chromoly tubing, where to buy?

[NOT A TA]

I'm having a shop install a 10 point cage in my Firebird and dropped it off at the fab shop a couple days ago. After the shop owner talked to the sanctioning body I want to run the car in about whats required they decided on .095 1-5/8 chromoly for most of the cage.

His regular suppliers don't have tubing any in stock so he asked me to check around and see if I could locate it. Anyone have any ideas? We're in New England.

[B Schein]

There is an airplane supply place in Pennsylvania where Bought some chromoly tubing when I used to live up in the norther part of Maryland But i can't remember there name I know John Parsons knows who it is because he is the one who told me about them. It the closest thing to New England that I know of.

[chicane]

Any real reason to why you want ChroMo other than to say its made of ChroMo ??

What kind of events are you considering and which sanctioning body are your rules from ??

I only ask because there is no benifit to using ChroMo unless you heat treat the finished product... and in the fashion of a tubular cage... that would mean that you would have to heat treat the entire chassis, which... isnt going to be done. Not to mention that unless you properly preheat the material before weldment and normalize the material after... there is absolutely no benifit to using ChroMo. The extra expense in material cost yields you zero...

A bit of advise ?? I would pick up a copy of Carroll Smith's "Engineer to Win" and then make your determination on what material you should purchase. In fact... if you are going to be doing any kind of motorsport... I would highly recommend that you purchase his whole line of books... trust me, after you read them... you will look at things in a whole 'nother light. >> Click here <<

I believe... that you would be much better off with using 1018 or 1020 DOM. Especially considering inch and five eighths... o-nine five. That is considered to be the absolute bare minimum size/dia in chassis weights under 3000 to 3200 lbs. Not to forget to mention... in the science of safety... the majority of sanc bodies are making the move towards DOM over that of ChroMo in a unitized chassis. Just the mere fact of 4130/N weld embrittlement would make me run the other way.

Im not saying that ChroMo doesnt have its place, because it sure does and I like to use it myself... but definately not in a unitized chassis. If you built the entire chassis out of ChroMo and had the entire chassis heat treated... I would be all over that !! But... the truth of the matter is, that it is not going to happen.

Educate yourself now... before you make a possible mistake.


Aircraft Spruce, Industrial Metal Supply, Metals Depot, All Metals Inc, Online Metals... all of which can ship or source the materials you need and in some instances, even locally to you.

[Tig Man]

aedmotorsports.com

They have the best prices most of the time!

[Musclerodz]

Originally Posted by chicane

Any real reason to why you want ChroMo other than to say its made of ChroMo ??

What kind of events are you considering and which sanctioning body are your rules from ??

I only ask because there is no benifit to using ChroMo unless you heat treat the finished product... and in the fashion of a tubular cage... that would mean that you would have to heat treat the entire chassis, which... isnt going to be done. Not to mention that unless you properly preheat the material before weldment and normalize the material after... there is absolutely no benifit to using ChroMo. The extra expense in material cost yields you zero...

A bit of advise ?? I would pick up a copy of Carroll Smith's "Engineer to Win" and then make your determination on what material you should purchase. In fact... if you are going to be doing any kind of motorsport... I would highly recommend that you purchase his whole line of books... trust me, after you read them... you will look at things in a whole 'nother light. >> Click here <<

I believe... that you would be much better off with using 1018 or 1020 DOM. Especially considering inch and five eighths... o-nine five. That is considered to be the absolute bare minimum size/dia in chassis weights under 3000 to 3200 lbs. Not to forget to mention... in the science of safety... the majority of sanc bodies are making the move towards DOM over that of ChroMo in a unitized chassis. Just the mere fact of 4130/N weld embrittlement would make me run the other way.

Im not saying that ChroMo doesnt have its place, because it sure does and I like to use it myself... but definately not in a unitized chassis. If you built the entire chassis out of ChroMo and had the entire chassis heat treated... I would be all over that !! But... the truth of the matter is, that it is not going to happen.

Educate yourself now... before you make a possible mistake.


Aircraft Spruce, Industrial Metal Supply, Metals Depot, All Metals Inc, Online Metals... all of which can ship or source the materials you need and in some instances, even locally to you.

You don't need to heat treat 4130/N. The problem is people TIG it and don't pre-heat and post heat to normalize the weld. The heat is so concentrated in MIG and TIG, the welded area is heat treated and needs to be normalized to prevent failure right next to the weld. I have been welding 4130/N for years on vintage airplanes and only gas weld it to prevent embrittlement. It becomes much harder to gas weld large tubing and keep the heat in it so TIG works much better. However extra steps in pre and post heat have to be taken to prevent the embrittlement.

The only real gain to using 4130 is weight savings. Due to its higher strength than DOM, you can run lighter wall tubing. If you are just running a 4 point, I don't think it is worth it, but if you are building an entire cage, I would go the extra to use 4130.

[chicane]

Ok... with all the talk about ChroMo being stronger than mild steel... lets clear up the real questions to what is behind it all.

For one to just drop the 4130 tag into a discussion is somewhat futile. To specify which 4130 material to use would be respectable. And to suggest the heat treatment of the stated 4130 would be down right noble. You cant just throw the 4130 tag around like its cool... without explaining the difference to your audience... because they might not know any better. In consideration to what is relevant, this response will only deal with 4130A (the typical 4130 material used; hot worked and annealed, and not recommended), 4130N (what should be specified and used for almost everything you would make any worthy part from), and of course... 1018 and 1020 carbon steel. All materials have an 'ultimate tensile strength' and a coinciding value to which they "yield." So, with this, all of the following numeric values will be in psi.

