Building a Bean Box

By Tony Wickman, RTPO

As an exhibitor at O&P conventions, I find that between the waves of kind and inquisitive potential customers, there are periods of boredom when all the exhibitors stand around and talk to each other. Mostly we swap tall tales, but sometimes we actually share useful information.

During such a lull at a recent convention, I heard about a tool I instantly knew I had to have. I was talking with a fellow who works for a shoe company that sometimes does shoe modifications. He mentioned that his company uses a tool called a bean box.

What is a bean box?
My acquaintance described the bean box—as you may have guessed—as a box filled with beans. The hinged lid is a frame with a rubber bladder suspended from it, and in the side of the box there is a vacuum port, with a filter attached on the inside. The device basically works just like an arch press, but it allows you to form material around the bottom of really tall items such as boots.

To hold an object such as a boot or mold motionless while you work on it, you just stick it into the beans. The vacuum forms around the bottom of the object, and as the bladder comes in contact with the beans, the beans compress and become a solid mass, holding the object still. The bladder suctions the material you are forming onto the mold while it cools.

What can it do for you?
The bean box seemed like an idea with potential. One way you could use the box is to put, say, a three-inch heel lift on a work boot. The fastest and easiest way to attack such a problem would be to vacuum-form at least the first layer. This would allow you to sand that layer flat and then apply subsequent layers to a nice flat surface.

However, at my shop we don’t do very many shoe lifts. But we do a lot of CROW boots, so I thought it would be great for applying the walking soles.

CROW boots are especially challenging because the plantar surface is usually highly contoured and it’s difficult to get a nice tight crepe sole onto it. In the past, we had to heat up thin layers of crepe (usually 1/2-inch to 3/4-inch), wrap the mold with an Ace™ bandage and allow the whole thing to cool. Sometimes when we removed the Ace bandage, we would discover that the crepe had shifted or the wrap wasn’t tight enough. We would have gaps, so we would have to start the process all over again. When I heard about the bean box, I felt that this frustrating, time-consuming step in the process of fabricating a CROW boot was about to be hugely simplified.

Building the box
Back at my shop, as we started planning how to build the box, we knew it would have to be big in order to accommodate a CROW mold. A quick scan of all our archived molds showed that it would have to be at least three feet tall and 18 inches across. If it were square, the walls would have to be rather thick to keep from collapsing, but if it were round, it would be more stable—more of a “bean tube.” All we needed then was a piece of schedule 80 high-pressure steel tubing about three feet long.

Well, after making 20 phone calls and looking through the Thomas register, we decided to cut to the chase and call a metal fabricator. We had the fabricator roll a piece of 3/16-inch steel into an 18-inch-diameter tube 36 inches long and weld the seam. Then we welded a flat base onto the bottom.

To make the lid, we used one of the products we manufacture: a machine to make arch supports, called the Arch Express®. As a part of this machine, we have metal frames designed to hold a flexible rubber bladder. Conveniently enough, these frames are 20 inches by 20 inches, but they are square. To accommodate the frame to the tube, we welded a piece of the 20-inch-by-20-inch-square steel that was 1/4-inch thick to the top of the tube, but cut the center out to match the diameter of the tube. That allowed us to bolt the hinges, latches and retaining wire from our standard arch express to the top of the tube. It also meant we would be able to use standard die-cut bladders.

Next we installed a vacuum port with a three-way valve and a vacuum gauge on the side of the machine, and we made a small vent to allow air to flow into and out of the machine without sucking the beans into the vacuum pump. I don’t know how many beans it takes to stop a rotary vein pump, but I’m in no hurry to find out.

Full of beans
That just left one minor detail. Where in the world were we going to get six cubic feet of beans? When this device was first described to me, I was told the shoe company used real dried beans, such as black-eyed peas. I wondered what happened when the water from the molds was absorbed by the beans. I’m a vegetarian, but I don’t know what I would do with six cubic feet of bean sprouts.

So we started looking for synthetic alternatives. Later that night while I was playing with my sons, I found the solution: Beanie Baby™ guts! For those of you who aren’t aware, inside each Beanie Baby toy is a small amount of slippery, round polyethylene beads. They are really just plastic pellets designed to be used in injection molding. The beans are waterproof and they are very slippery, so jamming a three-foot-tall cast upside-down into them turned out to be relatively easy.

I made a few calls to friends, and within a week or so, a pallet of ethylene pellets arrived. If you make your own bean box, you could probably purchase pellets from an injection molding company.

As we were building the bean box, I could see the skepticism on the faces of almost everyone in the shop. Eyebrows were raised, snickers could be heard across the shop floor and everyone voiced doubts about whether it would work at all, and even if it did, whether it would really help speed up the process. That’s the nature of innovation—you can’t just say it will work, you have to prove it.

The proof is in the pellets
Fortunately, it does work. After a few tries and some practice to figure out the ideal amount of beans to include for each mold, we were able to very easily insert even the biggest CROW molds into the tank. Not only do we use it for the walking sole, but we use it for the removable inserts, as well as for heel lifts on just about any other orthosis. It doesn’t take much vacuum force (usually only 8-10 hg) and it is easy to see if the molding material is in the right place. We can even use compressed air to cool the material, since the bladder is very thin.

All in all, the bean box is a great addition to our arsenal of wacky tools, and its applications would make it a practical tool for all technicians to have in their shops. Just call it the world’s largest Beanie Baby.

Tony Wickman, RTPO, is president of Freedom Fabrications in Havana, Fl.