Seven Laws of Metal Work
October 2015 Issue
Almost every time I give an O&P fabrication presentation someone says, "I hate metal work." Because many of the technicians who are most comfortable working with metal have retired and the newer generations aren't comfortable with it, it's no wonder the art of metal fabrication in O&P has been pushed aside by the use of thermoplastics and composites. But here's the thing: It's really not that hard. It takes some tools and a little practice, but it has about the same learning curve as any other material we deal with; you just have to know the rules.
As I started teaching people how to bend metal, I realized that I had never fully formed an idea of why I did what I did, and why it came so easy to me when other technicians seemed to struggle with it so much. I found the answer in a book by Tony Robbins, the self-help expert, in which he describes teaching soldiers to pass marksmanship training and reduce the overall failure rate, which was high. However, Robbins says he knew nothing about how to shoot guns. So instead of teaching the soldiers to shoot, he interviewed expert marksmen and discovered their secrets-their "beliefs" about shooting-and taught those things to the soldiers, and it worked. As soon as the soldiers realized what things they needed to believe, the shooting became easier. Following that model, I set out to find people who worked with metal and figure out what they believed. From there I developed a series of what I call high-order beliefs.
Metal Doesn't Hate You
This rule is simple but true. A lot of people become convinced that there is something about working with metal that they don't get, when in fact metal, like a computer, only responds to your input. If the output is wrong, it is because you did something wrong. Metal is completely indifferent to your desires.
To End Square You Have to Start Square
This rule is critical. When you are building a device with interfacing surfaces that will be required to move in unison with each other, those surfaces need to be square, or parallel, in all three planes. If you want the surfaces to end square, you must hold the parts in the correct plane when you bend them. Bending parts even a few degrees out of square can produce unsuccessful results. So hold your parts flat and level, and mind the angle of your bending tools. A good tip is to look at the marks left by your bending tools, and if the compression marks aren't perpendicular to the desired bend, then the part will not be square.
The Elastic-Plastic Moment Is Invisible
The elastic-plastic moment is when the metal ceases to be elastic (able to return to its original shape) and becomes plastic (it assumes a new shape). Probably the most critical skill when bending metal is to understand and feel the elastic-plastic moment. Most people start bending metal by looking at how far they have bent the metal with each application of force, but here's the thing: It's invisible. Every time you bend a piece of metal, you must bend it just beyond its elastic state such that when you release the bending force, it will spring back to the shape you want. This is something you have to be able to feel with your hands. I recommend bending some scrap metal bar ends with your eyes closed. First try to bend it as far as you can without actually getting to the plastic state; that is, bend it only as far as it will bend and still be able to return to its flat state. After getting good at that, close your eyes and try to bend it by a specific amount, just a few degrees, by feeling the bend in your hands. Feel the point at which the material starts to "tear" and yield permanently to the bending force. Unless you can feel the metal tear, you will never have good control over the bend force you need to apply to achieve a desired result.
Tools Will Damage Metal
The changes you make to the metal occur at the molecular level. Every time you ding the metal, even if you sand out the ding, it leaves behind an area of compressed or work-hardened metal that will always be there as a stress riser and potential area of failure. For this reason, you need to tune your bending tools and do whatever you can to minimize the bend marks. Whatever tool you use to bend, the marks should be as small as possible and as smooth as possible. Not allowing huge disruptions in the quality of the metal is the best way to avoid having to do a lot of sanding.
If You Overbend It, It Will Break
Any time a device breaks, it can be dangerous to your customer. Knowing what the metal feels like when it is bent will also alert you to an overbend. When you are just beginning your adventure in metal bending, every bend will take a few tries to get it just right. Some of the more extreme bends may take several tries, and that's where the trouble starts. You bend the metal, then unbend it, then bend it again, with each successive bend further weakening the part until you finally get it just right. But you have to ask yourself if the metal is too fatigued to support the forces that will be required of it. Don't gamble. When these devices fail, they generally fail catastrophically, and nobody wants that.
Always Paint With Broad Strokes
I always try to imagine the longest possible bend I can make in every situation. Longer bends put less stress on the metal, take less time, and are generally smoother. When most people approach metal bending they usually see each bend as a thousand incremental bends, when in reality, just a few bends are necessary. I was taught, and subsequently try to teach others, that a side bar for a metal AFO only requires three bends: one to narrow the gap above the malleoli, one to bring the bar into plane with the calf, and one to bring the proximal portion into plane with the calf band. If it takes you more than that, think about where your tools need to be placed to do it in three bends. If you typically use a tool with a fixed bend space, like bench-mounted benders, try using a set of bending irons to give you greater flexibility in your technique.
The last rule is one of the most often overlooked. For some reason, a lot of people in O&P seem convinced you can make stuff without using tools, but they are wrong, especially when it comes to metal work. To do a high-quality job, you are going to need quality bending tools, a stirrup bender, a good anvil, squaring tools, and some specialty screwdrivers. These things cost money, but like any tool, if you use them to improve your results, they are a good investment.
By using these foundational rules to build your skills and practicing as often as you can, your metal bending skills should improve. If that doesn't work, maybe rule number one is wrong.
Tony Wickman, CTPO, is the CEO of Freedom Fabrication, Havana, Florida. He can be reached at .