Showroom Tube Steel DIY Build

Hi All! Sharing my 4DOF build with a tube steel frame.

Here's what it's replacing:

This is my second rig, made from mild tube steel. The computer is in a 4U rackmount case built into the base. The pedals, wheel, and monitor slide on an adjustable platform while the seat is static. The plan was to add movement to the seat with a 2DOF system (the seat base unbolts from the front part of the frame with this in mind), but then I decided to scrap it and go with a 4DOF when a friend gave me all the 3D printed pieces for a SFX100 setup (after he decided not to go with motion).

While it's not as easy to modify and put together, I like tube steel over 80/20 because it's cheaper and I can make it look more "race car-like"

I didn't just slap the SFX100 actuators on my old rig for a couple of reasons:
1. It's very heavy. I way overbuilt it with pretty thick wall tubing. I wasn't sure how much weight I could really do with the SFX100, but as Colin Chapman said, "add lightness." I figured the lighter the more responsive the SFX100 would be.
2. The computer and monitor are built-in. I can't imagine all that shaking is good for either one. I could just imagine my video card coming unseated every other week.

Ended up selling the "old" frame to a fellow Lucky Dog racer up here in Seattle, which paid for the new metal and a few other minor bits.

Went through the usual process of ordering parts and waiting... and waiting.
Everything from China came pretty quick (1-4 weeks) and I was stuck waiting for the aluminum extrusions from Germany another month.


Because I got the 3D printed parts third-hand, they were never test-fit before printing and the sliders didn't fit. They were free, so I'm not complaining, but took a bit of careful block sanding to get them to fit.


Used my impact driver to put all the threaded inserts in the aluminum. That worked well for a while until I hit one that didn't want to go in as easy (not sure why). Managed to twist off the (non-impact-rated) driver inside the chuck, ruining my impact driver (tried drilling it out and still haven't got it). Did the rest by hand with no issue.

I'll spare you the rest of the SFX100 assembly since after that they went together without drama.

Looking forward to updates, please share url's to parts

With the other SFX100 builds I read, they used a small rackmount enclosure to mount the controllers, so I thought, why not just get a bigger rack and put everything in one place?

I bought a 12U wall-mount rack, added some wheels to the bottom, and voila!
4U for the computer, 5U for the motor controllers, 2U for the shaker amp, 1U for the power strip/switch panel.

The first problem I didn't think about, just assuming "rack mounts were rack mounts," was that my old 4U rackmount case was way too deep to fit into the wall-mount enclosure. Apparently, those are meant for networking and audio components. After lots of searching, I finally found a 4U case that was (just barely) the right depth. The case is for a "Home Theater Computer" which has an option to add rackmount tabs.

Swapping from the big server case to the small HTPC case:


Had all kinds of fun squeezing everything in the new case. The power on the top of the video card has to be folded over and a harsh angle and shoves up the top of the case. The CPU fan fouled against the drive tray, so I had to buy a "low-profile" fan to fit. After lots of fussing, eventually, it all fit.

Because the HTPC case just barely fits in the rack enclosure, I needed to cut a hole in the back to get the plugs (and so they fit). This was a lot of planning and measuring because I didn't want to mess this up.


And here's everything in:


The switch panel has a 15amp breaker built-in, saving me from having to add one to the motor driver circuit. For the motor controller, I mounted it to a 3U blank panel to keep it up out of the way, but the DB25 cables stick out the front so I can't use the glass door for the enclosure. I looked into low-profile, 90 degree DB25 cables but they're pricey! Not worth it (for now) to spend $100+ so I can put the door on. I thought about making some spacers and mounting the panel back, but the cables on the drivers wouldn't allow me to go back far enough anyway.

Also on the list to fix someday, a black amplifier so everything matches!

So here's the new design. I played around in CAD for a few weeks before I settled on this:


Ignore the monitor stand sitting in the wheel base. I was being lazy using a stock screen model.
At one point I had a more complicated section for the wheel base mount, with the uprights (where the Fanatec clamps connect) in closer, but scrapped that when I realized they would stretch just far enough to make the uprights at the base width.

Wheel base won't move (except for some angle adjustment on the mounting plates and up/down on the uprights, if needed), but the seat and pedals will be on sliders.

