min radius for roll cage tubing

M

mom'sZ

New member
I'm attempting to 'design' a piece of roll cage. What is generally considered the minimum (smallest - tightest) radius bend that can be made to a piece of 1 1/2" DOM roll cage tubing. Not the apsolute min, but what most tubing benders can handle. Please state the measurment is inside, outside or on the centerline.
Thanks
 
If this is for SCCA, the good book will list the main hoops min legal radius, IIRC.

Ninja edit: Words "main hoops" added..
 
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Good call Jake, thanks
9.4.G.3 states:The radius of all bends in the roll cage (measured at centerline of tubing) must not be less then three times the diameter of the tubing.
So.... 1.5" tubing x 3 = 4 1/2" radius at centerline. So my question then becomes is your average tubing bender capable of bending 1.5" tubing that tight?
 
I'd think it would be 6" on the centerline as it sure would make everything easier to design but I'm just guessing.
 
A tubing bender die uses CLR (center line radius) for its measurement. So a die with a 6" radius means a 6" radius measured at the centerline of the tube. The radius on the inside would be 1/2 the tube OD less then 6" and the radius on the outside will be 1/2 the tube OD more then 6".
 
The fab shop that did my 1 1/2 O.D. Miata hoop did an inside radius of 3 7/8. NO wrinkles. The main hoop, halo & front down tubes fit within 1/4 inch of the roof/body full length of all tubes other than the corners, but they are as tight as one can get them. Ya need the room in a Miata. I figure this is my last race car therefore I'm being real anal. :cool:
 
I use the JD2 bender and have the dies for a 4 1/2 ctc radius. That is the min. for 1 1/2in tubing, I have never had any issues with crinkle/wrinkle etc. with bends. I also have had no problems with following contours with 4 1/2 radius. I' in Orlando if you need anything built let me know. 407.463.0312
 
Just wanted to give Chris Leone (DoubleXL240z) a big thumbs up. I called him Wednesday afternoon, sent him my little sketch of what I needed done and Friday evening the new roll cage member was waiting on my doorstep. Great work, fast and cheap!!! Thanks so much Chris and I'll ring you up when I need more stuff done!!
Highly recommend Chris's work and service.
 
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