How do I weld my own roll cage?
Welding a roll cage requires applying a variety of techniques and mathematical calculations. Among the factors to consider are the interior dimensions of the vehicle, applicable safety regulations, and your particular set of welding skills. By no means a beginner’s project, building a roll cage can, however, be an incredibly rewarding experience.
Simply put, a well-built roll cage can mean the difference between living and dying. Just ask this driver, who earned a place on the Pikes Peak International Hill Climb with his infamous crash. If it weren’t for the robust structure of his roll cage, the outcome of that video would not be so joyous.
There’s a lot that goes into welding your own roll cage. From mathematical calculations to welding time and techniques, the task of creating a roll cage is not an easy one. But it can be very rewarding experience, even if you’re not the one driving the vehicle protected by the cage you just created.
To help you tackle this ambitious project, we’ve gathered a quick reference guide to welding your own roll cage. Below, we’ll discuss what you’ll need to consider before getting started, what materials you should stock up on, what welding techniques you should be familiar with, and how to make sure the cage you produce is one that safety officers will approve. Along the way, we’ll share tips and tricks from various welders who’ve completed their own roll cages.
Start at the Drawing Board: Your Roll Cage
Most people consider a roll cage’s primary purpose to be about keeping the driver safe. While that is mostly true, “there’s more function to that puzzle of bars than just safety.” Additional benefits include strengthening the frame of your vehicle. This in turn improves handling, speed, and a number of other features.
Before we get too in-depth on roll cages, let’s first clarify the difference between a roll bar and a roll cage. You can easily think of a roll bar as the very basic skeleton of a roll cage. Both aim to protect the driver, but the roll cage is going to do much more than a simple bar can.
Be Clear About Your Intentions
However you came to the decision, you know you want to build a roll cage. Given that, consider your intentions with the roll cage for a moment. Because “what’s designed to save your life in a dedicated race car isn’t necessarily optimum for a car that spends all or most of its life on the street.”
Building a roll cage for your personal dune buggy or off-roader is one thing. Really, there’s no legal or technical rules involved. It’s up to you and the ute and well, fate. But if you’re looking to compete at a racetrack with your roll-caged speed demon, it’s time for a little research.
Oftentimes it can be hard to know where to begin with a roll cage. Believe it or not, rule books for the races you’ll be entering are a great place to start in that case. They’ll guide you along on what’s legal, what’s going to prevent you from racing, and where you can take creative liberty. “NHRA, SCCA, NASA, and Formula D all have different rules for fabrication, so you’ll want to study up and build to the highest spec possible. This is especially important when it comes to tubing material, size, and wall thickness,” notes the team at Blvckflagd. You may find the hard decisions are already made for you when you take a look at the rulebook.
As soon as you’ve figured out where you’re taking your yet-to-be-built roll cage, keep that rulebook close at hand. You’ll be referencing it a lot as you work through the fabrication process.
Roll Cage Points
One of the most common terms you’ll hear in conjunction with the term “roll cage” is “points.” These points refer to anchoring locations where the roll cage meets the structure of the car. Depending on the type of car you’re working on, you may need to adapt the roll cage to the structure already present. You may even want to build a subframe beneath the car. But we’ll talk more about this when we get to the actual process of fabricating your own roll cage.
In the industry, a 4-point roll cage is considered basic. In a 4-point roll cage, you’ll find the “main hoop behind the driver, two rear struts, and an optional cross brace on the main hoop should you need it or the rules require it.” You can add additional points in pairs to get a 6-point, 8-point, 10-point, 12-point, and even 14-point cage. Anything above 10-points is generally considered professional, for drivers who man Funny Cars for example.
Measuring Your Vehicle
Okay, so where do your points start in your vehicle? Well, to even get going on a design requires you to measure the interior of your vehicle. Now, this is the step that can really confuse a lot of people, since you’re not exactly taking a tape measure to a square box. But you want to make sure you build the roll cage into the car before it gets too far along. It’s much easier to add in components than to take them away and then have to reinstall them.
Professionals will tell you to measure a lot. Your survival—or someone else’s—rides on how well you can fit this metal skeleton into the vehicle before you. Drag your tubing into the car as much as you can. Rough out a design with a hands-on approach because you’ll be doing most of the welding inside the car. That’s one of the best—if not the hardest—ways to obtain a tight fitment and trust us, that’s something you’re going to want to strive for.
Work with pen and paper as much as you like. Use drawings to visualize how the roll cage will look inside of the car, as if you took a cut-away of the vehicle. Even if you have to label each piece of tubing as to where it goes in the puzzle, work with a system that supports your success.
One easy way to get some ideas and jumpstart your creative engine lies in perusing the internet for examples of what other people have done. Watch videos on roll cage fabrication (many of which you can find scattered throughout this article), talk to fabrication shops, head to the track, and overall, learn as much as you can about the construction before you take a stab at it.
