Sunday, March 30, 2008

Entstort Motor Testing at Mike's

Today I dropped by Mike Senna's house to start our testing of the Entstort motors, which are potential replacements for the Trico wiper motors.

The first thing we did was measure the RPMs. At 12 volts, the Entstort motors ran at about 36 RPM, and at 24 volts they ran at almost double that, 76 RPM. The Trico motors run at about 88 RPM with 24 volts applied, so the Entstort motors are about 15% slower.

Of greater concern was the current draw. The Entstort motors draw about 1.5 amps under no load, while the Trico motors draw less than half that, about 0.6 amps with no load. This is bad news for battery life.

Curious as to why the Entstort motors draw more current, Mike theorized that the brushes and magnets might be different. We opened up both the Trico and Entstort motors, and they were actually quite similar in windings, brushes, and magnets.

Later, Mike measured the motor resistance, and found that the Entstort motors measured a resistance of 3.7 ohms, while the Trico motors' resistance measured only 1.8 ohms. Mike suspects more windings are present in the Entstort motors.

We decided to open up the gear area of the Entstort motor to see how similar it was to the Trico motor. This required a Dremel to hack off the rivet heads.

The Entstort motors look pretty similar to the Trico motors. A steel worm gear meshes with a nylon wheel to turn the shaft.

When I got home I took a picture of the emptied motors side by side, and I tried swapping the nylon gears to see if they would fit in both motors.

It turns out the nylon wheel in the Trico motor is just slightly larger than that of the Entstort motor, and it doesn't quite fit in the Entstort motor. Likewise, the Entstort wheel is a little too small in the Trico motor, and wiggles slightly in the Trico housing.

It looks like we cannot cannibalize these different motors for part swaps. Also, the worm gear on the Entstort motor doesn't appear to be quite as beefy as that of the Trico motor, especially in the base area.

The Entstort motors have not yet been tested under a droid load yet. I may get to that someday, but not right now.

The preliminary conclusion is that while the Entstort motors probably supply stronger torque, they do not appear to be quite on par with the Trico motors in most respects (power usage, RPM, potential worm gear failure). In a pinch, they may have to step in, if the supply of Trico motors has really dried up.

It's time to start trying to contact Trico to find out the what the real story is on their motor availability.

Saturday, March 29, 2008

Autism Hyperbaric Chamber Anniversary Event

Today R2 visited the Hyperbaric Center that helps treat autistic children in Irvine, CA, as they celebrated their first anniversary. The last time I was there was for the Christmas event where I drove Chris Romines' R2-A1 while Chris filled in as Darth Vader. Today Chris and I returned, each of us driving our own droids.

It wouldn't be an event without this pose.

Members of the 501st and Rebel Legion were also in attendance, helping entertain the visitors.

R2 kept the kids happy.

R2-D2 and R2-A1 got into a mist war, it ended in a draw.

R2 also used his mist to fend off a stormtrooper, he may need a refill soon.

A good time for a good cause.

Thursday, March 27, 2008

Entstort Motors Arrive

With the recent dearth of Trico wiper motors, I ordered a couple of Entstort motors, which are very similar in appearance at least, if not performance. The pair that I ordered arrived today.

There are a couple of fairly noticeable design differences between these Entstort motors and the Trico motors. First, the shaft is much longer on the Entstort motors.

Second, the motor gear is on the reverse side from the Trico motor. This means that the main bar that holds the motor mount on the H&A drivetrain will either need extra holes, or possibly be flipped over and re-countersunk on the opposite side, if enough material is available for countersinking on both sides.

Neither of these differences appear to be show-stoppers.

I tried a shaft adapter and a mounting screw on one of the new motors, and they both fit perfectly, so that's good news.

I plan to go to Mike's on Sunday and we'll start testing the electrical characteristics of these motors. Once we have some findings, I'll report them.

Wednesday, March 26, 2008

Black Paint for Frame

This evening I sprayed some black paint onto those areas of the frame that might be seen by the outside world. Black is a good neutral "color" for making things disappear into the dark background.

The LDP area and utility arm areas are candidates for viewing.

I turned the frame upside down and sprayed the bottom side of these ribs. The bottom plate of the frame itself will eventually be painted white around the skirt area.

I also painted the areas behind the octagon ports, as these have slits in them that can be seen through.

Sunday, March 23, 2008

Cut Back Door

Today I cut the back door from the back inner skin.

