Simchair MKIII I2C AB412-style collective head

by hc625ma Jul 4, 2018
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do you have an estimate for what the total cost for electronics and hardware are? I'm also assuming it uses a buttload of filament, but filament is cheap.

Basically, it's Arduinos (clones), buttons, switches, potentiometers, and ADS1115 ADCs. Nothing particularly expensive, but prices can vary depending on where you are and how long you are willing to wait for them to arrive =) I will be porting this particular head to the latest firmware quite soon.

Alex, another question. In the tutorial, you show 2 pots (one on each side). Did you recently add the second pot, because my print of the dual head has only one pot, on the inside (right). What's the second pot for? I can just drill a hole for it. Also in the tutorial you do not list the type of pot. Could you identify it please?

BTW, I went with simply on-off toggle switches and one big on-off-on. I can add another on the side, but I need to add the pot(s) and then I can wire up to the arduino and move to the other side of the head....

Let me again congratulate you on this excellent work. Really, it is amazing and you should offer it as a product.

These 2 pots are just additional generic purpose axes. There are no such pots or a side mounted mode-switch in a real 412, but their presence does not really ruin its look or anything, the head is not 100% scale anyway, and stuff like that may be useful. Yet, the pot on the left is really hard to reach in flight, so the default option (there are a few more under "Mods" directory - https://github.com/hc625ma/simchair_models/tree/master/Mods/Peripherals/AB412%20collective%20head/STL) goes with a mode switch and one pot. One pot is totally fine, I would not have worried about adding the 2nd one at all =)

About your picture: the idle stop switch (to the left of the big starter switch) should move sideways, like the starter. The governor switch can move either vertically or horizontally, as in a real 412, this is a 4-way switch. The head looks great =)

Excellent, I will add the one pot and the one mode switch as planned. Any particular pot I should use? The switch directly to the left of the big starter switch is indeed left to right. The 2 switches above that are up and down. The one below the left joystick is side to side and the one below the right joystick is up and down. The switch to the top right of the starter is side to side as well. This is really an awesome project. Don't know if I will have it ready for the Maker Faire here in March, but I am going to try.

Thank you! =) I think it's perfectly possible, 1-2 evenings should be enough to build any one of the peripheral devices.

About the pot, something like this one will do: https://goo.gl/vbi1Zh , basically you need a linear pot, something like 5 to 10 kOhm that will fit the slot =)

About the direction of switches, basically in a real one (if we omit the fact that the governor switch is a 4-way switch), all switches except idle stop and starter go up-down. But I think its perfectly ok to turn them as you like ^_^

Excellent. I ordered the pots. I think we can work with the switches as is and go from there.

So while cleaning up the dual throttle, I snapped both cylinders inside the outside throttle handles. Are these just spacers and can float freely, or do they need to be glued back? (The throttle stops are still there, mind you--this is just the long cylinders that were attached...)
Thanks in advance!

These two cylinders are just built-in supports because some of the slicers do not add them correctly to this part and they are very critical there, so just throw them away!)

It is possible to see an assembly diagram of the AB412 lever? It seems like the levers stay hollow and nothing is inside to re-inforce the grips. I am wondering if they could snap in half if there wasn't something like a PVC pipe inside. I have already printed the head.


Hi! This picture can shine some light on the internals of the levers:

A 10x10 aluminum pipe goes through the lever and connects throttle grip frames assemblies together and with the rest of the lever. Each throttle grip frame consists of two parts, that are connected to each other with a pin on the p1 and a slot in the p2. This is a very tight connection (do not connect p1 and p2 frame parts without a throttle grip - it will be almost impossible to separate them, the throttle grip itself reinforces the assembly), and it is reinforced by a 4x80mm screw with a nut, that is press-fitted into throttle grip frame p1. There's also a cable channel for wires, that goes through the whole lever. If you follow the assembly manual here:


you should not have any troubles while building it (it has been written while I was assembling the lever for my friend).

