Started Dome Servo Mounting Plate, Trimmed Foot Shells for Drivetrain Gears, Removed Some Door Holders, Drilled and Pinned Dome Drive Wheel

Today I worked on an eclectic set of droid building tasks.

First, I started working on a mounting plate for the servo mechanism that will trigger the spinning of the dome. The mechanism's workings will become clearer over the next day or two, but this particular piece will house a servo.

First I traced the servo outline on the PVC mounting plate, and then I used the Dremel with the cutoff wheel attachment to cut out the rectangle.




The servo fits in just right. This will be mounted to one of the vertical wooden planks in my frame.



Next, I returned to the foot shells. When I installed the drivetrain chain the other day, I had to move a couple of the gears on each foot outward, causing them to interfere with the foot shells. I was able to trim a small amount of material from the inside of the foot shells with the Dremel drum sander, and now the gears fit inside the foot shells with a small amount of clearance.



I needed to remove the two bottom door holders on the back of each outer foot shell door, as these also interfere with the gears. I didn't consider the positioning of these very carefully when I first installed them. So I trimmed the holders off with the Dremel drum sander. Once I got down to the last sub-millimeter, I could just peel the rest off. I'll recut and reglue some new ones in better locations on each outer door shortly.



Finally, I wrapped up by pinning the dome drive scooter wheel to its shaft adapter.

A while ago I had drilled a hole into the wheel, and pushed some 1/8" diameter rod through to act as a set screw. I was able to pull that out and recycle the hole.

This time I drilled through the wheel and shaft adapter, much like yesterday's exercise.



Then I cut a new section of 1/8" diameter rod, and pushed it through the hole, pinning the wheel to the shaft adapter.



I need to do a little drum sanding on the wheel to ensure that there is zero wobble as it spins, and I need to install the spring that pulls the dome drive wheel into the Rockler bearing. Then the dome drive itself will be done.

Mounting Board for Sound Card, Drilled & Pinned Shaft Adapters, Drivetrain Finished

Tonight I made a little mounting board for the CFSound III board, so that the enclosure can attach to the inside of my frame.

First, I cut a spare strip of PVC to size.



Then I attached the PVC strip to the enclosure by drilling holes in the strip that match where the pre-existing screws on the bottom of the enclosure go. Now the PVC strip gets screwed onto the back of the enclosure. I also drilled a couple of mounting holes on the ends of the strip, so that I can mount the enclosure onto one of the wooden vertical planks of my frame.



Next came a part of the drivetrain build that I had been fretting over for quite a while, the drilling and pinning of the shaft adapters to the Saturn motor shafts. It turned out that I had nothing to worry about, it was not as hard as I thought it would be.

I clamped down the shaft adapter in my drill press vise, and then secured the vise to the table. When I was sure that the drill bit was ready to go dead-center through the shaft adapter and shaft, I fired up the drill press and slowly drilled a 1/8" diameter hole through it all.




I got the hole just where I wanted it, toward the very bottom of the shaft adapter, near the thickest part of the motor shaft, and right through the middle.



In all, I drilled the two foot motor shafts, and the dome drive motor shaft. I still need to drill another hole in the dome drive shaft adapter to secure the dome drive scooter wheel to it. I'll deal with that soon.

Next, I JB Welded a 3/4" long, 1/8" diameter steel pin into each hole. The steel pins are from McMaster-Carr, and only come in quantities of 100. The pin will secure the shaft and shaft adapter together, so that the two won't shear when the motor torque kicks in.

It's important to secure the pin to the thickest part of the motor shaft, as the threaded area of the shaft has been shown to be too thin and/or weak to handle the stress when running the motors at 24 volts.




And with that, my scratch-built Heath & Alex drivetrain is done! I'll put it all back together again once the JB Weld has dried.

More Parts Shopping, Worked on Shaft Adapters, Vantec Mounts, Rockler Bearing Screws

Today I picked up a bunch of 30-amp fuses from Kragen, and some tie-downs for the wire from Home Depot, so the remaining items on the shopping list is getting shorter.

Just when I thought I was done sawing steel, I found that the dome drive shaft adapter was just a little too long, it was hitting the D-cell battery holder in the dome as the dome spun. So I sawed that down, and now the dome spins freely.



I also sawed open the dome drive plate, so that I can get the motor in and out of the assembly. With the shaft adapter permanently installed (see below), I did not want to lock this in place for eternity. Hopefully now I'm done sawing steel, for a while at least.



Of course, there's always aluminum to saw. I'm using 1" angled aluminum to mount the Vantec speed controller and Keycoder.



After cutting the aluminum to size, I drilled and installed it with #6 screws.



The bare side of the aluminum will be screwed onto the inside of my wooden frame.



