Some sections of the drawing pack have omitted dimensions for hole locations, to assist the builder who might not have a full machine shop; or precision inspection tools. The construction steps are arranged in a manner of stacked parts; clamping and drill-through holes which will allow for greater accuracy on the finished assembly. All holes should be drilled 1/32”-1/16” undersized and reamed to finished size.
Rectangular bar stock may not be flat ,square ,or may have some bow or twist, and may not be the precise dimension described. The surfaces that join or bear on each other may have to be filed or machined flat to match drawing dimensions
(comment )
variation from sizes stated is ok by a small amount but basic geometry must not be altered ,tolerances and press fit dimensions must be kept to)
 

CONSTRUCTION STEPS

Upper Fork Assembly

-5
 Fork

            Drill (2) ¼” holes in one piece only,
Drill and ream (1) hole in each piece to 0.875” + - 0.005”
Press in a 12-DU-08 Bushing into each hole.

-8 
Housing

Square and parallel the (2) 3.750” sides of the block.
Bore the 2.24404” + - 0.0003” hole ( make sure the hole is in the centre of the block .
Face both sides of the block square to the bore.

-6
Stop

Carefully centre and drill the 1 ¾” hole
Drill  (4) ¼” holes as shown
Mill or file  (2) 8.5 degree bevels parallel with the faces of the block.Make sure the 3”  dimension is flush or slightly undersize with the sides of -8 Housing.

-9
Retainer

Centre and drill the 1 ¾” hole.

-4
-5
Top centre
Bottom centre
 

Machine to dimensions shown: O.D. 1.1812 +/-0.0002”. Faces must be 90 degrees to 1.1812 Dia.and the 0.500” hole must be concentric with the diameter.
 

-22
Teeter Block

Square and parallel the 1 ½” x 2” sides of the block.
Drill (4) holes and ream. ( make sure the 0.750” +/- 0.003” location of the 0.500” hole and the 0.375” hole are located from the same side of the block . The placement of these holes determines the centering of the rotor rotating axis with the bearing centre.

-3
Pivots

Carefully machine and maintain a GOOD SURFACE FINISH on the                           0.7497” +/- 0.0002” Dia. Make sure base and flat on shoulder are 90 degrees to O.D. The 0.375” hole must be centered with the O.D. as otherwise this would cyclic the offset blade pitch
Drill the 0.375” hole

Press 5206 Bearing into -8 Housing. Flush bearing race with face sides of block.

Insert -4 Top Centre into bearing I.D.

Install -3 pivot with washer into each 12-DU-08 Bushing on -5 Fork . Attach Forks to -22 Teeter block with 3/8” hardware. Tighten nut to 300 “ lbs.
Insert ½” bolt through bearing and -4 Top Centre . Place -10 Bottom Centre
over bolt, and on top of -4 Top Centre. ( this is used  temporarily as a spacer)

Locate Forks and -22 Teeter Block over ½” bolt, and on top of -10 Bottom Centre ( Spacer ). This assembly method will assure the centering of the Teeter Bolt with the Bearing Centre, and also determine the height of the Teeter Bolt from the Bearing face .

Align the -5 Forks with the -8 Housing and clamp. Pick up the (2) drilled ¼” holes in -5 Fork and drill through the Fork and Housing assembly .

Attach assembly with AN hardware and torque to 50 to 70 inch/lbs.

Remove -22 Teeter Block from -5 Forks

Centre -6 Stop on top of -8 Housing. Make sure bevelled edges are up. Centre -9 Retainer on bottom of -8 Housing and clamp assembly.

Pick up and drill through the assembly, the (4) ¼” holes in -6 Stop. Attach assembly with AN hardware and torque.( Saw off bolt ends to leave two threads beyond lock nut.

Remove the ½” Bolt and install -10 Bottom Centre used as spacer into 5206 Bearing I.D.

This completes the Upper Fork assembly
 

Lower Gimbal Pivot Construction

-12
Torque Tube

Machine as per drawing. If the overhead Azimuth Stick is to be used drill a 1” hole, 2 ½” deep in end of Torque Tube, to accommodate the 1” tube of stick. The (2) ¼” drilled holes are laid out and drilled for the -18 Slotted Angle. Use the locating dimension shown on the -17 Crossarm (Note : If the joystick is to be used the front 3” of the torque tube can be cut off. The (2) ¼” holes for the -17 Cross Arm attachment are transferred from holes drilled in the Cross Arm.

