My OSW direct drive steering wheel is up and running, with a Granite Devices Ioni servo drive on an Ionicube 1x board. I’m on a budget, so I built everything possible from timber, with many hours of work. I used some 100 year old palings from a fence we pulled down, which are a beautiful dark hardwood. I also made an adaptor for the Momo to clamp onto the motor shaft from timber, I shaped a circular piece of timber, cut a 24mm hole, and cut it into two c shaped pieces, with m6 bolts to clamp onto the shaft. It works perfectly. I didn’t need to buy a motor mount, enclosure, and b-com connector for the steering wheel, saving hundreds of dollars. I’m very happy with how it’s worked out.
A big thank you to Martin Ascher and all the other guys that put together the OpenSimWheel project, MMOS for his Disco firmware, and Beano for his pioneering work with the Ioni BruteForce 2 project. Tero at Granite Devices has done an exceptional job with the Ioni servo drive, it’s a marvel of engineering. His support is top notch as well. I wouldn’t ever bother looking for an alternative brand of servo drive at this stage, the Granite Argon and Ioni drives are brilliant.
I have mounted it on my temporary couch rig for now, we’ll be moving house in the future and I plan to setup a dedicated rig with a proper racing seat and use a VR headset when they go on the market. It’s rock solid as it is, and I can sit on the couch and drive
Assetto Corsa iRacing on our 80″ projector screen this way. I’m hanging out for VR.
I also saved money by using a Mitsubishi HF-SP102 ac servo motor I bought off ebay, and changed the encoder to a CUI AMT-102V. The Ioni servo drive and disco work with incremental encoders. The motor swap seemed a bit risky at the time, but it’s working great. The other huge benefit for me is that the Mitsubishi motor weighs only 6.5kg, compared to 12kg for the smaller Mige motor, so I can move my rig around and sit it on the sofa.
The servo drive enclosure is about 320mm x 220mm x 220mm. It has a duct on the front of it, and a 80mm fan on the rear to keep the Ioni nice and cool. It was fiddly to mount the electronics, with only a bottom access panel, but it worked out fine. With just the one opening on the bottom, it keeps it nice and tidy on the top without any visible screw heads.
The motor mount is made from old scraps of fence paling which were left over from the main enclosure, I laminated them together and used a jigsaw and an angle grinder with a sanding disc to shape the side profiles.
The controller for the servo drive is a STM32F4 Discovery running the MMOS firmware, which also interfaces with my existing G27 shifter and pedals, here’s a post describing how you get them working.
The most important thing is how this wheel drives – it is simply amazing. In a different league to the Logitech G27. It is quicker and more dynamic, which allows you to feel the car start to lose grip in time to counter-steer and hold a slide, rather than tank slapping like on the Logitech. In Assetto Corsa I am now able to catch slides in the most twitchy of cars, like the Sauber Mercedes C9 at Spa. I always struggled with my old wheel. It turns absolutely smoothly, with none of the cogging or notchiness. There is no play in the bearings, it’s made to cope with industrial loads. It’s going to last for a long long time, unlike the plastic cogs and bushings in consumer steering wheels. There is a huge tactile range of feedback, from the smallest ripples to huge cornering loads.
Finally, as you would expect, it has incredible torque that will wrestle your arms into submission. The Mitsubishi hf-sp102 puts out less torque than the smaller Mige, but it still provides huge amounts of resistance compared to a non direct drive wheel. Specifications list constant torque at 5nm, and max torque is about 15 nm and that’s enough for me. I’m running 12A constant, and 18A max current in the Ioni setup, which would give me about 8nm of constant torque and 13nm max torque, and it only gets warm to the touch after a big racing session. My arms get tired, I definitely don’t need any more torque. It is an understatement to say I’m happy with this project, it was money very well spent.
P.S. – If you plan to build an OpenSimWheel of your own, I’d highly recommend getting a membership with iracing (even a 3 month trial) so that you can access the main BruteForce 2 build thread. The iracing guys are super helpful and will try very hard to answer any questions/issues you have with the build. There are also some guys there who are offering kits with simple wiring harnesses, motor, mounts, and everything you need.