For cold rolled 1018/1020 the number is 82,000 and yield at 70,000
For 4130A the number is 85,000 and yield at 65,000
For 4130N the number is 97,000 and yield at 85,000

By the numbers, metallurgically... there is not that much of a difference... especially when looking at the yield values, which is where we need to concentrate our focus on, for the individual, material strength.

Since 1018 and 1020 don't respond to heat treat, they will be left out of this. But 4130N on the other hand... when heat treated to a C scale of 25 to 30... the heat treat will increase the yield value to somewhere near 130,000 to 135,000+ psi. THAT... is a considerable difference and increase in strength. It almost doubles that of CR 1018/1020 and it does double that of 4130A.

So basically, if you don't heat treat 4130N... all you end up with is an expensive part with the same strength as 1020... and brittle weld areas.

4130 is often considered to be the ideal material for high strength and stress applications... but it really isn't. I keep hearing... "since 4130 is so much stronger than 1018/1020, you can get away with a thinner wall and save some weight." Well... that just isn't true. Unless you heat treat the 4130N material. With the yield strengths being as close as they are with like material diameters and wall thickness'... if you were to actually listen to those who would say this and go to a thinner wall... you would end up with a roll cage structure that would be measurably weaker than that of using 1018/1020.

If you dont heat treat the entire 4130N component... you will end up with embrittlement issues just outside of the weldment because of the martensite appearent just outside of the pearlitic structure formed by localization and not treating the entire structure. I brought up your same arguement a couple of years ago at work... and it went over the same way. I learned not to question the super genius' from that point on. But, at least I got an education out of it...

[Musclerodz]

I have never dealt with 4130"A", always 4130"N" in repairing vintage aircraft structures.

Why is there a need to heat treat 4130"N", when you can remove the embrittlement by pre-heating and post heating the weld when TIG or MIG welding it? I never suggested a huge savings over DOM or even 1020. It is a marginal gain for the cost increase.

I think we are in agreement, just coming at it from different directions. And the day I quit learning will be the day I die.

[Musclerodz]

Originally Posted by B Schein

There is an airplane supply place in Pennsylvania where Bought some chromoly tubing when I used to live up in the norther part of Maryland But i can't remember there name I know John Parsons knows who it is because he is the one who told me about them. It the closest thing to New England that I know of.

Dillsburg Aeroworks or something like that.

[B Schein]

Originally Posted by Musclerodz

Dillsburg Aeroworks or something like that.

That sound like it.

[NOT A TA]

Thanks guys!

Chicane, First let me say thanks for helping knuckleheads like me on these forums. Having read a lot of your posts here and elsewhere it's obvious you're knowledgable and just want to help. Seems like you're an honest to goodness nice guy with no hidden agendas. It'd be a pleasure to meet ya someday.

I don't really care what what the cage is made out of as long as it helps save me should the need arise. Balsa wood would be OK with me if it saved my butt!

Car is a 70 Firebird. Weighs about 3500 lbs (may go on a diet at some point)I have been using the car at NHRA tracks, NASA HPDE events at road courses, and the ECTA. The NHRA tech guys at a couple tracks made it clear that they didn't like my harness setup (Schroths but a little to much angle)and wanted me to have at least a roll bar with a harness bar. The NASA tech guys made it clear that I was kinda going too fast at Road Atlanta for no bar. The ECTA won't let me run over 135 MPH.

Like a lot of folks I was trying to avoid spending the loot and I really liked my interior the way I did it. I have used the car for vacations etc. sometimes driving thousands of miles and the idea of a Kirkey seat, no sun visors, and 5 or 6 point Harnesses on a 12-14 hour drive didn't appeal to me. However the car is slowly evolving into a limited street use car so now's the time! I'm thankfull I never had a mishap at speeds up to 150 and know I should have done these things before.

So I'm on a safety mission and promised myself I won't make the car any faster or run it anywhere till I get few things done so I might live to run again should something go wrong even if the cars totaled. Full cage, Fire system,elec fuel pump shutoff by oil pressure switch,better helmet (got an Arai), fire suit(thinking alpine stars).

The fabricator is familiar with mostly drag car stuff so I got him in touch with Joe Timney of the ECTA. I had spoken with Joe previously about requirements up to about 200 MPH. He'd mentioned door nets etc. as well as some of the requirements most of which went over my head since I'm not a metalurgist, fabricator, or welder. So I thought the fab guys could chat and figure out what I would need to run up near 200 later on. It was after they talked that my fab guy asked about the 095 chromoly and said my other option was the 1020 DOM. I'd be very interested to learn about these things but right now I just want the experts to tell me what needs to be done and someone with the correct skills to do it so I can concentrate on other things. I've built my cars by myself and it 's killing me to let someone else work on it but know someone else can build a safer cage than I can.

I'm going to continue to work up through the NASA groups (I'm in 2 now) and think the TT's would be fun but no side by side racing in this car. I'll be going back to the ECTA probably a couple times a year. I'm planning a west coast trip (trailered) for fall 2009 hoping to run the Silver State classic and/or possibly Bonniville and maybe hit a track day or two at road courses in California. I'm not trying to "win" anything just go out and have fun driving different events. Eventually once the safety stuff is in place I'd like to work on the aerodynamics and add power till I can safely hit 200 MPH.

John