Bending 6X2X1/8 Rectangular Tubing

I need to put a shallow bend (sweeping radius) in 6X2X1/8 rectangular tubing. The depth of the bend needs to be about 1 inch over a 52 inch length. Seems easy enough... The length of the material is 12', but the sweep needs to be towards one end. The end result will be frame rails for my 30' Chevy. I'm trying to follow the contour of the floor pan from the firewall back to the rear wheel openings. The car will be fenderless and the frame will be in a bit from the sill. It'll be flush at the firewall and rear wheel well openings. The rear wheel wells are about 1 inch in from the outside contour of the body at the floor.

The backup plan calls for slicing the tubing to allow movement for a nice subtle controlled bend, then welding the slices back up. I'll be using this method to "straighten" the rails for the forward section of the frame. The idea I'm chewing on is setting up two work knees 52" apart, lightly clamping the tubing to the knees so they can slide, and pushing the tubing with a hydraulic ram. My concern with this method is that I'll end up with more of a "V" shape than a sweep.

Any suggestions would be welcomed.
Thanks...

Here's what I did recently using 2x2 x1/8 tube to make rockers for my 47 Chevy. Needed a slight curve to match the door bottom. Using a 41/2 in. grinder with .045 thick cutoff wheel I made several cuts thru 3 sides of the tube about 8 in. apart. Pulled the tube to the curve I needed then welded the cuts. I have done this with 2x4 frame rails, it works the same way.

fuzz,
thanks for the response. I've used this method before and it's my backup plan. The frame will be exposed so I'm hoping to avoid this technique due to the faceting that will occur. I will be using this technique to put the front part of the frame in the correct position and the rear section may call for this as well.

This may be hard to follow, so I'll type real slow.
Use a log chain and a hydraulic jack. Set the jack where you want the deepest part of the bend. Hook the chain in one end, and run the chain over the jack and hook the other end. Use a boomer to take up the slack in the chain. Then jack the jack until you get the tube bent. Remember there will be some spring back, and be very carefull when the jack has tension on it, so the chain does not slip off the top of the jack. I have used this method to straighten truck beds and trailers for the past 35 years, and it works well. It will take some patience to get them both the same, but it can be done.

Also, you can add a short length of lumber under the jack, so it does not make a sharp bend at the edge of the jack plate.

I use a less technical way of laying the piece of stock up on a block of wood say 6"x6". then I run the front tire of my 1 ton up the piece. the further up I run it the more pronounced the bend is at the front. you can stragger other pieces of wood along the length if you want a gentle long curve. [

jfg455,
Not a bad idea. I want a little more control though. When you did this how much of a lump or depression did the short sides of the tube have? I'm thinking that such a shallow bend should produce very little shift but the metal has to go somewhere.

I didn't get any kinking due to the long shallow curve that I put into them. we are talking 3" over 6' of tube. I was using 2x4x1/8" tube. it is kind of like rolling it. put boards under it so it only deflects a little all the way up. then progreesively add more height or less boards for mor cuve. if you try and do it all at once you might kink it.

jfg455,
Thanks for the input. I only need about an inch and a half over 52". I need to do it twice... should be fun.

Is there a reason that you are using such a tall frame?

Ive used the slice and bend method on alot of different sizes of tubing with good and its easy to control your bend.

21willys said:

Is there a reason that you are using such a tall frame?

Ive used the slice and bend method on alot of different sizes of tubing with good and its easy to control your bend.

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The body is going to be sitting on top of the frame... just like a Model A on a 32 Ford frame. The bends are needed to match the outside curvature of the body. I've also used the cut and slice method with success, the only problem is it will leave facets on the "face" of the frame. There's really no way to avoid the facets (flats) when slicing so I plan on just bending.

I got the material and it doesn't bend easily. It'll bend if you don't care where or how... So it'll either be slice it, bend it and weld up the slices or remove the top, back and bottom (leaving only the portion that will be seen when the body is on it) bend it, remake the top and bottom and reuse the back. My original plan was to make the frame out of flat stock and weld the pieces all together... BUT I don't have my frame jig, so keeping all them pieces square can be tough.

