Started Cutting Permanent Center Foot

Way back in February of last year, I made a quick, sloppy center foot to get my droid on three legs. Now it's time to make the permanent center foot that will fit inside my PVC foot shell.

Today simply consisted of lots of cuts to make up the top part of the center foot.

First, there is the rectangular base that the wooden channels will ride atop.



And then there are the channel walls themselves.



I cut the channel walls 1/2" higher than normal so that I could add 1/2" thick supports on each side to help keep them from buckling.



The final result is a nice channel that fills the foot shell groove in the middle. The center ankle fits perfectly in there.



A layer of rubber will go underneath today's work, and beneath that will go a couple of layers of 1/2" plywood glued together. The two caster wheels will attach to the plywood. I may have to find smaller casters (I can salvage the nice wheels), the footprint of the top of them is too large.

I wrapped up by test-fitting the outer foot shells on the ankles to see if they fit. The left shell fits fine, but the channel gap in the right shell needs to be widened a tad in order for the right ankle to fit. I'll do some light filing and all should be well.

Drilled Drivetrain Channel & Main Bar

I went to Kelvin's again today to drill some holes in the drivetrain channel that we cut last weekend. His drill press has a fence, which I wanted to use to get a nice, straight row of holes.

Twenty-four holes were drilled and countersunk (twenty-five if you count a practice hole) with a 0.266" drill bit and a 1/2", 82 degree countersink bit.





When I came home, I worked on drilling and tapping the main bars that will hang from the channels, and from which the motor mounts will hang. I used a #7 drill bit, followed by a 1/4-20 tap to drill and tap these.



Everything seems to line up properly, the screws go through the countersunk holes in the channel and they screw into the main bar. I still have four more holes to drill into each of the main bars for the motor mounts, and I need to drill some holes in the aluminum wheel holders.

Dome Motor Wheel, Yet More Foot Shell Finishing, Cut Door Holders

I managed to squeeze in some building tonight, while also participating in the weekly R2 Builders chat.

I picked up a couple of Razor scooter wheels from Play it Again Sports in Costa Mesa. These have a 3/4" inner diameter, to fit around the 3/4" shaft adapter attached to the Saturn motor. A spring will pull the motor and wheel into the Rockler bearing, causing the dome to spin when the motor is powered in either direction. I'll have to put a layer of tape on the shaft adapter to ensure a snug fit.

I only need one of these wheels (one dome per droid), I can use the second one to build a miniature unicycle or something.



The foot shells are nearly done. I used a little super glue to fill in small voids, and I sprayed accelerator onto the glue to instantly dry it. I sanded this smooth afterward, and now there's not much else that needs fixing. Maybe one more pass...



I wrapped up by cutting the door holders that will go on the back of the foot shell doors.



I now have a PVC tank infantry.

Two sets of these will be glued to the bottom and top of the back of the doors. On the top, the thin pieces will tuck behind the door frames to help hold the doors in place, while on the bottom the thin pieces will swivel to lock and unlock the door from the bottom of the door frame. I also will have some pieces cut to help ensure the door is centered on the frame.



Tomorrow I plan to drill mounting holes into the aluminum drivetrain channels that were cut last weekend.

Foot Shell Finishing Continues

Nothing too exciting to report. The foot shell finishing cycle of sanding/filling continues. I think they'll be just about done in a day or two.

I still need to attach the doors, I hope to have that done by the end of the weekend.

Redrilled Motor Mounts Correctly, Started Sanding Bottom Foot Strips on Outer Feet

I made pretty decent progress tonight, especially if the definition of progress includes fixing previous errors. All of the do-overs have the effect of making these blog entries look very similar. Oh well.

I drilled the new motor mounts that I cut last weekend to fix the problem with the last set, where the motor was riding too high on the motor mount. I drilled the main 7/8" hole where the motor shaft and shaft adapter fit through, along with the three 5/16" holes that lie in a triangular pattern, where the screws go that hold the motors onto the mounts.



