Supplies for stout ring roller build
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  1. #1
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    Default Supplies for stout ring roller build

    Hi all, I've been away for a while, but get to get back to work soon!

    I work at a fab school in West Africa and get to send a limited amount of stuff in a shipping container headed out soon. One of the things on my wish list for some time is a stout ring roller. It's main uses would be 2"x1/4" bar the hard way, angle, mostly leg in, up to at least 1-1/2"x3/16", and some solid rounds up to 3/4". I'd like to design it to be able to get close to 1-3/4" OD 1/4" wall pipe if needed as well.

    The plan would be to build it from scratch, and I've spent a fair amount of time collecting build threads around different sites to come up with a final drawing. I don't have the final drawing yet, but have just this weekend to carefully choose from my stock shelves here in Michigan what to send over.

    There were a few threads a while back on PM debating what kind of bearings to use for such a project, and I realize the answer to that will affect the diameters of the tube. I'd like to build one like the industrial models, with the rolls on the outer side of the two vertical pieces of plate, not one of the horrible freight type models where the rolls are in between the two plates.

    I can scavenge the solid round from the scrap yards over in Africa, so I'm not worrying about that part now.

    Here's what I know:
    1) I have a 13" long piece of 4.5" dia solid 4140 that I assume must be heat treated, because it has black mill scale on the outside. I'm hoping that will be enough material (and hard enough) to make the adjustable width rolls and spacers that come standard on most of these machines, where you can vary the gap to roll bar either way, solid square, angle, and solid round in a pinch.

    2) The actual shafting will be scavenged over there

    3) I have two pieces of 1/2" wall tube that are candidates for the three tubes that hold the bearings/shafts. One of them is 29" long and 3.5"OD x 2.5"ID. The other is 4.25" OD and 3.25"ID, but is only 19" long. Bigger is probably better, especially if using something other than bronze plain bearings, but I don't know that a third of 19" = 6.333" is long enough for this kind of machine's width.

    4) I have a 1/2 hp motor on a 60:1 worm gear reduction to power it. I assume that should be plenty of torque through a big sprocketed drive system, even if it's a little slow. The motor will be on a VFD, so I can overspeed it some.

    I need to get the heavy parts over now, but can have someone hand carry the lighter stuff later, like bearings or bronze to make bearings from.

    So, here are my specific questions:

    A) Am I an idiot. I'm not a super fast machinist and all work will be done on decent manual machines. Does this sound like a 20 hour project or a 200 hour project?

    B) If no on A, is 4.5" rough OD enough for the rolls? Bonus points if I can find out the ID of rolls from an established mfg so later I could buy their tooling to use on my machine.

    C) Do I go for the 2.5"ID tube where the three sections could be up to 9" long, or the 3.25"ID tube where each can only be a hair over 6" long?

    I have seen these machines work on youtube, but never been around one in real life. I would like to try the build, even if I end up making a machine that has less capacity than I was hoping for, my fab students will still get a lot of use out of it.

    Advice is appreciated!

  2. #2
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    Mill scaled does NOT denote heat treated.

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    Quote Originally Posted by digger doug View Post
    Mill scaled does NOT denote heat treated.
    Thanks Doug. Dimple or file test to see if it's pre hard, or what's my best way to get a good idea?

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    I have an Eagle CP 40 roller, which is just a bit more capacity than you are talking about- it will do 2" schedule 40 pipe.
    It has a 3 1/2 hp motor with chain drive. It weighs 1500lbs. Its about right, in terms of mass and power.
    So I think you need a bigger motor.
    And your vertical plates should be at least 1".
    remember- the force required goes up with the square of the increase in size. So, to bend 1/4" bar the hard way takes 4 times the power, rigidity, and mass as bending 1/8".

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    Thanks for the feedback. I have heavier duty motors here, but none with that nice 60:1 gearbox on them. I'll probably use this and have the sprockets just run it slow to get enough torque until the machine has been proven and we can send over a heavier motor/gearbox.