Klink, if you haven't done the bend yet, I bend truck arms for a truck circle track racing series that are 2x4x1/8 and the best way I've found is to cut a piece of 2x4 lumber (in your case 2x6) about 16" long or how ever long the radius is and slide it inside to the position of the bend, then go to a press brake using a piece of round bar stock for the upper insert then set 2 steel blocks on the bottom of the press at 14" (or whatever distance you need) apart and make your bend.
In our case the 2x4 breaks in the middle and falls out each end of the tubing and doesn't make and unsightly wrinkles on the inside or outside of the finished piece.
You can start in the middle of the piece and make a series of smaller bends each direction to make a radius.
Good Luck

I haven't made them yet. How much force do you think it would take to bend the 2X6x1/8? I ran a truck over it while it bridged a gap and it went right back. I was a little concerned with "destroying" it so I only allowed it to drop 4 inches. I only need a little bit of a loft.

I've bent 2 x4 tube before using a basic cheapo hydraulic jack type tube bender and made gentle curves like you are looking for. Even though the dies are for round tube, I've had good results on box tube - I mark the tube every couple inches for reference and just use a little pressure then advancing the tube to the next mark and so on. Very slow but it does work if you are careful, without major divots in the tube - go too hard and you will dent it. I also made a plate shoe to cover the lower die, that reduces the damage too.

klink said:

I was a little concerned with "destroying" it so I only allowed it to drop 4 inches. I only need a little bit of a loft.

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The ones i bent I rooled at 6" off the ground 3 times, then about a foot off the ground. I just kept rolling up and down it then lifting the end up some more. Takes a while kinda like using a ring roller.

I managed to bend a piece of 2X4X1/8 using my floor jack. I chained both ends to my welding table, placed the floor jack under it and applied some force. The 2X4 bent nicely. Then I mounted up the 2X6 and it blew the seals. I re-built the jack and paired it up with a bottle jack (small one like you'd keep in the vehicle) and nothing. The 2X4 required about 2 inches of "over" bend to get what I want. The 2X6 moved about 4 inches and went right back. I've already paid for the material and it's sitting there waiting. Knowing what I know now, I should have used 2X4 and stacked it with 2X2.

Since I'm building a high boy I want the taller frame. It's a Chevy so I didn't like the idea of using 32 Ford rails. I looked for rails without the reveal but no luck.

So, I bought a new welder; a Miller Matic 180. Nice... The extra frustration from "failing" made it easy to get away with. The wife was happy to see me happy...

Plan A is to cut out part of the box tube, set it aside and bend the rail. Then re-fit the removed piece. The piece would be the top, bottom and inside area, like a "C" channel.

Plan B is similair, except the removed portion would be the outside face only. Slice and bend the top, bottom and inside, then re-fit the outside face.

Plan C is to slice every few inches from the inside towards the face and "bend" it, re-weld the slices. This plan has ONE draw back I don't like, facets. The outside face will be flat between the slices. If I choose plan C I'll do a "dry" run on some 1X or similar.

My twin daughters graduated from High School this year, so I've been tied up with that... that ends Sunday! [cl

If you're going to slice off the outside face....

Mark out the curve you want on the top and bottom of the beam, cut the face away where needed, remove the extra metal, clamp together, reattach. Easy...[

ive thought about this also and thought of making a giant ring roller with a big bottle jack to make the radius. possible some track rollers from a piece of heavy equipment or?? just a thought.

Heat shrink method of tube bending

tube sections can be bent-straightened with heat.
To move them in this way you heat the tube to redhot(dont heat it till the metal starts to sparkle or melt) on the 'inside' of the area needing to be bent or curved with a heating torch in a line about 1" wide across the face of the tube.then cool down the heated part with your garden hose.this process will make the heated section of tube shrink a little resulting in the tube bending around this spot.repeat this several times along the length of tube where the bends are needed & it will come around.This doesn't cause mild steel to crack but not advisable to use this method on moly or other hi tensile types of material.In my 30 years in engineering & metal trades I have straightened countless driveshafts,diff housings & numerous other bits & pieces of machinery using this method.for Round sections all thats needed to be heated is a spot 1-2" diameter.Youl be surprised how much you can see it move over a longish piece of metal when you do the cooling process.
The other method is to locate a business in your area vith a mandrel tube bender and consult them with your needs

Klink, did you get your tubing bent? If so how and do ya have pics?