I also drilled and tapped the 1/4" holes on the top of the motor mounts, so that they can hang from the main bars of the drivetrain.



Hooray! The motor now fits under the main bar!



I wrapped up the evening by sanding down the bottom foot strips on the outer foot shells that I attached yesterday. I'll hit them with primer to see what needs further work, and go from there.

Trimmed Bottom Door Frame, Attached Bottom Strips for Outer Feet

R2 is going to be getting new shoes soon.

Today I trimmed the bottom of the door frames on the outer feet that I glued in yesterday. As with the center foot shell, I started trimming with the Dremel cutoff wheel, and finished with the drum sander.




More importantly, I finally attached the strips at the bottom of the outer feet. I used PVC glue to attach each strip, one at a time.



There were some visible gaps here and there, so I used Bondo to fill those. I'll sand/fill/sand again as needed. Experience shows that this step usually takes a few days of finishing work. Right now everything is a PVC-primer-Bondo mess, but it will look a lot nicer soon.

Cut and Glued Outer Foot Shell Door Frame Bottoms, Bondo for Outer Shell Foot Strips & Center Foot Shell

First off, I should mention that I had to do some photo maintenance tonight. If you see anything wrong with photos from the past, especially between February 17, 2007 and March 11, 2007, please let me know so I can address the issue(s). Now, on to today's update.

I love daylight savings! It means I get more daylight after work, and that's a good thing. This evening I used that extra daylight to cut the 34 degrees from the strips that make up the bottom of the door frame for the outer foot shells.



As usual, I used the smelly Oatley PVC glue to glue the strips in place.



I normally don't use clamps to hold the bonded surfaces of PVC together, but on a particularly thin strip I decided to do so. I will trim the freshly glued-on strips down with the Dremel soon, much like I did those for the center foot shell yesterday.



I wrapped up by doing some minor gap filling on the strips for the bottoms of the outer feet, and on the center foot shell. I plan to glue those strips onto the outer feet sometime this week.

Recut Drivetrain Aluminum Again, Finished Center Door Frame Bottom

Today I visited Kelvin and his band saw yet again, and for the third time I cut the aluminum channel for the drivetrain. This was necessary because the channel in the outer foot shells is about 1/4" longer than the H&A drivetrain spec, so there was a gap between the foot shells and the aluminum. Recutting these channels eliminated that gap.



I also had to recut my motor mounts, because when I drilled the holes on the former motor mount for the screws that hold the motor on, I drilled them too high. I need to drill the holes in these pieces a bit lower this time.



When I got home, I trimmed the bottom piece of the door frame on the center foot using the Dremel. I started with the cutoff wheel, and finished with the sanding drum.



I just need to keep moving forward on these foot shells and the drivetrain. The center foot shell is almost done, the outers aren't far behind.

Chris' Rockler Install, Finished Cutting Door Frames on Foot Shells

Chris Romines joined us today, and Mike and I helped get his Rockler bearing installed on his Imperial droid.



Mike and I finished cutting the door frames (that also double as reinforcements) for the foot shells today.



The bottom door frame strip on the center foot shell is intentionally high for the moment, it will be trimmed down with the Dremel. The bottom door frame strips for the outer foot shells have not been glued on yet, I hope to do that tomorrow.

Finished Sanding Center Foot Shell, Door Work on Outer Foot Shells

Tonight I finished up sanding the center foot shell, all surfaces are reasonably smooth now.

I spent some time working on the gap between the door and the shell for the outer feet. The width needed to be increased a bit. These may still need a little more work, but I'm waiting to see how the door frame looks after this weekend before I continue.

Bondo, Sand, Repeat

Infinitely.

Another round of minor filling and sanding on the center foot shell. It is getting very close to being done now.

Rubber for Center Foot, Foot Shell Gap Filling

I'm starting to think about construction of my permanent center foot. The goal is to have it look like Mike's.



