Question about sportsman rollcage construction: (1 Viewer)

[.]

The down bars on both sides that come from the halo bar, and go down along the windshield pillars to the rocker sills.....

Can a tube be 2 pieces welded together?
-Or does it have to be one solid, un-cut piece of tubing?

Does it matter what method/process or machine bends the tubes?

Thanx....

 

[Wes]

Such bars can be, in some cases, butt-jointed, but the process is very detailed. First, the two tubes to be joined together must be of the same material, outside diameter, and wall thickness. Second, there must be an inner tube placed inside to act as reinforcement. Thirdly, there must be rossette welds within 6 inches of the butt-weld.

When I was an IHRA chassis guy I did certifiy a few such roll cages but only to the 8.50 spec (the cars in question were all mild-steel, basic cages). There were some that did not pass muster based on the poor quality of the splice or the owner's reluctance to allow me to drill 1/8" holes to verify the presence of the inner tube (which told me there wasn't one). To be on the safe side, I would advise to refrain from the practice of butt-joints in any roll cage. All of the commercially available cage kits on the market are offered with continuous tubes for all the major points.

I suspect you are trying to pass the A-pillar bars through a dash, correct? It can be done without removing or drastically clearancing the dash, but it takes A LOT or patience and time.

Mandrel bending is the only accepted method of bending mild steel or chrome-moly tubing for use in race cars. For very slight bends you may see some chassis builders heat and manually bend a tube, but never beyond 10 degrees. Crimp bending will not pass in the roll cage area.

Hope that helps!

 

[.]

Yes, it helps tremendously! Thank you kind sir Wes!

Eh, I bent some CM with a hydraulic tube bender from harbor frieght and it pinched the tube. Wanted to know if I could cut out the pinched bend and weld in a new properly bent tube.

I ordered new tube from Aircraft Spruce in SoCal.
Going to bend it properly if I can find a pro shop with a bender around here and return the hf bender.
Car has no dash.
Thanx Wes!!!!

 

[ex-nsp]

True Radius bending in Santa Barbara is about as close as my feeble mind can recall a quality tube bender- they've been around a long time. Ph 805 962 2512

 

[TJ]

Most high-end muffler shops have good/quality benders..

 

[unclebob]

Mandrel bending is the only accepted method of bending mild steel or chrome-moly tubing for use in race cars. /QUOTE]

Wes; to my knowledge, very few chassis shops own "in house" MANDREL tube benders. A "mandrel" is a ball end plug that is inside the tube for support while the bend is being done. The draw die (or rotating die) is many times erroneously called a mandrel, even saw it on Monster Garage ! Many chassis shop machines are "draw" machines with NO mandrel, i.e. Mittler, JD-2, Ercolina, Pro Tools, and the old faithful Hossfeld.
Also to clairify the term DOM tubing means it's drawn over mandrel, and you can't find the weld seam.

Bob

 

[unclebob]

Most high-end muffler shops have good/quality benders..

NO they don't ! Unless they are a major header manufacturer. Muffler shops use "squash" benders, typical price being $5500. with a fair amount of tooling.
You may be able to find a used mandrel machine with maybe 5 sets/sizes of tooling for about $25,000. or $65,000 ++, new.

Bob

 

[Wes]

Sorry about the outdated nomenclature, Bob That's what they were called when I was growing up in the chassis shops of Ed Mabry, Tony Caserez, and Paul Peyton (bet my dad feels old now!). The name just stuck even though it has been many years since I have seen an actual, real life mandrel bender.

A nice unit with the proper die sizes from JDSquared or Mittler Brothers, to name a couple, will suffice. Just stay away from the muffler shop benders!

 

[stanman]

Paul,

Do yourself a favor and find someone that has a real tubing bender. There are several chassis guys in your area that would probably bend the tubes for a small fee.

Butt welding roll cage tubes that are part of the SFI spec is roundly frowned upon.

Question:

Is this a simple cage install in a street/strip car or a full blown race car?

If it's a race car and you're installing a dash tube you can simplify things by making the dash tube the same size as your A-pillar tubes. Then you can use two straight pieces of tube for the A-pillar welded to your dash tube rather than a sinlge tube.

BTW... you do realize you have to TIG weld 4130, right?

Check out the Cavalier roadster I built for local racer, Art Hoover.

Bumracing.com Photo Gallery :: Stanman Cavalier Build

 

[stanman]

BTW...

The wall thickness and diameter of the tube, along with the radius of the bend will be the limiting factor on the angle you can bend the tube.

Rick Santos built his cars in the home shop at his dad, George's place. He uses a Hossfeld/JD-2 style benders and it produces the absolutely best bends I've ever made. I use it to make my bends were the angle exceeds certain angles with the larger diameter tube and thinner wall thickness... ie. 1-1/2" x .058".

If I were to do it over, for the price I would by one of the JD-2 or Pro-Tools manual benders over the Power Tools "bottle-jack" hydraulic bender I have. My bender won't produce a wrinkle free bend past 60 degrees in larger diameter tubes... even with .083" wall.

 

[.]

Hi Stanman,
yeah, it's a street car.
UPS delivered the new tube today.
I am using 1⅝" tube for the whole cage.
Aircraft Spruce said they didn't have .084 thickness, so I got got their .095"
I won't butt weld any of it.
Going to try to find a proper bender around here tomorrow now that I have the material.
TIGing is one of my favorite activities in life

so, that will be the plan.
Thanx for the link, that is fabrication pr0n (porn) to me.
Gonna check out and study each pic in detail tonight after work.
Looks really good!

 

[stanman]

...Aircraft Spruce said they didn't have .084 thickness, ...

I hope you were asking for .083" or the salesman was probably laughing under his breath? LOL

Going to try to find a proper bender around here tomorrow now that I have the material.

You've got Hansen and Victory down in your area. And I'm sure there's a few dozen others too.

TIGing is one of my favorite activities in life

so, that will be the plan.

You're one sick puppy. We'll be fast friends...

Thanx for the link, that is fabrication pr0n (porn) to me.
Gonna check out and study each pic in detail tonight after work.
Looks really good!

No problem. Though I've never got a chubby looking at fab work... ROFLMAO