The base frame is 1.5" 0.065" wall square tube and the upper section is 1.5" 0.065" wall round tube. Both are mild steel (A513). I picked up six 5ft sections of each (easy to fit in the car and base frame length was planned for 60").

First step was playing with the placement of the components so I was sure everything in CAD would work IRL.


I built a temporary upright for the wheel base with two of the round tubes tack welded onto some scrap angle iron so I can test the placement of the wheel.

I cut some 2x6s down to 100x100mm to use as spacers where the actuators will go. Turns out that I was a bit too exact and the tolerances were too tight to easily slide in this corner. Next spacers were cut to 102mm.


Drilled holes to mount the actuators on the "inside" and "outside" frame rails. 50mm apart, 8mm inside and 15mm outside (to fit the bolt head through). Bolting through both sides of the tube would cause it to deform when you tighten down hard (unless you "sleeve" the hole).

Made a bracket to attach the belts to the seat from some angle iron and scrap 1" tube.

I attached the bracket to the seat and not the frame so I don't have to completely re-size the belts anytime the seat moves (and so things don't get yanked out/caught). The belts (and the seat) are expired pieces out of my old Porsche Spec 944 racecar. I think they'll hold up just fine in a crash here

Buttkicker Gamer attaches to a bracket that bolts to the bottom of the seat. I had this on the last rig, but just needed to trim an inch off the tube so it didn't touch the floor when it's off the jack stands.

I used to have a Buttkicker mini attached directly to the seat here (hence the triangular bracket), but then tried a friend's rig with a gamer and found I liked how it feels better. I feel it "wiggles" a lot more, unlike the Mini direct to the seat, which could rattle my fillings out.

Next step is the build the upper section that will hold the wheelbase and button box.

From the temporary wheelbase structure (above), I estimated about how long the "upright" tube should be where the Fanatec mounting brackets will attach. I wanted a few inches of travel up/down from my "preliminary position" in case I find it's not right after I spend some time actually driving.

I cut the upright tube first, then stole a sheet of particle board from another project (arcade cabinet) to make a jig. On the temporary structure, I measured from the top of the lower frame to the bottom of where the upright would be (the blue tape). Then I used the short end of the board as a reference for the bottom so I could just measure up from the corner and lock the upright tube into place. I then spent a bunch of time just placing tubes at various angles to see where they would sit - what looked nice and how much room I would have to swing my legs under the wheelbase. It came out pretty close to the CAD drawing.


Once I notched and cut all the pieces I took some 2x4 scraps and screwed them down to the board, holding the tubs all in the right spot for tack welding and making the other side match.

One change from the CAD design was that I originally had a piece running from the cross bar (upper left) down to the bottom (lower left). I soon found that I can't cut an angle that steep on my Eastwood (non-Pro) tube notcher. And once I had the first side together I realized it's plenty strong enough. The back piece would have been just for looks (more "roll-cage-y") and just added weight.

Once I had both sides tacked together, I did a test fit with the DD2 and mounting brackets.


Then only to find that the cross bar was short by 1/4" inch because I used my original width to cut it. I added a little width to the spacer blocks to allow the SFX100 actuators a little more room. Luckily it was only tack-welded in, but still a pain.

Now that the upper section is the correct width, I re-installed the DD2 for another test fit.
The strap connected to the bucket of scrap metal is there to keep the weight of the DD2 from tumbling forward. Totally safe for ~$2000 of equipment

Everything felt good so the next step is to mount the upper to the lower frame.
For this, I added a plate to each leg, with the back (closest to the seat) sticking out with a tab that I can bolt through. On the front, because the angle is too steep to fit a bolt in behind it, and I don't want to push the frame back to attach a tab in the front, I ended up notching about an inch up on the leg and putting the bolt hole on the inside of the tube.

Then everything is apart again to drill the mounting holes on the "inside" beams for the SFX100s in the front, then tack the rest of the lower frame together.


Now I can finally install the actuators in their locations.

I was cursing the spring-loaded t-nuts that came with the profiles because the spring wouldn't hold the nut in place. They would just slide down when the profile was vertical!!! I used a screwdriver to hold it up in position while I bolted through the frame. I made it through three corners (12 bolts) before I realized I can bend out the spring so it actually pushes against the t-slot. Duh! Made the last one waaaaay easier to do.

