday towards final assembly. The NPC motors come with a shaft on both sides, one of which needs to be cut off to allow the Battery Boxes to fit over them. I failed to take a good pic of the motors with the extended shafts still on the droid, but they can be seen here with the motors attached to the JAG foot drives:

At first I tried cutting the shafts with a metal blade on a chop/miter saw. It cut fine but was only able to get close enough to end up leaving about a half inch of the shaft still on the motor. It also made the shaft extremely hot, which probably wouldn't damage the motor, but I didn't want to take that chance again. Since something else was needed to finish the job I decided to just use a hacksaw. With it, there was no problem getting extremely close to the shaft housing. It only took a few minutes to trim off the remainder of the shaft, then a couple metal files were used to clean up and smooth out the finished product.

The same process was repeated on the other motor shaft, minus the chop saw. Fairly quick and easy. Definitely easier with two people so that one can hold the motor while the other saws. Now onto getting the Battery Boxes to fit. That requires grinding the tops of the motors, and a cut or two to each box as well.

Move Along

Decided to try the captive studs on the body hinges today. I marked the holes on the outside of the Inner Skins first just to make sure they would be under the Outer Skins once they were glued together. Everything looked ok, so I drilled and bolted the hinge for one panel then placed the Outer skins back on and clamped them down. You can see below that there is a pretty good gap. So I'm nixing using the studs on the hinges altogether and will just glue them to the inside instead. Some may be able to live with that gap, but not me. I think its just because the studs are so close to the edge, in fact, they may have even stuck out a tiny amount once glued together. So lesson learned, at least I only tried it on one hinge.

Also yesterday I went to the parents house and used the drill press again. This time on the other foot drive to foot shell holes. I still had a similar problem as with the first one and had to use a larger hole and even ended up filing a little on a couple holes to get everything to line up right. I started wondering was why Jerry doesn't go ahead and have the holes drilled in the feet when they are made. Seems like a machine would be able to be exact and alleviate a problem on the builder end. The only thing I could think of was that other drive systems may not use the same holes, and you'd end up with unnecessary holes in your feet. Something I may ask one day if I ever meet him in person. I also decided not to countersink the holes. The steel is just too thin. Looks like maybe 1/8th inch think at most. I'll still use the low profile flat head screws though. I think they look a lot better than the rounded fatties and will hopefully blend in a little more when everything is painted.

License to Drive

Spent the weekend doing various things on Artoo. First I took him all apart, so he's not standing on his own legs anymore. I'm going to do some work on the skins again in an attempt to get some white painting done before the heat of summer gets here. So they're screwed/clamped back on the frame at the moment. 

I looked through my box of blue painted parts and wet sanded some of the ones that needed touchup. The first three pieces turned out good, then the next three looked pretty cloudy and flat, so I'm holding off till it cools down a little this evening to do anymore. It was in the low 80s this afternoon, but felt a little warmer in the garage while I was painting.

After re-reading every post I could find about center foot casters, I proceeded to order a couple sets from Lowe's website yesterday since they weren't available at any local store. Hopefully one, or a combo of these will work.

I decided to tackle the foot drives this afternoon. I followed this tutorial, so I can't take any credit for originality.

Here's the steel foot shell and foot drive.

I took the large wheel out to get access to the screw holes, then placed the mount inside the foot shell.

Then I took a blue sharpie and marked all 6 holes. I also took a pencil and circled it around the hole too. The angle makes it look like the outer marks are off center, but they are not.

I center punched the marks and then drilled a small hole first just in case.

They all lined up just fine after putting the bracket back in for a visual inspection.

So then I drilled the holes out larger. First I used a 1/4 inch bit which should be large enough. I was having a little trouble getting them all to go in with ease, so I went ahead and used a 5/16 inch bit to help loosen it up. I wish I didn't have to and that they had lined up perfectly with the 1/4 inch hole, but it should be fine. Then I put the large wheel back in the foot drive bracket and screwed the whole thing in from the top/outside with the 1/4-20 screws Jerry provided.

Like the tutorial I followed, I may end up getting the low profile flush style screws and countersinking them. The bulky screws take away a little in my opinion.

One thing I noticed after I had the drive in was that the smaller back caster wheel in the drive needed to be lowered because the foot wasn't sitting level. I figure I'll fix this one later since I'd have to remove it to do so, but I went ahead and leveled out the other foot drive. It was fairly easy. I loosened the two screws using a T-bar allen wrench through the two holes in bracket. Then I sat the whole drive upside down and put a metal ruler across both wheels. Then, I used my trusty Dollar Store level to check the position of the small caster wheel and then tightened it down.

One foot drive down, one to go. With the new center casters coming this week I'll hopefully have all the wheels figured out and done soon. Then I'll have to go ahead and order the NPC motors and get busy on some electronics side of things. Can't wait for that first test drive!