Choosing the Right Underpinner Advice from manufacturers on buying and using production joining machines By Patrick Sarver

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The ITW AMP Mitre-Mite Multichannel memory program underpinner holds up to five different size nails and can store information on up to 1,400 profiles.

production framer needs an underpinner built for quality with heavy duty construction, that is easy to operate without needing a lot of adjustment, and meets the specific needs of a production operation,” says Justin Convey, sales manager of ITW AMP. “All V-nailers basically do the same thing; it’s just a matter of how big a moulding they handle and how fast they are for different types of production,” says Robert Pistorius, president of Pistorius Machines. “V-nailers are designed to fill certain niches. High production requires a machine that can withstand hours and hours of continuous cycling. A high volume custom framer needs versatility and a fast set-up time.” Whether you call them underpinners, joiners, V-nailers, or just nailers, choosing the right one for a production framing operation is largely a matter to matching a machine’s capability to your specific needs. “How adjustable and effective are the inside and top clamping systems?” asks Clay Simpson, national sales manager of Active Sales. “What kinds of nails does it use? Is a machine fast enough to do the amount of production or have the nail positions you need. There are machines with 2 to 10 positions. Pick the one that works best for your particular production demands. A machine that will put in two nails at a time and in different sizes is a dedicated machine, which means making changes could be difficult. A machine that changes nail sizes offers excellent flexibility but may be too slow for a high production environment.”

Durability “There are so many mechanisms inside machines today that people tend to look at the outside of a machine and make a judgment based on appearance,” says Pistorius. “There’s nothing wrong with looking at the size of the machine, the thickness of the steel table plates, the diameters of the clamps, and so on. But people often make a decision based on the exterior, even though some of those things may not be that important. Does the fact that a machine is a couple of inches wider make it any better? Manufacturers ‘juice up’ the exterior of their machines, knowing that buyers make judgments based on that.” “The plate thicknesses and the steel can tell you a lot about a machine’s durability,” adds Gary Haines, general manager of PAM Fastening Technology, which sells Brevetti underpinners. “But you should also look at the balance supports, the weight of the machine, if it vibrates during operation, and if it has pieces made of thin materials or small driver plates.” A machine also should have a driver that can stand up to all the pushing it has to do and be much bigger than the nail itself. “When the driver is the same size as the nail, the nail can get wedged between in the throat of the machine, jamming it,” says Joe Moriconi, president of Tech Mark, with distributes Taurus underpinners. “And with all the materials people today are using—MDF, plastic, hardwoods, and softwoods—you need a machine with enough power to insert nails in different densities.” Haines recommends raising the top of a machine and looking underneath at the pneumatic systems, the cylinder sizes, how it’s assembled, and the quality of finish materials and how well they’re used. “I would look at any movable part, any pivot points,” adds Eric Pistorius, vice president of Pistorius Machines. “Are there bearings or is it just a sleeve where brass moves on steel? Are there cheap linear bearings? Those are the wear points where some-

The Pistorius VN2E electronic underpinner has six nail positions and can store nailing information on up to 1,500 different profiles.

thing may break down. I would also look at the handles. Are they made out of plastic, which will crack eventually, or are they more substantial? And if you have some experience, you can also take a look to see if the driver is built to last.” Clamping “Good clamping systems are essential for good quality joins,” says Simpson. “Having hold-downs that will handle the wide variety of product is essential. There are typically two areas of clamping: a top clamping or hold-down system and a front

or inside clamp system. There are advantages and disadvantages to both. Having an inside clamp that does a good job on your mouldings will improve the quality of the joints. You just have to try the different systems.” “There are three standard types of top clamping,” adds Eric Pistorius. “The most common uses two cylinders to pull a stationary pad or stop down onto the material. It’s very strong and rigid. The second style involves two cylinders pulling down a fixed bar. That’s another very strong system that’s great when you’re working with wide material. Everything The Fletcher-Terry 5700 CornerPro is a pneumatically operated manual underpinner that was designed for ease of use and durability.