The levers are quite strong (I am mostly using the single one, but my friends have been using a pair of twin levers for a while without any issues). Note that I recommend printing stuff with slightly higher temperatures (205C) and moderate cooling (that depends on your fans, I use something around 60-65%) with 40% infill. I use regular (inexpensive) PLA.

This video shows the single lever and other hardware in detail:

Take a look at the pneumatic mod, it's really good:

Please feel free to ask questions (you can also leave comments on the site)!


Excellent, thank you. By 10x10 pipe I presume you mean a square cross section pipe that is 10mm x 10mm that goes through the square channel through all the head and grip parts. I will definitely look at the pneumatic mod. Thanks again. I am sure I am going to have a ton of questions. This is going on my existing Fixed Wing Sim that was a hit at the Maker Faire here in VA this past March and adding heli controls will make it an even bigger hit. Plus I always enjoyed my few hours in an R22 and this way I can return to that world.

Yup, you're right. Your questions are welcome =)

P.S. Can you please post a link to your fixed wing sim?)

Hello again,

I've been looking at the conversion to the pneumatic design and could use some help. I have the parts printed from the head of the twin collective to include the throttle (twist grip) up to, but NOT including the part that has the ring at the top. I stopped there because based on the video and the pneumatic mod, I am using different parts from here. I have printed all the twin collective parts located in your GitHub repository here:


However, I do not see the actual mod files that I need to print to add the pneumatic modification. I thought they were all here:


But it seems that the parts I need are actually not in STL form because they are all here:


I don't have SolidWorks and I appear to not be able to convert any of these files to STL. Can you point me at the the specific pneumatic mod parts? I'd like to get those printed on my farm and order the electronic components to move forward with the implementation. Also, you have, in the video, a multiple throttle quadrant, which is great, but I already have one of the Logitech/Saitek one of these. Is your Collective linked to the throttle quadrant you show or is it completely independent (I am not clear from the documentation and video). I hope it is completely independent as that would make life easier. I can, alternatively also link my collective to one of the 3 levers on my Logitech throttle quadrant like what I saw done by RogerDodgerAviation.com, but that still means having to program in twist throttle controls separately. I also had planned to use a standard joystick as a Cyclic, I presume that is ok as well.

I am sure I am going to have a ton of other questions, so please bear with me.


Hi! The files for the pneumatic mod are under "Mods" directory:


Pneumatic mod can be applied to both single and twin collective levers (haven't tried it with the twin lever yet, but will be assembling it in a few days). Here's a crude manual (will improve it when I will be building another lever for my friends):


Throttle quadrant is totally independent (as is everything else, any part of the set can be used standalone). The cool thing about it is that you can add as many axes as you want, and it supports secondary axes by default (e.g. reverse, when you move throttle lever past the (programmable) mark, another separate axis begins to increase)

I don't recommend you to use a regular joystick as a cyclic, take a look at a new reinforced cyclic gimbal + b8 stick. I believe it allows for more realistic movements (you can make a floor-mounted lever, or mount the gimbal under the chair Bell-style), also firmware pseudo force trim feature really changes the way you fly helicopters. If you want a spring-loaded cyclic, it's probably the most realistic option (another option is to pretend that force trim is "off" and to fly without springs, and there's a special force trim mode for that as well in firmware). The cool thing about force trim is, it also affects pedals, just like in a real helicopter (so you may want to print pedals as well :D ). Anyway, every controls piece can be assembled in about an evening, so shouldn't be too much of a problem =)

Please feel free to ask questions =)


I have now started assembly. Looking at the head, and seeing how the joysticks fit, the ones I picked up (which I thought were the ones I should get) have 9 pins instead of 5 (as depicted on the website). They are 3 sets of 3 pins. Here's the link from Amazon (https://www.amazon.com/gp/product/B01M5L1BMS/ref=oh_aui_detailpage_o05_s01?ie=UTF8&psc=1). Are these usable and if so, how does that change the wiring? To be clear, what I ordered came with 9 pins, but the picture on Amazon shows 4.

