Rollers, also called slip rollers, are tools that use adjustable hardened-steel rollers to make an even cylindrical bend in sheet, plate, tube, or solid stock. Rollers can be either manual or electric powered and come in a variety of widths so as to be able to roll Richard Serra–sized work all the way down to compact jewelry work. Rollers consist of one or two drive rollers that force the material through an adjustable gap in a trailing roller to give it its bend, as seen in Figure 8.1. The closer the adjustable roller is to the guide rollers, the tighter is the bend. Thicker-walled tubing may be able to be rolled on a regular slip roller, but thinner-walled tubing usually will be crushed without the extra side support provided by a specialty tubing roller. Another type of small roller is called a ring roller. The ring roller is much like a tubing roller, but it has flat rollers. Ring rollers have a very limited capacity and are used mostly for scrollwork.
FIGURE 8.1 Slip roller in use.
Slip rollers used for sheet and solid stock will be wider than tubing rollers and have long, smooth rollers. These slip rollers have two feed rollers in the front with an adjustable gap to accommodate a wide range of materials. Just behind the feed rollers is another adjustable guide roller that when brought up will decrease the diameter of the bend and when brought down will lessen the bending force. On one side of the rollers there usually will be a series of grooves meant to allow for the rolling of round and square stock and wire. I am going to focus on this type of roller in this book because I believe it is the most versatile. Rolling sheet metal opens up many design opportunities, and because you can use a sheet metal roller to roll solid stock, there’s a lot you can do.
In a mechanical slip roller, a hand crank is turned to feed material through the feed rollers, and when the material comes in contact with the third roller (slip or guide roller), it slides over it, creating a bend between the pinch point in the feed rollers and the tangent on the guide roller. After one pass like this, the material is reversed to help form a uniform, symmetrical bend.
More affordable rollers will be hand operated, which somewhat limits the rolling capacity. For your purposes, a hand-operated roller is ideal (and you get a great workout!). Electric rollers have more safety concerns, and for beginners, a manual feed is the way to go. Check your roller manual to see what the maximum capacity of your tool. Never exceed this rating because you could easily damage the rollers or supports.
NOTE: Never run round or textured steel through the flat rollers of a slip roller.
Given steel’s excellent workability, you don’t need to worry about affecting its strength while rolling. If you rolled a length of material back and forth, alternating the direction of the bend each time, eventually you would cause significant damage to the structure (think of bending solid wire many times with your hand). For normal use, though, the steel structure is not weakened, and the new shape actually may increase the potential strength of the material. When rolling a relatively tight bend, multiple passes should be made to ease the steel into the curve. This technique will prolong the life of the roller and make the rolling process much easier for the operator.
Figure 8.2 shows the parts of a slip roller.
FIGURE 8.2 Parts of a slip roller.
1. Adjust the feed rollers so that the workpiece fits between them snuggly. Keep the feed rollers parallel.
NOTE: Only roll material that is flat and smooth. Grind off any burrs or slag with an angle grinder, and never roll anything with protruding surface welds.
2. With the workpiece extending through the feed rollers, adjust the guide roller so that it will contact the workpiece but not block it from rolling through. Keep the guide roller parallel to the feed rollers.
3. Start feeding the material through the rollers by turning the hand crank. If the material slips, either increase the feed pressure or lower the guide roller.
4. Always keep your hand that is supporting the work at least a foot away from the feed rollers.
5. Start with the material perpendicular from the beginning and keep it so the whole way through. This will ensure that you have a symmetrical bend. If you desire a spiral or cone, you can feed your material through at an angle.
6. The first pass will put a gentle curve in the work that helps you to feed the steel through for the subsequent passes.
7. For the next pass, increase pressure from the guide roller by bringing it up. Don’t start out with too much pressure on this pass because it’s much harder to undo a roll than it is to make one.
8. Continue increasing pressure on the guide roller until the desired curve is achieved.
9. If you are rolling multiple shapes that are meant to be the same radius, run all of them through on each pass before making any adjustment to the roller.
10. If needed, undo the quick release to pull your work out along the length of the top roller rather than bend it over the roller.
NOTE: When rolling multiple pieces, always put them through in the same location on the roller. This will ensure that they all come out with the same radius. Mark the location on the roller with soapstone.
• Be mindful of where you put your hands and fingers.
• Your support hand always should be at least a foot away from the feed rollers.
• Roll one piece at a time.
• Watch out for loose flakes of mill scale when rolling.