First, I picked up where I left off yesterday, and marked the lines to cut on. I did this by extending the small marks I made yesterday on the inner skin, showing midpoint of the area of the inner skin where I planned to cut.

I used a tape measure as a guide for marking the horizontal line that forms the top of the back door.

I checked the line against the skins, and it was just where I wanted it.

To avoid any goofs, I erased the outside lines, leaving only the lines to cut on.

Next, it was Dremel time. I started with the top edge of the door.

Every once in a while I checked the line I was cutting, against the back door of the outer skin, to make sure all was well. I'm using a slightly thicker cutting disc on droid #2, but it gets the job done better than the comparatively weaker discs I used for droid #1.

I took a page out of Chris James' book, and used some scraps from the outer skins as a guide for cutting the vertical sides of the door.

Repeat for the other side.

And finish the cutting with a hacksaw blade.

Afterward I sanded the sharp edges smooth.

Everything overlaps the way I want it to when I hold the skins together. The curve seems to be a bit different between the two skins, I'll try to work that out in the next few days so that the back door will hug the body properly.

Saturday, March 22, 2008

Started Marking Back Door for Cutting

Today I got a start on marking the lines for where the back door will be cut from the inner skins.

First, with the outer skins still attached, I traced the outline of the back door cutout that outer skins provide.

With the outer skins still on, I put the back door cutout piece from the outer skins in place, to locate where I will do the cutting on the inner skins. I drew part of a box at each upper corner, then I removed the outer skins. I will extend the lines from the partial box the entire length of the skins, and these will be the lines that I cut on. (This will be clearer in my next update.)

Friday, March 21, 2008

Styrene for Roy

I'm still in lazy mode, so I got nothing done today. Roy Powers did drop by to cut some styrene to cover the areas at the bottom sides of the skins, and some plastic to cover the PSIs.

Tuesday, March 18, 2008

Finished Countersinking Skins

Tonight I finished countersinking the back outer skins.

That's all I have to report. End transmission.

Sunday, March 16, 2008

Mike's Girl Scout Event at the Nixon Library

Not content with eight hours of droiding yesterday, I joined Mike Senna (and a few thousand others) at the 96th Anniversary of Girl Scouting at the Nixon Library in Yorba Linda, CA today. I'd never been to the Nixon library, so I was interested in seeing it, along with the Star Wars presence at the space-themed event.

Mike drove R2 around the crowded venue, both outdoors and indoors.

Wherever R2 was, the mob followed.

Elsewhere, young padawans were trained in the Jedi arts by the Jedi Training Academy.

After their training was complete, they faced their final test: A battle with Darth Vader.

While there, I took the opportunity to look around. The presidential helicopter was moored toward the back of the grounds.

Hey, is that a holoprojector?! Well, I guess I better leave it alone.

No visit to a presidential library is complete without a visit to the presidential gift shop. Well, maybe next time...

Saturday, March 15, 2008

Wizard World 2008

Today R2 returned to the Los Angeles Convention Center for the first time since Celebration IV, to entertain guests at the Wizard World convention. R2 joined members of the 501st and Rebel Legion, along with Chris Romines' R2-A1 and Max Cervantes' RT-R2.

R2's first assignment was to greet the visitors as they awaited entrance into the main hallway at the South Hall.

Ever have a feeling someone was sneaking up on you? R2 knows this Jawa from the Laguna Niguel Holiday Parade and has developed a sixth sense.

Following his Jawa encounter, R2 was stopped by a pair of Stormtroopers. He used his Jedi mind trick and narrowly escaped.

Free to go about his business and move along, R2-D2 joined R2-A1 for pictures, while their associated droid builders hid incognito in the background.

Kids and parents took their opportunity to pose with R2.

Chicks dig R2 too.

As do princesses and Jedi.

R2 digs muscle cars.

When R2 wasn't busy entertaining the crowd, he was allowed to crash (metaphorically) at the 501st booth (thanks guys!).

R2-D2 and RT-R2 were guests of honor as they were stationed in front of the stage for Steve Sansweet's Lucasfilm presentation. Robot Chicken creators Seth Green and Matthew Senreich joined Steve on stage, talking about their Star Wars episode, and what it was like to direct George Lucas. It was a very funny and entertaining presentation.

Afterward, Steve and I posed with R2 (which we had done once before).

It was a fun and tiring day, and it was nice to get R2 out in a large public setting again. Nothing scheduled quite yet for the future, but I'm sure something will come up sooner or later.