I think there shouldn't be any problem with these, 9 pins are actually 3 +5V pins, 3 GND pins, 2 signal pot pins and 1 button =) Just solder 5V and GND together (they may be already connected internally, check that,in this case, just use one of each!) and bend/cut pins so they will fit into the box. If you decide to build the B8 stick grip later, 9 pins can be a problem there, most likely there wouldnt be enough space for them (you can still desolder them and connect with wires).

I have updated the assembly manual for 412 head recently: http://hc625ma.org/ab412-collective-head/ , check it out!

Excellent, thank you. I would have to drill mounting holes too. Very annoying from that vendor really. My toggle switches are taking forever to arrive. Any alternatives I can try?

Sure, pretty much anything that fits into the box with pot boards installed)

Thanks yet again for all this information. I have started to make my shopping list. I have located a Leonardo (R4), a bunch or Arduino Minis and the joysticks. I have also located a Push Button Switch (7mm) that suits (PBS-110 because I could not find PBS-10B-2 switches on Amazon...I'm trying to one-stop-shop as much as I can). For the MTS-223-A1 and A2 switches, I am able to find the -D1 switches (DPDT). I might have to go to AliExpress for those.

PBS-110 looks the same as PBS-10-B2, MTS-223-D1 looks like it will fit as well =) Any variations of switches will do, as long as their base dimensions are the same (space is tight inside of these heads!).

It's starting to look like something. The big switch I have there has to go to front to back instead of side to side if I want it to fit, and when I do, the little switch at top right can't mount. I might have to relocate that hole a little to the left (to accommodate that big fat switch). A bit lazy to wait for a reprint, and might just drill a new hole and plug up the old one...or I might print it again. I like that ON-OFF-ON switch to go side to side instead of front to back and it's pretty tight in that enclosure anyway. BTW, I ordered new joysticks and they should be here shortly. One joystick can run a chin turret and one can run a searchlight.....or so my helicopter flying buddies tell me. I used to fly (an actual) R22 and all that had was a throttle......

I think it would be better to use a different switch as the space is really tight there. Your joysticks seem a bit out of place, do they have different dimensions? Are you sure you positioned their frame correctly? As i've been told by an IRL Huey pilot, switches can be wired differently in different helicopters, basically according to company's needs. There's no such thing as "this button does that and only that", except maybe for smth like starter/idle stop and things like that, so feel free to adjust everything to your needs without any harm to realism =)

By the way, being an IRL R22 pilot, how do you find the dreamfoil one for xplane?

Yeah those Joysticks are the 9 pin ones and their board is too big. The new ones arrived today so I will try them out tonight and that should get them set up right. I just jammed these in there to see how it looks (just because this whole process is so darn cool). I haven't delved into dreamfoil yet. I ordered a few planes for my sim but none were the R22. I need to do that too. Right now I have multiple mods going on: retire the Saitek 6-pack and replace with a DIY monitor made out of a dead laptop's LCD, a GNS530 instrument, a GNS 430 instrument and a G1000 PFD panel. Out of 6 Saitek round instruments, I will keep 3 as 'steam gauge' backups with the other 3 going to the Heli Sim. I am also adding dual engine controls so I can fly Multi-Engined fixed wing planes. So quite a lot of work. Last week I rigged up a seat adjustment crank based on a TR8 leadscrew and some V-wheel rails from a defunct CNC machine. I am debating using the same sim to fly both fixed and rotor wings or just make a new sim unique to rotors....but I suspect my bride might have something to say about 2 sims in the house....

Take a look at this post:


Somehow I haven't even posted it properly yet, but it works =) You can stack any amount of axes you want, hell, you can fly a Stratocruiser with it :D The cool thing is, it has analog reverse support (secondary axis with a programmable threshold can be assigned for each potentiometer) also it is super easy to make.

