I build roll cages

[Chilezen]

Ever since I've played with Lego as a kid, I've loved putting together cool shit. I went to college for art, automotive, and welding, and those skills have gotten me into this industry for almost 10 years. From basic tools to now computer-assisted designs, these are a few of the many cages I've built. And since I'm an E30 guy, I'm happy to share that I finally had one in the shop to build a cage. Here's how it went.




This is our plasma table. I first design and measure the crap out of what I want to make, sometimes using paper/cardstock templates, and other times using 3D scans of the car. I take the flat outlines and send them to be cut out here.



The shapes with the little indents are markers I've added to designate where a bend will be.



Since this particular "box" needs to be bent to more than 90°, I use a press and a special die to achieve the result I need. There's nothing accurate about this procedure; I have to guess and check and bend some more until it's the right shape I need.



The plates that were cut out are going to become boxes, or otherwise known as plinths-- they are what the cage will sit on in the car. They also act as supports that can be removed during the installation process, which is necessary to "drop" the cage (off the boxes) in order to gain access to the topsides of the cage. These top areas are unreachable until the cage is dropped/lowered off the boxes. Once the cage is off the boxes, I can weld the top sides of the cage/tubes. And then, lift the cage back up and weld the boxes in place. Anyway this^ pic is of me welding the plates together to create one of the boxes.

[82eye]

love anything welding, and sweet lady plasma cuts.
will never have your skills but i love seeing the art.

[Chilezen]

This is the machine I use to mark and cut the tubes. A 20'+ tube is loaded in the back, and comes through here on those rollers.



This assembly is known as the head. It goes up and down and left and right, above the tube. Here, a plain ol- Sharpie is marking the location for where a different bar is going to intersect/mate to this bar. A "trolley" in the back is holding the tube. The trolley has a 360° rotating chuck, which holds the tube but spins according to what the computer tells it to. In other words, the tube is spun under the Sharpie, while the Sharpie sits on the tube, held in place by the head. I'll share a video one day.



When the Sharpie is done marking, the plasma torch moves over the tube, and cuts the tube (as the tube spins under it). The computer controls the exact motion of these different parts simultaneously for fast, repeatable results.



And here's how the bars look after being marked & cut. The numbers on some of them are bending information- the values and locations and rotations I will need next to bend them correctly.



This is the bender. It is also computer controlled, but it's awful and I hate using it. I would never recommend it to anyone, but sadly there aren't many alternatives within a reasonable price point. For the cost of it, you wouldn't believe how poorly it performs in regards to accuracy and consistency. Anyway...
It's a pretty simple device. The right side holds the bar and pulls the bar as it rotates. The die on the left is stationary. The bar is pulled around the right/rounded side, and the bar slides through the stationary side. As the bar gets pulled around the round part, it takes the shape of the rounded shape. The amount that the die rotates effectively determines how much the bar is bent. If it rotates 20°, the bar has (theoretically) been bent 20°.



Since the whole cage is designed in the computer, it knows where exactly each bend needs to be, and how much to bend it. Here, I line up a horizontal and vertical Sharpie mark on the tube, to the indent on the die. The number is, of course, how much to bend the bar. I enter the number into the keypad on the screen of this machine, and it bends the bar. It's not fool-proof, but it works.

[Chilezen]

love anything welding, and sweet lady plasma cuts.
will never have your skills but i love seeing the art.

Thank you! Lots of welding coming :)



This is jumping ahead in the "story" or process of building a cage, but frankly I was on a time crunch and this is where I was able to bring out the camera again.



The long-exposure photography exaggerates the sparks, just for the cool effect.



As mentioned earlier, I build the cage on top of boxes, and then I have to cut the boxes out to drop the cage. So the process is, install like half the bars, weld them, and then give yourself enough room to drop the cage, weld more, put it back up, and then weld the rest. It's a big game of strategy. Things must be done in the right order.



