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Discussion Starter · #1 ·
Has anyone ever bent 1.75x.120 DOM to a 3.5" radius? Not having any luck, the tube keeps tearing if we try and bend it past 45 deg. Any help would be appreciated. Will post pics when I get home.
 

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I have never tried to bend to that tight of a radius. My tightest is 4.5 at that diameter, but Wagner Railing systems can do it if you have the time to give them. They can give just 90degree bends or most any you want with the tangents you need. Their website is RBwagner.com. Coming from a structural fab background they do some trick shit for custom handrails and all and may be able to help you with your problem. If not sorry to be a dumbass answer.:D
 

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Air Bag said:
Has anyone ever bent 1.75x.120 DOM to a 3.5" radius? Not having any luck, the tube keeps tearing if we try and bend it past 45 deg. Any help would be appreciated. Will post pics when I get home.
rotary draw?? seems like too tight of a radius for that tube.. thicker tube might go farther.. but i would thinking bending just short of the tearing point would weaken the outer part of the tube waaay too much.. i guess this would have to be bent w/ a different machine and technique.. has anyone been able to do this?
 

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Yup, its just to tight for that thin of a wall. If it didn't break it would stretch to a point that there would be no strength at all. I think my 1-3/4" is a 6.5" but I know they make a 5.5" for the JD2 mod 3
 

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Discussion Starter · #7 ·
The convention on tube bending is 2x the diameter is as small as you can go and that is right where we're at.

Next question does anyone know what temp it would take to anneal DOM?
 

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I think yer on the right track with the heat. !!!!!I AM NOT A METALLURGIST!!!!! BUT - From what i know, i think if you were to heat to heat the tube with a torch to a reddish color, then bend it, then heat it again to an orangeish color, that'd be the best way. DOM can't take much temp to anneal, maybe 750-1000 deg.?????

anyways, try heating it just before bending, what could it hurt??
 

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is that the only try at it or was there several? I know at work we bend tubing all day long and once in a while, we get a shitty peice of material and every peice out of that stick will break. and we are using 6.5" diameter dies. just a thought.

-Scott
 

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Maybe just try to bend it when it is hot it seems to make sense and would allow it to stretch better, but i don't know what its integrity would be afterward. What do you need such a tight bend for any how?
If i remember i will ask my Engin. materials profesor on tues, and see what he has got to say.

Ian-
 

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Discussion Starter · #11 ·
SCOTTS_4X said:
is that the only try at it or was there several? I know at work we bend tubing all day long and once in a while, we get a shitty peice of material and every peice out of that stick will break. and we are using 6.5" diameter dies. just a thought.

-Scott

We wasted 10' or so. This is on a CNC mandrel bender so heating it while bending is not an option. Was thinking that we could anneal the area of the bend. The work hardening of the mandrel bend might make it close to its original strength. Can anyone back me up on this? Metallurgy was a long time ago.
 

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find someone with a bendtec it will bend that tight of a bend .. also heard of puttin VERY fine sand in with the heat to keep it from crushing in and breakin

just my 2cts
 

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it's a cnc mandrel bender, but are you using the mandrel (the part that is inserted into the tubing during the bend)? does the machine have a rotating arm and a follower shoe? it's most likely a rotary draw bender with a mandrel option.

EDIT: I went and looked at the pictures of the bender that camo posted up a while ago and it apears that you are not using the inserted mandrel. I'm still thinking that you might have a bad material sample. were all 10' out of the same stick? maybe try another stick? do you have another bundle? maybe try a stick out of that bundle.

-Scott
 

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kling-on said:
find someone with a bendtec it will bend that tight of a bend .. also heard of puttin VERY fine sand in with the heat to keep it from crushing in and breakin

just my 2cts
it's BENTEC, that's what I use at work all day. In this case I don't think it has anything to do with the quality of the bender, seeing as how he paid quite a bit of money for this little jewel.

-Scott
 

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SCOTTS_4X said:


it's BENTEC, that's what I use at work all day. In this case I don't think it has anything to do with the quality of the bender, seeing as how he paid quite a bit of money for this little jewel.

-Scott
sorry i can't spell i'm not a tube guy just had a friend who had one and wow can it bend...
 

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kling-on said:


sorry i can't spell i'm not a tube guy just had a friend who had one and wow can it bend...
oh it's cool, I wasn't flaming you I was just spelling it right so that people could check it out if they wanted to look into it.

-Scott
 

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Discussion Starter · #18 ·
We are using the mandrel and we tried it adjust to extremes in both directions with no positive results. All bends were from the same stick of material, but it all has the same lot number. So I don't know if trying another piece would help. Never had any experience with bad material.
 

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you might just want to try another stick. we get material like this at work all the time. I can bend 100 parts in a day (3 bends per part) and not have one peice break, and the next day cut 5 more peices out of the same bundle and have all of them break. it just depends on the smooth operation of the foundry that is making that lot. raw materials may have needed to be added right in the midle of making your bunch of tubing and that nay be the stick you are trying to bend.

-Scott
 
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