Showroom 3 DOF racing sim

Unfortunately, I haven't finished the frame yet for the pedals and FFB wheel. I have been waiting to finish the rest of the frame before I get Simtools. Once I get that and run it, I'll know if the motor drivers will be able to output enough current relaibly for the weight when it's running. If not, I'll have to add some gas struts to offset the weight the motors have to move.

It's tough for me to get time lately to work on this between my job and two young children but I'm slowly chipping away at it when I can. The attached picture is where I'm at right now. The tube steel where the pedals go will be shorter of course, just have to figure that out when they're mounted.

Thanks for your reply! Yep there are more important things in life . No worries but please keep us updated. It's looking awesome already, looking forward to see the end result.

How are you getting away with such low wattage motors? I’m new to all the motion sim racing but everywhere I research says that you need something in the 700 W range, 80nM or more torque for each motor. which makes it really hard to find on eBay and you have to special order off of Alibaba.

It is a 300W 12VDC motor with a working speed of 3000 rpm and a 50:1 gear reduction off the worm gearbox. Using ideal calculations without losses, the torque off the motor is 0.96 Nm where the torque is the power to the angular velocity. To calculate the torque then provided to the output shaft of the gearbox, it is the motors torque times the reduction which is 48 Nm. However, if you consider the efficiency of the gearbox (which I don't know) it is much less. If we conservatively say 60%, then that makes the torque off the output shaft 28.8 Nm. This torque 70mm out off the attached lifting lever arm, generates a force of 411.4 N (force equals torque over radius). Converting that static force to a mass (F=ma) equals to 41.9 kg or just over 92 pounds. Multiply that by three motors and you have 276 pounds of static lifting force (or so I hope lol). Again, I don't know the efficiency of the gearbox so it's rough estimate.

Now, with the materials I've chosen to work with, I may need to add some gas struts on the frame to help take some of the load. Hopefully, I will know soon as I've been slowly chipping away getting to test it out.

Little update:

I've got most the frame done now (with the exception of the mount for the shifter and hamdbrake).

Once that is done, I can clean it up a bit better and paint it. Then I can test it out with simtools. I also need to wire up my mini contactor I'll set up with a momentary start to create a latching circuit with an emergency stop in series. I can do that later on though. Just gotta keep looking for time for when I can work on this project, I'll get there one day

Got the handbrake and gearshift mounted with a cut up piece of aluminum from the base of an old server rack I demoed for work. I'll likely cut out a triangular section from the back to get rid of that sharp edge and make it look a bit more asthetic as well. In the process of doing all this, I dropped my drill and broke the gear off my potentionmeter bracket. I've done this like 3 or 4 times now and need to redesign. Unfortunately, until I fix that I can't test with Simtools . I have an idea though that should be more robust, just have to redesign in CAD and 3D print it. Hopefully I will get to that in the next couple of days.

Ok! I've got my potentiometer brackets redesigned where the drive gear is directly attached to the output shaft of the motor.

In doing so I had to shorten the bracket and just flip the driven gear around (should've done this in the first place). There is no movement at all whereas the previous design there could be some movement in the drive gear because it was attached to a flex coupling.

I also have wired up my latching start circuit using a mini contactor. I mounted the start/E-stop on the right corner of the frame so the it was within arms reach but still out of the way. I wish it was more obscured though.

This is a diagram of the circuit I used:

I opened up the 20amp power strip I have and cut the line and neutral wires to then terminate to the mini contactor and come back to the protection circuit (listed as single phase motor in the diagram).

Here is the power strip:

It has a switch for each outlet in case I need to turn two off and troubleshoot one motor.

Now I think I can finally test with SimTools! Only problem is that it's late and I can't test now. Late at night after the children have gone to bed is usually the time I can get to work on the project. Soooo, let's hope that I can get some time this weekend between the birthday parties and having the replace the tie rods on my wife's car lol.

In any case, I have purchased a license for simtools and started reading through the manual and installed a couple of plug-ins. Really excited for the next time I get to this because I'll get to see it move with some load on the motors and can get an idea on how I can tune it and whether I need to add some gas struts to help with the weight.