In this shot, you can see that the cage is on the floor and some of the bars are partially welded. The box has been removed from its corner, so I can get access to welding the top sides of the cage. All the scars you see around the black circles are from when I was test-fitting those respective bars, to ensure their shapes. But I've cut them out for now because they were in the way.



I take all my own photos, by the way. I prop the camera on something, wherever I can, try to level it, and then enable and interval timer--it takes a picture every 5 seconds or so. I walk away, do the welding, and then I come back and select my favorite picture of the batch.

[Panici]

Pretty cool stuff!
I'm just an amateur fabricator but would love to build a cage some day.

[82eye]

like to weld but sure don't have that talent. definitely inspires.

[ForcedFirebird]

Sweet equipment! I'm old fashioned and use a hole saw for notches, and a Hossfeld bender I converted to air-over-hydraulic lol. Little envious :P

Which pipe bender is it?

[Chilezen]

Sweet equipment! I'm old fashioned and use a hole saw for notches, and a Hossfeld bender I converted to air-over-hydraulic lol. Little envious :P

Which pipe bender is it?

In my early days, I didn't even have a hole saw; I cut the notches with a chop saw, Burr King belt sander, and a bench grinding wheel. I don't miss those days. I had a hydraulic bender but I never measured bends in degrees; I measured the distance the ram/piston traveled and wrote down that distance. My new boss couldn't understand how ridiculous that was, but it worked!

The current bender I use is the Baileigh RBD-250. It's stupid money for what is essentially a powerful servo housed under a few machined blocks to hold the dies. The dies aren't even included in the initial purchase price. I can't stress how disappointing the performance is for the price. I'm only happy about the fact that it can rotate nearly all the way around without having to reset the arms of a traditional hydraulic-ram-style bender.

For my cages, I require highly accurate bends, so nailing the degree amount is key. When I overshoot the amount, I use a different tool to unbend it. The tool is a large-radius tubing roller, from Harbor Freight. But instead of rolling a large radius, I can use it to press a bend down, when effectively unbends it, without kinking/ deforming the bar. It's also not accurate, but very useful.

[OSAH racing]

impresive work.

[Chilezen]

Thank you!

Suppose I should finally post up the pics of the cage...



This cage was built to meet the rules of Spec E30. Naturally, I build all cages to meet the specs of NASA and SCCA.





There are some cages out there that have these style of door bars, I've known them to be called "Nascar Bars". Since they protrude into the door space, they allow better/easier ingress/egress for the driver, compared to standard "X" style door bars. They also serve the purpose of better protecting the driver in the event of a side collision/T-bone incident. These bars stick out as far as they can, thus creating a barrier further away from the driver.
I always recommend any racer to opt for this option when deciding between styles of door bars. Their benefits greatly outweigh the slight weight penalty. The only other reason you'd want standard X bars is if you are weird and want to retain your windows in your racecar



I'm happy with how these turned out. I 3D scanned all the corners for where these "platforms" or "boxes" or "plinths" would go, and then I built them in the computer, cut them out, bent, and fitted. Super great how nicely the edges are contoured to the spot I want them to be in! I'll show more details in that part of the process down the line.



Before my digital/computer days, the best way to build a metal box like what you see here, would be to use paper/cardstock templates. I'd sit there and cut out a shape with scissors, mark it with a sharpie, and cut some more until it fit. I might tape one piece in, and then work on the next face. Or I'd go ahead and transfer the outline to a sheet of metal, cut out the outline, and then fit it. Wash rinse repeat until a box is made. Some shapes are easy and could still be done this way, but with a computer scan, I get accuracy and infinite repeatability—we send out the design and someone can cut 10x or a 100x, whatever we need.


I'll stop here for now. More pics to come later.