-13
Lateral Pivot

Square and parallel the (2)  1” x 2 ½” sides of block . Lay out, drill and ream the 0.375” hole .
 

-11
Long. Fork

Locate, Drill and ream the 0.375” hole in both -11 blocks. Drill (2) ¼” holes in (1) piece only.

Attach -11 Forks to -12 Torque Tube with AN hardware. Insert  -13 Lateral Pivot block in position , flush with base and sides of -11 Forks and clamp. Pick up (2) ¼” pre-drilled holes in -11 Fork and drill through.

Bolt assembly together with AN hardware and torque

Loosen 3/8” Pivot Bolt ,and check for free pivot action ( 0.003” to 0.005” clearance ) if assembly is too tight, file or mill sides of -12 Torque Tube. If assembly is too loose file or mill sides of -13 Lateral Pivot Block.
 

-14 and -15
Lateral Forks

Machine complete as per drawing

Attach to -13 Lateral Pivot with AN hardware. Clamp torque Tube assembly in vice ,and level with a bubble protractor. Pivot  Gimbal assembly fully forward, stopping on -14 Front Fork. Check angle of tilt  with bubble protractor, placed on -13 Lateral Pivot Block. Correct tilt angle: 9 ½  to 10 degrees. File if necessary the 10 degree bevel of front fork to obtain the correct reading.

Now  pivot the Gimbal assembly fully rearward, stopping on the-15 Rear Lateral Fork. Check the angle of tilt with bubble protractor, The correct angle is 7 ½ to 8 degrees . File if necessary the 8 degree bevel on the -15 Rear Lateral Fork to obtain the correct reading.

Gimbal Head Assembly

Mount the Upper Fork Assembly onto the Torque Tube with ½” bolt . Torque up the castellated nut to 360 in-lbs. Don’t forget to COTTERPIN THE NUT ! Without the cotter-pin there is a danger the nut may unscrew in flight.

 Lubricate the Gimbal Pivot bolts and the mating faces with a light film of grease.
Tighten castellated nuts as you would a wheel bearing. ( snug up the nut to expel excess grease, and then back off (1) castellation at a time until a free pivot is obtained.) COTTER-PIN BOTH PIVOT CASTELLATED NUTS.
For Joystick use ,attach Cross-Arm and -18 Slotted bracket.
For Overhead Azimuth Stick attach -18 bracket

TO INSTALL OVERHEAD STICK : Clamp entire head assembly in a vice. Level Torque Tube both londitudally and laterally. Insert overhead stick in drilled 1” hole and align stick to be vertical to cross arm
(this I think is a typing error but is includes as it is the original text )
and through drill Th (2) 3/16” attaching holes. Secure with 3/16” bolts and torque.

Rotor Hub Assembly
Centre the -22 Teeter Block on the Hub Bar, both span-wise and cross-wise, and clamp. Drill (2) 5/16” through holes. Secure with AN hardware. Torque 5/16” nuts to 140 in/lbs.

Clamp head assembly in vice and level Torque Tube and -6 Stop plate. Attach Hub assembly with AN hardware . check flapping angle clearance of Hub. Tilt Hub fully rearwards in contact with bevel on -6 Stop Plate .Check angle of tilt. Correct angle is 8-1/2 TO 9 DEGREES. File bevel on -6 Stop Plate if necessary to correct tilt angle. Repeat procedure by tilting Hub fully forward, contacting bevel on -6 Stop Plate. Tilt angle should be the same.

The Hub MUST pivot FREELY  in the “DU” Bushing when the Teeter bolt nut is torqued to 300 in/lbs. Lateral clearance of -3 Pivots should be 0.003” to 0.010”. If excessive machine the seat end of -3 Pivots to correct lateral clearance .If clearance is to tight ,machine the shoulder faces of -3 Pivots.

The “DU” Bushings are self-lubricating dry bushings, requiring  no lubrication. They are made of globular bronze and teflon-lead coat material. Do not grease them to avoid the accumulation of grit.

Every time the Hub is installed, the Teeter Bolt nut MUST  be torqued to 300 in/lbs. and COTTER-PINNED ! This then assures that the -3 Pivot bushing becomes an integral structure with the Teeter Block.

This completes the rotor head ,the remainder has been abridged to cover mounting the assembly between the cheek plates and setting the spring pressure

Mount head between cheek plates with a gap of about  0.170” between top of plates and bottom of  -13 Lateral Pivot Block, adjust to give 51/2 to 6 degrees of travel either side.

Tilt Torque Bar fully back and pre-load the trim  spring to 30lbs tension using a spring balance.