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clamps tight with these two systems. The third system involves a rod coming down on the material, but it has no pressure. Then it’s locked tight. Every time you fire a nail, the whole thing releases and you change position, reclamp the material, and fire again. Sometimes this is done manually, sometimes automatically. It’s slower because it has to release and re-clamp each time.” Air Supply and Control The joiners surveyed for this article require between 80 and 116 p.s.i. of pneumatic pressure to operate. But control over the pressure to the driver and the clamps is also essential. “You want to be able to control how fast a machine will clamp the moulding and insert the nails,” says Curt Brey, vice president of marketing for the Fletcher-Terry Co. “Softer, more delicate mouldings like plastic require less pressure. But you may also be looking for a certain volume of productivity from an employee per hour, depending on how busy your shop is. To do that you have to be able to control how fast a machine clamps and nails. On our machines, air pressure is controlled with simple knobs and dials. Adjusting a machine for speed and control comes with experience as you learn about mouldings and the pressures they can withstand.” “Each of our machines has an air gauge and flow control valve that allows you to adjust the hold-down pressure,” adds Moriconi. “The nail driving pressure is always at maximum. For hardwoods, you need 90 to 100 p.s.i. If you have pine with gold leaf or gesso, you back the pressure off to about 40 to 50 p.s.i. so you don’t dent it.” “The air pressure coming in is for the driver, but if you use inexpensive nails you have to lower the pressure or the driver will crush them,” says Eric Pistorius. “You should also have control over the pressure for each clamp—the top clamp and rabbet clamp individually. This lets you tune your machine for the job you’re running.” 34 PFMPRODUCTIONWinter2006

The Cassese CS3099 Ultra is a programmable memory underpinner that stores 1,500 profiles. It has six nail positions and uses disposable nail cartridges that allow a quick changeover of nail sizes.

The MitreNailer StepMaster from Active Sales is a high production step joiner with two nail positions. It also offers quick changeover from traditional V-shaped nails to corrugated nails.

Stacking vs. Multi-channel Changing nail sizes and types can take some time but gives a production line the flexibility to use the right nail. “On the Brevetti, you can change the nail heads to go from one type of fastener to another,” says Haines. “This would require changing the nail head, which takes about two hours. The head comes in a kit.” Another option is a multi-channel joiner, which can insert nails of different sizes into the same moulding. “The Taurus 2KDE has two heads to insert two nails simultaneously,” says Moriconi. “Each head can push in a different size nail, such as a 5 /8" and a 1/4". These heads can be moved to a second position to fire two more nails. It can stack up to three nails in four different locations, with half of those nails a different size. You use a selector switch to tell the joiner that you want two nails in one position and three nails in another and so on. On the 2QE you can put nails in nine different positions.” “Stacking nails makes a join stronger, but it’s not as strong as using a specific size fastener,” says Convey. “Five years ago, you had to manually make a change if you wanted a bigger nail. Now you can do it with a multichannel machine. You can also save about 30 percent on fastener usage. Instead of stacking two 10mm or two 7mm nails, you could use one 15mm nail. The advantage is a stronger assembly. For a quality production assembly process, a multi-channel nail system also lets you possibly get away without using any glue. You would have to test the moulding with and without the glue.” Cycle Rate The cycle rate of any machine is important because it affects labor costs. “For a V-nailer, however, the cycle rate is about three or four times faster than what an operator can actually do,” says Convey. “The main factor is the type of material. With soft wood or plastic, the cycle rate can be

very fast. The harder the material, the slower you have to set the dwell timer and the cycle rate. You want to make sure the nail is fully inserted before going to a second or third nail position. Cycling too fast can cause the material to move or create poor stacking of nails.” What often slows down production, especially when you are constantly changing the types of moulding you’re joining, is the set-up time for changing from one moulding to the next. In that case, it’s important to look at the set-up capability of a machine. One that can be changed easily can save a lot of time. An automated machine that remembers the nailing and clamping requirements of specific mouldings speeds things up dramatically, especially for operators without a lot of experience. If you have to change nail types or sizes, find out how this is done and how long it takes. Programmable Memory “Sometimes when I’m in stores, I check out the frames,” says Pistorius. “I have found 2" moulding with 10 nails in it. Or they’re in the wrong position, and the outside corner is open. Or the face of the moulding is open because the nails were too long. This is why more manufacturers want intelligent machines. Electronic machines with memory can store certain parameters for mouldings according to part numbers. For example, they record where the clamps should be set. We put numbers on the top clamps and horizontal clamps. When an operator enters a part number, the screen says to put the top clamp at position five, the rabbet clamp at position three, and what size nail to load. The operator puts the moulding in the machine, steps on the pedal, and the V-nailer automatically puts the right number of nails in at exactly the right places. The machine guarantees the quality of the joint. This information is easy to put in the memory, and it can even be done offline and downloaded into the machine memory.”

“When you recall the information for a particular style moulding, once you hit the pedal, the machine will engage the clamps and the firing sequence will initiate according to the recipe you’ve set up,” says Haines. “This provides repeatability. The head will insert nails in any order you want, which can be an advantage with some difficult mouldings and give you flexibility as to how a corner is drawn in. You still need someone with experience setting up the profiles, but it takes a lot of operator judgment out of the equation.” The placement and number of nails is subjective and depends a lot

The Taurus 2KD from Tech Mark is an automatic double-head underpinner that is shown tilted with wooden wings attached for joining a larger frame by using gravity to seat the moulding against the fences.