    I did finally find a piece of plate to make the frame of the machine from though. It's 3/4" by 23"x63". Could be thicker, but I do have some 1/4" plate around as well, so I can do a triangle of the 1/4" plug welded to the 3/4" to reinforce the zone between the rolls that'll take all of the pressure.

    Could anyone who has a commercial machine like this give me an idea of the area of the face of the machine, then the center to center distance between the left and right rolls? The shaft dia would be great too, so I can make it match something existing to be able to buy tooling off of the shelf!

    Thanks!

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    Rolling 1.5" angle with the leg in requires a deep groove in the rolls. Starting off with 4.5" OD material might be a tad on the small side because you end up with a minor diameter of 1.75" (or smaller) which doesn't leave a whole lot of room for a sturdy shaft and keyway through the roll hub.

    Consider that the 'angle of bite' is lower when the roll is larger diameter. So if you go larger with the rolls, then if makes it easier to start the material in and keep it feeding, rather than have it skidding past the rolls. I've never used an outboard ring roller, but from what I recall seeing, maybe the rolls on commercial units were 6 to 8" diameter?

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    Thanks for the feedback. Old thread, but I now have a carrier to bring over the precious bronze I need for the bearings for this. I ended up watching amazon and scooping up "last one in stock" discounted parts. I think I'm going to be in good shape to get this started now.

    After your advice, I've made everything bigger.

    I paid $27 for a 7" long piece of 4" ID x 5" OD 932 bronze bearing, which I plan to part into three ~2" long pieces for the roll side bearings. A 4.5" shaft, turned down to 4" for the journal, and then down to 3-3/4" for the roll bore should allow me to have plenty of strength to turn some fat 6" or 8" dia rolls. Is leaving the roll bore that big going to make for unnecessarily large rolls though? I want diameter through the bearings for stiffness, but maybe coming out of them I should turn the roll bore down to something smaller like 3"?

    I got a 4.5" long 3.5" ID x 4.25" OD also 932 bronze bearing for $17. Figuring that the drive side doesn't see nearly the deflecting force as the roll side, I think a smaller OD and bearing length back there (only 1 3/8" long after the part) will be ok.

    Any input on how long the shafts should be - how far apart the front and back plate should be? Longer will be stiffer, I assume. 10" or so seem about right?

    I think I can scavenge a hydraulic cylinder tube for the three tubes the bearings will sit inside to hold the shafts. I should be able to find some solids for the shafts, I have plate for the body of the machine, and then I think all that's left is to find some 6 or 8" solids to turn the rolls from. Oh, and then scavenge some big sprockets to drive with. I've seen some machines with three driven rolls and some with two. I think the three were the higher end machines, is that feature important?

    Should be fun.

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    This is a really old thread, but I now have a shipping container headed over to West Africa and want to make sure I'm sending what I need to get this build done. I now have a 3hp Baldor on a gear reducer, so per Ries's recommendation, I think I'm up to the proper torque (presuming that my gear reducer is somewhere in the right range in terms of ratio, but whether it's 30:1 or 60:1, I don't mind going half as fast if necessary.) I'm sending sprockets and roller chain over. I assume that #60 chain should be tough enough for this, or does it seem worth the money to jump up to #80?

    I'm not sure I understand the recommendation that HuFlungDung was making on the shaft diameter question though. I'm envisioning a shaft like the attached sketch.

    shaft-detail.jpg

    UGH! Every time I upload a drawing to this site I hate the way it handles images even more!!! It's 2019, we can't store and show a 207kb image file at full size??? Godaddy has unlimited hosting space and bandwidth for $14/mo, is space really still an issue????

    Here's the file on google drive - a service that *does* seem to be able to handle such a *massive* file.

