Roll Cages

[burrhead]

Could someone tell me what aws certification you need to weld chromemoly roll cages, or if you even need to be certified? What is the best tig filler wire for that also?

[ASKANDY]

Burrhead,

Welcome and thanks for the question!

I know of no specific code or certification regarding Chrome-Moly tube weldments for race chassis. I would think that the sanctioning body would have a weld proceedure (if they did their homework) outlined. Most will just do a visual inspection and because of the nature of motorsports, alot of sanctioning bodies let it up to the chassis builder to do their own destructive testing and determine what best suits the builder as far as proceedure. It lets them off the hook as far as liability. Some sanctioning bodies just specify that it must be tig welded, but you and I know it should go alot further than that.

If your rules don't specify weld parameters, do your own testing.

Sorry this was so vague. But there is no real good answer. If you find anything out, please let us know.

Thanks and good luck.

Andy

[johnptc]

tig rod for cr moly tubing

I would suggest 80S-D2 welding rod. It a high strength 'mild' steel rod that has about 90ksi strength so it a good match for chrome moly when teh entire weldement is NOT being heat treated.

[Blondie_486]

Andy,

You're right there usually aren't any certification specifications on race cars. I know the NHRA now requires chrome-moly to be TIG welded and mild steel may be either TIG or MIG welded. However years ago and I'm talking back in the late 60's and 70's oxy-acetelyne welding was also acceptable for chrome-moly. I think with the increased availability of TIG machines it brought about the change in procedures. Back then TIG's were really expensive, oxy-acetelyne was all most guys could afford to weld with. With the technology breakthroughs TIG machines have become more affordable so much so that if you play your cards right you can get a new Econo TIG for under a grand. With the gas shield of the TIG arc it really almost eliminates the possibilities of contamination from the atmosphere so it makes better sense to TIG weld than oxy-acetelyne weld on chrome-moly. The TIG also heats a smaller area which reduces the chances for stress cracking although I recommend "stress relieving" on all welds on chrome-moly.

Maybe someday they'll come up with a weld certification for chrome-moly in race car situations but I think the general consensus is that each driver knows when they latch the 5 point harness and put the helmet on that they may not come back. So as a driver it would be in your best interest to pick a chassis builder carefully.

As a chassis builder it would be in your best interest to build a chassis wisely and double check and triple check your work. There'd be nothing worse than wondering if an accident occured because of your negligence in building the chassis or wondering did that last weld I did at 3am break?

As a driver I built my own chassis and felt safe about leaving the starting line.

Good luck and be safe.

Blondie

[1320Fabrication]

Currently the NHRA/ IHRA does not require certification to weld roll cages. There wording they use is "approved method" .I've been building race cars since 99. I got into it because I had trouble getting quality, timely work done. I took evening classes at a local community college. I told the instructor exactly what I wanted to do, build racecars and roll cages. I picked up a lot of scrap pieces (4" to 6" long) of 4130 tubing and notched them to practice welding. I must have welded over 1000 tubing joints, along with plate coupons, etc.. before ever attempting to weld a roll cage together. I even took test pieces and did some destructive testing by putting them in a press brake and just about smashing them flat to see if the weld or tubing would break. You'll find that you may weld excellent on the bench, and just ok in the car. I built my first car for myself and stopped working on it to build one for a friend. When I got back to my car I realized it wasn't good enough, so I cut the chassis up and threw it in the dumpster, and started over! One of my other race buddies was mad becuase I didn't offer the chassis to him, but I didn't want people seeing poor work with my name on it, or even worse someone getting hurt in something I built if I new it wasn't up to par.

Since there's really no certification use your best judgement, and seek the opinion of others to exam your sample work to see if it is acceptable and good enough to possible protect someones life.

I'm real big on tubing fitment. I started with a hole saw notcher. They work well for light duty use. I even know a guy who notches everything with handtools. I now use a .Mittler Bros. ultimate tubing notcher. It makes life easy. You can notch at any angle, easily repeat the same notch, and precisly fine tune the length of the tubing. i mostly use 1/16" filler rod and never leave a gap I can get my filler rod into by doing so It makes a stronger joint and is much easier to weld. I've seen guys notch thin wall tubing and try and tig weld a 3/8-1/2" gap! Maybe if your buiding grocery carts, but not racecars. I built a car for a friend and he took it to one of the top chassis shops in Houston to get the tinwork done. When the owner saw my work he made his guys stop what there doing and made them come look at the car and told them "This is the way you fit and weld tubing" man that made my day as I have the most respect for that guy and his work.


I along with most chassis shops use ER-70S2 (I've seen it at Jerry Bickel's shop). I've been wanting to try the 80SD2 as many say it is a better filler metal for 4130 tubing

[1320Fabrication]

Can't believe I forgot this.

If you get serious about building rollcages you may want to check with the:

SFI Foundation

The list different chassis spec for different types of drag cars.
I've purchase several different specs, and they are very helpfull on choosing the correct tube size, and wall thickness for different applications.

Also following these specifications and getting the chassis cerified ad alot of value to the cars.

[burrhead]

Roll Cages

Thanks to everyone who replied to my post. I'm finding the infomation very helpful. I too am new to welding also. My Grandfather was a gas welder from the old days, so I wanted to learn about welding. I started taking some welding courses at the local college at night whenever I could fit it in my schedule. Now I am in the process of getting a tig machine, any suggestions would be helpful also? The reason I asked my post, is that I have a '72 Nova street car that I want to backhalf, 4-link, 10.5 tire, and a full chrome-moly cage to do a little street car style racing with. Problem is I'm on a budget, like most, and I need to do most of the work myself!
Thanks again to all who replied,
Burrhead

[RLRacing]

I would use a mild steel cage it would be easier to weld with a mig welder and cheaper than the 4130 tubing and less chances of cracking.