Plans for a rollcage?

[villemil]

Does anyone have plans for a drag racing rollcage?
I need a rollcage that goes from front axle to rear torsion bars with door bars.

[Ol'fogasaurus]

https://www.bing.com/search?q=plans+for ... 75&pc=U531

This might get you started as it is (supposedly) a start in design. There are different rules for different car/speed stages for a certified cage.

Lee

[Lo Cash John]

There's about a million pics in the Gallery at The Samba. Go look there for inspiration. Most important is to have a current copy of the sanctioning body's rule book in hand as specs change over the years. What was ok 10 years ago may not pass tech now.

Have you ever worked with tubing before? Bending and notching with precision is a learned skill. It's VERY fun and rewarding but does take practice and patience.

[Ol'fogasaurus]

There's about a million pics in the Gallery at The Samba. Go look there for inspiration. Most important is to have a current copy of the sanctioning body's rule book in hand as specs change over the years. What was ok 10 years ago may not pass tech now.

Have you ever worked with tubing before? Bending and notching with precision is a learned skill. It's VERY fun and rewarding but does take practice and patience.

The statement about 10 years ago is a very good statement for sure.

If you are talking about bending using kerfing you are disturbing the grain of the tube which is taking strength out of the material. Also, for each cut the end of the cut needs a round hole at the end of the V-notch to stop potential cracking.

sleeving joint for tube copy.jpg

thNU9NFFPC.jpg

cagesamplesW[1].jpg

This was posted by "DustyMohave" many years ago on making joins on cages and things that might apply to the roll cage subject. Again, the rules change and quickly so.

Lee

[Lo Cash John]

I'm not sure what you're referring to with kerfing cuts? I've never seen anyone "bend" tubing like this and I'm pretty sure EVERY legit sanctioning body would ask you to leave or park that thing off property for insurance reasons. I have a JD2 model 4 bender and a Harbor Freight tube notcher (there are better on the market).

[Ol'fogasaurus]

I'm not sure what you're referring to with kerfing cuts? I've never seen anyone "bend" tubing like this and I'm pretty sure EVERY legit sanctioning body would ask you to leave or park that thing off property for insurance reasons. I have a JD2 model 4 bender and a Harbor Freight tube notcher (there are better on the market).

IMG_2490 copy.jpg

This is an example if kerfing and I use it for mockup purposes only but I have seen it done before welded up for cages. Maybe not for sanctioned events but it has been done in the past. Remember... "ignorance is bliss" (definition: if you do not know about something, you do not worry about it.)

Bending tube can be done in several ways with some of those ways not really acceptable. Without getting into this again deeply, when you bend something, in this case like a tube for example, the outer portion of the bend's surface is stretched while in the inner portion is compressed. Some styles of benders push the tube to bend while other styles pull/wrap the tube around a mandrel. One style is better and stronger than the other.

The inside radius of the bend is also very important.

Lee

[slayer61]

I have seen handrails (not "sand rails") done that way

[Ol'fogasaurus]

I got interested in riding on the sand back in the early 90's. Back then you saw a lot of home made and home fixed things out there. I even saw it earlier than that on the street and on the track before things got normalized with good info.

People also used exhaust tube benders to make cages which is not a good idea either as they (depending on the type of bender) can deform the tube.

For mockup kerfing is OK I guess but that is about the limit of it. Once the grain of the tube is cut things weaken up more than often understood by a lot of people.

Lee

[Lo Cash John]

That's one of the most terrifying VW builds I think I've even seen!!!

[Ol'fogasaurus]

That's one of the most terrifying VW builds I think I've even seen!!!

You understand what a mockup is don't you?

I was looking into what I can do with the limitations the fiberglass body design had and the limitations it put to me.

Mocking up things is not a new idea and I'm pretty sure that even with CAD/CAM the need for it (probably) is still there. I worked with 4 different CAD design programs and even then we occasionally had to rely on full size mockups to determine certain things.

Lee

[Lo Cash John]

Oh for mockup yes, that's a great idea actually. The only issue I can imagine is your tube bender not being able to exactly reproduce the bends that your kerf cuts allow. Having a box of bend "samples" of different angles is the easy way to do it for me. I have a few laying around for similar reasons.
My buddy and I bought Bend-Tech Pro several years ago and it works VERY WELL once setup. The latest update is giving us fits I must admit but we just need to spend some time to figure out what we're doing wrong I guess.

[Ol'fogasaurus]

I was told the minimum bend radius of the material that the cage would be made of so I made a mockup circle of the arc and used it when forming the bends: simple isn't always obvious .

I don't have a tube bender as I don't have enough room for it and it (hopefully) is going to be a one time use (I am very old now ).

Lee

[Ol'fogasaurus]

I just did a search on roll bar dimensions and minimum bend radiuses. Holy cow are there a lot of specs for different styles of racing and different countries. The minimum bend radiuses are "wow!" as some say the radius is X times the radius of the tube taken at the center line of the tube while others are more specific plus the method bending is critical.

Also the dia. of the support tubes also change too.

Do a search and try to find where (race location) what you are going to use it for and type of racing/use you will be doing and even the type of vehicle being used. Whoof!

Lee

[RLFD213]

Whatever you do with your cage make sure you build it so you can get the body on and off. Most cages around the B-Pillar get wider then the heater channel and you can’t get the body off or on because of that. Speaking from experience myself.

[gbaker770]

Just call Rhodes Race Cars and order one of their 12 Pt cages and be done with it or call a chassis shop, mild steel or chromoly. That way you’ll get an NHRA cert.