Here's the current state with everything together. I have it all plugged in and did some light testing with "Live for Speed" and was grinning like an idiot because it was so fun! This weekend I'll finally have some time to setup the other profiles for Dirt Rally 2, iRacing, ACC, etc...


Next big project is the frame for the 49" ultrawide screen. This will sit over the DD2 with enough clearance so I don't bonk the screen. I'll also work on cable routing/management, maybe snaking some cables through the frame, and a mount for the shifter/handbrake (with a quick release to swap a flight stick).

Other thing I need to figure out is how to keep the rig from "hopping" around the floor. I saw these "cups" I can print then attach to a beam so they don't move around, but I'm going to try making cups in a 2x4 first to see of that helps keep it from moving. Any suggestions here would be greatly appreciated.

I also need to decide if I want a shaker up front. I have a Buttkicker Mini available and thinking of putting it on the front of the lower frame, but not sure if it's going to add much in the way of immersion since (for me) the seat vibration (and now the SFX100) gives my a lot of vibration for the engine, shifts, bumps, etc.

After the monitor frame and shifter mount is done everything comes back apart for (hopefully) the last time.

• Fully weld the lower frame.
• Smooth all the welds with the grinder and flap disc.
• Get off to powder coat.
• Reassemble back in the house.

really good job and nicely illustrated story!
keep going

....aaaaand I'm back!
Been a while since the last update so get ready for a pile of posts.

Next up is a mount for the shifter and handbrake. On my last rig I just connected the Fanatec handbrake to the side of the shifter with t-nuts, which simplified mounting but I couldn't get it in a spot where I didn't tag my knuckles on it shifting into 5th. For this I wanted the handbrake spaced off to the side a bit more.

The first design had the "throw" of the handbrake parallel to the shifter, which made it awkward to pull.


So I cut the corner at 45 degrees, which pointed the handbrake right at the driver.


Next up is the piece that will bring the shifter up from the base. I want the shifter assembly to be removable so I can easily swap it out with a joystick, so I got a piece of tube with the same ID and the mount's OD. The shiter mount can just slide in and lock with a quick-release pin.

The plate on the bottom has captive M8 nuts inside, allowing me to bolt it through the bottom of the frame like this:

Now it's time to get the monitor off the table saw and much closer to my face.


First made the two "legs" (sitting up there on the left) then a cross-bar with a section dropping down the middle that would allow me to move the monitor mount I got up and down.

The little section of square tube at the bottom of the mounting shaft is there as a stopper just in case the monitor mount's grip slips and slides down. Don't want the monitor landing on the floor!


The pole-mount monitor mount I bought was on the very edge of its weight limit for the Samsung 49", so it couldn't hold itself up. The zip ties were a temporary solution to get the right angle. Not sketchy at all!

For a permanent solution, I created a bracket that used a piece of angle iron and some plastic feet. I tapped the holes on the angle iron so I can feed the feet in/out and adjust the angle of the monitor as needed. The angle iron is attached to the screen bracket with a longer bolt through the pivot point, allowing the whole thing to still pivot as needed.

This is probably my 5th design, as I kept overcomplicating how it would attach (like from the pole instead of the monitor mount).

The monitor mount was the first thing to get painted. I kept thinking I would get everything powder coated for a nice, tough finish, but in the interest of time and rapidly escalating cost, I decided to use some enamel roll-ball paint.

Added some rollbar-mount wheel hooks and wrapped/routed the cables.

The plastic caps I found matched up perfectly to clean up the ends.

The "upper section" was next up for paint. First task was to grind down and clean up my ugly welds. Spent a lot of time with the angle grinder and die grinder to clean it all up. The final finish was with a scotchbrite pad on the die grinder to polish it up, which was probably way overkill.


In a few spots I had to fill a few gaps with the MIG (especially if I found a spot that had poor weld penetration). Other spots I just filled with some body filler to smooth it out. That was then a lot more sanding to clean it all up. Then put a coat of high-build primer on it and painted with roll bar paint.


Found some round tube plugs to cap the ends. The hole in the middle of the cross-bar will be used to route cables through, so I cut the middle out of a rubber grommet to cover the edges.


Here's with all the cables routed through:


I had extensions for all the cables except the DD2 power. This required a long search for the type of plugs they use so I could make one. Finally found the right pieces from Mouser and some 16AWG cable (meant for a trailer wiring harness).

Have plenty of spares if anybody needs me to make them one!