The foot will be made from wood, with a layer of rubber to cushion the ride. The rubber is for joining large pipes together.



I sliced it so that it can be cut flat. I have to pause until I start cutting the wooden parts of the foot, so I'll know how large the piece of rubber needs to be.



I also did some gap filling and smoothing on the center foot shell. As usual I'll sand this down, and repeat as necessary.

Finished Cutting Slots from Foot Shell Tops

Tonight I finished the cuts that Mike and I started yesterday on the tops of the foot shells.

I started by using my Dremel with the cutoff wheel attachment to slice the main part of the material away.



Next, I smoothed out the remaining part with a file. I switched to a finer file, followed by an emery board, to smooth these out.



I will still need to bring these slots down a bit further, but I am waiting to do some more drivetrain work first, so I can fit the aluminum into the foot shell and see exactly how far down the slots need to be brought, in order to line them up with the channel that will fit within them.

Worked on Foot Shell Top Slots, Reinforcements & Door Frames with Mike

Mike and I continued working on the foot shells today.

We started off by cutting the grooves to form the slot in the top of shells. Mike pushed while I pulled on the sled to feed these through on the table saw. The cuts turned out very good. A couple of simple horizontal cuts and the slots will be open.



Next we cut some reinforcements for the inside corners of the foot shells, and glued them in.



We wrapped up by starting work on the door frames for our center feet. We got the top, left and right sides cut and glued in. We plan to finish up the door work next weekend.



I also asked Mike for his opinion on my motor mount boo-boo from yesterday, and he advised me to recut and redrill. That's the plan.

Mike's foot shell quote of the day: "Remind me never to do this again."

Drilled Drive Train Motor Mounts, Marked Foot Shell Tops for Cutting, Fun with Remote

After another evening of chatting with R2 builders last night, I returned to work on my droid.

I did a last bit of sanding on the filling I've been doing on the outer feet, and I think they are good to go, at least until I glue the bottom strips on. Then another round of filling and sanding in that area. :/

Most of the day was spent drilling holes in the drivetrain motor mounts. In some cases I measured, marked, and drilled.



Four of the holes on each motor mount are tapped with a 4-40 tap.



In other cases, I used a spare H&A drivetrain that Mike loaned me to use as a template, which I found handy for some of the trickier hole patterns.



Things turned out pretty good, but I found afterward that the motors are riding a bit high on the motor mount. This will cause the motor to bump into the flat metal bar that the motor mount hangs from. I will either shim the motor mount away from the metal bar, or simply cut out the material from the metal bar that is getting in the way. I haven't decided yet.



I also marked up the foot shell tops, Mike and I plan to cut the slots out of the tops tomorrow.



And I couldn't avoid playing with the remote some more. I hooked up the Keycoder 16 to the CFSound III, and I played R2's sounds using the remote for the first time! I had the sound system and speaker in the droid, and he was chirping happily. That was neat.

Remote Arrived!

Sixty-four days after I ordered my remote control, it finally arrived. This was the last (and by far most expensive) piece of the puzzle.

Included were the Futaba T9CAP transmitter with the Vantec Keycoder 16 module installed, the radio receiver, the Keycoder 16 receiver/demultiplexer, the RDFR23 speed controller, and four digital servos (along with some other goodies like the wall charger, neck strap, etc.).



The transmitter battery was fully charged, but the receiver battery had just enough charge to test a couple of the servos for about five seconds before the juice was gone. I'll charge the receiver battery for a good 18 hours and play around a bit. I have a lot of reading to do. (Don't let the airplane graphic on the LCD mislead you, this is tuned for a 75MHz ground frequency, channel 79.)



Oh yeah, I also applied a bit more Bondo to smooth out the remaining seams and bumps on the outer foot shells. I'll sand tomorrow, and then the foot shells will be ready for the gluing of the bottom strips, and the cutting of the slots at the top.