How about flying formation with your bride?) A perfect way to justify the 2nd one! :D

I once talked my friend into flying the 172 on autopilot in FSX (she had no joystick lol), has been quite fun, I even managed to almost land her :D:D:D

I saw that thing of beauty and wondered.....Might have to get that in place of my current CH Products and Logitech controls. Sale!

When I first rolled out the sim last year, my wife had me put up the Cirrus Jet and she started to fly it and I couldn't get her off the thing for a full 45 minutes. But she won't fly with me in a real C172, or any of the twins....sigh.

Super, thanks! Parts on the way!

Ty, looks great!

Hi Alex,

It's been a while since I worked on my collective. I spent a lot of time upgrading my FW Sim and then sold it to my flight school. It's time to return to the collective. I know we discussed this before and you said it was unlikely that the collective would be usable without also making the cyclic and the pedals, but if you are inclined, and have the time, maybe we can collaborate on a way to make that happen. The reason is the commonality of components. In any case, I will let you know soon when I return to the project.

Hi! It seems like you have understood me incorrectly - it's very usable all alone :D If you don't want a master controller (which can be mounted onto the pneumatic mod rail so it won't take any extra space) and know just a tiny bit about Arduinos, you can easily make it a standalone USB device.

Btw, the previous post was in 2018, the project has changed a lot since then. The current version is MKIV, the software was completely rewritten, look it up in simchair4_models and simchair4_software repo.

I'm guessing that one could alter the chair mounts for something a bit sturdier like this?
The cheap chair is a great idea. I'd need something a bit more... For A Fat American.

:D:D:D That lightweight GUNDE chair is just a legacy from days I wanted to use these controls to fly RC helicopters (these days are yet to come, I hope =) ) I think there will be no problem with changing mounts (you will have to measure an inclination angle of the chair frame). Would be cool if you choose some chair available worldwide (like IKEA one), this way our efforts in redesigning the frame for it may be useful for someone else (i hear complaints about that chair constantly lol) =)

No one's commented on this?!
No one's tried to print this?!
Okay, first question: PLA, ABS, or PET? It seems like PLA wouldn't be especially durable. I tend not to trust it when mixing with metal screws that would love to snap it like a twig, especially on sim-gear that I probably wouldn't use in an especially gentle fashion when I'm getting shot at.

This seems like a GREAT concept though, and am looking forward to testing it!

What slicer settings are you using regarding infill and supports? I have a Prusa Mk2S, which I suspect is up to the challenge, but would like some good settings to start with.

One more thing, all the STLs are oriented for better print results, try printing them as is. Some of them are actually oriented in an unusual way =) This is either for better print quality or to get better precision where it is especially needed (like Hall effect sensor sockets).


Thanks for the info! I'll start making the parts tomorrow morning!

Hi mate! Sadly, there is a lot less hardcore helicopter pilots out there then u think =) I have even seen guys flying DCS Huey without pedals...
You should have no problems printing it in PLA (I use PLA PEDALS almost every day for quite a long time) ;) All screws have nuts on the other side of the hole, but you still have to be careful when tightening them.

This is just the switch panel, collective levers are here:

Single: https://github.com/hc625ma/simchair_models/tree/master/Components/Peripherals/Single%20collective
Twin: https://github.com/hc625ma/simchair_models/tree/master/Components/Peripherals/Twin%20collective
Huey switch panel: https://github.com/hc625ma/simchair_models/tree/master/Components/Peripherals/Huey%20collective%20head

The single one is probably a bit more durable (but this is a collective lever, you normally do really gentle movements with it, because you don't want that fan overhead to detach lol). I usually print everything with 30-40% infill, 0,2 to 0,25mm layer with a 0,25mm nozzle.

I can say that as long as you stay within operational limits of the helicopter you won't break anything :D