    Take a deep breath... Ok, that drawing is what I'm imagining. A large diameter for the main body of the shaft, to eliminate any flex, but then a reduced diameter coming out of the machine, to fit the bore of the tooling. That tooling diameter, I understand, can't be too small or it'll be weak but can't be too big or it won't allow the leg of a piece of angle, for example, to sit down into the tooling.

    If that's how the machines are generally made, then I'm reasking the earlier question. Approximately what diameter should the "shaft inside the tooling" diameter be? How about the "shaft inside the bearing"?

    Now that I think of it though, maybe the shaft being bigger in the bearing area doesn't really help, since that part has support behind it in the form of the back bearing area anyway.

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    this is the exploded diagram of my Curvatricci, which will do 2" pipe.
    Attached Thumbnails Attached Thumbnails img_0953.jpg  

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    Quote Originally Posted by Ries View Post
    this is the exploded diagram of my Curvatricci, which will do 2" pipe.
    Beautiful, Ries - thanks!

    Could I ask for three measurements to get me going?

    1) Diameter of the shafts the tooling slides onto (tooling bore)
    2) Distance between the centers of the two lower roll shafts (approx)
    3) From the line between the two lower shafts, what's the height adjustability of the upper roll? In case I'm not explaining well, if you tacked a string between the centers of the shafts of the two lower rolls and then ran the top roll all the way to the top of its travel, what would the distance be from the center of the top shaft to the string? And then if it were all the way down? (approx)

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    Quote Originally Posted by JasonPAtkins View Post
    Beautiful, Ries - thanks!

    Could I ask for three measurements to get me going?

    1) Diameter of the shafts the tooling slides onto (tooling bore)
    2) Distance between the centers of the two lower roll shafts (approx)
    3) From the line between the two lower shafts, what's the height adjustability of the upper roll? In case I'm not explaining well, if you tacked a string between the centers of the shafts of the two lower rolls and then ran the top roll all the way to the top of its travel, what would the distance be from the center of the top shaft to the string? And then if it were all the way down? (approx)
    For posterity, I had looked at Eagle's site, which didn't answer these questions, but their manual at https://www.eaglebendingmachines.com/eaglepdfs/CP40.pdf does. I'm glad to use their shaft diameter, so that I can use tooling off the shelf from them in the future!

    Shaft diameter: 40mm (I assume that means the shaft at the part where the tooling is, aka 40mm bore tooling
    Roll diameter: 162mm (presuming this is the biggest part of the tooling)
    Top roll downforce: 10t
    Drive motor: 2.25hp (higher submodels)

    The next one up, the CP60 is:
    Shaft diameter: 60mm
    Roll diameter: 225mm
    Top roll downforce: 20t
    Drive motor: 3.5hp

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    screen-shot-2019-11-12-6.33.13-pm.jpg

    Looks like you need a total of 1:240 gearing from a 1440 rpm motor (50hz) to the final rolling shaft output. In my case, with a 23:1 gear reducer on the motor, I need a further 10:1 external to the reducer, either in sprockets or gears. Since it's 10:1, it probably needs to be gears.

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    Thanks a lot for the help. Now that I have some hard data about diameters and rolling speeds, I'm much closer. Ries, that diagram was super helpful - most of all in showing that my previous idea didn't have anywhere close to enough gear reduction! I was planning to come out of the motor/wormgear combo into sprockets with maybe a 2:1 reduction onto the rolling shafts, but now realize the arrangement needs to be more like 12:1 @ 60hz.

    Now that I know what I'm looking for, I'm looking for gears. It looks like, if going toward a CP-60ish design, that the shaft centers between the two driven shafts is about 40cm. That means gears on those shafts that are about 11" OD and a gear in between of 3-4".

    Next question: I see that they are using ball bearings for everything. I had assumed (above) that bronze plain bearings would be best for this application because they seem to be king for radial loads like this. Do you think they are using ball bearings because they're better? Or perhaps it would be tougher to use bronze plain bearings on the load side and ball bearings on the back (gear) side? The cost of the bronze, if you hunt for deals, isn't any more than the ball bearings.

