So I'm considering building my own rollcage for my car. I know, I'm crazy. I've been researching this like crazy for the past several weeks and think I have a lot of the little stuff covered (i.e. gusseting plates, dropping the cage to weld the roof joints, etc)

The only thing I have left to figure out is what is the best way to cut and measure bent tubing? Like how do you measure then cut the halo and main hoop without going through tons of extra tube and still have it fit tight?

The only answers I have gotten is basically trial and error and I'm not ok with that.
There has to be a trick or other method.

so cage builders, give me tips. (on anything else for that matter )

 

This is what I used to get off the ground and start bending the main hoop.

http://www.pirate4x4.com/tech/....html

There is another link here with much the same idea.

http://tool.off-road.com/tool/...14818

I also use a lot of 1.5" muffler tube and or mig wire to estimate the bends and angles. This allows you to test fit the parts before committing to the real thing.

Dave
- #76 ITS

 

Great links.

 

WOW that helps alot! thanks!!

that first link is awesome!

 

Yep, good links.

I'm not one to give away the milk for free (anymore), but there are tons of ways to do it. Flexable exhaust tube, 3/8 rod, bend up a bunch of different angles and use them as templates... I've used all kinds of methods... and still do on occasion, even though I've got some software that I use. I still prefer the hands on approach as it gives me a tighter fit. I still use the 3/8 rod to double check my lateral hoop bends and any time I do a halo (pretty rare).

Be prepared to waste some tube when you're first starting out. Practice on some ERW tube first. MUCH cheaper than making a pretzel out of DOM

 

comeon spill the secrets

what you just said is like saying "im not gonna help you with your engine swap cause it takes away business from my shop" the whole point of this website is to help each other. people who pay to have work done, always will. you sure as hell arent gonna convince someone to build a cage with a few fab tips. people are VERY afraid of cage building lol

 

:D I just spilled em! It's your turn to run with em and get creative!

Use the flexible exhaust tube. You can slip short sections of tube into it to fill in the straigt sections, then bend the flex tube to whatever contour you need.

Same with the 3/8 rod. MUCH cheaper than tubing, stays fairly sturdy... you can actually build an entire cage model out of it, tack it together, use it as patterns or measure the cut length....

Just remember that tubing will grow as you bend it. A main hoop can gain about 2" or more per side.

Honestly, there are so many fab tips/tricks/pit falls, it's hard to even focus on one.

 

and the biggest tip... don't be afraid to cut long and trim to fit. Much less wasteful than cutting too short and having to do it over again or change your design to make a bad measurement fit.

 

thank you
and i was DEFINATLEY planning on starting way too long and trimming haha, cant really add length as easily as you can remove it!

 

I don't recall what I was smoking a week ago... but 3/16 rod... not 3/8

 

Once you've figured out the angles for all of your bends, I would use short sections of rollcage tubing (shortest length that will fit well in your bender) to practice achieving those angles. Remember that metal does spring back...

 

Can any of you guys reccomend a good place to get dom tubing from ?

 

Might help if we knew where you were from...

Look under Metals in the phone book

http://www.shapirosupply.com is where I get mine from... but they're local to me.

 

The biggest issue i see is a cage is a life saving safety device and if you are not experienced in structural engineering, or fabrication this is not something you should attempt.

Here's an example

I can fabricate
I know engineers who can design a cage
I can get all of the tools to do it.

But at what point is saving dollars worth a possiblle life.

A roll cage is the foundation of your racecar and should not be skimped on nor built by somebody that has a large lack of experience.

Either way good luck measure twice cut once

 

what bender will work without scrrewing up the bends.....im looking to spend 50-150$.....should i go with a HARBOR freight one?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ekasey &raquo;</TD></TR><TR><TD CLASS="quote">The biggest issue i see is a cage is a life saving safety device and if you are not experienced in structural engineering, or fabrication this is not something you should attempt.

Here's an example

I can fabricate
I know engineers who can design a cage
I can get all of the tools to do it.

But at what point is saving dollars worth a possiblle life.

A roll cage is the foundation of your racecar and should not be skimped on nor built by somebody that has a large lack of experience.

Either way good luck measure twice cut once </TD></TR></TABLE>

im definatley not an engineer but a rollcage is a VERY basic structure.

**** the rules tell you how many bends and what angles you can have for your major safety pieces (main hoop, rear braces, front a pilar hoop/halo)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allricedout &raquo;</TD></TR><TR><TD CLASS="quote">what bender will work without scrrewing up the bends.....im looking to spend 50-150$.....should i go with a HARBOR freight one?</TD></TR></TABLE>

An OK bender for cages is the Pro-tools unit, with options mine was approx. 1800$ canadian(exchange was high) I'm sure you could get it cheaper, but 50$ to 150$ It's not going to happen.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kamin &raquo;</TD></TR><TR><TD CLASS="quote">

im definatley not an engineer but a rollcage is a VERY basic structure.

