Lets build a legit 6DOF Motion Rig for less than $800 USD!

Salutations everyone!

Prolog: I have been lurking for a while anonymously dreaming and contemplating about a build. The various options and extensive knowledge required to successfully complete a DIY motion simulator build was beyond my skill set. Watching others here in the forums build their dream rigs gave me the inspiration to at least try to bring my dream rig to reality. Today I begin, I have chosen a pathway forward and made the first significant purchases to get the ball rolling (or the seat moving!). I am hoping I can get a helping hand along the way from the folks that have been around this block a few times to bring this dream into reality!

My goal: Build a 6DOF chair for both flight and racing purposes for a target price of $800.00 USD without compromising on quality and function. (No wood, and no junkyard parts) This build does not include the seat, wheel, stick, pedal, sim buttons, or shifter in the costing. This is strictly the 6DOF parts and assembly requirements. This build does include all required electronics to move the seat and interface with the computer.

Description: At a high level the rig I envision would be described as a 6DOF seat mover using 250W 24V 75RPM motors mounted to a triangular metal frame. I want the seat to be as low as possible so the cockpit may have a cradle type configuration. The design intention is similar to that of the "Roman Designs" 6DOF DIY plans but I aim to make it both more compact with inverted motor placements and a much lower seat placement by means of cradle supports and higher mounting points.

Bill of materials as of 4/24/2025:
1. 250W 24V 75rpm or 120rpm Low Speed Brush Motor, 44mm Longer shaft, Shaft Diameter 17mm Wheel Chair Used DC GearBrushed Motors. - 6x @ $28.41 USD each on Aliexpress
2. BTS7960 43A H-bridge High-power Motor Drivers - 6x @ $3.80 USD on Aliexpress
3. TBA..

I'm also a long time lurker.....
I have access to a cnc router & lathe to build one, but the price of 6 x servo motors & all the other gear kind of turns me off a bit.
If I build a cheap one it'll motivate me to build a better unit down the track.
Im Very interested in what you come up with here!
My aim is to build a sprint car simulator, so my motion frame will be in a sprint car seating position.

I’d advise against using DC motors for this purpose. Based on credible sources, if the motors are supporting your weight, you’ll likely need at least 750W for reliable performance. A 500W motor might work, but it’s a compromise that could lead to issues. I’m aiming for an affordable SFX-100 setup. I currently use gear motor DC drives, which have been very reliable, running for hundreds of hours with only routine maintenance.

The only reasonably priced DC brushed motor I’ve found in the 500W+ range is the AmpFlow motor on Amazon. However, after many hours of testing and two years, I haven’t had success with it. It tends to overwhelm every motor driver I’ve tried. My recent attempts resulted in a driver that only worked in one direction. While I can get the motor to move and track briefly, the driver typically fails within minutes.

I suggest asking your favorite AI to search for DC motors in the 500W+ range. You’ll likely find slim pickings—options are limited, and reliable ones are pricey. Curious why? It’s because DC motors, especially brushed ones, wear out quickly under heavy loads, and brushless DC motors need complex controllers, making them less popular. Meanwhile, AC servo motors dominate for high-power, precision tasks.

Now, try asking about AC servo motors. You’ll see dozens of options! The SFX-100 project’s website recommends 750W AC servo drives from AliExpress, typically around $220. I snagged a different one for $150, and there are even cheaper ones out there, though watch for high shipping costs. These kits often include 3m cables and some offer quadrature encoder outputs for precise control.

For control, you can build a PID position controller using the quadrature inputs for tight feedback or go open-loop with more complex math. Alternatively, grab a Thanos AMC-AASD15A motion controller—for about $349.

So, there you go—motors and cables
for around $800. Oh, you wanted ball screws too?

It is impossible to build 6DOF on BTS7960 controllers, you will only lose money and time. Roman design used Cytron controllers I in my 6DOF used 3 pieces of 100A controllers
https://www.xsimulator.net/community/threads/reasonably-priced-100a-motor-controllers.17638/

Hi, 10 years ago a guy built a six dof simulator with smolka DC motors 16 Nm, but the motor drivers ( which seem to me very important ) were very good ones, Sabertooth series from Dimension Engineering. The problem is they're not cheap......

You can find the topic on xsimulator :
6dof dc 24v smolka zigzag49

"without compromising on quality and function"

And then you start the project with the cheapest motors and drivers, which will only give you a headache.

Using brushed motors today is not just a compromise, it's simply the wrong choice for the application.

Unfortunately, there are many reasons why almost everyone uses higher quality and therefore more expensive motors and drivers. This is certainly not intended as an offense, but rather as good advice, as there are already several similar threads here, all of which ended in a similar way. With the purchase of proper hardware or the early ending of the project.

What about the latest DOF Reality offering with the planetary/ballscrew/brake combo? Is there still a cost savings going that direction with that design vs. a stepper/ballscrew, and will it prove to be a poor choice?