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Are homemade tools for press brake operations a good idea?

Done right, homemade press brake tools can be just as practical as factory-made tools

Homemade press brake tool for bending metal

Should a bending operation rely heavily on homemade tools? That depends, writes press brake guru Steve Benson. If made well and for the right application, homemade press brake tools can be very workable and as practical as factory-made tools. Images provided

Q: I’ve taken a new job as a press brake department lead in a large job shop. At my previous job, we used homemade tooling occasionally but we didn’t make it an everyday practice. At my new job, I’ve found the company not only allows but even encourages homemade tooling on the shop floor. Our quality control department even uses several homemade tools for qualifying parts. To my mind, this practice cannot be right.

I have had several discussions with managers on the virtues of top-quality measurement tools, and I’ve spelled out all the reasons I feel this is a bad practice. They always have a counterpoint that sounds reasonable, but I am still not buying it. The daily debate goes on.

I hope you can help clear this up: Who is right when it comes to relying heavily on homemade tooling? Is it a good idea? Your insights on this topic could go a long way in enlightening us. Thank you for your time. I read your column every month and have learned a lot. With your knowledge of sheet metal, you seemed to be the perfect person to ask.

A: Homemade tooling falls into three categories. The first includes the working and gauging tools that help you perform an operation—a side stop, for example. The second type helps you measure or qualify a part to ensure the operation and part are to specifications. These might include radius or countersink angle gauges. Third are the operational tools that assist with machine operations, such as dial indicator mounts and custom tooling.

Gauging Tools

Pin Gauges. These gauge a flange from a feature to a bend line—a bit of old-school craftsmanship that is still valuable today (see Figure 1). When the called dimension is from the feature to the bend line, and you gauge out of the feature to locate the bend, the dimension is held, and any error goes to between the feature and the edge. Gauge from the edge to the bend line, and any error shows up in the called dimension.

Side Gauge. The side gauge is a right or left side stop along the bed, or the brake’s Z axis. The part is held against the backgauge to hold the dimension, while the side gauge keeps the previous flanges, embosses, hardware, and other features out from under the punch.

Bend-line Gauge. This helps line up a scribed bend line with the center of the punch radius (see Figure 2). It can be made from a square lathe cutter set on its edge and cut back on one end. When placed on a V die, the gauge’s cut-back section forms a vertical line that the operator uses to align the scribed bend line with the center of the bend.

Measuring Tools

You can make a variety of measuring tools quite easily, assuming you have access to a laser. In fact, all but one of the examples that follow can be easily cut in-house.

Radius Gauge. Once you make your initial program for cutting your radius gauge on the laser, you need only scale your laser program up or down to create a gauge for the radius you need to measure. In many ways this is better than buying a set of gauges that come in common imperial or metric sizes. Most of us air-bend these days, and when we air-form a workpiece, the inside radius is produced as a percentage of the die opening. That floated radius rarely will be one of the fixed values from a purchased gauge set. By making your own radius gauges, you can match them precisely to the radius you need to produce in the part (see Figure 3).

Rule. Using a laser, you can cut a rule to the exact size and create the exact marks you need, be they imperial or metric. It’s just as accurate as the average shop rule. It’s perhaps not entirely as accurate as an inspection-grade tool, but it gets you close enough for many situations on the shop floor (see Figure 4).

Homemade press brake tool for bending metal

Figure 1. This pin gauge is made from sheet metal and a PEM standoff.

Steel Balls. You can use steel ball bearings of various sizes to chamfer a hole, slightly changing its diameter. Whether the hole is too large or slightly off-dimension, these steel balls may be the tool you need to save a prototyped part (see Figure 5).

Countersink Angle Gauge. Again, these are simple to cut on a laser and simple to use. Like custom radius gauges, you can cut these to the exact countersink angle you need to measure (see Figure 6).

Operational Tools

Dial Indicator Mount. Say you want to check the backgauge for accuracy and repeatability, or you need to adjust the backgauge manually on a non-CNC machine. A dial indicator is just the right tool, but mounting it to the bed of the press brake will require another custom, though very simple, tool. It’s nothing more than a dowel pin welded to a bolt that fits into any of the many threaded holes along most press brake beds (see Figure 7).

Small Punch and Dies. If you’re forming very thin material and you need a very narrow die opening, like 0.035 in., you might have trouble finding one. Figure 8 shows a 0.500-in. square bar with two narrow V grooves, creating a miniature double V die that snaps into a custom holder. The holder is made from hard urethane and is designed to fit a European-style mounting rail.

You probably won’t be able to find a punch for this job in a tooling catalog either. Here I’ve used a thin cutting rule meant to cut cardboard boxes to shape (see Figure 9), effectively making a 0-radius punch. You can cut the rule to the length you need, and you can even add ears, cutouts, and other features you need to form the part. You’ll also need to make a punch holder that resembles a European wedge block or custom holder for a planer-style machine.

Centering such a small punch over such a small die requires exceptionally fine adjustments, much more nuanced than the average centering process. You can accomplish this by again making a holder that mounts to the press brake bed and holds a micrometer head, which is attached to a homemade tool that clamps on the die mount rail. This allows you to move the rail in and out in 0.0001-in. increments (see Figure 10).

But wait … there’s more. You have the tool, the mounts, and the adjusters, but you still cannot see the punch and die when you center the tools. Again, you can turn to a homemade answer.

How do you center a 0-radius punch into a 0.035-in.-wide V die? You cannot put your head between the bed and ram, of course. But you can get a magnifying lens with the right focal distance for the centering process. You’ll need a couple of blocks cut to mount on a European rail style (or whatever rail style you have) to hold a small webcam. Now, with the help of a few monitors for viewing, you can center the tooling (see Figure 11).

Urethane Dies. You can make a small urethane toolset, complete with deflection bars and an air channel under the pad to reduce the forming tonnage (see Figure 12).

Gusset Tool. Say you need to form a gusset, a stiffening rib perpendicular to the bend. This little gem will help you produce gusseted bends by merely placing it between two sections of tooling. Small spacers on either side allow the material to flow out from the gusset tool. The gusset tool in Figure 13 was made from stainless steel. Just cut it to a dimension slightly shorter than the tool height, and it’s ready to go.

Homemade press brake tool for bending metal

Figure 3. A homemade radius gauge can be cut to match the exact radius you need to form in your part.

Be aware of the load the gusset tool will be subjected to during use. Tonnage will be concentrated on the gusset tool edge and can become embedded into the mounting rail or bed of the machine. It’s best to place a protective strip under both sides of the die and along its full length, raising the tool enough to protect it.

Gauge Blocks. If you’re using traditional planer tools, you’ll need to use gauge blocks to calibrate the backgauge to the center of the bend during setups (see Figure 14).

Just a Sample

I hope I have given you a few ideas that you can use when the creative need strikes. The ideas presented here just scratch the surface of what homemade tools can do for your shop. Some homemade tools might not be good enough for quality control, but some are certainly good enough for the production floor.

Is relying heavily on homemade tools a good idea? It depends on how your operators work, the level of precision you need to achieve, and how well the homemade tools are made. If made with care, such tools are quite workable.

About the Author
ASMA LLC

Steve Benson

2952 Doaks Ferry Road N.W.

Salem, OR 97301-4468

503-399-7514

Steve Benson is a member and former chair of the Precision Sheet Metal Technology Council of the Fabricators & Manufacturers Association. He is the president of ASMA LLC and conducts FMA’s Precision Press Brake Certificate Program, which is held at locations across the country.