The next thing was to tackle the throttle. Carl was having to hold the throttle stick with his pinky finger which made it difficult to have complete control over the primary stick. Off to Solid Works again to design a throttle lock out plate. The first iteration was printed and test fit. Some tweaking was in order, so back to the CAD software and then the printer. One hour latter and we had the final part. The plate has the diameter and the bevels built into it, so it just dropped right in and was secured with a couple of micro screws. Now that the throttle stick can only move up and down we needed to design an adjustable lever assembly. The lever assembly took a bit longer to find the right mix of feel and adjust ability. Four iterations were needed before the final parts were installed. The stick on the transmitter has threads. These were used to lock down the lever in the desired position. Our biggest problem centered around the distance between the primary stick and the paddle of the lever. The paddle ended up 2 inches farther away from his other transmitters throttle location. It also ended up 1 inch above. Carl can adjust the side to side movement of the paddles position by 1 inch.
The final hurdle was the primary flight controls. Carl’s first transmitter had and off-the-self enclosed potentiometer mounted to the primary stick. The wires exited cleanly thru a piece of copper tubing. The problem was that the tubing was bending and caused a pinched point at the base. I am not sure how many more flights he had before the inevitable flight of the phoenix would occur. It could not have been long. The DX8 has a robust gimbal and a solid stick. Carl and I looked at each other with doubt as we started to drill the stick out. This was the moment when I asked myself why I get myself into these jams. It all worked out and the wires were feed thru the new stick. An outer support column with a square base was designed and printed. Once this was glued over the gimbals stick, the rudders enclosed potentiometer was attached. The wires from the DX8s rudder gimbal were cut and the new wires were soldered into place. The throttles spring tension and ratchet tab needed adjusting, as did the primary control sticks. The weight of the rudder potentiometer would not let the stick center. this proved to be a problem for awhile. The final fix is a helper spring and a lot of tension.
The transmitter was buttoned up in preparation for testing. It did not work!!!! The radio wouldn’t even turn on…. This is when I vowed to never stick my neck out again; Ha Ha! It took some cursing (which always helps) and a little time away to figure it out. It turns out the SD card was corrupt and wouldn’t let the radio turn on. After removing the SD card all systems were GO. The final item on the list was to design and print a holder/handle that could be attached to a board that Carl sits on. The transmitters handle is used to click the transmitter into a groove in the handle and the bottom is located with a strip of velcro. When Carl stands up after flying he has a handle that allows him to carry the transmitter and the board. Well, that’s about it. 3D printing is just the beginning of the desk top manufacturing boom. There are tabletop CNC wire benders, and desktop CNC milling in my future. Hope you are inspired to bring some of these new affordable technologies into your model building.
