Flysky FS-i6X (FS-i6) 3rd Gimbal

Welcome to my tutorial on modding your Flysky FS-i6X (or FS-i6) transmitter with a 3^rd gimbal!

Although there are many alternatives out there now a days (especially with ELRS slowly becoming the norm) the Flysky FS-i6X with its 10 channels, 20 model profile slots, channel mixing, expo settings and user community with plenty of tutorials to help, it is an excellent budget friendly controller with plenty of features that still makes it a popular go to even in today’s market.

This radio has two Aux’s; VRA and VRB, which are dial like variable potentiometers that allow various options such as mode switching on flight controllers to controlling servo positions for things like camera gimbals, retracts, robot arms, etc.

The only thing that lets these Aux’s down is the positions and user interface. I love putting FPV on my models and having pan and tilt really adds to the experience! Using the VRA and VRB Aux’s is a good option for handling this task, however, I’ve always found them in the wrong position on the controller and the dials too difficult to use reliably while operating the model that I usually end up avoiding the use of them.

Solution, the 3^rd Gimbal mod! This modification not only allows you to use the VRA and VRB Aux’s like a 3^rd joystick, but does so while also maintaining the full functions of the VRA & VRB Aux dials at the same time (in fact they can also be used to trim the 3^rd gimbal). The installation is easy and doesn’t require and extra programming with minimal modification the original components! And to switch from the gimbal to the VRA/B dials, there’s no disassembly, no switches and no programming.

I have designed this to fit into the ergonomics of the controller so it doesn’t get in the way of normal use and if like me you use your thumbs for the main joysticks, you can use the 3^rd gimbal comfortably with your index finger at the same time making it perfect for pan and tilt operations.

On top of making it as user friendly and as easy to install as possible, I have made considerations to make use of the gap under the controller so it doesn’t look like some ugly add on and so you can still use your favourite controller storage bag without removing it or modifying your storage bag as well.

Parts needed:

1. Flysky FS-i6 or FS-i6X Controller
2. 3D printed parts (listed below)
3. 16x16 B502 2 axis gimbal – also known as joystick or rocker - these can be sourced off most toy style transmitters or very easily online (I got mine from an old Syma controller) - (Ideally you want one with both axis self-return but non-self-return variants work too)
4. 6 x approx. 300mm lengths of 22AWG wire (of different colours) OR
5. 2 x sets of prewired 3 Pin 1.25 mm JST Plugs or similar (optional)
6. Heat Shrink
7. 3 x M2 Threaded inserts
8. 3 x M2x6mm screws
9. 3 x M2 Washers
10. Option – if you don’t want/can’t use threaded inserts. It is possible to use M3/M3.5 x 6mm self-taping screws instead.

See Pics: 2 All Parts and 3 Parts To Purchase

Tools:

1. Philps (Cross head) Screw Driver
2. Screw driver/Hex key - suitable for the type of screws you are using for mounting the gimbal
3. Soldering iron
4. Solder
5. M2 insert tool
6. Modelling knife
7. Wire snips
8. Wire strippers
9. Small plyers
10. File, Sanding Block or Sanding Paper
11. Tweezers
12. 2.5mm/3mm/8mm Drill Bits
13. Heat gun/lighter (for heat shrink)
14. Scribe (or something appropriate for marking out)
15. Blue Tack/soldering jig
16. Masking tape

3D Printed Parts:

1. Gimbal Housing
2. Gimbal Locking Insert
3. Gimbal Stick
4. Gimbal Mounting hole Template

See Pic: 4 3D Printed Parts

You can download the parts above or for free from my Makerworld or Thingiverse pages. If you have a Bambu Lab printer you can print them straight off the app too.

Makerworld: Click Here

Thingiverse: Click Here

The first thing to do is print all the parts needed. There are 4 parts, the housing, locking insert, control stick and template that will make marking out the holes on the transmitter very easy.

You can download the parts above or for free from my Makerworld or Thingiverse pages. If you have a Bambu Lab printer you can print them straight off the app too.

Makerworld: Click Here

Thingiverse: Click Here

All the parts in the files have been pre-orientated for best orientation for printing for most FDM printers, however, all printers vary slightly in terms of print quality so the advice below is more of a rough guide.

For reference, the parts in this tutorial have been printed in black PLA Basic.

Gimbal Housing –

This is the only tricky print. The best orientation is right way up as the STL file is loaded and use supports.

Gimbal Locking Insert –

For best results print upright and supports shouldn’t be needed.

Gimbal Stick –

Print upright and use a brim to support it.

Gimbal Mounting Hole Template –

Very simple to print and will only need to be used mark out where to holes need to be drilled in the transmitter. This can be printed flat with no supports and as finish quality is not important so quickest printing settings are recommended.

This step will be showing how to test fit and adjust the parts to make sure everything fits together properly without any play in the parts.

