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.

Worked on Right Foot

Today I repeated several steps from yesterday, this time on the right foot.

I had another opportunity to drill and tap, this time on the right foot's motor mount bracket. I drilled a 0.201" hole, followed by a 1/4"-20 tap. Like yesterday, this was done to move the motor mount that hangs from the main bar closer to the wheels, so that the motor will reside mostly within the foot shell.




Next, I opened up the base of another shaft adapter so that it could fit closer to the base of the motor shaft when it screws on. I used a 13/32" drill bit and the Dremel with a grinding attachment for this modification.




I had to trim some of the wheel housing out to allow the 22-tooth gear some room, just like yesterday.



Things are so tight in the right foot drivetrain that I even had to file down some hex cap screws.



I wasn't kidding. You can barely see daylight between the gear and the hex cap screws on one side, and the gear and the wheel on the other. Making matters worse, I think my shaft adapter has problems, the gear has a slight wobble as the motor turns. It still clears everything, but just barely. That likely portends of problems to come, I'll probably have to make a new shaft adapter.

Lots of Work on Left Foot

Today was a long but fairly productive day. I mainly concentrated on the remaining things to be done for the left foot.

First, I had to hack off one of the fasteners on each motor, so that they will fit inside the foot shells and battery boxes.



I found that if I followed the H&A drivetrain blueprints exactly, then the motor would collide with the inner part of the edge of the foot shell. I needed to move the motor inside the foot shell, by sliding the motor mount toward the wheels by 5/16", recycling previous motor mount screw holes. That necessitated a couple of changes.

First, I had to hack into the front wheel housing, to allow the large, 22 tooth gear some room.



Second, I needed to drill a new hole in the main bar and the motor mount.



While I was working with the motors, I decided to modify one of the shaft adapters, to get it to fit snugly near the base of the motor shaft. With this modification, the shaft adapter screws on very close to the motor, and later I can drill a 1/8" hole through the middle of the shaft, and pin the whole thing with a 1/8" steel pin.



Next, I cut the side of Craig's battery box that faces the foot shell, to allow the motor to enter into it from the foot shell. It feels like I'm vandalizing a piece of art here, but it has to be done.



I needed to trim some material off of the motor mount to get it to fit into the battery box.



With some iterative fitting and sanding, I was able to get the battery box to mount perfectly on the foot shell, and get the overhang of the drivetrain to fit perfectly within the whole thing (foot shell and battery box).



The modifications to the drive train mean that I will have very little room to tension the chain, but hopefully what I have will be enough. Of course, I still need to build up the chain first...



Despite all the cutting I did on the foot shells and the battery box, none of that is visible to the outside world, which is a relief!

Recut Center Foot Again, Started Cutting Foot Shells for Drive Train

More help from my friends today.

First, Matthew Henricks came through again for me with some more high-quality plywood for the rebuild of the center foot. Thank you again Matthew!

Mike helped for the three millionth time, this time with the rebuild of the center foot, and the start of the cuts on the foot shell for the drivetrain. Fortunately, my unintentional buffoonery usually makes Mike laugh, so he's somewhat entertained.

Stop me if you've heard this story before... I cut the basic pieces for the center foot on the table saw and miter saw.



Then Mike did the dado cuts that hold the channel pieces.



Meanwhile, Mike had all of about five minutes to work on his own building activities. He ordered some incomplete battery boxes from Craig, and is finishing them himself.



While we were waiting for the glue to dry on my center foot, we started cutting into one of the outer foot shells, since the drivetrain will not fit within them. The drivetrain will continue into the battery box. Mike and I both worked on cutting the foot shell.



If I look like I'm going to puke, it's because the thought of accidentally destroying months of work with a bad cut on the Dremel makes me nauseous.



Next, Mike attached the casters. It is a really tight fit inside the foot shell, so the casters have to be mounted very precisely.



It's so snug in the foot shell, Mike had to grind off some of the overhang of the caster mount plate. More cool sparks!



As we wrapped up, we started checking to see if we could drill the ankle bolt hole. Unfortunately, we ran into some trouble. The blueprints call for the ankle bolt hole to be 0.625" from the tip of the ankle, but it really needs to be closer to the tip (say, 0.500") for my 1/8" thick foot shells. So I'm going to have to figure out how to get a bolt into the foot shell without hacking too much of the shell, and verify that the foot will tilt at the 18 degree angle. If it doesn't, then some minor hacking is in store for the center leg. I really hope it doesn't come to that, though.