Bending 1/8" plate to a uniform curve

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I've spent a while searching but haven't been able to find anything solid. I'm making some steel chairs and want to bend some 8"x12" pieces of 1/8" steel plate into uniform curves to form the pieces for the backs. What's the best way to do that? I currently have an oxy-propane torch, a HF bar and rod bender, a 36x60" 3/4" plate welding table, a small vise and a variety of clamps and jacks (hydraulic, screw, bottle, etc.). I can buy more tools if needed but I'm short on space, so I'm trying to avoid anything big.Thanks!Jacob
Reply:Are you making a cylindrical bend or something more complex?  If you just had a couple bends to make you could do it with some pieces of heavy angle iron or channel, clamps, and the edge of your work table.  Clamp the sheet to the table using a heavy structural piece(channel, angle or tube to span the width of the sheet.  Clamp another heavy piece to the edge of the sheet hanging off the side of the table.  some downward pressure, then shift the plate and reclamp.  repeat over even distances and you should get a fairly uniform curve.  Might take one or two attempts to figure out the spacing between bends.  You should also allow for some scrap at the start and finish that will be cut away when the curve is done.The alternative is a 3 roll bender.  you could build one with the tools you have, some threaded rod, heavy wall pipe, and some plate.  Buying one sturdy enough to roll 1/8" plate would be expensive.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:here's an example of what I mean.  The hardware would be heavier for your 1/8" sheet, but the principle remains the same.http://www.jettools.com/us/en/p/sr-2...ip-roll/756020Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:It's just going to be a simple cylindrical bend. Should I apply heat with the oxy-propane torch along a line where the individual bends will be, or should I be able to do it cold?This sounds like something I can do, thank you!
Reply:Why cant you just weld a couple pieces of pipe to your work table. Set the flat bar into the Jig and bend it? I could make a drawing of this if need be.... This is how we made Fire extinguisher holders and life rings to hang on top of handrails offshore. We probably made 20 of each one day. all out of 3" flat bar 1/8" thick.You take two piece of 2" pipe or handrail pipe. depending on how you want the curve of your flatbar to be. Take them on the table spaced apart from each other just enough to fit the flat bar in between. Leave it a little lose for when you have to pull it out. Heat the flat bar and bend it around the piece of pipe. Is this what your trying to accomplish?It would be the same concept as 3" flat bar instead your using larger plate.... you will definitely have to heat it to cherry red then bend the plate around the pipe. It sounds like your making a curved lip to a chair's top backrest.Last edited by AndrewDavenport89; 04-27-2015 at 04:32 PM.
Reply:Ah that would work too. I have some extra plate laying around so I could probably weld the pipe to that, then clamp the plate to the table so it's easily removable. Or do people tack stuff onto their tables and grind it off all the time?
Reply:I tack stuff to my table pretty often - but my table is only 1/8"-3/16" thick (free steel) and it warps.If it's something I'll use more than once, I drill holes.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Ok. this is a very crude drawing I did in just now. so please don't judge on my drawing skills. They are better. just had to do this in a hurry for you. However large you want your curvature. You just get the correct Outside Diameter curve you need. Look at a 3" piece of pipe or a 2" piece. 1.5" pipe is the most common bend I use. Unless they use 2" handrail we use that. Now if you go up to 3" or 4" curves it will start looking pretty large. You will bend majority of the plate you have if you get that big of pipe. Because you got to think your bending around it so you will lose material length. I personally always tack my pipe to the table itself to bend these. You will need to as well since your bending 8" or 12" pieces of plate around the pipe. You will have to heat it up cherry red up and down while bending it with a crescent wrench. It will take a little muscle but it is definitely do-able.If somebody has a better drawing of this Jig show him please. I think he may be able to understand my method of bending flat bar. He can use the same method to bend the plate just with longer pipe that cover the length up the plate vertically.Last edited by AndrewDavenport89; 04-27-2015 at 04:55 PM.
Reply:full 180 degrees or partial?   We sometimes bump form stuff like that:  Basically you place the plate between a very rigid slot (preferably 2 pipes close together or similar) and sort of bounce it to do a series of tiny bends, moving the material as you go---A few of dozen of those and you have a pretty good approximation of a smooth bend. You can do the same with a round die in a press but have to be very careful to keep the bumps small enough to not make a "set" that shows. Works better for longer material and large diameters when you are doing the hand method.  Have never tried "hot" bending with this method but that might make up for the small size.Not the perfect solution to lack of a proper slip roll but works to get 'er done.
