Recently I purchased an RC Transmitter - more specifically a FlySky FS-T6 on eBay. It was a killer price - less than $50, and it has 6 channels.
To my surprise however, I discovered that the left throttle stick does not bounce back when moving it up or down. Everything else springs back - side to side and the right stick springs back when moving up and down and side to side.
Here's a little demo of the transmitter. It shows that the left stick just stays put when you move it up/down. For my application, I was expecting/wanting it to bounce back to vertical center.
I started searching and reading about RC transmitters. Then I took my little question/issue to the appropriate section of the RC Universe forums. So apparently what I bought was a cheap (as in $$$ and quality) airplane/helicopter transmitter. The behavior of the left stick is by design - you don't want the left (usually throttle) stick to bounce back to center when flying a helicopter/airplane.
The smart people over at the forum though were kind enough to tell me I had a cheap-o transmitter (FYI I'm not being sarcastic) on my hands. So they told me that maybe I should buy a better transmitter. I almost sent it back, but then had some other good suggestions such as 'modifying' the transmitter to install a spring inside which will make that left stick bounce back.
Doing a little more research on this route, I came across this:
The problem is that I don't have a 3D printer (yet). It did give me the idea of designing/making my own part from scratch that could be laser cut.
What I did was remove the existing 'control arm' (the one for the right side), and scan it into my computer. However, it kept coming out terribly no matter what settings I used for the scanner. Then I realized that it was because the piece was black. So I took it outside and sprayed one side of it with some white spray paint, then scanned again...success!
Then with some sign software, I had it perform a 'vectorize' function on the image, and boom! I had a nice new vector file. I did modify it just slightly before I prepped the file for laser-cutting. A couple minutes later and boom! Now I had a nice shiny new part for my cheap RC transmitter:
|Original spring, control arm (painted white) on the left; new spring, control arm on the left|
The above image is showing the original control arm that I temporarily removed and spray painted white. The original spring is to the left of that. That was my other problem - I needed a spring to go with my new control arm, otherwise that piece is useless. So what I didn't mention yet, I took dimensions of the existing spring, and found a very very similar spring on McMaster.com (part# 9654K942.
When I received the springs (come in a package of 12), I excitedly put my new control arm and spring in there, and tried it out. I had to 'open' the little loop on one end to get it installed correctly, but that was no problem. When done, I was a little disappointed however - the spring is very strong/tight, so there is a lot of resistance when moving the left control stick up or down.
I took the spring back out, and tried to stretch it out a bit. I think I made it better, but it's still tight. I would like to find a better replacement, but I'm going to live with it for now. (I actually ruined 1 spring trying to do that - I stretched it way too much/far so now it's permanently very long)
You can see that it's now installed in the photo below (control arm circled):
Here's a video demonstrating the new behavior of the left control stick moving up and down thanks to the new parts:
Could you tell that the stick doesn't bounce back the same way as the other control stick? That kind of bugs me but I think it will be ok for what I'm doing.
One last thing - if someone wants to make their own custom control arm for this transmitter, here's the .ai file for cutting your own:
FlySky FS-T6 6 channel RC transmitter centering control arm
Well, I hope this helps someone out there. If you have any questions/comments, you know what to do!