I JB Welded the two motor shaft adapters and the dome drive shaft adapter to their respective Saturn wiper motors.



I will also drill a 1/8" diameter hole near the base of the shaft adapter, and insert and JB Weld a 1/8" steel pin, to help secure the shaft adapters to their shafts.



Finally, I picked up some #10 lock washers and installed them on all six screws that secure the dome to the Rockler bearing. With the lock washers installed underneath the bottom nut on each screw, the screws are now on the bearing nice and tight.

Electronics Shopping, Dome Drive Shaft Adapter Fixed

In preparation for R2's first steps, Mike and I went shopping for things like wire, switches, fuse holders, and other related items. We ended up going to Radio Shack (spare battery holders, switches, 12 gauge wire), a local electronics store named Orvac Electronics (CAT5E cable with multiple strands for wiring up sound, fuse holders, main circuit breaker, wire connectors), and Home Depot (power blocks).



I still need to buy some 30-amp fuses and some tie-downs for the wires.

The other day I tried drilling the shaft adapter for the dome drive, but either the drilling or the tapping (or both) turned out crooked, so the shaft adapter wobbled as the motor turned. Mike helped redrill and retap, and the result was a much cleaner rotation.

Rather than tapping by hand, Mike had the idea of putting the tap onto the drill press and manually turning the chuck to tap the hole. That way, the tap would go in at exactly the same angle as the hole that was drilled on the drill press. It worked out well.



I still have a ton of work to do before the droid is wired up for movement. I have to build a small assembly for the dome drive electronics. I also need to set up a mount for the sound board. And I still need to pin the shaft adapters to the motor shafts. Looks to be a busy upcoming week.

Built & Installed Drivetrain Chain

Another learning opportunity, this time in working with chain. I had purchased 10 feet of ANSI 35, 3/8" pitch chain. I didn't even know there were ANSI standards for chain until this project. Tonight I worked on getting the chain installed on the drivetrain.

First, I lengthened the slots on one of the wheel housings with the Dremel, to allow more room for chain-tensioning.



I used an awesome chain breaking tool that I purchased from McMaster-Carr. It's a bit pricey, but to me it was worth every penny. It made unlinking the chain effortless, and it came in handy several times tonight.



Once the chain was of the the approximate needed length, I had to install connecting links and sublinks to get the chain just about right. I adjusted the wheel housings away from each other to tension the chain.



Four lengths of chain (two for each drivetrain) were installed. The motor drives one wheel, and then the other wheel is driven on the other side of the drivetrain with gears and chain. I tested the setup with the battery, and all the wheels are spinning like they should. A four-wheel drive droid.



My only concern is that due to the overhang of the axle bearings on the outside of the wheel housings, I had to slide the small gears out a bit to clear them. I'm worried that the gears will have trouble fitting into the foot shells now, but I haven't test-fitted them yet.

Finished Cutting Battery Boxes & Foot Shells, Trimmed Axle, Test Fitted Feet

Today I cut the battery boxes and foot shells to allow access to the bolt that will hold the feet onto the ankles. This pretty much wraps up the cutting on these parts, except I'll need to open a small hole at the top of each outer foot shell for the motor wires to pass through.

It isn't necessarily pretty, but it doesn't need to be.




I also had to trim one of the axles, Sunday's drivetrain modification brought the 22-tooth gear closer to the axle overhang, so this got rid of the overhang.



And then, it was time to do a test fit of the drivetrain, foot shells and battery boxes on the droid.



The biggest problem is that the round areas at the bottom of the center and right ankles are running into the foot shells as R2 leans back. I think I'm going to have to sand or file down (and repaint) these curved areas on the center ankle, and do something to the right ankle cylinder holder to get it a little higher. Without these modifications, R2 won't be able to tilt the standard 36 degrees.

Still, it was nice to see him on three feet for the first time in a long while.

Fixed Dome Motor

I would have gotten nothing done today if it weren't for the fact that a solder joint on my 24-volt conversion of the dome motor had worked itself loose. I re-soldered it and all is well now.

Tomorrow I should be able to finished cutting a little more material from the foot shells and battery boxes to allow access to the ankle bolt hole on each foot. Then the feet and battery boxes can go onto the droid.

Drilled Center Foot Ankle Bolt Hole

Tonight I finally drilled the ankle bolt hole for the newest incarnation of my center foot. The hole is 0.40" from the top of the foot channel.



I lined up everything on the drill press and clamped it down, and then did the drilling.



Did it work??

I don't know! I thought I had some more bronze bushings so that I could try it out in the foot shell with the ankle bolt, but I don't have any, so I can't do a true test just yet. Hopefully I'll get my hands on the bushings shortly.