Reply:Just a gentle partial bend, like the top back piece on this chair:I guess it doesn't have to be perfectly uniform, I just don't want it to look like it's got 5 separate bends and 6 flat sections.
Reply:that needs to be rolled. I was thinking of a more drastic bend. But you could heat it up and bend it to a piece of 12"-16" pipe(Possibly even larger, I would have to look at a piece of pipe tomorrow at work to see what size I would use to bend use). Heat bend tack, heat bend tack, until it is tacked all the way across the large O.D. pipe. Heat the whole plate up hot and break the tacks off. It will curve to that. lol But that would be the way I would Sleeve a Gusset plate onto a Large O.D. pipe. Or I would do that to make a patch on a Leg of a platform.
Reply:Does this help you at all for your project? I mean how I have explained it and somewhat showed you? I hope you can get the idea in your head and roll with it. Because I would do it the old school way of heat and bend around a piece of large O.D. pipe rather than buy a roller system and roll it out. It will bring out your inner blacksmith my way
Reply:Find a small steel car wheel cut it in half and weld on some bracing across where you've cut it.The other half remove the center  and brace the outside so it cant move, take the two formers you have made to someone with a decent press and bend as many you want...
Reply:How many are you making? I recognize that style chair. There are several companies out there that sell those steel frames, you just put the wood on it. They sell those frames dirt cheap. Way cheaper than I could compete. Then again, my customers buy these in bulk, so they may get a much better rate. Sorry, I can't remember what they pay, but it's cheap!John 3:16(2) Miller Pheonix 456(2) Millermertic 252Dynasty 210DXHobart 210MVPDoringer D350 SA Cold SawScotchman 350LT Cold SawWebb 10x50 MillWebb 15x40 LatheGeka Bendicrop Ironworker
Reply:Originally Posted by EcondronHow many are you making? I recognize that style chair. There are several companies out there that sell those steel frames, you just put the wood on it. They sell those frames dirt cheap. Way cheaper than I could compete. Then again, my customers buy these in bulk, so they may get a much better rate. Sorry, I can't remember what they pay, but it's cheap!
Reply:Originally Posted by AndrewDavenport89Does this help you at all for your project? I mean how I have explained it and somewhat showed you? I hope you can get the idea in your head and roll with it. Because I would do it the old school way of heat and bend around a piece of large O.D. pipe rather than buy a roller system and roll it out. It will bring out your inner blacksmith my way
Reply:Dig a little rut in the dirt.  Place plate on it.  Drive your vehicle over it.  Done.  For precision work, jack up the vehicle and lower a heavy wheel over said plate."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:For producing gradual curves out of 1/8" X 2" or narrower flat bar I use my flat bar ring roller anymore.  Before the ring roller, I used a simple jig  made out of either wood 4x4's and 2X4's or  steel square tube, and a heavy dead blow hammer for striking the metal. Hopefully my crude paint sketch gives you a good enough example of the jig and how to use it. You strike the metal with the hammer a the location the blue arrow is pointing at. After striking the metal with the hammer you move the metal length wise a little and then strike the metal with the hammer again. Keep repeating this process until you reach the desired curve.  With this jig, you need to calculate some waste material into the overall length. Attached ImagesLast edited by Dan; 04-28-2015 at 08:44 PM.ESAB Migmaster 250 Hobart Ironman 230Multimatic 215TWECO Fabricator 181i & 211iHH125EZ - nice little fluxcore only unitMaxstar 150 STH - very nice
Reply:try to find a fab shop with a brake and have them brake it for you   if you can it rally will look good
Reply:If you're taking it to a shop just get them to roll it. It would take them about 5 minutes and give you a perfect curve on all 3. Probably be cheap enough that there's no sense even trying to do it yourself.
Reply:Take a long piece, bend it into about a 3' to 4' circle around a plywood template, cut out your pieces.  I made some 4'x10"x1/8" fire rings that way.  Bent cold.  You will want a piece at least 3' longer than you need for leverage.Start with a 3' pattern.  If that isn't a tight enough curve after spring back, you can cut it down to 2-1/2', then 2', etc.My name's not Jim....