Ask Yourself: Professional or Original?
Right now you know about what it takes to get a roll cage together. We haven’t mentioned the welding skills involved, but if you’re already thinking, “pump the brakes,” relax. You’re at roll cage junction and there are 3 paths before you.
Really, your roll cage options are these: you can order a bolt-on cage, purchase a weld-in frame, or have the entire thing custom built, either by you or someone else. You have to ask yourself the following questions: how good are my welding skills? Do I want to spend time and money on creating this roll cage myself? Would I rather pay someone to do the work instead?
Dragzine reports RideTech offers stainless steel bolt-in roll cages, but they’re not NHRA legal. Weld-in roll cages do offer a tad more strength. Given they become part of the body structure, they will at least provide some protection in the event of a rollover. But keep in mind, “installing a roll bar or cage is not something that a novice fabricator should attempt.” There’s very little room for error when it comes to roll cages.
Unfortunately, as Speedhunters puts it, “A properly designed, bolt-in cage isn’t going to be something you can order off the internet.” Automotive manufacturers design safety systems by employing a team of engineers to work on singular models that vary minutely. Adding a roll cage to a custom racecar isn’t that process. In fact, it’s much more intensive, even if there’s only one vehicle involved. The roll cage has to be “custom to ensure that harness bar height, seating position, and tubing positions are perfect for each individual person and vehicle.” An error in measuring, fitment, and/or placement could result in disastrous consequences.
So, if you’ve chosen to create your own roll cage, keep reading!
A (Basic) List of Roll Cage Materials
A roll cage is one of those projects that’s going to start out with a few supplies and end with you searching through your whole shop to find certain tools. This is especially true if it’s your first time making a roll cage.
With that in mind, there are a few things we can recommend you’ll need for sure. Remember, treat this as a broad shopping list, not ingredients in a recipe. Here are the basics:
- Tubing (see next section for more details)
- Angle finder
- Tubing bender
- Angle finder
- Tubing notcher
- Metal pipe cutter
- Permanent marker (or other marking device)
Note: if you are working with a unibody frame, you need to make provisions for putting in steel plates. These 6-inch square plates “must be welded to the floor as a base for each bar that makes its point of contact inside the car.” Project cars with an OEM frame don’t require this. Simply attach the frame of the roll cage to the frame of the car.
Roll Cage Tubing Types
Of course you need tubing if you’re going to build a roll cage. That’s a given. But what kind of tubing should you use?
Currently there are 3 types of tubing to choose from: hot rolled electrically welded (HREW) steel, mild/drawn over mandrel (DOM) steel, and chromoly. While HREW steel will make the least impact on your bank account, most often mild steel and chromoly make up the majority of roll cages out there.
Between chromoly and mild steel, the first is stronger and lighter but also pricier. It’s often reserved for dedicated racing platforms where a few pounds can translate to one less second. That being said, we recommend using mild steel for your first roll cage. That way, you won’t feel so bad when you have to throw out a few scrap pieces. Because it’s better to start over and do it the right way than risk your life later on.
Oh, and for that matter, order more tubing than you think necessary. Better to have extra and not need it than skimp.
Roll Cage Welding Skills and Techniques
Every weld cage is different than the next, at least if they’re custom made. But at minimum, a roll cage should have a roll bar, which sits behind the driver’s (and passenger’s) seat, and a roof hoop, often referred to as a “halo” bar. From the halo bar typically extend 4 legs, which stand upon the 4 corners of the floorboard. This is your basic 4-point roll cage. If you’re looking for double that, 8-point roll cages include “a main hoop, a windshield brace across the roof, a back brace, sides, subframe struts, and gussets.” From there, you’re really just adding more contact points in groups of 2.
The roll bar, or “main hoop” as it’s sometimes called, usually contains a pair of 90-degree bends. This main hoop needs to be level and centered within the car. Most often, MIG welding is used to construct roll cages, but some race classifications require TIG welding. Typically you’ll be TIG welding chromoly if that’s the case. You can MIG or TIG mild steel. As you’re working in the car, it may be advantageous to have a remotely controlled torch. This will help free up both of your hands for better placement.
After you’ve welded the main hoop and halo bar in, you can add as many points as you want to increase strength. You’ll most often be replicating what you do on one side. The only exception would be for drivers who will be alone in the car. This may require different patterns on the driver’s and passenger’s side, but keep in mind strength comes in a mirrored image.
In the next few sections, we’ll give you plenty of tips and guidelines for how you can increase the success of your roll cage. Then, it’s up to you to start building.
Tips As You Build And Weld
Keep the following in mind as you weld your roll cage:
- Check the guidelines for races you’ll be entering to see what is and isn’t allowed when it comes to cleaning up welds. In certain competition series, grinding your welds down is prohibited.
