Flysky FS-i6X Accessory Mount

This started out as a project to attach a Kyber button board (and more to the point, the buttons) to my FlySky R/C radio transmitter.  It has since evolved into a modular accessory mount; the button mounting parts are still included and described in case they are useful to anyone, but I changed direction and don't use those parts anymore.

Background

Many droid builders active today have likely heard of the Kyber system.  Kyber adds several additional inputs to a standard R/C transmitter, which are generally used for triggering sounds and animations.  The system (excluding the newer EthOS based setups) works by replacing one of the potentiometers on the radio transmitter with a series of momentary buttons, housed in a 3D printed “button box”.  The necessary signals are read and processed by the Kyber main board through SBUS compatible R/C receivers such as the FrSky RX8R.  This allows one R/C channel to carry the data for as many as 15 buttons (potentially more with alterations to the circuit).

I wanted to use a similar setup for a droid that was already controlled by the Flysky FS-i6X, adding my own iBus based processing system on the droid side.  I had a bare Kyber button board PCB and I got it working with the Flysky radio, but I needed a way to mount the actual buttons to the radio, so I designed these parts to attach everything.

Ultimately, however, I changed direction to use my own custom board with PCB-soldered buttons instead, housed in a box between the gimbals.  As such, I no longer needed to use this mount for the buttons.  Since I had included accessory mounting points and a USB Power bank holder to attach to them, I decided to leave the base mounting parts on my radio, and this turned into a generic mounting solution.

In place of the original button box, I designed a lanyard mounting point for my harness setup. This serves a similar purpose as the silver mounting point that is located on the radio between the two vertical trim controls, as that will be obstructed by the new version of the button housing.

What You Will Need

• A Flysky i6X radio
• Common tools such as a Phillips screwdriver
• A drill and a bit appropriate for making M3 screw holes.
• Various M3 screws.  I would suggest 8-15 of them be between 5 and 8 mm long (the exact number depending on which accessories you choose to install), and 2 more that are between 8 and 10 mm long.
• M3 (4.6 mm OD x 5.7 mm long) threaded heat set inserts, similar to this type.  You need the same number as the total quantity of M3 screws (regardless of their length), so 10 to 17 inserts, depending.
• A soldering iron to install the inserts.
• Some 10mm wide velcro cable strips (if you are using one of the battery mounts)

Note that these instructions only cover assembly and installation of the mount itself.  Wiring any buttons, connecting the circuit to the radio, and/or wiring a USB cord to the radio's battery compartment are all beyond the scope of this document.  (If you join the Mouse droid builder's club, my build thread has much more detail on these topics.)  I also did not supply any sort of housing for the Kyber button PCB, because I abandoned that version before I designed one.

Just as a pointer, though, to assemble the button circuit itself, you would also need a Kyber button board or similar PCB + resistors, wire, soldering supplies, and the necessary normally open and momentary pushbuttons.  I originally got this set of buttons from amazon, which includes enough for two radios, but I ended up switching to an Elegoo 5 x 7 cm protoboard from this pack and using these PCB mounted buttons.

To connect the power bank to the radio, you'd want a USB pigtail soldered to the positive and negative battery terminals (the same place that the internal battery wires are soldered).

Pre-Installation

Make sure you've printed all of the necessary parts, as described below.  There are only two required parts…  

• Mount_Arm.stl - This is the main part of the mounting system.  You will need to repirent this in your slicer so it lies flat on the bed.  It should be printed two times … once in that orientation, and once mirrored (to get the part for the opposite side of the radio).
• Mount_Brace.stl - This is only used to temporarily hold the Box_Mount_Arms at the correct separation so you can mark the mounting holes to drill in hte back shell of the radio.  

