Chopper's Head Assembly
Step By Step Instructions

[updated 07/29/18] I've created a .zip file with all of the V3.1 documentation - click here to download. It includes: Cleofett's head drawing with added information in both .dwg and .pdf format. A 9 page Chopper Parts Drawing set in both .pdf format (1 file with multiple pages) and in autocad .dwg format. Copies of the 3D.pdf files. If you have not already, download it NOW. Study the drawing files - part names are on the drawings. I will use those names in the descriptions below.

Acknowledgment: PaulG assembled the Version 0 Prototype. He assembled a pile of parts, working mostly from the 3D.pdf files, and took the pictures shown here. He also provided a lot of input that helped shape the improvements made to get this design to Version 3.1 release.

The Arm Boxes

Image above links to a 3D .pdf file as does the image to the right

The Skin Attach Blocks Upper & Lower
were added to the design after the prototype was completed.

they are not in the pictures that follow.

As a first step, glue the two .188 thick attach block pieces together. you should have 2 upper sets and 2 lower sets (one set for each arm box) when you are finished. And then glue those to the Front Edge pieces.
.


Dry fit the parts. Hold the Arm Boxes together with rubber bands & check the fit in the Head Bottom, Top Magnets & Shelf Rings
The Head Top Sandwich

Image above links to a 3D .pdf file as does the image to the right
[updated 07/29/18] The head top is a sandwich of four pieces. Top inner, Top Outer and Top Magnets and newly added, Top Periscope Socket. The fifth piece, the Head Top Periscope Hat is not glued in place, set it aside. The Top Inner is held in place by magnets,
[New 07/29/18]

Left: The periscope socket, the lower of the two parts shown, is glued into the hole in the Head Top Inner.

When flush with the Head Top, The Periscope "Hat" will have a  .0625 panel line around it.That matches the other panel lines on the head. The taper allows for a small mis-alignment between the Hat and the Socket as the periscope decends into the head.
Left: The three sets of holes circled are alignment holes  for the assembly of the Head Top sandwich. The hole in the Top Outer ring is a blind hole.
Below: use a small piece of filament  to align the two rings
Left: before proceeding with the installation of the magnets (see drawing files for magnet details) make small .0625 in holes in the pockets where the magnets get installed in the Top Magnet ring. You'll need the holes to push out a magnet in case you get the polarity wrong :-(
Not Illustrated: Magnet Installation -
Install three magnets in the Head Top. Orientation (North/South pole) is not important. Note there are no holes in the Head Top to allow you to push the magnets out. Place three magnets on top of those. They will naturally align (N/S) themselves with the first set. Turn the Head top over and align it with the Head Top Magnets ring (the periscope hole has to match up) If you squeeze gently you should be able to force the loose magnets into their pockets on the Head Top Magnets ring. 
The Head Skeleton

Image above links to a 3D .pdf file
Start by inserting the ribs into the Shelf Ring. The Index Ring will only fit into one slot. Make sure the sharp edge of the Shelf Ring lines up with the sharp corner of the ribs. Tape the ribs in place.

Add the Arm Boxes to the assembly. Also add the  Lower Skin Attach blocks to the shelf ring. Tape in place.
Add the Head Bottom to the assembly. Make sure that all of the Rib ends, the Arm Box Ribs and the Lower Skin Attach Blocks fit in place. Tape the Ring.

Add the Head Top Sandwich to the assembly. Make sure all of the Ribs, and the Upper Skin Attach blocks on the Arm Boxes fit into their respective slots.		 Before starting to glue the parts in place, verify that the Periscope "notch" in the Head Top Sandwich is lined up over the Periscope Lifter "bulge" in the Shelf Ring and that both of those features are on the right hand side of the front of the Head Skeleton.

Cad drawings were used to illustrate this part of the assembly because the Version 0 Prototype did not have a Shelf Ring.
The Lower Taper and Bearing Skins

Image above links to a 3D .pdf file		 There are 6 pieces of .080 "Skins" to be attached to Chopper's Head Skeleton. The Large Front and Rear Skins, and two sets of the Lower Taper and Bearing Skins. All of the skins are oversize in length to make aligning onto the skin attach blocks easier. They are also oversize on the top and bottom edges to allow for some trimming after the glue has set.

Assembly starts with the Lower Taper Skins. Once that is in place and the glue has set the Bearing Skins are put in place. Then Front Skins and lastly the Rear Skin.

Note that because the head is cone shaped the skin installation is a little more complicated than it would be otherwise. Review the pictures here and plan ahead: Have the resources you will need to hold the skins in place before you apply ANY glue!

The version 0 Prototype didn't have a notch to help hold the Lower Taper Skins in place.
Left: It also did not have a Lower Skin Attach block for either the Lower Taper Skins the the Bearing Skins. For the both of these Skins start at the middle of the Arm Boxes and work around to the Front and Back where the Attach Blocks are.
Above: stretch the tape up and around the ribs to hold the skins in place.
Left:  Trim the ends of the Lower Taper Skins to meet together at the Lower Skin Attach blocks.
Above: the Bearing Skins are Cylindrical, so their installation is a lot easier than than the Lower Taper Skins.

Left:  Trim the ends of the Bearing Skins to meet together at the Lower Skin Attach blocks.

The Front and Rear Skins
Installing the Front and Rear Skins is a lot like the Lower Taper Skins, only  bigger, bulkier, stiffer and more awkward to deal with. :-(  Start Installing with the Front Skin. You will need a LOT of tape.
Not Shown: I'm going to suggest you draw a pencil line down the center of the skins on both inside and outside. Do the same on the Skeleton. Start taping at the midline and work your way out to the ends of the skins. From time to time
verify the alignment at the midline and also when you get to the arm box openings where the panel lines terminate.

Tape alone will not be sufficient to guarantee a good joint between the Ribs and the Skins. Particularly at the ends where they meet the Arm Boxes.  PaulG used weighted (soft sided) bags. Only apply glue to the section that's being weighted down!

Trim the ends of the Skins where they meet at the Skin Attach Blocks
Take your time during the process of gluing the Front and Rear Skins. It's the feature most people will see first and you will want your droid to be putting his "best" face forward!  

Check your alignment frequently during the glue up process.


Links to Downloadable items - I've created a .zip file with all of the V3.1 documentation - click here to download. It includes: Cleofett's head drawing with added information in both .dwg and .pdf format. A 9 page Chopper Parts Drawing set in both .pdf format (1 file with multiple pages) and in autocad .dwg format. Copies of the 3D.pdf files.

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