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Written by 2:17 pm 3D Printing, Star Wars

Building BD-1, Part 4: The Head

We’re in the home stretch! This is the penultimate installment of my Building BD-1 Series! Today we’re cranking out the head, which houses almost all of the servos.

A big shout out to Michael Baddeley for creating these amazing 3D files! Go support him on his Patreon (https://www.patreon.com/mrbaddeley/).

And now, the instructions! Oh, and the Amazon links are affiliate links so please help me out with a cup of coffee and buy from the links!

Main Head Gear

Parts Needed

  • Main Head Base A
  • Main Head Base B
  • Main Head Gear
  • Main Pivot
  • Main Head Bearing Seal

Tools & Materials Needed

Step 1

The first part we’re going to assemble is the Lazy Susan, which will rotate the head. Simply place the Main Head Gear onto the Main Head Base A.

Step 2

There’s a slot that lets you pop in your 5mm bearings, just keep poppin’ until the channel is full.

Step 3

Once the bearings are packed in, take the Main Head Bearing Seal and attach it to the Main Head Base A with a M4x10 bolt and nut.

You may want to use some oil or WD-40 to lube the bearings, this will help keep them rolling smoothly.

Step 4

Next, grab two 3mm pieces of the 4mm brass tube, and fit them inside the holes on each end of the Main Head Gear. You may need to use a thumb drill to widen the hole to fit the tube. You can use a bit of epoxy here to hold them in place, but only use a tiny bit.

Step 5

Take the Main Pivot and glue two pieces of 4mm brass tubing into the holes on long sides side, these will act as bearings. These pieces are about 4.5mm in length.

Step 6

Place the Main Pivot and screw M3x8 bolts (with some epoxy) into the end holes, through to the brass tubing you placed in the Main Head Gear to create a pivot point.

Step 7

Finally, take the completed Main Head Base A and place it into the Main Head Base B. This may or may not be a tight fight. Mine was a tad loose so I used some E6000 to secure it in place. Just make sure that the bottoms of each part are flush with each other.

Drive Gears

Parts Needed

  • Head Drive Gear
  • Head Servo Gear

Tools & Materials Needed

Step 1

The easy part, just screw in the Adafurit board. The holes should line up perfectly. I set it so my power input is facing the outside.

Step 2

Take the Head Drive Gear and place it on the post. You’ll notice that the head gear has some tooth slots in it, that’s to get the drive gear to seat correctly. Just rotate the head gear until the teeth line up with the drive gear, and then rotate back into the correct orientation.

Step 3

Grab your Head Servo Gear and attach to a MG92b servo with the provided screw. Make sure to tighten it as tight as possible.

Step 4

Center the servo with a servo tester and then fit the assembly to the frame using the two self-tappers which came with the servo.

Tilt Control

Parts Needed

  • Servo Rods
  • Servo Arm A
  • Servo Arm B

Tools & Materials Needed

  • Flexible Filament (https://amzn.to/3ifrChO)
  • Adafruit 12bit 16 Channel Servo Board (https://amzn.to/2BkoIYF)
  • Servo Tester – you’ll need a battery source for this (https://amzn.to/2Vthit7)
  • Soldering Iron
  • E6000 (optional)

Step 1

Crack open your MG90 servos, take the standard arms that come with them, and epoxy or E6000 them into Servo Arm A and B. Make sure the screw hole in the standard arm is at the rear (facing out the big hole on the Servo Arm).

Step 2

Cut two lengths of flexible filament, about 6 inches each.

Step 3

Using a soldering iron, melt one end so that it forms a glob. You’ll want it big enough to make it impossible to pull through the holes in the Main Head Gear. Pro tip: let the filament sit for a good 15 minutes or so to let it fully cool and cure. Otherwise it’ll just pull right through those tiny holes!

Step 4

Slide the filament through the hole in the Main Head Gear (coming in from the bottom). I put a few drops of E6000 in for added strength.

Step 5

Slide the filament through the Servo Rod.

