How possible is it to bend 3x5 3/16 wall tubing. I want to use it as the framerails of a frame for my future buggy. Don't suggest round cuz I want rect. down there for multiple reasons. I'll use round everywhere else.

My question is, how much will the tubing cave in at the bends, the sharpest bend will be less than45*, and there's only going to be 4 bends per framerail. Will I be losing a ton of structure at these bends? If so, should I cut it (miter) and reweld it? I would think that bending would be better than cutting/welding.

Easy

JD2's can bend square tubing so it seems possible..however, finding a bender that will handle that size is gonna cost ya $$$$$

Cut & Weld
That's what's so nice about square tubing. You can lay everything out and do your cuts on a chop saw. You can't screw up a bend and lose a twenty foot section of material.
Just my $.02

call your local steel fabricator (if you were in Dallas i could help ya out) tell him the size of the tube and bends required he will be more than happy to quote you a price.

side note i get aluminum bent all the time and it usually runs 100$/part/bend i wouldnt think steel would be that much more

Brian

Chalk up another vote for the cut and weld option. JD2 doesn’t make a die that big and if you found one you would probably want to buy an Atlas instead.


(M3B Square Die Set - 1 1/2" (6.5-180) biggest available.)
:eek:

I assume you are going to bend it the hard wayyy (across the 5 inch measurement) if so it is not that difficult. Our bender here at the fab shop I work at will bend up to 7" tube, problem is the radius you want. on 5" you can get down to about 12' radius with about 1/2 in deformation of the tube. If it is packed full of sand first it will help but not stop it completely. You might be better off with the miter cut and then fish plate it. If you do call a fab shop call it 5x3 not 3x5 the larger size is called out first.

here's my solution
a little butch, but it should be bomb-proof

A trick used when bicycle frames are cut and mitred is to put a plate (which they call a diaphram) inside the joint. Basically, you cut a plate that exactly fits the end and tack it to one tube. Then you add the second tube, and run a bead that penetrates into all three pieces. Not too hard, because you are welding on the edge of them all.

The internal plate keeps the walls of the tube from buckling (which bicycle people call lozenging) at the joint due to the stress concentration.

The diaphram is typically the same, or next size thinner as the tubing wall. If you are torch or tig welding, make the plate just slightly oversized, and you can use the overhang as filler. Drill hole(s) for lightening, wiring, or using frame as air tank prior to welding.


Nearly as strong as adding scabs, but lighter, and neater looking.

Originally posted by fcfred
here's my solution
a little butch, but it should be bomb-proof

Hey Uncle Freddy! Why don't you give your son's wagon back to him! He's probably missin'it! :)

I don't have a son that's mine:D

mint green sbc??

fresh scent:D

Easy, Not sure what places are out that way. But here in PA the guys up at Auto-weld, they have a bender for there race car products. I know that they bend 2x4 nice and tight and have very little to no deformation(sp?) of the tube.

The machines to do this are serious bucks. I was gonna have a set of rails bent by a fab place. I think Chris Alstons chassisworks does it or maybe chassis engineering, I cantremember who I talked to about it. They can do it...in the end I just did it myself with chop saw and stacking the front part of the frame on top of the main rails to give the effect of a bend.

CJ

This topic has caught my interest.... I bought some pre-bend/manufactured cj7 frame rails from Advanced Frame Works.
And I had them leave-out a few bends at the rear of the frame.
Now I'm wondering if I could even do something else a bit
off-the norm and narrow the rear-section a bit to allow for
the coil-overs to clear and run outboard of the frame still...

question: about how much force would you guess it would
take to bend 2x4x 3/16 wall ret tube on the narrow (2") dim
on about a 12" radii????? I'm hoping it's 40> ton and under,
since that's what the ironworker is rated for.....

I have a 1.5" box die for a jd2 and it does a pretty good job but 3x5 would be very hard to find a big enough bender to do it. I say cut it and weld it. This will save you time and $$$$.

Originally posted by fcfred
here's my solution
a little butch, but it should be bomb-proof

The pic is a little dark, it's hard to tell what you used to create the bend.:confused:

no bend
stacked the tube,
then learned about stress risors
then 45ed the ends and boxed it all in plate.

woops I did bend the top and bottom plate

I would think cutting and welding would be ok. I am pretty sure that is how Matkins makes there frames from the info I got. I would think if done properly and gusseted it would be quite strong.

If you are set on bending it over cuttingtry putting a call into AFW and seeing if they can do the rails you want? AFAIK they are the only ones who make frames that are bent and not cut and welded on any large scale.

I remember trying to find someone to find to bend 2''x4'' tube and finally gave up. I guess the machine that does the bending is way pricey.
The guy at Matkins said it wasn't a good idea to manderal bend the tube anyway because it strecthes the metal to thin.

The machines in wieght lifting gyms are made from square and rectangular mandrel bent tubing, 'get a hard on when I look at them :D