Wednesday, June 24, 2009

More Leg Work

R6 is really taking shape now. I have nearly all the major parts made and ready for assembly.

Following the "Senna Leg" design, I have the five main parts for both outer legs. Both legs have the same parts. In the picture the parts are layered on top of each other to show how they will be glued together. From left to right wood thickness: 1/2", 1/2", 3/4", 1/2", 1/4". You'll notice the 3/4" piece was hollowed out.

Both outer leg parts stacked to test fit and show off how they'll look when glued. I still have some minor work to do on them before I glue. More on that next time.

Close up of the outer ankles. Note the hollow space. This is for the electrical wiring for the foot motors and for the 2-3-2 transition leg rod.

The standard Astromech Droid has a center foot connected to the center ankle which extends and retracts from under the body. Following the "Senna Design" the center ankle is made of four layers of wood, two 1/2" and two 3/4" with the 1/2" in the middle of the sandwhich. The two 3/4" pieces will be cut short of the ankle tip in a half-circle. The picture below shows one of the 3/4" pieces before cutting with the half circle drawn on it. BIG NOTE: I goofed here. The circle outline was positioned incorrectly. Each end should start at the bend points. Technicaly I believe it's a half-inch higher than it should be. Sadly I didn't realize this until I had already cut both pieces and test-fitted them.

This board has an 1/8" dia pin in it for the 3/4" ankle pieces to rotate on. Mike Senna goes into more detail about this in his tutorial. Basicly, the ankle will rotate through the bandsaw perfectly in line with the half-circle. Too bad I messed up the measurements which also affects where the pin is located.

The ankle ready to be cut. If only I could stop myself here. Now I'll have to remake these two pieces and try again. Good thing I still have the template.

I'm on vacation this week so I'll be spending more time at the shop than just one day this week. More updates coming soon.


Tuesday, June 16, 2009

A Wooden Leg Named Smith

Sorry I didn't post last week. Last week was very busy. So here are two weeks worth of updates.

To start, you should know that in making the leg template, I have had to remake it 3 times due to making little mistakes that would distort the correct shape. The Leg pic from last time is of the second attempt. Well I messed up when I was trimming it and had to make another one. Luckily, 3rd time is the charm. Using the lessons I learned from the first two, I was able to make a perfect cutout of the full leg pattern.

In order to keep the edges straight, I set a pivot point in the leg which would allow me to rotate it agaist the sanding disc and get the correct curve angle. I then put stops on each end of the base board under the leg so the leg would stop moving in a straight position.

Rotating the leg.

This is the template after using the disc sander. Now I just need to trim the middle edges.

I came up with the idea to use the router table with the riding head. I screwed straight blocks right on the line I wanted to trim to. These blocks will stop the router bit.

The silver disc on the router bit rest against the blocks, trimming the template flush with the blocks. Perfection.

Template is now complete. Now I can use it to make copies to build the legs.

Here are 3 rough cuts of the legs.

Here I have screwed the template on top of one of the rough cuts. I will now use the router to trim the rough cut to match the template.

Eight 1/2" trimmed legs. I still require four 3/4" and two 1/4" cut outs.

Unfortunately the bandsaw broke again before I would cutout the rest of the pieces.

Here I am trimming off part of the ankle of the leg. This is so the leg will look correct once all the pieces are layered together. I'll explain more once I have all the pieces.

While I was working, one of my older cousins stopped by to see my Grandmother and her 2 kids found me in the garage. They were impressed with my "robot" (Industrial Automation R6-series Astromech Droid) and wanted to "buy" it. Sure. Got a few thousand dollars in the piggy bank, lol. I will hopefully have the bandsaw working again by next week so I can continue the leg building.


Monday, June 1, 2009

R6 has a neck, legs started

Did more work in the shop yesterday.

This is version 2 of the PSI circuit I made a loooong time ago. This one is printed instead of little wires connecting all the componets. Also, the LEDs will be separate from the pcb instead of attached to it. Have yet to test it.

Using my Dad's Shop Smith Mark V in drill press mode (sounds like something from the power rangers doesn't it, "Mark V Megazord Drill Press Mode!!! Hiyaa!"). I'm drilling holes into the outer ring of the Rockler Bearing so I can attach it to the top of R6's body. I used a 3/16th" drill bit. Be sure to put masking tape over the gap between the inner and outer rings to keep metal shavings from getting into the bearings, a MUST do.

The Rockler Bearing comes in various sizes and is available at McMaster-Carr. The size we use in the Club is the 17-3/8". Use the outer ring for the body and the inner ring for the head.

Here I'm checking the measurment all the way around the Rockler to ensure it's perfectly centered on the bottom of the head.

Used #10 1-1/4" wood screws to secure the inner ring to the head. Note that the inner ring already has six pre-drilled holes.

The Rockler Bearing sitting on the upside-down head. The white dots are little rubber standoff feet. Keep these in place.

You don't want to perimently attach both rings of the bearing so you can remove the head. Normaly the outer ring is attached to the body and the head is placed on top of it. But because of the way my wood head is designed, I have to reverse this setup. So I put four #10 1-1/2" metal bolts, secured with nuts, into the holes I drilled. These will be pointing down and will slide into four holes in the top of R6's body.

At last, the two are one. That slotted screw on the right loosens the inner ring. Best not to mess with it I discovered.

Here's video showing off how the head rotates. Note that the body is facing backwards.

With the head attached to the body, I can now start choosing the electronic parts needed to bring R6 to life. I will need a motor for the head rotation, motors for the outer feet, batteries to power everything, all the Radio Control junk, and a sound system.

Here I've used a 1:1 scale cutout from the blueprints to trace the outline of the leg onto a 1/2" piece of plywood. This piece will be the master template I will use to cutout exact replicas to make both the left and right isde legs. I advise using a bandsaw to cut close to the line and then sanding it down to as close as you dare. It's ok if it's off by a millimeter or two. No one will notice. Just keep the edges straight.

My Dad will have the Mark V's bandsaw repaired today so next week I can cutout the template and if that goes well start cutting out all the pieces for the legs. See ya then.