Step 6

Slide the filament through the Servo Arm.

Step 7

This part was a bit tricky but you want to repeat melting a glob with your soldering iron. The idea is to make the filament taught, however I didn’t have much luck stretching it and then melting it. I did the best I could but there’s still a bit of slack, not a lot, just a wee bit. They’ve been holding up though through testing so fingers crossed!

The most important thing is that these Tilt Controls both stand unaided due to the tension of the filament.

Blink, Neck and Head Tilt Servos

Parts Needed

  • Blink Gear
  • Neck Servo Gear

Tools & Materials Needed

Step 1

Attach the Blink Gear to an MG90 servo with a servo screw. This sits vertically and screws into the front of the frame with the provided self-tapper. Note that at this point you only need one screw (the second will come later).

Step 2

Screw in the second MG90 in the space next to the Blink Gear Servo. Notice that there’s a space to run your cord, this helps you orient the servo correctly.

Step 3

Remove the M3x35 bolt that we previously placed in the neck. Place the Main Base over the neck, and use the M3x35 again to hold it all in place. The M3x35 goes through the brass tubing in the Main Pivot.

Once that’s in place, just be prepared for it to be super floppy. That’ll be resolved soon.

Step 4

Grab two MG90s and attach them to the Head Frame.

Step 5

Next grab your Neck Servo Gear and attach it to the other MG92b Servo. This is what lifts the head using the Neck Tilt.

Step 6

When you’re ready to attach this to the head, run all the cables from the body, and from the servos on the Head Frame through the hole as shown. This will help keep everything nice and tidy.

Step 7

Connect the Head Frame to the Neck with a M3x20 bolt.

Step 8

Finally, level and center the head, and attach the two servo arms to the MG90s.

Holoprojector

Parts Needed

  • Front Frame
  • Eye Holo
  • Holo Servo Arm
  • Holo Servo Rod

Tools & Materials Needed

  • 4mm Brass Tubing (https://amzn.to/2SSEGPf)
  • Flexible Filament (https://amzn.to/3ifrChO)
  • M3x5 Countersunk Bolts (https://amzn.to/31yLM0i)
  • Soldering Iron

Step 1

Take the supplied servo arm from the MG90 and epoxy or E6000 into the Holo Servo Arm.

Step 2

Similar to how we made the tilt servo arms, we’ll duplicate that process for the holoprojector. Start by inserting a few inches of flexible filament into the small hole on the Eye Holo and pull through about an inch, just enough to…

Step 3

Use your soldering Iron to make a glob at one end. Once cool, pull taught on the inside of the Eye Holo.

Step 4

Slide the filament through the Holo Servo Rod.

Step 5

Slide the filament through the Holo Servo Arm.

Step 6

While holding the filament as taught as possible, use your soldering iron to make another glob, ensuring the filament wont slip through the Holo Servo Arm hole.

Step 7

Take two pieces of the brass tubing (about 3mm long) and glue into the Holoprojector socket on the Front Frame. You may need to file these down to sit flush with the Front Frame.

Step 8

Insert the Eye Holo into the socket and hold in place with two M3x5 bolts. This will allow it to move from side to side. I was able to pressure fit the screws, however if you wish you can put a bit of E6000 or epoxy to hold it down more permanently.

Red Eye

Parts Needed

  • 4x Iris Leafs
  • 4x Iris Leaf Pins
  • Eye Red Ring
  • Eye Red Ring B
  • Rear Red Eye
  • Rear Red Eye Gear
  • 2x Rear Red Eye Pins

Tools & Materials Needed

  • Tweezers
  • 5mm Blue LED and Cable
  • 5mm Yellow LED and Cable
  • DuPont Crimper (https://amzn.to/3g6B3OS)
  • DuPont Connectors
  • M3x20 Countersunk Bolts (https://amzn.to/2YHkhzP)
  • M3 Nuts (https://amzn.to/2YFhvv0)

Step 1

Glue the leaf pin to the leaf with a bit of super glue.

