Rollcage bending

Evening everyone. I am new to the forum, looks like a great site. I have a rollcage bending question. I am building a new race truck and I'm at the rollcage stage. We borrowed a friends bender, but it is only pinching the tube. The die is a 1 1/2, and the stock is 1 5/8. I believe with the stock being slightly larger than the die it isn't allowing the tube to move at all and crushes it. I ensured the die is smooth and lubricated the pipe, all to no avail. Does anyone have a trick for the 1 1/2? I also have access to a 1 3/4 die, any trick there? Thanks for the help.

Nope no tricks, just gotta have the right die for the tube. I assume you are doing mild steel, wall thickness is a big deal. If you get too thin it'll crink on you as well.
What you probably have is a pipe bender, they measure stuff different than tubing. Are you doing full cage? or a hoop? If full cage then 1 5/8 is right, if you are doing a hoop then you'll need 1 3/4". I find it is less expensive to get the auto-weld kit and bend only a few tubes for special concerns, you go bending the whole mess it'll take a whole lot more material than you think. Look them up on the internet, they may sell you just a few critical pieces and then you can do the rest yourself. Thier kits are very good and precise. They are in Pennsylavania, it is either autofab or autoweld - i get them confused. One is a race shop in MD and the other is the bender folks with the kits.

Thanks for the reply. I am using mild steel, got it at cost or I probably would have went with a kit. The wall thickness is 1.40, again, got it on the cheap or would have went for 1.34. I am doing a full cage. I'll keep looking for someone around here with the right die, was hoping for a little McGyver magic someone had. Thanks again.

What type of truck are you building? Road? Drag? NHRA cage rules call for 1 5/8ths by .118 wall. You could go heavier but thinner won't be allowed if you are doing any class racing...
You should pick up a specific rule book if you plan to do any sanctioned racing.
Mark

There are no shortcuts on this one, you need to use the proper size dies with the tubing you are trying to bend. You wouldn't think an 1/8 inch would make any difference but it does, the tubing won't bend smoothly, as you found out. If you are building a full cage you probably are thinking of racing it, so as Astroracer mentioned most sanctioning bodies have standards that you have got to adhere to.

Don

Drag. It's a 95 s-10. I'm already at .140 so no tech problems there. I'll check again, but I thought min thickness was .134? Either way I should be good.

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Originally Posted by GaReb

Drag. It's a 95 s-10. I'm already at .140 so no tech problems there. I'll check again, but I thought min thickness was .134? Either way I should be good.

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Minimum wall thickness is .118 but many people use .134 because mild steel tends to vary in thickness a little. The .134 gives you a little fudge room. As mentioned I would get an SFI book & follow it to the letter. Another good idea is to get in contact with your local Tech & ask questions about any parts of the SFI rules your not sure about. If you get your tech information from the guy that will eventually be slapping a tag on it, you'll save yourself some headaches.
I owe a big thanks to Techinspector1 & division 3 tech Rich Bowers for walking me through my build.

There are so many kits out there for the main hoop and side bars,it's hardly worth going threw what you are.Then you just take the material you have fish mouth it to "X" it or "Z" it in.Your going to find as you add bars to the main hoop how solid the main hoop gets.Tight seams are key.This assumes your as good welder.Yrs ago I did see a roll bar fail in a rollover.The bars ginzoo'ed the driver causing serious injury and he ended up loosing a leg.Not a pretty sight.

McGyver----OK--get the 1 3/4 die, some 1/16 thick sheet stuff, use it for a shim with the 1 5/8 tube, it'll form into the die---

BUT, as others have said--get the tech manuels and specs, because there areany different types of TUBING ( and even PIPE ) and most likely what you have isn't legal--if you got it cheap its probably welded tubing and what you'll need is seamless-----

also the design, where certain tubes,braces,gussets are fastened make a differance not to even get into the welding part of it.

