Off topic in terms of traditional rods but perhaps the mods will give me some slack as this does have to do with getting salvaged metal to take a shape and lay flat. I am helping my daughter build a robot for a science compe***ion. Today she used a bead roller, die grinder, abrasive flat disk, cut-off wheel, drill press and sheet metal brake. First time she used these tools and she did better than the first time I ever tried them. Anyway, the sheet metal ch***is is being fabricated out of the cover from a dead CD player. The ch***is needs to sit flat. The aluminum angle seen in the photos was riveted on prior to rolling the beads. At some point during the rolling of the beads, the ch***is took a set and now wants to oil can one way or the other. The beads were needed to stiffen the bottom. There will be some more holes on the bottom, maybe four more, about half the diameter of those already drilled. There are no beads in the rearmost area of the ch***is. We could extend the center bead staight through to the back end if that might help get rid of the twist. As you can see in the photos, the twist is some 1 inch, one way or the other. I tried tweaking the metal but no correction and before I go and mess something up I thought I'd as you all for advice. What is the best way to get this thing to lay flat without messing it up? I can remove the aluminum angle, and reattach later. I thought of removing the angle, clamping it to a flat plate (the 3/8" slab of aluminum pictured) and then heating areas red hot and letting it cool - maybe this would let the stress that is tweaking the metal relax. But I am not sure this would work and I am afraid that if we heat the wrong area we will make it worse. So, all, any ideas on a good way to get this to lay flat? Thanks in advance.
I think the issue here is that you have shrunk some areas of the metal, which is causing the curl. Heating it up may work, but it will take some effort. I take it you can't add any reinforcements to keep it flat? If not, I would try to tweak it in the opposite direction to reduce the curl. You might try inducing a depression in the center of the panel, that might force the corners down. You need to relieve the pressure from somewhere. Heat might do it, but it might cause more problems.
Just whisper in it's ear that you want to make long, deep, hard love to it and I will bet a 6-pack a your fav Barley Malt that it will never move! He, He!! pdq67
I can't add any reinforcements because the design needs to be open and flat, and because of weight limitations. We rolled the beads to add stiffness without adding to the structure. I can't seem to tweak it to eliminate the flex as it oil cans either one way or the other with determination. You might be on to something with tweaking it in the center. I first tried this. I placed square stock on each side, and used a big billet to bring the center down. However, I did not do this forcefully enough to change anything as I was concerned about making things worse. I am trying to figure out where the stress is coming from that makes the darn thing rack so much one way or the other. It is like a coiled spring: it sits one way, and if you tweak it is pops the other.
I am not a metal pro but from working with metal for decades, a flop from side to side is usually a stretched center. Best way to describe it is take a square, low side edge, bake pan and sandblast it, and when the center flat area is stretched by blasting, it will flop from side to side. If it is sheet steel? you can try light heat shrinks. Very little heat to start off with, if it is as thin as I think. If it's aluminum, I have no idea if it will shrink like that though. Never tried it.
You could try and hammer and dolly around the edges of the beads. try and stretch the area to settle it down. There is a lot going on in that small area with the beads and the dimpled holes. You should try and prestretch the area that you are going to put a bead in, it does help a lot. Good luck, Jon.
its flexing because when you rolled it you didnt hammer the bead lines first to stretch the metal before bead rolling.to fix it you can put a piece of 2x2 tubing under the center of the piece,hold down with clamps the two sides that are flattest and push down on the two high sides.wear gloves and keep pushing more and more until it locks in your desired result.whenever you want to bend metal back in shape you have to bend it past the zero point,such as if you take a piece of flat and bend it to a 90 degree angle then bend it back straight you would have to go to 120 degrees then when released it will spring back to straight although it will have a crease in it because you displaced the metal by bending.heat and hammer takes out the crease.i wouldnt try heating your piece if your not familiar with how it affects the sheet,you will do more harm than good and the piece looks pretty good now.steel has whats called memory and once a piece has been changed from its normal state its not going to go back without a fight.
Yes, it is steel. A thin but tough alloy. How should we attempt to shrink it? Heat a small area to red heat and quench with a wet raq?
Yes. The 90 degree lips were there from the factory (they were on the original CD player steel cover panel). Before we rolled the beads it lay flat. I am wondering if part of my problem is that aluminum angle iron. We riveted it on before we rolled the beads. What if riveting the panel to that angle iron introduced some stress? Maybe the bead rolling made it a lot worse. Maybe we should remove the aluminum angle before we attempt to work the twist out.
The twist is diagonal, one way or the other, front the left rear to the right front (and vice versa). So, which bead lines would we hammer and dolly? Fore and aft, side to side, or the diagonals? For some reason I am having trouble visualizing which direction the shrink runs.
The buckling you've got commonly happens when a bead is rolled inside the perimeter of a sheet, without reaching out to the outside edges anywhere. The bead roller dies have gathered up the material needed to form the beads from the surrounding area, creating a disagreement between the length of the beads and the parallel outside edges of the sheet. In contrast, a sheet with a bead rolled all the way through it will lay perfectly flat afterwards, as the material to form the bead was gathered evenly all the way across the sheet, allowing it to maintain it's proper shape. It's when the beads start and stop somewhere within the outside borders of the sheet that the problems arise. As others have pointed out, pre-stretching the beaded areas with an english wheel before rolling in the beads can help provide the extra material needed to minimize the buckling effect. The trick is knowing how much stretch to put in there first, it sort of takes a little experimentation to see how things respond. Another method some people use is to roll the beads all the way across the panel, and then use a hammer and dolly afterwards to pound down the areas on the ends where you want the beads to end, basically using the shrinking approach instead. Sounds like a lot of work, but it really goes a lot faster than you might think. These ideas might not be too helpful for you at the stage you're at with your panel, as they need to be applied as the beads go in. Pretty much all you can do is to wrestle with it for a while and see how it works out. I don't think heat will help too much, as the shape is pretty much locked into the panel by the 90 degree flanges around the perimeter. Ken
like someone else said, you shrank it when you rolled the beads, the metal that is pulled up had to come from somewhere, maybe you could take the aluminum off and clamp it to your oven rack and give it an hour at 500 drgrees, then let it cool down while still in the oven with the door closed, that oil canning effect is always a problem.