[OSAH racing]

Before my digital/computer days, the best way to build a metal box like what you see here, would be to use paper/cardstock templates. I'd sit there and cut out a shape with scissors, mark it with a sharpie, and cut some more until it fit. I might tape one piece in, and then work on the next face. Or I'd go ahead and transfer the outline to a sheet of metal, cut out the outline, and then fit it. Wash rinse repeat until a box is made. Some shapes are easy and could still be done this way, but with a computer scan, I get accuracy and infinite repeatability—we send out the design and someone can cut 10x or a 100x, whatever we need.


I'll stop here for now. More pics to come later.[/QUOTE]

I am sure that early process of building templates really helps your skill set improve. Total understanding of the craft of cage building.

[e30davie]

Very neat work. Out of curiosity what do you use for scanning?

[Chilezen]

Very neat work. Out of curiosity what do you use for scanning?

We use a scanner from a Canadian company called Peel 3D. The unit we use is their oldest model, the Peel 1. It does a pretty good job, it gets most of the details, and it can almost get the whole car. But you have to go slow with it, and it's temperamental about the distance you hold it at. Still way better than not having one though!

It comes with scanning software that I don't find intuitive, but once you're past the learning curve, you can get the info you need and export the surface data to another program to actually build parts on it.

Our scanner operates using protection mapping, which means it projects a black & white image (think like static on an old TV) onto the surface. Right above the projector, is the camera, which sees the size and shape of this grid of black and white. Then the software looks at the grid, it measures the grid, and that's how it knows how far away the surface is. It does this multiple times a second as you move it around, so it can capture the multiple sides of your surface.

Granted, it's not a fancy laser scanner, but as a budget option, it works very well.

[Chilezen]

I am sure that early process of building templates really helps your skill set improve. Total understanding of the craft of cage building.

Judging by your username, I assume you have experience as well.

I enjoyed sitting in a car and cutting paper out to make the templates. Kinda methodical; relaxing. Seeing it come together in real time was pleasing.

Now, I get the feeling that the old fashioned way takes less time, versus setting up and scanning, then refining the scan, then aligning and orienting planes, then exporting and working on it in another program,

...then doubling checking the real car to make sure you're designing it in exactly the right spot, and then adjusting your model so that you're totally happy with the shape...

...and then flattening the 3D model so that the profiles can be cut out in a 2D sheet of metal, and then exporting that to the plasma table...

and at that point you've met up with the old fashioned way; you now have shapes cut out of metal.

But here's why all that extra work is worth it:

I've been able to mock up a crazy difficult shape that wouldn't have been easy with the old fashioned way. Here, on the rear strut towers— see next post

[Chilezen]

Strut tower boxes, where the kickers* land. (*that's the name for the bars that descend from the main hoop to the rear of the car)

Normally, cage builders do 1 of 3 things with these bars. 1, they land the kickers on the rear wheel well, which is a terrible spot, because it's a weak area of the car. 2, they build an excessively large box around the strut tower, because it's easier to engulf it than to bond right on it, due to its complex curves. Or 3, they'll go down to the floor of the trunk, which can be justified if it's over the spring perch, but that's not always the case. 4, they might brace the towers laterally (like a strut bar) and then terminate the kickers on that bar, which might be illegal if the kicker isn't extended and braced down to the floor.

I went with option 5, which is like 2, but I kept the box small and close to the tower, so that the transfer of energy during hard loading isn't exacerbated by excessive metal. I also wanted to stay on the strut tower instead of keeping it closer to the spring perch because the tower is a known weak spot in these cars. Some rules, like those in Chump Car/Lemons, even say you cannot place any point of the cage past the centerline of the rear wheel; that rules out option 4 and maybe 3 if the angle of the kickers isn't too sharp.

I'm rambling. Pictures!









I'm pretty happy with how it turned out. I hated welding it though, these cars have a ton of putty that needs to be cleaned out, and it smokes so bad if you miss even a little. Plus the metal is fairly thin, making it a challenge to weld the relatively thick 1/8" metal to the body. That goes for all the attachment points, not just the rear.