Thread: Roll Cage

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do they not offer a pre fabbed roll cage for your car? I know they are pretty much offered for anything now days. I would not build a cage from scratch unless I had a shop set up for bending tubing the right way....

Big truck driver; I've got nothing but time on my hands, though I have to do a little at a time. I became disabled about six months ago, seems my lungs are giving out on me.
So I want to get this done, before I am. Since I am now on a fixed income, and have lots of time, I don't mind trying something new. Beside's there is not gonna be one to fit my frame, Since me and my son made that from scratch too. Kurt

most auto fab shops will bend to your specs around here anyhow for $10-$20 per cut, and bend.
may be cheaper to pay to have it done right, rather than buy a tool to do it wrong.
not to mention all that sand, and moisture in the tube

Streetwerks; If it does not look right I won't use it.
My air compressor should be able to blow the sand out of the tubes,
if not I already wasted $2000 bucks.
And if I had 20 bucks a bend or a cut, I would have a small fortune
and could buy a new bender. I just need some thing to tinker with
to keep my mind right. On a good note last week when I liked to skin
my lttle finger to the bone, I didn't feel a thing.
I guess the morphine works like that, HE! HE! HE! Kurt

lol, I know the feeling, sometimes a guy just has to tinker

I have the same bender shown in that Youtube video. Bought it at Harbor Freight when I started building my roadster. I have had good luck with it, but I am using black iron pipe for my roadster's frame, roll bar, and radius rods. I did a couple of things different than the vidieo, too. First, I used damp sand and rammed it in tight with a broom handle. Second, I did not cap my tubing with duct tape; I welded a piece of scrap steel over the ends so it couldn't blow out under the pressure created by bending. Finally, I cut a short piece (4 inches) of tubing and split it down the middle and used these under the rollers so they wouldn't dimple the tubing. Here are some pics of my roll bar when I bent it...

Black iron pipe as in plumbing ??????surely you jest!!!!!

Originally Posted by jerry clayton

Black iron pipe as in plumbing ??????surely you jest!!!!!

100% agreed.....But you get a A for effort.

J. Robinson; I think we could all learn some stuff from you.
Thats where I got my bender from too, It sat under the bench till
I recoopted. I was getting little dimples in the pipe to so I slid the rollers out and that seamed to help, But I think I'll give the 4in. plates a shot.
Your roll bar looks real nice, I've got to take some photo's tomarrow.
That way I don't jump to far ahead on my progress. Kurt

Originally Posted by jerry clayton

Black iron pipe as in plumbing ??????surely you jest!!!!!

Jerry and BTD - Yes, black iron. The same stuff used for well pipe and natural gas. Do not confuse black iron pipe with galvanized water pipe; they are not the same. Galvanized pipe is low grade steel, hot-dipped in molten zinc when it is manufactured. The process causes nitrogen embrittlement of the steel. When welded, the zinc coating causes crystalization of the weld and also gives off deadly toxic fumes... Black iron, on the other hand, is just ordinary mild carbon steel tubing with a varnish-based coating. The steel welds very nicely and the coating burns away completely causing no weld contamination. Black iron is heavier than DOM tubing because of the wall thickness, so if weight is a factor, go for the more expensive DOM.

I know of a couple of sprint cars built from black iron back in the late '60's that were still racing in the early 80's (when I lost track of them) and never had a metal fatigue or other material related problem.

The coating on black iron keeps it from rusting while it is being worked with. Later, it can be sanded and painted over or it can be sand blasted off completely. I have been using the stuff for years and I have done it both ways. If you're interested, check out the build thread on my roadster ("Another Build Thread? Yep, My Track Style T"). The entire chassis is built from black iron of assorted sizes.

Kurt - Depending on the size of the tubing, I discovered that the location of the rollers has a direct effect on whether the tubing bends smootly or kinks/ flattens. I start the bend with the rollers fairly close together and move them outward as I go. On 1 5/8 o.d. I think I start in the 5th hole from the outside. When I get to about 45*, I move the rollers out to the next hole.

I know people have used black pipe on frames and cages, and I've also seen a couple of those cages collapse.... Heck, I feel like I'm tempting fate when I use DOM instead of chrome moly!!!! Guess it all comes down to a cost vs. risk thing... I just never was much on saving a few bucks on the tubing cost for having the risk of a cage come down!!!! Maybe I've just done too much "cage testing" over the years????

BTW, Speedway sells a tubing bender with 5 sets of dies for $800.00.... Probably not something you would want to bend tubes with all day every day, but certainly good enough for a hobbyist who might only bend a couple a year.....

Yes---galvanized gives off fumes when welded---but don't worry, I won't be welding any galvanized or black pipe roll cages---

They aren't safe

They aren't legal

If you are fast you need to be legal

If you are fast you need to be safe

They aren't fast

They aren't legal

But galvanized and black pipe do bend easy

I, too, have done some "cage testing". I believe yours was with sprint cars, Dave; mine was in stock cars. I, too have seen a couple of cages collapsed or severely bent (not mine, thankfully). If a cage collapses, it usually is a problem with the design of the cage or some really bad welding, not the material used. Chromemoly is nice if you can afford it. Its elastic limit is substantially higher than mild steel and therefore allows the use of lighter (thinner wall) tubing to achieve the same strength. Most sanctioning bodies allow the use of .083" wall thickness for Chromemoly in place of DOM at .095" or .120" wall thickness, a savings of 14 to 33% in weight while retaining the same strength. The downside to Chromemoly, aside from the cost and limited availability, is the fact that it has to be TIG welded to retain its strength. A lot of us home builders don't have TIG machines, so even if we go the expense of buying Chromemoly and the high-dollar bender to shape it, we still can't weld it. If you want to commit suicide the expensive way, build a moly roll cage and weld it with your ordinary MIG or (worse yet) stick welder. That will guarantee its failure in a collision.

As for black iron, METALURGICALLY SPEAKING, it is virtually the same material as mild steel DOM tubing. The difference is that drawn-over-mandrel tubing has a uniform wall thickness and has had the seam shaved off both inside and out. Also, the process of drawing it over the mandrels slightly work-hardens the material by compressing and elongating the molecules. The advantages to it are that it is very smooth, has no coating to deal with, and is available in various wall thicknesses. Schedule 40 black iron does not have the inside seam scarfed off, sometimes has minor pits or scratches on it, and only comes in one wall thickness depending on the size of the pipe. Generally, it is heavier than a comparable size DOM tubing. Like DOM tubing, black iron welds beautifully with an ordinary Mig or stick welder.

As for bending it, I have bent both on a Hossfield manual bender and I can tell you with certainty that 1 3/4" o.d. DOM with .095" wall (typical roll cage material) is EASIER to bend than 1 1/4" black iron pipe (1 5/8" o.d.). The reason it is not legal in some sanctioning bodies is simply because there are a lot of dipshits in this world that don't know the difference between black iron and galvanized, so they just outlawed all types of pipe.

I just can't see a reason to use pipe.... it's not deemed as legal by any sanctioning body I know of... Hate to see someone use it to save a few bucks then get denied the access to a bit of drag racing. And for safety's sake, I'll go with DOM or moly for a cage every time. I'm not a metallurgist by any imagination, but if it's been outlawed by every major sanctioning body there's got to be some good reasons for it... IMO just too many other places to save a buck on a build, the cage shouldn't be one of them....