Firstly, test fit the gimbal into the housing before adding any wires. This part was designed to be as snug as possible so depending on your printer and material quality you may need to fettle the inside of the housing until the gimbal can be pushed into place.

See Pic: 5 Gimbal Housing Fitment

Once the gimbal is in the housing, the next is to test fit the locking insert. This is the piece that secures the gimbal into place and prevents it from moving about so if it is loose, you’ll find the gimbal will rock around in the housing and make the operation of it feel sloppy. As these are cheap gimbals, their tolerances can vary and along with your printer/material quality tolerances, there can be a bit of variation on how big this part needs to be so the part has been designed with some post modification in mind to make the install easy and successful for all. Start by pushing it in behind the gimbal firmly until it won’t go in any more. The goal is to modify this part until it is flush with the housing under side.

See Pic: 6 Locking Insert Test Fit

File/sand the surface of the locking insert that sits against the back side of the gimbal component until it becomes flush with the housing. Depending on your printer/material quality, you may also need to take a tiny bit off the top of the Locking insert.

See Pic: 7 Locking Insert Fitment Correct Position

Now place the gimbal housing, (gimbal and locking insert assembled) on to the transmitter where it is going to be mounted and check that is sits flush. Any adjustments needed will be easier to carry out now rather than later.

See Pics: 8 Gimbal Seated Flush On The Transmitter 1 & 9 Gimbal Seated Flush On Transmitter 2

At this point it is a good time to test the physical function of the gimbal. Make sure the stick moves in both axis smoothly and returns back to it home position. If it snags or sticks in position you may find the pivot rod that protrudes from the gimbal is rubbing slightly on the housing. Remove the gimbal and using a modelling knife remove some material in the housing where the pivot rod maybe rubbing it. Test fit and repeat again until the gimbal moves freely.

Now we know all the parts fit together correctly, this step will be showing how to build up the gimbal ready for mounting onto the transmitter.

Insert the M2 threaded inserts. There are 3 inserts to fit make sure they are straight, flush and if there is any excess material, remove it using a modelling knife.

See Pic: 10 Threaded Inserts

If you don’t want to use inserts. It is possible to use self-tapping screws instead. Depending on your printer or material quality/type, you will need 3 x M3 or M3.5 x 6-8mm self-tapping screws. you won’t need to fit these now but best to work this out at this stage.

Time for soldering! The wiring is fairly simple, just follow the simple wiring diagram.

See Pic: 11 Wiring Diagram

There are 6 wires in total, however, all the wires will be coming out of the same hole in the transmitter casing and as it is best to mount the gimbal before soldering into the transmitter, working out which wire goes to which terminal in the transmitter once the gimbal is fitted can be tricky, so to avoid confusion later, here are three options I recommend (remember which ever option to choose, once the wires are connected to the gimbal take photo of the connections for easy reference later!):

First option: Use different colour wires for each of the 6 terminals on the gimbal and note which colour goes to which terminal. Cut 6 lengths of 22AWG wire to approximately 300mm, these will be cut down but best to leave long until we know exactly what length they need to be. Strip one of the ends and prepare them for soldering along with the 6 terminals on the gimbal.

Second option: use the same colour wires that correspond to the wires already attached from potentiometers terminals going to transmitters main board (White, Green & Yellow) with one of the centre wires (Green) being a different colour (to differentiate which of the gimbals axis it comes from) and twisting the cables into two groups so you know which group of wires goes to which potentiometer. Cut 6 lengths of 22AWG wire to approximately 300mm, these will be cut down but best to leave long until we know exactly the length they need to be. Strip one ends and prepare them for soldering along with the 6 terminals on the gimbal.

See Pic: 12 Wire Colour Coding

Third option: This is what I have gone for in this tutorial. If you are using pre wired plugs (make sure they have around 10mm to 15mm on each plug), is to use opposite plugs (Female/male) for both sensors so they can’t be mixed up when plugging them in. you can use any type of 3 pin plug you want so long as it fits though an 8mm hole. In this tutorial I have used 3 pin 1.25 mm JST plugs.

See Pic: 13 Prewired Plugs

Once the wires are soldered, if you have any excess wire exposed, cover it by but putting some heat shrink on the terminals.

See Pic: 14 Gimbal Wired Up

Next, loosely feed the top 3 wires into the top hole of the insert and feed the 3 wires on side into the side hole and both through the bottom hole.

See Pics: 15 Insert Wire Routing 1 & 16 insert Wire Routing 2

Insert the gimbal into the housing and then while carefully feeding the rest of the wires though the holes in the insert, push the insert into place so it is flush with the housing.

See Pic: 17 Insert Fitted

Your gimbal is now ready to mount onto your transmitter!

See Pic: 18 Gimbal Assembly Ready To Mount

Time to take apart your transmitter to get into the insides.