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    The Eagle machine is made by BPR, in Brescia Italy. I actually visited the factory, at least ten years ago, and got a tour from one of the engineers. They are prettty diligent people, and my guess is that if they use ball bearings, for example, its for a reason. Their production is small batch- they use a wide network of job shops in Brescia, which has been a manufacturing town for a thousand years or so. So they have a dozen or so machines being assembled on the floor at the time I was there. That means their ability to improve designs is quite easy- small iterations can be done right way. And they have a pretty wide installed base of machines in Italy and southern Europe, and Eagle has been selling them a long time in the USA- mine is at least 20 years old, I think.

    All of which means, they choose the best way.
    I am pretty good at breaking things- and I have basically only managed to break a couple of sacrificial pins, and wear out some of the spacer rings, which are actually point of contact dies in their own right.

    The shaft centers on my CP 40 are about 12" for the lower two.
    The upper, center wheel, goes from about 2 1/2" above the centerline of the two driven rolls, up to about 6 1/2" above, for a 4" range of motion.

    And the shafts are basically 1 1/2" at the tooling end- but bigger as they go thru the bearings.
    My guess is bearings are more universally available in standard sizes, making for easier drop in replacements, globally, and that they work just fine.

    It does turn quite slowly. I would guess no more than 10 rpm, but I havent done the math.

    You definitely want to make a set of the stacking ring spacers, in whatever size increments you use most- that is, if your material is all metric, make 10mm, 20mm and similar increments. You need washers, too- 1/16" or so, and 1/8". Because when rolling pipe, obviously, you use lathe turned dies, but for everything else, you stack up an outer, 6" die, and then the right amount plus a smidge of spacers, then a 6" inner die. You need a slight oversize space, as material will deform during rolling. Thus the need for a whole set of varying size spacers. I find I use these much more than dedicated pipe dies.
    Also, the two driven rolls need a keyway cut in the shaft, and all the dies for them need matching keyways to lock them to the shaft. The upper, middle roll, doesnt need a key, and I think its kind of a good thing to let it slip if something jams, rather than breaking the machine.

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    Late to this thread, but early this year I built a heavy duty roller for work. All three rolls are powered by hydraulic motors, the shafts are 1.375 4340 at the bearings, reduced to 1.250 where the rolls mount. Not heat-treated. The ctc distance L-R is 8" and the rolls are just over 4" diameter A-7. It will roll 1" solid round 1018 but that's the absolute max (probably break something if I did that a lot). The frame plates are 1" thick A-36. Weight with stand is around 250lbs.

    Might be a little off on shaft diameter. But I can check if you want.

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    Quote Originally Posted by Gordon Heaton View Post
    Late to this thread, but early this year I built a heavy duty roller for work. All three rolls are powered by hydraulic motors, the shafts are 1.375 4340 at the bearings, reduced to 1.250 where the rolls mount. Not heat-treated. The ctc distance L-R is 8" and the rolls are just over 4" diameter A-7. It will roll 1" solid round 1018 but that's the absolute max (probably break something if I did that a lot). The frame plates are 1" thick A-36. Weight with stand is around 250lbs.

    Might be a little off on shaft diameter. But I can check if you want.
    Thanks a lot, Gordon! Good to have more data points. I'm going to follow (as much as I can) the Eagle CP60 dimensions, which have a 60mm (little over 2-1/4") shaft dia where the rolls mount. Their rolls are 225mm (close to 9"). The ctc distance as nearly as I can measure from pictures was close to 40cm, but I'm going to reduce that a little, just because of the size of center gear I was able to find a good deal on. Things sound proportional though, so I think I'm on the right track. Thanks for the info!

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    Thanks everyone, I have my initial design, and my gears all ordered.

    I'll pick this thread back up in six months or so when the shipping container gets over to Africa and I start the build!

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