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[hama]

Hello!
I think I just made my own "twinstick". I have a Robbe/Futaba F14 navy that I got for my birthday this winter. I intend to use it in my Smit London eventually and I've been struggling with how to control the bowthruster in a good way without buying devices that cost more than the radio itself. One idea was to get another twinstick and put it 45degr to the other and have rudder and thruster above eachother, but it's to expensive I think. I've talked to Stallspeed today about how to make your own control with a potentiometer and that gave me some ideas. So, tonight I dismantled a E-sky transmitter that I got for free from a friend and built a twinstick. Just chop, chop and trim, trim and glue, glue and voila! It was so much fun, mostly because the tx I chopped up was for free so I didn't risk anything, YET! I just put it together so I don't know if it works yet and I need some help. IF I shall put it in my brand new F14 I'll have to use it for engine control and use the original twinstick for rudder and steering. This is because it has the pots on the outside of the framework while the original has them on the inside, so I believe the only way to fit it would be horizontal and then cut a slot in the tx box for one of the trims. If anyone has any ideas how to do it differently please let me know. Another question is whether the E-sky pots will work or if I have to change them to Futaba ones? I'm afraid that I got carried away while working so I only have pictures of the completed device. I still have to figure out a way to make the sticks center or at least put ratchets on them. Here are some pictures, let me know what you think. Will they work??
Hama

[stallspeed]

F14 has resistors on the circuit board & 5k plug-in rotary pots with atravel of 270^o
A transmitter stick only moves them by 90^o so the wiper is restricted to 1/3rd travel.

To replace with a full-travel 10k rotary or slider pot you must either put a 5.2k resistor at points Y or a 150k (I think)resistor  at X.That will ensure the voltage at the encoder input sees the same voltage swing as with a normal f14 stick

[nick_75au]

Hama,
Very Very Nice
more detail is required 
Not just the F14 that could share this trick methinks
Nick

[boatmadman]

I have a twinstick f14 set, I use the vertical movement of the right hand stick for thruster operation, works ok for me.

Of course, if you are not using an esc with the thruster, another option is to use a switcher unit, set to operate the thruster when the rudder stick is at maximum, plus max trim added. This will allow full rudder swing whilst underway without the thruster coming in.

 I have read somewhere that use of a thruster whilst underway should be avoided due to motor loading issues. I havent had any problem with this, maybe its only relevent to full size?

Ian

[over_powered84]

Hama,
Very Very Nice
more detail is required 
Not just the F14 that could share this trick methinks
Nick

I'M Thinking Me Spektrum Could Do With This Upgrade

[hama]

Hello!
Thanks for your replies.   
Offcourse this could be done to any tx, in fact I think I'll probably test it on my old futaba radio first just in case! Offcourse it helped that the parts I used were free.
Haven't been able to test it yet and tomorrow morning it's off to work for a week again so it will take some time before I can check it. I still have to fix a centering device and some friction break, probably just install the ratchet devices in a way. The biggest issue with my rebuild just now is that it's to wide to fit good in any tx case. If mounted vertical in the F14 the PC-board is in the way. Mounted horizontal seems to work if you cut a new slot for the trim tab. That and the fact that I don't know if it works at all that is!!     Perhaps I can take it apart and show the parts, but now I have to make dinner!
All the best!
Hama

[hama]

Hello again!
I think I'm done. After a week at work thinking how to proceed, I choose to redesign. The first attempt was too wide to fit. I decided that I wanted to use the original twinstick for throttle control and my own design for rudder and thruster. I managed to squeeze in the top potentiometer within the frame structure. The top stick has friction brake and the bottom one has spring centering device. I think I will use the top one for rudder and the bottom one for thruster. I tried to use the E-sky pots as they were labelled 5K as the futaba ones, but the pot only used half the range for same servo travel. It was a simple task to dismantle the futaba pots and install them on my twin stick. The E-sky and futaba radios have almost the same construction, everything was exchangeable with for instance all screw holes on the same place. So with the original pots everything works great! Perhaps I should get back to building on the boat now!!   

All the best!
Hama

[boatmadman]

Nice conversion, now I want to do the same!

Could you please do a 'dummies guide to twinstick conversion'

Thanks Ian

[hama]

Hi Ian!
I was afraid someone was going to ask! I'll see what I can do. In the meantime, the best advice I can give is to try and get a radio tx that you can chop up and just get going. Once you start to take it apart you will soon see how to put it together your way.
Thanks for your interest, I'll get back to you.
Hama.

[FullLeatherJacket]

As an alternative, single-axis self-centring sticks are available from SLM Model Engineers for £Not-a-lot. We use them on our show demonstration boards. An opposing pair of these might serve the same purpose. http://www.slm.uk.com/ will get the contact details, although the sticks aren't shown in the lists.

The pots supplied are 220K but can be replaced with 4K7 types from Farnell, as long as you strip them down and remove all the gunk from the spindles.

Suit yourselves - I still can't fathom how you'd get your fingers around those twin throttle sticks while trying to steer the thing!

FLJ