Die radius for 1.75 and 1.5 ?

I've read the rule section for what should be allowed as a radius for 1.75 and 1.5" 0.095. It seems most commercially available dies meet those requirements.

Wondering what you guys are actually using. Tried searching, found 1 sorta reference, kinda surprised this hasn't been covered here.

Thanks
Jason

I think I asked about a month or two ago this same question with limited responses.
I got the smallest radius JF2 offers for each.

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NoCoast
I think I asked about a month or two ago this same question with limited responses.
I got the smallest radius JF2 offers for each.

Yeah.. it was buried in a thread about a bunch of stuff and things seem to get a little sidetracked here. Found your thread and its poor 1 response.

thanks for the update, manage to use them much yet?

Done 8 bends with it. Allows a nice tight fit so far.

I have the 4.5" die for the 1.5" and I would buy a 5 or 6" if I were to do it over. It makes a nice bend but starts to deform when you get close to 90 degrees. The V in the door bars could be nicer with a longer sweep. My 1.75" die is 6" and works nice. I would buy tighter dies for 1.25" and 1" stuff for building the silly fun toys like gokarts and bar stools.

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Reamer
I have the 4.5" die for the 1.5" and I would buy a 5 or 6" if I were to do it over. It makes a nice bend but starts to deform when you get close to 90 degrees. The V in the door bars could be nicer with a longer sweep. My 1.75" die is 6" and works nice. I would buy tighter dies for 1.25" and 1" stuff for building the silly fun toys like gokarts and bar stools.

I'm still not convinced that bent door bars is a good idea. I only got a 90 degree die in my 1.5".

Im sure the door bar debate will go on for years. I have the opposite opinion Im not convinced the X is the safest. I do think long sweeps are safer and are still a really tight fit in most cases.

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Reamer
Im sure the door bar debate will go on for years. I have the opposite opinion Im not convinced the X is the safest. I do think long sweeps are safer and are still a really tight fit in most cases.

Getting to my next set of questions already.. The nasa cage guide seems to lean towards a pair of bent tubes to form the X, not 1 straight and 1 cut.

I was wondering about deforming of the 1.5" @ 4.5".. moving to the 5-6" radius sounds reasonable for those.

Yeah I was just reading that to. how is .9 deforming measured? or how ever it was written is smarter then me.

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Reamer
Yeah I was just reading that to. how is .9 deforming measured? or how ever it was written is smarter then me.

Yeah.. saw that. I get what it means, but I've got no clue how to accurately measure it.

I just measured mine with dial calipers. The narrowest part of the bend is .60 smaller then the widest . I believe if this is how its measured Im good? (this is 1.5" 4.5 die on my door bars).

The bent door bars in rally cars is a North America thing inspired by the Lovell crash where had the internal injuries not been the cause of death, bleeding out from the torn X bar which impaled the leg and severed the femoral artery would have caused death from blood loss. They were never seen before then as far as I know.
I'm no engineer so I can't fully comment on the two designs, I just go with what I've seen work. I can imagine that the V results in more length of tubing and more ability for those tubes to deform inward.
Regardless, I like a sill bar and a traditional X with nice big gussets.

I think the Nasa rule missed a word.

If tubing is ovalised during bending,the ratio of minor to major diameter must be 0.9 or greater. ^
not
If it was 0.9 or greater it would be flatter and easier to kink correct?

I have a 6.5" radius 1.5" die and a 7" radius 1.75" die for my JD2 bender and I always get a nice tight fit and completely smooth and undistorted bends.

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Reamer
I think the Nasa rule missed a word.

If tubing is ovalised during bending,the ratio of minor to major diameter must be 0.9 or greater. ^
not
If it was 0.9 or greater it would be flatter and easier to kink correct?

No.

A perfect circle will have a ratio of 1 (both diameters are 1.5".

A highly ovalized tube might have 1" minor and 2" major, for a ratio of 0.5.

If your ratio is 0.6 you've got a heavily ovalized tube. Likewise, if you're measuring diameters 0.6" off on a 1.5" tube...you've got heavily ovalized tube.