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  • Ring roller question

    I'm building a ring roller using three rolls as usual. The idler rolls are about 4" diameter and the center driven roll about 3.5". How much travel of the driven roll is required? I'm guessing about no more than a couple of inches. Even better if it is a lot less.
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  • #2
    It depends on your idler roll center distance and the material dimensions you intend to roll.

    If the centers are close like 4-1/2" and you intend to roll flatbar 1-1/2" of travel would do it realizing of course that the maximum opening would be capable of passing a flatbar of your maximum capacity through the rolls without bending it.

    If you want to roll tubing,then add the dimension of the maxium size stock you wish to roll to the above figure.4" rolls means you could manage 1x1x16ga square tubing fairly easy with some removable rings to keep the side walls of the tube from bulging out.


    Are you going to drive all three rolls or just the one?
    I just need one more tool,just one!

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    • #3
      I'm driving only the center roll. The idlers won't present any turning friction as I have some 4" twin row angular contact bearings to use as rollers.

      The center driven roll is hard cast iron ( semi steel maybe) and so will develop sufficient friction. Pain to machine though.

      I only intend to roll flat stock since the rolls can't be changed, obviously.
      Last edited by Evan; 05-12-2007, 09:35 AM.
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      • #4
        An improvised roller.

        These are conveyor rollers with integral bearings. They are bolted to details that replace the vise jaws. I just pushed/pulled the workpiece through. I should replace the center roller with something with a crank.
        I also need to polish the roller faces as the conveyor rollers are hardened and have the manufacturer identification roll stamped on the o.d. The stamped letters transfer neatly into the face of the workpiece.

        Edit:
        I went back and reread Evans original post. I would think that your roll travel need be no more than from the point where the center roll contacts the thickest straight piece of material you will be working to the point where the thinnest rolled material you will be working is trapped between the three rolls.
        Last edited by Weston Bye; 05-12-2007, 10:26 AM.
        Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
        ~Practitioner of the Electromechanical Arts~

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        • #5
          That's a cool and simple idea for little stuff.
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          • #6
            Here is a patten pending one that I was given 25 years ago, They didn't have all the parts that came with it.




            no other name on the vise body other than 528 and its base is a swivel one
            Glen
            Been there, probably broke it, doing that!
            I am not a lawyer, and never played one on TV!
            All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only

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            • #7
              It will be interesting to see how it works with just the center roll driven- it will probably be OK for the little flat bar the easy way, like your gate- stuff like 1/8" or 3/16" flat bar- but its still not a lot of friction, compared to two rolls driven. Of course, I expect my machine to roll things like 1/2" x 3" stainless flat bar, the hard way.
              The easy way is, well, easy... the hard way, on edge, gets a bit tougher, especially in big material.

              The cheap commercial models drive the two rolls, connected with a chain drive.
              The more expensive commercial models drive all 3 rolls, with hydraulic motors.

              Here is mine, store bought, unfortunately, rolling some 1 1/4" round stainlesss bar.
              It has around 4" of travel, but with the interchangeable die system, sometimes thats still not enough.

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              • #8
                I see several designs out there that only drive the center roll. I figure that by using BIG ball bearings for the idler rolls I can get away with it. If not, then there is always plan B which at this time doesn't exist...

                Thanks for the info on the travel guys. I guess I'll give it at least two or maybe three inches. I will want to bend square bar and perhaps tubing. The unit will be heavy enough to take whatever I can crank through it.
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                • #9
                  "...I have some 4" twin row angular contact bearings to use as rollers."

                  I tried using a large ball bearing to do some bending, and the outer race fractured with surprisingly little pressure. I think you'll need to make a strong wheel that fits around the bearing.

                  Roger
                  Any products mentioned in my posts have been endorsed by their manufacturer.

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                  • #10
                    Evan...will this roller be open sided or a closed roller?
                    The one I built is open sided and I was amazed at how much flex I got on the top axle. It's a piece of 4140 1" dia. I've bent 1/4"X 4" wide 6061 flatbar with it.
                    Sorta made a bit of a conical shape as the axle flexed just enough to allow this. Next time I'd build either with bigger axles or a closed roller.
                    I've also bent 1/2" square tubing. I was really suprized at how tough that was to bend. Took a lot of force.
                    My roller is top drive also. Had some traction problems with the 6061 4"W but just slipped a piece of 600 grit wet and dry sandpaper inbetween. That stopped the slippage.
                    Russ
                    I have tools I don't even know I own...

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                    • #11
                      I was building one also using 4" rollers I was going to pretty much copy the one in the bender catalogue it seems to use a hydr. jack to move the two undriven wheels third roller sits on top driven by a big hoop hand wheel the method looked super and fast and simple to fab and there not much sense in reinventing the wheels.

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                      • #12
                        Russ, for square you typically have the inside roller made like the male side of a bead roller. That's why bent square pretty much always has an inside trough. Easy enough to make/try with a lathe.

                        Evan, coming from fabrication (where I know a LOT more than machining, though it would be hard to know less) I've also seen the single drive style. Thing is, with only a single drive wheel, you generally have to make a lot more incremental bends because taking too much at once will cause it to slip. I saw one home brew that started as single, then after a few months had a simple chain coupling drive added, and I'm told the results were strongly positive. Heck, even a belt drive would probably make a lot of difference and allow for some minor differentiation that would force slippage on a gear drive. Main thing is just to get he "idler" wheels wanting to turn, doesn't need full torque.
                        Russ
                        Master Floor Sweeper

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                        • #13
                          adding some sprockets isn't a big deal. While its just barely a related project, from using my little tube straightening mill I can tell you how readily the piece wants to slip, bit like a loco with one driver.
                          .

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                          • #14
                            I won't be adding sprockets. Because of the way the bearings I'm using must be mounted and because they are bearings there isn't any way to drive them.

                            As far as the bearings being fragile, I guess I'm going to find out. I don't have any material to make an outer shell with.

                            Russ, it will be an open sided roller. I'm using 2" shaft in a 4 1/4" main bearing with a smaller one further back. The main shaft for the driven roller weighs 9 lbs. The drive roller is cast iron/steel. When I turned it it made tiny curly chips.
                            Last edited by Evan; 05-13-2007, 01:15 AM.
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                            • #15
                              One drive wheel works pretty well but knurl the center roll and it will bite the material a little better. It also helps to have a locking, slip flange on each of the two idlers so the piece will track straight. Make all three 5" wide but put the flanges on the two idlers - you can bend 1/2 inch up to about 4" or so - depending on the width of the flanges.

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