- Avoid bending roll cage tubing whenever possible. Bends are much weaker than straight tubing. Include them only where you have to.
- Measure and level before you begin welding. It’s better to check and double-check your measurements than have to start from scratch. Leveling your tubing will also increase the rigidity and strength of the overall cage.
- Make sure your work pieces are clamped tight before you weld. As you move the torch along the seam, keep the cone close to allow gas to continue flowing. You’ll want the gas mixture to continue shielding the weld as it cools.
- Use a minimum of 3 tack welds to keep your tubing in place. With only 2 tack welds, you risk the pieces twisting apart.
- Ensure as little gap as possible between your joints before welding. The more perfect the fit, the stronger the fusion between the two pieces.
- Trim your welding wire frequently between tack welds. This will ensure better contact. You can also divide your welds into 4 sections if you’re working with round tubing. Think of the tubing like a 2 X 2 square, with 4 quadrants. Weld each of these quadrants separately.
- Leave the roll cage unpainted. If rules permit, you can paint it at a later date to fit in better with the design of the car.
Are you ready for some more math? Yes, unfortunately there’s angles involved in welding a roll cage. The next section should clear up most of those concerns you might have.
Chris Jarman, owner of Eliminator Kustoms, explains angles and the related welding techniques in a short but informative video from Miller. After you’ve watched it, you’ll come to understand much more about how to approach angle welding in your roll cage. Here’s a distilled version for quick reference:
- Your roll cage will most likely have 30-, 45-, 60-, and of course 90-degree angles. Add to that complexity the pain of having to get in and out of a car and you can probably start to see where having your technique down ahead of time will come in handy.
- It’s better to continue welding in one go, rather than stopping and starting. A continuous weld will stand up much longer than a patchy one.
- “Tight joint preparation” is key, as we talked about above.
- When welding 30-degree angles, tack your work pieces in 3 points. Weld down the sides of the piece, and then weld up the bottom for best results.
- In the case of 45-degree angles, tack in at least 3 places again. It will be harder for you to get the torch and wire far enough into the welding spot. This means you’ll need to adjust your settings and pull the welding wire further out of the gun to reach the weld spot.
- Welding 90-degree joints sounds easy now! Simply tack weld in 4 main points, such as the corners of where the 2 work pieces meet. Push or pull the weld all the way around in one motion if you can, ending at the bottom to cover the seam.
As you see in the video, it’s much easier to practice these angle welds while you’re out of the car. Pick up some scrap metal and start practicing—including the technique we’ll talk about next.
Pulse Welding Technique
Experts who’ve created many a roll cage suggest using a pulse welding technique. This approach can be fast or slow, depending on what you want to accomplish. For example, slow pulse welding includes about 1-2 pulses per second. High-speed pulses, however, come at about 30 per second.
The trick to pulse welding lies in varying the current between high and low. This allows you, the welder, to control the heat intake and can reduce spatter as well. Pulse welding also reduces the chances of blowing a hole in the piece if the temperature gets too high. Though not an easy technique to master, pulse welding can come in handy as you weld your roll cage.
Triangulation and Gusseting
It won’t be long before you’ll start hearing more and more about triangulation and gusseting when it comes to roll cages. The fact of the matter is that triangulation is the strongest method of joining materials. Unlike a square, that can move side to side when pushed, triangles have a firm base to stand on.
The experts at Chevy Hardcore even suggest: “When building a roll cage, triangulate everything you can. This principle should be applied as often as possible to any chassis bars and cage design. In other words, every tube should be one leg of a triangle whenever possible. This is especially true with the primary structural tubes.” The point of your roll cage is to keep its structure in event of an impact. It needs to stay strong in a time when your body is at its weakest.
Another way to ensure strength is to use gusseting. This technique is “done very simply by just welding a piece of tubing diagonally into the corner, making it look like the letter A.” Gussets support the angles in your roll cage. It doesn’t take much time to add them in, so consider putting in a few gussets as you create your roll cage.
If you’re still having trouble visualizing how a roll cage goes together, 24 Hours of Lemons put together a basic but incredibly useful PDF. Drawings and explanations should clarify any lingering questions or doubts you might have about your roll cage.
And if you want to see how a roll cage was built for a rally car, check out this article on Miller’s website. It features the entire process of fabricating and installing a roll cage on a 2003 Subaru WRX. You won’t have to spend the countless hours alongside these guys but you can soak up the knowledge they received during the whole process.
Safety Check: How to Pass Roll Cage Requirements Before the Race Begins
Building your own race car brings with it incredible experiences and joy, even in the frustrating times. If you plan on fabricating a roll cage, we hope this article brought you one step closer to knowing more about how you’ll approach the task before you. You may even have a better idea of how to incorporate the cage into your vehicle’s design.
In any case, feel free to share your experiences with creating a roll cage. What did you learn and what would you do differently next time? Respond in the comments below!