Opinions on bend radius for 1 3/4 tubing

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Location
Sheridan, WY
I'm looking for opinions on the best radius for 1 3/4 roll bars. I'm going to buy a JD2 bender and they have a 5.5 and 6.5 "clr" radius die available. I'm thinking that a larger radius would be easier to bend, less likely to kink, and stronger in the end. I don't think I will need to bend anything where a tighter radius would be an advantage.

Thanks for your input!
 
I'm looking for opinions on the best radius for 1 3/4 roll bars. I'm going to buy a JD2 bender and they have a 5.5 and 6.5 "clr" radius die available. I'm thinking that a larger radius would be easier to bend, less likely to kink, and stronger in the end. I don't think I will need to bend anything where a tighter radius would be an advantage.

Thanks for your input!

I went w/ the 5.5 cuz there may be a situation where you need the tighter radius. Don't worry about kinking as I've never had a problem w/ 1 3/4" .120 wall DOM even on 180 deg. Never tried the non structural tube/ pipe though in that size.... Only time I ever kinked DOM was building headers using 1/16" wall - I could almost go to 90 deg. before major derformation & I was using 1 1/2". I also filled the tube w/ sand, compacted it & capped both ends.
 
Anybody have any comparison pics of 5.5 and 6.5 with at least a 90 bend? Always wondered which "looked" better for hoops?
 
I intend to also use hrew, at least for sliders. Any issues with the tighter radius on electric welded tube?
 
I intend to also use hrew, at least for sliders. Any issues with the tighter radius on electric welded tube?


I would opt for the larger radius die. the tighter the radius, the more the wall thickness of the tube on the outside of the bend will thin due to the bend. Its pretty standard in racing organizations to multiply the diameter of the tube by three to find the min bend radius required. I think the 5.5 meets that, but if you can get away with the larger radius die, I would use it.

Also, DOM is not that much more expensive than HREW and significantly more uniform in wall thickness. Having built cages in HREW and DOM, there is no way I would build a cage from HREW again. DOM bends much more predictably in multiple planes, and when countering springback, repeatabiltiy of bend angles is key, so something more uniform is going to be easier to learn.

For HREW, Make sure the seam in on the inside of the bend. when doing multiple plane bends this will present a problem.
 
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I have the 5.5 w/ 1.5".

I have never wished for a larger radius.

I'm sure I could not say the opposite if I had gotten a 6.5.

No serious issues with either HREW or thicker steel. Bend .125 all day. It has bent .25.
 
I've got the 5.5" and a friend has the 6.5". I have never wanted to use his, but he has wanted to use mine...

I've bent .120 DOM and HREW and not had any problems with kinking, including 180* bends.

The tighter the bends, the better the tube fits inside tighter spaces, like inside cabs of trucks, etc.

Ary
 
Okay, I went with the 5 1/2 clr. That was the clear recommendation from this forum and other input I received. Thanks for everybody's help. Bender should be here by next week.
 
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Bought my JD2 Model 3 about a month ago. I went for the 5.5 inch radius die for 1.75 tubing. The minimum wall thickness for that die was much too thin to be building cages out of (which is what I bought that die for), and I took a compass and some paper, and drew out a couple of 90 degree bends for the different radius bends... There wasn't a huge difference if you were to look at them from a distance, but the tighter bend could tuck into the corner of my Blazer's cab much more nicely... and my FJ55's roof is completely squared off also...

My project FJ55 has a cage in it now, that came with the truck...
It is made out of 2 inch tubing with a fairly large radius die (6.5-7.5 inch). The bends in the main hoop limit headroom quite a bit.
 
heres some bends
bend_radius_examples.jpg
 

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