First remove the batteries from the transmitter and remove the 4 screws that hold the 2 halves of the casing together and keep them somewhere safe.

See Pic: 19 Remove Casing Screws

Carefully pry the two halves apart and disconnect the trainer port and battery plug (Noting where they came from) so to make it easier working on the back half.

See Pic: 20 Battery And Trainer Port Plug Locations

Turn the casing so the back is facing you. When holding the transmitter, the gimbal is on the right-hand side, so with the casing upside down you will be working on the top left corner.

Now it’s time to mark out the holes to drill. The template is affectively an imprint of the corner of the transmitter. Turn it flat side facing you and line the edges up.

See Pic: 21 Template 1

To help you can place a piece of masking tape along the bend/line on the casing.

See Pic: 22 Template 2

While holding template firmly, using a scribe (or appropriate tool for marking out) mark out the 4 holes for drilling.

For the 3 smaller holes use a 2.5mm drill bits (or appropriate size if you are using self-tapping screws) and for the larger hole an 8mm drill bit. Once drilled clean the holes up if needed.

See Pic: 23 Holes Drilled

Feed the 6 wires though the 8mm hole and line up the gimbal. Turn the casing over and using 3 x M2x6mm screws and a washer on each, fasten the gimbal to the housing.

See Pic: 24 Gimbal Assembly Mounted

Bring back the front half of the transmitter and place it beside the back half.

Connecting the 6 wires VRA and VRB Potentiometers:

Choose which axis you want each of the VRA/B Aux’s to handle. It is personal preference which ones to assign them to but in this tutorial, I have assigned the pan/horizontal axis to VRA and the tilt/vertical to VRB.

There is no exact length required for the wires to the potentiometers. You want them long enough so you will be able to comfortably work on the transmitter in the future without straining the cables.

If you chose the plug option (as per this tutorial) so it is easy to disconnect them in future, make sure you use the opposite plug to the ones on the gimbal. I have used 2 sets of 3 pin 1.25 mm JST plugs, however you can use any 3 pin plugs that are of appropriate size that can fit though an 8mm hole.

As the VRA/B potentiometers are easy to remove (pull off the dial on the front, undo the retaining nut and unplug the leads going into the main board) I recommend removing them as it is much easier to solder them when they are out of the casing

Making sure you always refer to wiring diagram and the notes/photo you took of the gimbal, connect the wires up to the corresponding terminals on the VRA and VRB potentiometers.

See Pics: 25 Potentiometers Wired Up 1 & 26 Potentiometers Wired Up 2

Reinstall the potentiometers and if you are using plugs, plug them into the corresponding gimbal plugs. Reconnect the battery and trainer port plugs and insert the batteries.

See Pic: 27 Reconnecting The Plugs

Turn the transmitter on and either select a model you have already assigned the VRA and VRB switches or assign them on the current model profile you are on.

Make sure VRA & VRB dials are in their cantered position (Both dials facing right)

See Pic: 35 VRA & VRB Centered

Assigning switches –

1. Press and hold ok
2. Select Functions Setup
3. Select Aux switches
4. Select the channel you want VRA on (usually 5)
5. Use the Up and down buttons to select VRA
6. Press and hold Cancel to save selection
7. Repeat the process for VRB

There is no extra programming needed, but to confirm the gimbal is working and wired up correctly, go to the display selection to view the live channel feeds and press up and down to see the channels you have VRA and VRB assigned to.

When you move the gimbal stick or turn the original dials you should see the digital bars moving.

View Live Channel Feeds –

1. Press and hold ok
2. Select Functions Setup
3. Select Display
4. Scroll until you see the channels you have set VRA and VRB on
5. Move the stick and dials and you should see the digital bars moving

Alternatively you can turn on your model that has pan and tilt servos set up and check they are moving as expected when you move the gimble.

Trimming the Gimble:

If you find you need to trim the gimbal, you can simply use the VRA and VRB dials to adjust the trim.

If you find that the gimbal is not operating in the correct direction or behaving oddly, check all the wires are connected in the correct order and there are no loose connections or shortcuts. If one or both the channels are moving in the wrong direction, switch the two outer wires on affected potentiometer(s) to change the direction.

The last step is to put the transmitter back together!

Make sure all your wires are tucked away and won’t get trapped in the moving parts of the main stick gimbals or pinch when the casing halves are put together. Then reinstall the 4 screws on the back.

See Pic: 4 Casing Screws Reinstalled

If you haven’t already, install the gimbal stick, turn on your radio and do a final check that everything is working correctly.

See Pic: 29 Gimbal Stick Installed

And that it! All ready to use!

I am a hobbyist designer and creator and love to know how I can impove my designs so any comments or advice on how my design or guide could be improved are always welcome! Thank you for reading my tutorial and have fun making!