Building a cage is not as simple as it first appears, first you will need a Tube bender not a Pipe bender, they are 2 different things, Pipe is measured ID and Tube is measured OD
Like the others said use the .134 wall tube and the correct die.
Its important to read the rule book, I've had people build their own cages and fail tech, just because it looks like a monkeys playing frame don't mean its strong.

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Originally Posted by roadster32

Building a cage is not as simple as it first appears, first you will need a Tube bender not a Pipe bender, they are 2 different things, Pipe is measured ID and Tube is measured OD
Like the others said use the .134 wall tube and the correct die.
Its important to read the rule book, I've had people build their own cages and fail tech, just because it looks like a monkeys playing frame don't mean its strong.

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I agree except for the .134 thats a lot of extra weight. Most circle burner rules around here say 1 1/2 .095 minimum D.O.M.
I retrack the .134 statement as I didn't see that it was for drag racing.

Pro: I see your point about making nice with your tech guy. I run at an outlaw track, no tech to speak of.

Gary: If I knew then..... but... I've got the stock now so I'll forge ahead. My brother does the serious welding. He graduated from Tulsa a while back and has been doing it for years.

Jerry: I'll give it a try. Still have some scrap to use so I won't trash good stuff. The tubing is legal, I only said cheap in comparison to full price. A friend works in a local manufacturer who deals in bulk and we got it at their price.

Thanks again to you all.

If this cage is for drag racing..............it MUST be TIG welded!!!!...........rules state no more MIG welded roll bars or cages.

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Originally Posted by sunsetdart

If this cage is for drag racing..............it MUST be TIG welded!!!!...........rules state no more MIG welded roll bars or cages.

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That is not true:

http://www.crankshaftcoalition.com/w...legal_Roll_Bar

Untrue ! It says if using chrome molly it must be Tiged.

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Originally Posted by sunsetdart

If this cage is for drag racing..............it MUST be TIG welded!!!!...........rules state no more MIG welded roll bars or cages.

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I am inspired by the fact what I am about to post I will sleep well knowing I am trying my best to protect you.BUY A KIT.It ant worth pinching penny's when it comes to your safety weather or not your amongst us or view the world from a wheel chair for the rest of your life.This is serious stuff,no joke!!.

I think you will find only Moly cages have to be TIG welded, Mild steel can be either MIG or TIG.

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Originally Posted by sunsetdart

If this cage is for drag racing..............it MUST be TIG welded!!!!...........rules state no more MIG welded roll bars or cages.

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Originally Posted by roadster32

I think you will find only Moly cages have to be TIG welded, Mild steel can be either MIG or TIG.

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Exactly...
From the NHRA rule book

Section 20 - General Regulations 20.19
4:11 ROLL CAGE
All cage structures must be designed in an attempt to protect the
driver from any angle, 360 degrees. "All 4130 chromoly tube welding
must be done by approved TIG heliarc process; mild steel tube
welding must be approved MIG wire feed or TIG heliarc process.
Welding must be free of slag and porosity. Any grinding of welds
prohibited." Plating of chassis prohibited for all cars manufactured
after Jan. 1, 2003, unless otherwise noted in Class Requirements;
painting permitted. Additionally, roll cage must be padded anywhere
the driver’s helmet may contact it while in the driving position.

There is a multiplying wt factor of the vehicles wt as it gains speed that the roll-bar/cage must endure in a rollover.I used to have the formula for that,but at the moment I can't find it.That is why winkle free bents,bracing and good tight fish mouth seam welding is critical.The weld should fuse the metal together and not be used as a glue.Out riggers are ok for mounting points as long as they fall within the expected spec a roll-bar/cage would put on them in a rollover.I am not a big fan of floor pan plates for a mounting point because I have seen them deflect or punch threw.I prefer to see direct mounting points to the main frame or out riggers.Triangle bracing to spread the load and X bracing to tie it together are also very important.Again all tight seam welding is a must.