Some progress to report in the past few minutes. I removed the angle and indeed it was making things worse. I worked the sheet by hand using the tips mentioned so far, like in putting a piece of bar stock underneath, and gently tweaking past the 'memory' point. It is much better but not all the way there. The spring is definitely that the 'p***enger's' side front, or right side, is high. It looks like some of the problem stems from the extreme rear, where there is no bead. But somewhere along the lone, center rear to center fron, along the right side diagonal and the right sode front to rear, is the problem. We need this betty to lie flat at all four corners and also for the underside to be as flat as possible. I am wondering if we can hammer and dolly this - for some reason I can't see fixing this without heat. Like maybe heating the front center, where four beads intersect (there seems to be stress in that area) with the ch***is clamperd down at four corners. But would I heat and let it cool slowly, or quench?
I keep looking at the whole thing and all the shapes. Again, I am no pro by any means. Heating might make it all go to **** with all those beads coming together? I was thinking about one post said stretching... I wonder if you could lay/support the under sides of the beads on a very solid wooden surface and then lightly hammer on a fairly long hardwood board on top of each bead to barely flatten them a tiny bit? Maybe do it very slightly to see if anything changes?
OK, that makes a lot of sense. This is the first time I used the HF el cheapo bead roller I purchased years ago. My 12 y o daughter actually rolled the beads and she did a pretty good job. Unfortunately the metal piece we started with already had the flanges. In retrospect that was not so lucky. We can whack off the side flanges. We could also whack the front flange in three places (sides and center) just enough for the bead roller to p*** through. This would give us the ability to reroll each of the beads all the way through the panel. We know how much clamp we used with the beading rollers so it would be the same. Maybe if we did this before we try to hammer, dolly or heat the panel at least we will be starting from a better starting point. BTW unfortunately no English wheel.
Makes sense and we might try that. Want to get an answer about extending all of the beads all the way through first.
ANother option, though a tad drastic, is to possibly run an opposite bead along the outside of the two angled beads. I suggest this as a last resort, because it could make things worse. You could also add some opposing ribs to inner sections to shrink the metal and pull it in the opposite direction.
Turn the panel over and get a piece of wood that will fit in the inside of the flanges. If you have a ******* hit it at the point where the four beads intersect. You need to stretch that area some. The ******* will spread the force over a larger area than a hammer will. If the panel was flat when you started you don't need to shrink any where. It all needs to be stretched. Ken B is correct on what caused the problem.
Indeed the metal was flat before we started rolling beads.OK we will try that. We'll cut a piece of plywood to fit inside. We don't have a ******* but we can improvise. The beads are up (high side on top) because ground clearance is an issue. I ***ume you want us to put the wood on top and slap it from the bottom. Is that right?
The wood goes inside the flanged area you want to hit on the bead to spread it out a little. Once you hit on the area where the four beads intersect it should make the panel relax a little. You will probably have of continue hitting along all the beads a little. Make sure that you don't deform the area around the hole or that will put additional stress in the panel. The beads are on the Inside with the flanges. Use the wood to spread the load and you can hit it with the hammer. When I first looked at the panel I thought the beads were on the outside.
OK, so if we will be slapping the beads, then I can just clamp the piece down flat on that heavy piece of aluminum plate, yes? If I understand correctly, slapping the beads will help them stretch as the metal was gathered up and shrunk a bit when they were formed. Should we still (and before slapping) extend the beads all the way across (by cutting off the flanges on the edges)?
You will make the problem worse if you try to roll anymore. The stresses are already locked in the panel now. You need to relieve them to make the panel lay flat. Once you get most of the stress out of the panel there may be some additional places that need to be stretched. I can tell you how to find those area but I can't explain it in writing. You don't need to clamp the panel down flat before you hit it. You want it to move where it wants to go. Put the piece of plywood inside the flanged area and hit it at the intersection of the four beads and see how much the panel moves and relaxes.
I see the problem, the beads were rolled to a common point, this is where the metal was streached and caused the oil canning. Place a board under the center where the beads meet. Lightly tap to "separate" the ends of the beads, this should release some of the tension.
Thank you to all who have replied and provided tips and advice. I see where we went wrong, and tomorrow we will try to straighten it out. However, another issue has reared its ugly head - weight. We are coming in heavy, so we might have to start over with lighter material. Regardless, we are going to straighten this one out first so that we learn. Thanks again. It never ceases to amaze me that of the many many forums on the web, the HAMB has way more than its share of knowledgeable and friendly experts. You all are the best.
OK, just to close the loop, my daughter took first in her compe***ion, completely undefeated. She is absolutely thrilled and I am very very proud of her. A good thing about this exercise in robot building was getting her familiarized with various metalworking tools: bead roller, shear, brake, punch, spot welder, rivets, drill press, die grinder, whizz wheel, disk sander, etc. She really took to the air tools, watching the sparks fly and finally inscribing her name in the metal with a die grinder. Thanks to all for the advice as, obviously, everything worked out in the end.
We needed to abandon the original piece as it was coming in overweight. Redesigned and rebuilt out of different material, a little smaller, and being mindful of the advice given earlier in this thread. It worked.
Try removing the aluminum angle. The beads whould have been rolled prior to any other process as the metal will shrink when the beads are rolled.
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