Simchair MKIII I2C single engine collective lever

by hc625ma Jun 22, 2018
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So many parts choices :)
If my main goal is flying the Huey what's my selection of printables going to be? This collective and what else? :)
I've cloned the git repo but I'm a bit overwhelmed with everything there.

Hi! Well, for the best possible experience you will need:

single engine collective with the pneumatic actuator mod
Huey collective head
reinforced cyclic gimbal with springs
b8 stick grip

and the Arduino Leonardo based controller to drive all this stuff =)

I recommend using the set with IKEA GUNDE chair for better ergonomics (the frame for controls and MALINDA pillows mod for it are in the repo as well)

Although every part of the set can be used separately, special features like software pseudo force trim, DCS Huey throttle operation below idle stop detent, require several devices to be present.

Please visit my site http://hc625ma.org for detailed build instructions with photos.

Note, that there are 2 git repos, one for software (simchair_i2c), another for hardware (simchair_models).

Please feel free to ask questions.

Cheers, Alex

Awesome, thanks :D I'd been browsing the site and the git repo and I was just having info overload.
Man, you put a LOT of work into this project!

Yup, it took quite a lot of time and effort to bring it to its current state. A few guys supported it by ordering some hardware from me, that allowed me to further refine stuff and write proper build manuals =)

Do you sell a kit with some of the electronics or square tubes? I'd totally support that when I have some cash on hand :)

Happy to hear that =)

Sure, I can either send you everything assembled, or just printed parts (probably cheaper then printing them locally due to the current rates, if you don't have your own printer), or just some parts like switches or springs that you can't find locally =) Square and rectangular tubes shouldn't be hard to find though (but springs from Lada classic can be, so you can just use a similar one, spring holders are adjustable) =)

The only issue can be time, I am now working on an order, will finish it in a few weeks. Please contact me through email, hc625ma at g mail.com =)

Hi! I have a question about the Arduino pro mini: Should I use the 3V or the 5V one?

The 5v one as SS495A is a 5v sensor. You can also opt for using an SS495A2 as it seems to have slightly better precision (all of them work well though)

This is a brilliant project. I thank you for your efforts and for sharing. Where did you source your 6x6x4 magnet from? I cant find them on ebay or alibaba. Can you recommend a readily available substitute magnet or could I join four 5x5x1mm and hot glue/epoxy them in place? Thanks again :)

If you plan to build this, please visit my site http://hc625ma.org as this is the place where all the latest fixes and new stuff is posted before it appears here. For example, right now dev snapshots of the twin-throttle collective lever and the Huey collective head are available =)

Hi Mark and thank you for your kind words! The magnet seems to be a problem. I will add a 5x5 holder version, the only thing the lever movement range may be a bit different with it (but as the lever has hardware calibration now it doesn't really matter much I think). I am not sure that gluing 4 magnets together is a good idea (looks like a pain to me), it's better to buy a 5x5x5 or something one =)

Here's the 6x6x6 magnet on eBay:



Hello! Thanks for this great project! I am about to print and build it but there are many questions. For example: On your website and here you write that one 6x6x4 magnet is neccessary. But the link you posted is to a 6x6x6 magnet. Which one is the correct one? I am having a very hard time, finding a 6x6x4 one.

Also, please follow the news on the site and GitHub repo for the latest improvements (it's hard to keep things current in multiple places simultaneously). This lever is very good and doesn't need any changes except for maybe a better enclosure bottom lid (the one like this: http://hc625ma.org/wp-content/uploads/2018/08/gimbal_mount_v2.png).


Hi mate, you're welcome! Sorry, looks like my mistake. I use 6x6x4 magnets, but you can use a 5x5x5mm magnet, Mackshot have tested it and it seems to work fine. If it will need some adjustments, we will figure something out, just let me know how it went for you. Also, I will be posting a better enclosure bottom lid today or tomorrow (on GitHub).

new GitHub repo for 3d models: https://github.com/hc625ma/simchair_models

5x5mm magnet holders (Mackshot recommends using one with an offset) https://github.com/hc625ma/simchair_models/tree/master/Mods/Peripherals/Flight%20stick%20gimbal/STL

Thank you for the quick reply! I already ordered the print from the files I found on your website 1 week ago so I hope that will be fine. And of course, after reading your reply I googled again and found a 6x6x4 magnet on alibaba... I'll get back when there will be more questions. Thank you!

I haven't made any changes to collective levers recently, so everything should be fine. The only tricky part can be the lever frame (the one with SS495A socket in it, I usually print it in 0,2mm layer height with a 0,25mm nozzle. If it will be too tight, just widen it carefully with a knife, shouldn't be a problem. I'd be happy to know the details of how your build would be going. Cheers!

Thanks for the reply. I got hold of 5x5 magnets for $6 for fifty of them from ebay. I am about 3/4 through printing the single I2C collective and am waiting in the electronics from china. Will upgrade it after I have assembled and tested it to include the switch head later and maybe the cyclic for the DCS UH1. Have to figure out how to mount on to my simxperience motion seat. Thx again for your work :)

http://hc625ma.org/gimbal-magnet-holder-mod-for-5x5mm-magnets/ here's the link to 5x5mm magnet holders, there are two versions, try and choose one that suits better, and please tell me of your results (if they don't work at all, we'll figure something)

You're welcome! Will post the magnet holder for 5x5 magnets today in the evening. Motion seats are cool! Don't think that rubber band based tensioner would work well in this case, but as long as you'll be able to hold it while doing barrel rolls it should be ok) I will think about that. As a hotfix i can add an option for the force trim function of the cyclic to include the collective as well, or maybe a separate collective force trim function will be even better. This will allow you to use the lever without the tensioner at all)

Thanks. I recieved and tested the 5mm magnets and they seem to work fine in the offset modified holder. I am getting a range of 420 to 1023 before calibration. After calibration I got the full range. Does that sound acceptable? Hopefully will be able to do test in the next few days after I figure how to mount to the simXperience sim. Will probably be able to use your mount system but collective will be at awkward angle. After I do some upgrades to my printer will start on the UH1 switches next week or two. Loving this project....have never used arduino and am learning so much.....its not as hard as I thought. Thanks again:-)

Sounds good! Do u mean hardware calibration? If so, everything is ok =) Angles are not a problem - let me know what u need and I'll be able to change the mount for you, that's not a problem. The thing is, I have no idea how the tensioner and the whole lever will perform under dynamic load in a motion sim - looking forward to seeing your test results!


All works fine both software and hardware calibration. I had to mount using an angle bracket mounted under the chair temporarily until I figure a better system. It probably just will need to turn the rear cover 90 degrees and drill two holes. Took the UH1 for a fly and works great :)
Have you posted a build thread over on the DCS forums.....I couldn't find it if you did?
Cheers and thanks

Glad to hear that! Try to avoid using software calibration (in windows), it kinda kills precision =) Haven't posted build manuals yet - but will do shortly. If you want to build the head- look through the manual for the 412 one: http://hc625ma.org/ab412-collective-head/

The difference is the Huey head only has 1 Arduino in it, and it requires a bit more careful cable management. Otherwise, the stuff is pretty straightforward, you connect buttons and switches between pins and zero, the thumbstick to an analog input, flash the pro mini with software and that's it =) For 3-way switches, connect ground to their center and adjacent pins to their poles. Cable management is really the hardest part there =)