Hey guys, I don't know where else to ask this, but I need a hand.... Need to make a shallow, graceful bend in thinwall 1 1/2 square tube. Piece is 8 feet long, would like a gentle rise up one foot and level out. (Top of half a 16' driveway gate) No twist, tube stays on same plane. I have a large flat frame jig to build on, and oxy-acet torches if needed. Considered filling tube with sand, capping ends.... not sure if that's best? Thanks! John
See if you can find the Thread where ElPolacko was bending framerails. He had a cool way of doing that, and it might work for you.
To bend that is as simple as making a plywood buck and bending it around it. I have first hand experience with this method. Make the wood radius a bit tighter than you need to account for spring back. Did all my pool fence in about 6 hours. It's simple!
I made a 34" wheel for my beadroller out of 1" square tube. Pics and explanation here: http://glennsplace.com/bead_roller.htm
Never did like that show... But I think you could make a plywood buck maybe four feet in length with little tighter radius to account for spring back. A hoop to hold the one end fixed, insert a bar into the ID or over the OD to create more leverage and it would bend easy.
Drill a 1 & 5/8" hole in a hardwood plank - an oak floorboard is ideal. Put that in a vice and then feed your 1 1/2" square tube through it. Starting from the centre, gently bend it (you just need to lean on it) every few inches until you get the curve you need - it won't kink if you do it right. Turn it around and then do the other half. This method is ideal for the gentle curve you want.
I replaced the wood in my 33 above the doors with 1+1/4" Tubing,also created my roof bows using a leaf spring as a shoe with chain to an anchor pot in the floor,no heat ,just pulled the tubing through and bent a little each pass ,the leaf spring keeps the tubing from kinking up and to create the Convex Curves,I heated and bent angle Iron to create a Shoe for that,I used soapstone on the concrete floor and traced the shapes needed from the original wood,then bent to match,I know it is low-tech method , but it worked for me
If you have to do a single plane bend the plywood buck works great. If you need it to bend in both planes a roll bender works better. Harbor Freight actually makes a pretty good one for round tubing http://www.harborfreight.com/tubing-roller-99736.html You can make a set of flat dies for it that will allow you to roll square tubing in both directions or you could buy the square tube dies that HF sells http://www.harborfreight.com/3-piece-die-set-66598.html These are for 1/2" sq tubing but you could roll the 1 1/2" tubing on the flats outside the groove.
Not quite sure the radius your after, the quick and dirty way just lay out your curve with soapstone on the garage floor, then bend the tubing with small almost kinks / bends every inch or two checking aginst your layout every so often. My old boss had two 1 1/2 steel pins that fit into pockets on the bed of his welding truck just gradually work the tubing through. Anything tighter than a 3' radius probably be easier to have it rolled, I'v also used a Harbor Freight pipe bender in the same manner with good results.
filling tube with sand, capping ends.... Just make sure your sand is very, very dry if you cap the ends. Heat + wet sand = steam = kaboom !
If is a gentle curve 8'long just put 2 wood blocks on the ground maybe 18" apart, lay the steel on them and hit with a hammer (another block of wood protecting the steel) between the blocks. Each hit should curve it a little. Have a pattern, either cardboard or drawn on the ground and keep going until you get the desired curve. Sounds hokey but works great.
I've done it with a hydraulic jack type pipe bender. Take a few pumps, release, move a couple of inches and do it again.
I've seen a guy pie cut sq. Tubing, bend it, weld it back, grind it flush, all because he didnt want the distortion that comes with bending sq. Tubing. It looked like it rolled of the line at a steel mill when he was done, guess it depends on how anal you are!
If it's a gentle bend as I imagine for a arch top gate or a peaked top, then you don't need heat or sand. A roller is a nice tool but for a one off deal I'd use a MDF buck with a slighter tighter radius and make sure the buck is wide enough to catch the corners . Actually .095" or .125 will bend nicely if you use a cheater. You don't have to have a full length buck either, just use a feed along method and check against a pattern drawn on the floor or your table. Did ornamental iron as a living for more years than I care to remember.
If a gentle curve is all that's required, draw a full sise template on the floor / bench / mdf / wall wherever, the bending can be done by hand. in a jig consisting of two 1" dowels welded to a piece of angle some 1 1/2" apart, place the Box section between the pegs and tweak every couple of inches until you get the profile you require , check against the template, unintentional twist in the other plane can be twisted out easily using a stillson or large adjustable wrench, take your time and check the work often with the template. You may need a cheater pipe towards the end. Good luck, this is a method I have used with succsess in a school shop with very limited facilities. My method is very similar to others described here.
I take the outside rollers off and use just the pins. This lets the tubing lay flat against them. I use the largest pipe die on the jack.
Well it worked out OK. Used my HF with the roller wheels off, pretty easy job. Work it slow and steady. Have some kinks to sort out from the bender, but all in all decent outcome. Thanks all for the help!
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