The Brevetti Auto 2000 from PAM Fastening Technology is an electronic joiner that features a coil feed for nails.

on the moulding, advises Convey. The rule is to start from the inside miter and work your way out, placing the fasteners closer to the inside miter than to the outside of the frame. A narrower moulding will have narrower spacing between nails; a wider moulding will have wider spacing. He says it’s a good idea to test the strength of a corner by flexing it while you’re setting up the profile in the computer. If it doesn’t feel strong, reposition the nails or perhaps add more. Manual vs. Memory “I was watching a woman at a nearby production facility who was making eight frames a minute on a manual machine,” says Robert Pistorius. “You couldn’t do it any faster on an automated machine. The plant manager said, ‘Why should I buy an automated machine when she can do it faster on a manual?’ So I asked him how many women he had who could do that. He said, ‘She’s one of a kind.’ ” Manufacturers of manual underpinners—which are much like automated machines but without the electronic memory—don’t dispute the production benefits of adding memory. But, they ask, are those benefits worth the higher price? “Manual machines focus on simplicity of design, durability, and longevity at a lower price,” says Brey. “They still offer high-speed operation that any production line would want. There’s a hand-operated firing mechanism, which increases the speed with production stops. An average production lab wants an underpinner an average operator can run that’s extremely user friendly. In designing a manual machine, we brought in nonframers to operate joiners to determine the obstacles that an average operator would face. “PLC systems may be the best way for efficiency and productivity, but they also require a higher upfront investment,” he adds. “We had clients looking to buy two computer-controlled underpinners. Instead, they bought four hand-operated machines. In a real production environment, PFMPRODUCTIONWinter2006 35

speed is determined by the operator, regardless of the technology. There’s also a big difference between production line versus work-cell environments. Production lines are usually used in higher volume operations. Work cells are more common when you get into less than 1,000 to 2,000 pieces a day. PLC machines are usually better in production lines. Work cell operators usually see lots of the same product, while in a production line you could be getting anything. So computer control becomes much

more important there because it’s harder for an operator to remember what’s being worked on.” The advantage of a programmable V-nailer, says Convey, is that it’s extremely quick compared to a pneumatic V-nailer, especially when changing profiles. “Anyone doing more than 100 frames a day can get the benefits. A programmable V-nailer can produce two to three times the number of frames compared to a typical V-nail operator. Once an operator programs information into the

machine, anyone off the street can operate it. A production V-nailer is more expensive but will pay for itself over time.” “An experienced manual V-nail operator can do the actual nailing almost as fast as a computerized machine,” says Eric Pistorius. “The difference lies in accuracy and a reducing the number of rejects. That’s a bigger factor in production than actual cycle time.” Bar Code Scanning “We’re working with software from companies like SpecialtySoft and LifeSaver Software to offer bar code scanning with our equipment,” says Convey. “This allows an operator to scan a bar code on a work order to set up the machine. This removes even more variables in the assembly process.” Essentially, scanning replaces an operator keying in a product or profile number, saving up to 20 seconds that it can take to type in a profile number accurately, especially when profile numbers have up to 18 digits. “If an operator types in the wrong number, you can also have nails put in the wrong position,” he adds. Bar code scanning is especially helpful in operations like Michaels that have lots of different mouldings. “They need very flexible machines that are very quick to set up,” says Robert Pistorius. “To maintain quality control, they use machine intelligence. Bar code scanning has its greatest value when you’re doing continuous changeovers of moulding profiles.” Stands, Wings, and Tables Most underpinners are available mounted on stands or for use on a tabletop. Stands that allow a machine to tilt are most common, but some framers prefer other alternatives. A few can also be raised or lowered for operator comfort. Table “wings” that support larger frames during joining are a very common option. Some factories also put their underpinner stands on wheels so they can be

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rolled out to do a job and then be put away. The important thing when it comes to a stand or bench, says Simpson, is to get a machine that can be set up to work the way you want to work. “We have two stands, and they’re both popular,” says Brey. “One is a closet stand; the other is a tilting stand. The closet stand remains horizontal all the time but offers a lot of storage capacity with shelving. We find less tilting in production environments than in custom environments because production usually involves smaller mouldings and less complicated profiles. The smaller the moulding, the less weight there is and the less need for gravity to assist in the process of nailing. For 24" x 36" or larger frames and large mouldings—5", 6", 8" wide— you’re more in the tilting arena and need gravity. But tilting is really an operator preference—usually the production manager’s preference. Some were trained on machines that tilt; therefore they like machines that tilt.”

you can buy a machine tailored to your workflow. “If you have a job for 500 8" x 10"s, I’d stand in front,” says Simpson. “If I have to do 100 40" x 60" frames, I would push a machine down to table height and operate from the back so I can put it against a table for support. It’s easier to work from the front, but that’s not always possible. On the other hand, the clamps on some machines can get in the way when you work from the back.”