Step 2

Place the Front Frame face up on your work bench, and layer the leaves onto the eye. You’re going to overlap each one, making a complete circle.

Step 3

With the iris open, place the Eye Red Ring on top, and then fit the Eye Red Ring B over that. If you twist the Eye Red Ring B the iris should open and close smoothly.

Step 4

Glue the rear red eye onto the rear red eye gear.

Step 5

Glue a wired 5mm blue led into the Rear Red Eye, so the light is facing out.

Step 6

Now fill the rear red eye with some hot glue. This will act as a diffuser for the light. Make sure your heat setting is on low to ensure you don’t burn out the LED.

Step 7

Once dry, take the Red Eye Gear and attach it to the frame with two m3x20 countersunk bolts and nuts, bolting through the front.

Make sure that the teeth of the gear are on the left side (when looking from the back), this will ensure that the gears will line up correctly when you attach the face to the head.

Step 8

At this point, you can also glue in the 5mm yellow LED into the holoprojector.

Attaching the Face to the Head

Parts Needed

  • Front Wire Cover

Tools & Materials Needed

  • M3 Nuts (https://amzn.to/2YFhvv0)
  • M3x5 Countersunk Bolts (https://amzn.to/31yLM0i)
  • M3x15 Countersunk Bolts (if necessary)
  • Cable Ties

Step 1

Take two M3 square nuts and place them in the slots under each eye on the front frame.

Step 2

Carefully place the front face frame onto the head, and screw down with M3x5 screws.

Step 3

Attach the Front Wire Cover. You may need to remove the Blink Servo Gear to do this properly.

Step 4

Run all the cables from the left side of the head, behind the Front Wire Cover.

Step 5

Take two M3x15 bolts and push through the front if the face and secure the Front Wire Cover with two M3 nuts. NOTE: The official instructions say that you should do this from the inside, however my M3x5s weren’t holding this down tight enough, so you may have to get creative here if you don’t want visible screws on the front.

Once everything is in place, the Blink Gear should be meshed with the Red Eye Gear.

Step 6

Finally, tidy up the cords with some cable ties.

Head Skin

Parts Needed

  • Main Skin
  • Main Head Plate Cover
  • Rear Head Detail
  • Center Hub
  • Ear
  • Aerial Base
  • Tips
  • Rear Panel
  • Rear Panel Lights (link to Facebook if possible)

Tools & Materials

  • 2x MG90 Servos (https://amzn.to/3icRefy)
  • Servo Rods or Stiff Wire (for the antenna)

Step 1

Glue the Main Head Plate and the Red Head Detail in place.

Step 2

Take the MG90 Servos and screw them into the holes in the Main Skin, just note that the servo pivot should face the bottom so it’s centered on the ear.

Step 3

Glue the Aerial Base to the Ear and then glue the Center Hub to the ear. You also will need to drill out a hole in the center of the center hub for the servo screw.

Step 4

Center the servos, and then screw on the ears.

Step 5

To make the antenna, I had some servo rods that I cut down to about 6 and a half inches. I widened the hole in the Aerial Base to accommodate the thickness, and just screwed it in. You can use filament, piano wire, or whatever – as long as it’s stiff and achieves the look you want it to.

Step 6

Glue the Tips onto the ends.

Step 7

This step may be different depending on if you are soldering your own light board, or purchasing a complete one. I purchased one so I simply had to Hot glue (on the lowest setting) the Rear Panel onto my Rear Panel light board and then hot glued that into the head skin.

Step 8

Connect your LED Rear Panel to the Arduino Nano, and then connect this to any open header on the servo board.

Step 9

Carefully slide the Head Skin onto the frame.

And now the main build is complete! The last part is to create the base, controller and wire everything up to make this little droid go!

AP admiring his handiwork

Make sure you subscribe to the YouTube channel so you can stay up to date as to when the thrilling conclusion is posted!

Thanks and happy building,

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Tags: , , , , , , , , Last modified: October 11, 2020
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