Also:
Chrome moly requires special welding treatment, pre-heating, etc. The benefit is that it's stronger and lighter than mild steel, so it saves weight. Plan on tig welding it.
ERW tubing has a welded seam down the side. When bending you have to make sure the seam is towards the inside so that in a crash it doesn't split open. BEWARE THAT SOME SANCTIONING BODIES DO NOT ALLOW ERW TUBING!
DOM is the preferred tubing for cages. Its seam is treated after welding to ensure dimensional accuracy, but it also strengthens the seam. You don't have to worry about aligning the seam. Tig is nice, but mig welding works fine on DOM. Never arc weld a cage.
If you do more than one cage, it's worth the month to buy a JD2 tubing bender and bend your own tubing. I'm dreaming of buying one some day.
Our previous BMW used DOM tubing and was mig welded. When it ate the wall at Houston at 70 mph, it ripped the left front control arm out of the frame. The body of the car (convertible!) tweaked so bad the windshield spider-webbed. In the video (sorry, it's not public), you can see the tires from the tire barrier flying. There was absolutely no intrusion into the cab of the car. Our driver walked away and was a little sore from where the harnesses dug in. That is how you want a cage to work.
CORRECTION: Our BMW cage was mig welded, not tig welded. Brain fart.
Chrome moly requires special welding treatment, pre-heating, etc. The benefit is that it's stronger and lighter than mild steel, so it saves weight. Plan on tig welding it.
ERW tubing has a welded seam down the side. When bending you have to make sure the seam is towards the inside so that in a crash it doesn't split open. BEWARE THAT SOME SANCTIONING BODIES DO NOT ALLOW ERW TUBING!
DOM is the preferred tubing for cages. Its seam is treated after welding to ensure dimensional accuracy, but it also strengthens the seam. You don't have to worry about aligning the seam. Tig is nice, but mig welding works fine on DOM. Never arc weld a cage.
If you do more than one cage, it's worth the month to buy a JD2 tubing bender and bend your own tubing. I'm dreaming of buying one some day.
Our previous BMW used DOM tubing and was mig welded. When it ate the wall at Houston at 70 mph, it ripped the left front control arm out of the frame. The body of the car (convertible!) tweaked so bad the windshield spider-webbed. In the video (sorry, it's not public), you can see the tires from the tire barrier flying. There was absolutely no intrusion into the cab of the car. Our driver walked away and was a little sore from where the harnesses dug in. That is how you want a cage to work.
CORRECTION: Our BMW cage was mig welded, not tig welded. Brain fart.
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