The other parts are not all necessary.  It depends on what you are doing with the mount…

• Battery_Holder.stl - this is an accessory that attaches to the Box_Mount_Arms.  It is only really useful in its unmodified form if you have a similar type of small USB power bank to the one I have.  These are pretty generic powerbanks … rectangular, about 96 mm long, 22-ish across, have a USB A output and micro-usb input on one end, and a silver button and an LED on one side near that end.
• Anker_Holder.stl - This is an alternate battery mount.  I made it to fit my larger Anker power banks (the Astro E3 Gen 2 or the Powercore Slim 10000), but other powerbanks around 17 mm thick, 69 mm wide, and somewhere between 142 and 152 mm may work.
• Harness_Clip.stl - This is only needed if you are using the Box_Mount_Arms to attach a lanyard-style clip (such as the one I use for my harness) to the top of the radio, rather than to the silver clip normally located between the gimbals.  I need this because my buttons cover the silver clip.  You will need to reorient this part in your slicer.
• Button_Box_Bottom.stl, Button_Box_Top.stl, and Box_Mount.stl - These three parts are used together if you want to install buttons in front of the antenna

In order to install the mount, you will first need to open the radio by removing the four screws holding on the back shell, disconnecting the battery and USB port cables from the radio's main board, and setting the front half of the controller aside.  You don't want to accidentally drill into the radio's electronics…

Heat Set Inserts

Note: All inserts mentioned below should be mounted as flush as possible to the surface.  I used a technique similar to the Plate-Press method described in this Hackaday article.

You also need to install five of the heat set inserts into each Mount_Arm print.  

1. With the Box_Mount_Arm's mounting post facing upward from your work surface, install the first insert into the top of the mounting post,
2. With the part still in the same orientation, install one insert each into the topmost and bottom-most of the four holes in the main body.  These will face the rear shell of the radio.
3. It may be a good idea to install the remaining two inserts into the middle holes after flipping the Box_Mount_Arm over (i.e. with the mounting post facing down and presumably overhanging the edge of your work surface).  That's not required, but doing it from the original orientation means you may need to clear melted plastic out of the holes before screws can engage these inserts, and you may need slightly longer screws to do so.

While you have the soldering iron handy, if you are planning to use the Button_Box_Bottom and Box_Mount parts, you should also take this opportunity to install four inserts into the corners of the Button_Box_Bottom, and three inserts into the Box_Mount (for the latter part, install them from the side that has the recesses in the curved ends).

Assembly

The order of operations somewhat matters when assembling the mount, because some screw holes (e.g. those inside the radio shell, or those holding the Button_Box_Bottom to the Box_Mount) are inaccessible later in the process, and because you can't slip the assembled Button Box underneath the handle on the radio when fully assembled.

1. Attach the Mount_Brace to the Mount_Arms using four screws in the central four holes (vertically speaking) on the main portion of the Mount_Arms.  This spaces the Mount_Arms correctly.
2. Slip the parts above under the radio's handle so that the mounting posts on the Mount_Arms protrude toward what would be the front of the radio.
3. If available, attach either the Harness_Clip or the Button_Box_Mount to the Mount_Arms via the two longest screws among your fasteners.  This spaces the mounting posts correctly.
4. Align the Mount Arms such that the little curved parts of the notches near the top sit roughly outside the rims of the holes for the radio's screws
5. Tape the Mount Arms in place, then use the outer four holes (vertically speaking) on the main portion of the Mount Arms to mark the positions of the screw holes in the back shell of the radio.  
6. Remove the tape and printed parts (detaching whatever is on the mounting posts, if needed), then drill the four mounting holes that you marked into the back shell of the radio using a roughly M3 sized bit, taking care not to drill into anything important, like the cables attached to the inside of the shell.
7. Attach the back shell of the Flysky radio to the Mount_Arms by placing four screws from the INSIDE of the shell, through the holes you just drilled, and into the threaded inserts in the printed parts.
8. Reassemble the shell of the radio with the four original screws, making sure to correctly plug in any disconnected cables as you do.
9. (Optional) Remove the Mount_Brace and attach the Battery_Holder, Anker Holder, or your own accessory to the mounting points provided on the Mount_Arms.
10. (Optional) Attach the Button_Box_Bottom to the Button_Box_Mount using three screws.  Note that the central and the lower corner buttons may need their soldering feet shortened to avoid hitting the screw heads.  Or cover the screws with electrical tape or hot glue or other insulator.  Attach the Button_Box_Top (with your buttons installed and already wired) to the Button_Box_Bottom using four screws in the corners, routing the wires out the opening in the left hand side of the Button_Box_Bottom.

Update History

• 2024-08-24: Updated Anker Holder part to add a notch for the battery cable.