• Use a partner for large pieces.
• Wear safety glasses or a full-face shield.
• Gloves are not recommended.
• Do not wear loose clothing.
For this practice lesson, you’re going to roll a length of 1-in flat stock that should yield a 4-in-diameter cylinder. To figure out the length of stock needed, it’s basic math: 4 × π = 12.5, so the length of flat stock you need is 12.5 in. Make sure that your roller has a minimum roller diameter smaller than 4 in, and if not, increase the length of your material. Make sure that the surface and edges of your material are clean and smooth.
1. Hold the material in between the feed rollers, and adjust the movable roller so that the piece fits snug. Ensure that the two rollers are parallel by sliding your workpiece through at multiple points or with a gauge if your roller includes one.
2. With the workpiece held between the rollers, adjust the guide roller so that it just comes into contact with the leading edge of your material but not so much that the material won’t be able to slide past.
3. With your material perpendicular to the feed rollers, roll it through one time. This passage should offer little resistance but will result in a slightly curved piece of metal such as that seen in Figure 8.3.
4. Bring the guide roller up slightly using a few turns of the adjustment knobs. Turn each knob the same number of times.
5. Pass your material through another time, and note the amount of bend.
6. Adjust the guide roller again appropriately, and try another pass. Your workpiece should look similar to the one in Figure 8.4.
7. Adjust the guide roller one more time for another pass.
8. Repeat this process until the ends of your material nearly meet, as in Figure 8.5. It took five passes for me to complete this on my roller.
9. If you have a quick-release type of roller, undo it and slide your hoop off. If there is no quick release, just flex the steel and slide it over the fixed roller.
10. Inspect your cylinder. If rolled properly, the ends should line up very close together, and the radius should be very symmetrical. If the edges don’t line up, this means that the work was not fed through perpendicular to the rollers or the rollers weren’t completely parallel. A well-aligned roll will look like the one in Figure 8.6. Just apply a little pressure, and it will close right up, ready to weld.
11. Save this workpiece, and you’ll weld it together in Chapter 19.
FIGURE 8.3 After the first pass.
FIGURE 8.4 After the second pass.
FIGURE 8.5 Completed roll.
FIGURE 8.6 Edge alignment.
NOTE: Depending on the bend radius, there may be a noticeable flat section of metal at the start and end of the rolled piece equal to the distance between the feed rollers and the point of contact with the guide roller. Usually it’s not much, but if you want to remove it, just start with material that is slightly longer than you need, and cut off the flat section with an angle grinder. Or, before you roll your work, form both ends over another curved surface with a wooden hammer to start the curve.
For this exercise, you need to use the wire grooves on the rollers. If your roller does not have wire grooves, I suggest that you skip this practice. Start off with a length of 
-in round stock that is 37¾ in long (to make a 12-in hoop) with a 
-in miter on each end.
1. Align your length of round stock with the smallest wire groove into which that it can fit without getting hung up on the edges. Some rollers have wire grooves at ½, , and ¼ in. If your roller has three, try the middle one.
2. Adjust the feed roller to add the correct amount of pressure so that the workpiece doesn’t slide out freely.
3. Step back or off to the side to optically align the adjustable feed roller so that it is parallel with the fixed roller.
4. Adjust the guide roller so that the material makes enough contacts to achieve a slight bend on the first pass but not so much that the workpiece gets stuck when you start to crank the handle, just as in Practice 1.
5. Now you’re ready for the first pass. Start feeding the material through the roller so that a slight bend is made. Be sure to support the stock so that the bend continues straight up and doesn’t twist off to one side. If you start to develop a twist, it will take quite a bit of labor to straighten it back out. Figure 8.7 shows the first pass of my workpiece.
6. After the first pass, adjust the guide roller to make a tighter radius.
7. Feed the stock through so that the curve is vertically aligned again, and keep it that way through the whole rolling process. If it starts to twist, just twist the feed side to keep it straight.
8. Repeat steps 6 and 7, making small adjustments to the guide roller until the hoop is nearly closed like the one shown in Figure 8.8.
9. If you can bend the hoop to pull it over the top roller, do so, or undo the quick release and slide it off.
10. The ends should be close enough together that you can easily connect them with your own force, as shown in Figure 8.9.
11. Save this piece to practice welding later in this book.
FIGURE 8.7 First pass with -in stock.
FIGURE 8.8 Almost closed hoop.
FIGURE 8.9 Finished hoop.