Normally the suspense would be killing me, but I'm just about numb now with all the ups and downs I've had with this droid lately.

Lunch with Daniel, Mike Rescues Battery Box

Several of us got together for lunch today at Red Robin with Daniel Deutsch. From left: Daniel Deutsch, Guy Vardaman, Matt Munson, Victor Franco, Vince Sanchez, Mike Senna, Chris Romines.



Just when Mike thought lunch was over and he could go home, I dragged him over to my house and put him to work. I was at a loss on what could be done to salvage the right battery box to make it fit the drivetrain. Mike analyzed the problem and quickly came up with a plan.

First, he lengthened the slots at the top of the wheel housing with the Dremel, to allow the wheel housing to slide further back. This allows the motor to scoot back without running into the wheel housing.



Next, he drilled four new holes in the main bar, with the bar positioned about 3/8" further back than it had been. Since the motor mount hangs from the main bar, this moved the motor back, allowing the motor tip to barely fit inside the battery box.



Finally, to allow more room for the 22-tooth gear, Mike Dremeled some material off of the wheel housing near the bearing.



After Mike left, I got busy chopping on the right battery box, which I had given up for dead a few days ago.



I had to remove some material from the inside of the battery box, near the tip of the motor, to get everything to fit.



Success!! This was the last potential show-stopper (that I know of, at least). I just need to keep moving forward now, and not mess anything up.

Continued Working on Dome Drive

After a rare day off from building yesterday, I resumed work on the dome drive.

First, I needed to cut a shaft adapter that is longer that the ones used on the feet, since this one has to pass through the frame and wheel. More hacksawing through solid steel.



Next, I trimmed a couple of corners off of my dome drive bar (again hacksawing through steel), and then drilled the pivot hole.



I drilled a hole in the frame and attached the dome drive with a 1/4" bolt, using some washers to help with the spacing and to distribute the stress. The fit seems pretty much perfect. I'm using a foot shaft adapter as a temporary stand-in, until I can drill the longer piece that I cut today.



Oh yeah, and I also visited the R2 mailbox closest to my house (about 11 miles away). This mailbox is in Newport Beach, CA.

Started Drilling Dome Drive Bar

This morning I went to Industrial Metal Supply and picked up a 12"x3"x3/16" steel bar. I had them cut it in half, into 6" long segments. I plan to use this for the bar that the Saturn wiper motor will hang from for my dome drive.

Using one of my drivetrain motor mounts as a template, I drilled four holes into the bar. I was unable to use the 7/8" Forstner bit that I used on the drivetrain for the middle hole, that bit won't go through steel. Instead I used a regular 1/2" drill bit.



The holes seem to line up okay. I will probably try using the Dremel to widen the center hole to 7/8", so that the 3/4" shaft adapter can fit through it. Right now it is completely above the bar.

I will drill one more hole toward the opposite end of the bar, and that will be the pivot point through which a bolt will go. The bolt will then pass on through the top of the frame, and allow a spring underneath the top of the frame to pull the dome drive wheel into the Rockler bearing.

I'm using the hex cap screws to hold the motor on at the moment, but I will likely have to replace at least two of the three hex cap screws with countersunk machine screws so that nothing rubs against the bottom side of the top of the frame.

Cut Right Foot Shell for Drivetrain, Countersunk Screws in Motor Mounts, Battery Box Setback

Today I cut the right foot shell to accommodate the drivetrain.



On Mike's advice, I countersunk some new screws into the motor mounts, to allow more breathing room for the gear to spin.



The good news: The right foot shell surgery was a success. The bad news: The right battery box will not conceal the entire motor. On the left foot, this was not a problem, the end of the motor points toward the back. On this right foot, the end of the motor points to the front, exactly where the battery harnesses go. There really isn't enough room to slide the battery box forward, and even if I did, it would look funny compared to the left foot.

I have already set Plan A into motion, I have sent an e-mail to Craig Smith begging to get on a list for a set of longer battery boxes. I am formulating Plans B and C in my head now, but they are not attractive (cut & extend, or scratch-build).

Dang, I was so close.

Started Working on Shaft Adapter Tool

It's an inevitability that I will have to make more shaft adapters in the (near) future, so I started working on a shaft adapter tool. The idea is to take a 3/4" outer diameter, 1.25" long steel rod with a hole drilled perfectly in the middle and squeeze it half way deep into a tube that has a 3/4" inner diameter. Then a blank steel rod with no hole can be drilled. Here is an example.

I started with a pre-drilled shaft adapter, and sanded the corner off.




Then I started whaling on it with a hammer to force it into the tube. I'm finding it difficult to force perfect alignment in the tube. I should probably use a vise, or something other than hammer. It started getting late, so I put down the hammer and I'll get back to this another day.