**** the rules tell you how many bends and what angles you can have for your major safety pieces (main hoop, rear braces, front a pilar hoop/halo)</TD></TR></TABLE>

You're not an engineer yet you are deeming something basic? I'm lost good luck to you it's your racecar just don't crash into me



Modified by Ekasey at 11:16 AM 1/9/2007

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kamin &raquo;</TD></TR><TR><TD CLASS="quote">

im definatley not an engineer but a rollcage is a VERY basic structure.

**** the rules tell you how many bends and what angles you can have for your major safety pieces (main hoop, rear braces, front a pilar hoop/halo)</TD></TR></TABLE>

It may be a "Basic" structure, but I can't tell you how many times I've seen bad cage designs. And if it's so basic, why do so many people get it wrong? The answer is that a cage is not so simple and certain design parameters really need to be analyzed to fully protect the driver. My concern with cage safety has to do with the peak forces the driver experiences when tee-boned. On the other hand, roll-over safety is much less of an issue since the peak accelerations do not tend to exceed critical injury levels all that often. So it is with the side impact design which should be looked at very carefully. For example, should the door bars be a two or three bar design? Should the door bars be staggered so that the outermost bar starts to deform prior to other bars deforming? How many stringers (the vertical bars attaching adjacent door bars) should be used? How best to attach the a-pillar bar to the chassis using a rectangular plate or square plate? There are many questions like these that should be discussed before a cage design is finalized.

So other considerations: How much do the other cars on the track weigh? The more the other cars weigh, the larger the impact force will be at a given speed. When all is considered, the best cage design would help attenuate the impact loads better thus decreasing soft tissue damage to the driver. At the same time, the deflection of the structure should not be large enough where the driver is contacted by the deformed structure.

So you see, yes a cage is considered a simple structure, but it is not easy for most fabricators to know the answers to all the questions asked above.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allricedout &raquo;</TD></TR><TR><TD CLASS="quote">what bender will work without scrrewing up the bends.....im looking to spend 50-150$.....should i go with a HARBOR freight one?</TD></TR></TABLE>

The $50 "bender" is more like a pipe "crimper". No bueno.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ekasey &raquo;</TD></TR><TR><TD CLASS="quote">
A roll cage is the foundation of your racecar and should not be skimped on nor built by somebody that has a large lack of experience.

Either way good luck measure twice cut once </TD></TR></TABLE>

everyone has to build their first cage, nobody starts off having the experience of building 100 cages. i agree that a roll cage is a very basic structure. the only difficult part is making sure the mounting points are actually structural and can take the abuse of an actual rollover or impact. sure ive seen horrible cages before but that doesnt mean that just because some people suck doesnt mean that someone else wont do a good job the first time.

and why would you be scared of someone with a poor cage running into you if your cage is up to par .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Johnny Mac &raquo;</TD></TR><TR><TD CLASS="quote">

It may be a "Basic" structure, but I can't tell you how many times I've seen bad cage designs. And if it's so basic, why do so many people get it wrong? The answer is that a cage is not so simple and certain design parameters really need to be analyzed to fully protect the driver. My concern with cage safety has to do with the peak forces the driver experiences when tee-boned. On the other hand, roll-over safety is much less of an issue since the peak accelerations do not tend to exceed critical injury levels all that often. So it is with the side impact design which should be looked at very carefully. For example, should the door bars be a two or three bar design? Should the door bars be staggered so that the outermost bar starts to deform prior to other bars deforming? How many stringers (the vertical bars attaching adjacent door bars) should be used? How best to attach the a-pillar bar to the chassis using a rectangular plate or square plate? There are many questions like these that should be discussed before a cage design is finalized.

So other considerations: How much do the other cars on the track weigh? The more the other cars weigh, the larger the impact force will be at a given speed. When all is considered, the best cage design would help attenuate the impact loads better thus decreasing soft tissue damage to the driver. At the same time, the deflection of the structure should not be large enough where the driver is contacted by the deformed structure.

So you see, yes a cage is considered a simple structure, but it is not easy for most fabricators to know the answers to all the questions asked above.</TD></TR></TABLE>

i understand what you and Kasey are saying, but I am not some 18 year old snot nosed kid who wants a madd tiite rollcage for his street car. I have done (and will continue to do) my research till i am confident in my ability and confident in the design i have been thinking of.

 

if you haven't yet, look at this thread

https://honda-tech.com/zerothread/1855257

you have get some door bar ideas from there.

I input on the bender, JD squared model 3, I use one, works very well and not to expencive. About $650 shipped.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kamin &raquo;</TD></TR><TR><TD CLASS="quote">

i understand what you and Kasey are saying, but I am not some 18 year old snot nosed kid who wants a madd tiite rollcage for his street car. I have done (and will continue to do) my research till i am confident in my ability and confident in the design i have been thinking of.
</TD></TR></TABLE>

My comments were not referencing street car type cages, but were directed at so-called full-race type cages. When you say you are doing your research, just what is meant by that? Are you calculating loads including forces, moments, and torques on a given cage design or do you mean you are looking at cages built by different fabricators? I'm just curious on what you mean.

 

For fitting a tight cage, after you install the main hoop, how do you get a 360 deg weld on the pipe for attaching your roof beams?
Does that question make since?