Convey says it’s preferable to work from the front of a machine for frame sizes of 16" x 24" or smaller. If they’re larger, then work from the back. “You can also put the machine on an angle and use the optional wooden table supports for a larger frame or you could work on it flat and build it into your own table to support larger frames,” he says. “Most people go with optional table supports attached to the machine. You then pivot the machine so that gravity feeds the moulding down into the fence.”

Operator Positioning “Most people prefer working on a machine from the front position, meaning that you’re looking into the corner from the inside,” says Simpson. “If you’re doing small frames, that’s ideal because you can see right down into the V of the corner. If you work on frames that are too big to put your arms around but are too small to stand inside, you have to find a different option. “Choosing between a benchtop machine and one on a stand is often about workflow,” he adds. “One company I know uses a bench-top nailer. The long rails are placed on one side of the machine and the short rails on the other. This works because of the way they move material.” Others want a joiner on a stand because it tilts and because the material is on carts next to the nailer. The point is, you can either tailor your workflow to a machine or PFMPRODUCTIONWinter2006 37

“When you’re framing something really large like a 4' frame for mirrors, it’s common to put a table behind the operator that’s level with the machine,” says Eric Pistorius. “The operator stands in the middle, with the frame supported by both the table and the joiner.” Fences While fences on underpinners are set for perfectly mitered corners, some manufacturers offer adjustments that can be used to compensate for lessthan-perfect miters. “Our fences are adjustable to help with twisted and slightly out of square mouldings,” says Brey. “This feature is used mostly in custom environments on items like large frames and mouldings to make sure there’s a perfect join on every corner. There are two adjustments—in and out as well as up and down—controlled by one cam.” Convey says that ITW AMP has adjustments on its fences to correct for bad miters—whether on the 45 degree cut or on the vertical. “If you find a gap, you can dial in fence adjustments up to about 3 degrees to tighten up the gap,” he says. Fences are also available for joining hexagonal, octagonal, and other non-rectangular frames. “We can equip the machines with optional variable angle fences,” says Haines. “These replace the standard fences and are used for joining 6-, 8-, 10-, and 12-sided frames. Changing the fence takes less than 45 minutes.” Service and Maintenance Most underpinners built for production require little service and repair, and most of that is done by someone on staff. “The driver bars and the cutters and cutter assemblies for coil fed machines are the main wear items,” says Haines. “As time goes on, air switches or solenoids become worn, but it takes at least five years of heavy use before that starts to happen. We’ve seen machines with 20 years of service that have had little maintenance other than replacements of driver bars or a few pneu38 PFMPRODUCTIONWinter2006

matic assembly pieces.” While joiners are designed for durability, they do require cleaning and lubricating on a regular basis. The biggest item to watch for is glue build-up. “Cleaning an underpinner of glue can be a nightmare,” says Brey. “The nail head and the moving parts around it as well as the rabbet clamp mechanism all need to be kept clean of glue, sawdust, dust, and debris. Glue can be cleaned away with solvents or scraped off.” Haines agrees: “Keeping excess glue off the tabletop and nail head is the main item. On machines that use nail cartridges, keeping the nail tray free of debris, broken nails, or any kind of foreign objects is important. If you have glue build-up, you may be applying glue too liberally to the joint. When shops complain that they can’t get a good corner, they usually have a build-up of adhesive on the tabletop, which alters the position of the moulding. It can be cleaned up with alcohol and a small putty knife or even by

using a brass-edged ice scraper.” Many, but not all, underpinners have air filters and lubricators. These are usually used on very long lines from the compressor because condensation can build up in those lines as well as corrosion and rust. An air filter/lubricator cleans the air and suspends the right amount of oil in it so the machine is lubricated. Some Final Points Finally, there are three important ideas manufacturers would like production houses to keep in mind: ◆ A bad cut can’t be fixed by a great joiner. If your cuts are inadequate, get a good saw. Then get a good joiner. ◆ Saws are typically twice as fast as joiners, so you should have two joiners for every saw. ◆ You’re making thousands of frames. Get the machinery you need to do the job right. An underpinner is a necessity for production framing. Choose wisely to match your needs, and you’ll be rewarded with years of service. ■

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