A lesser grade wood gets high-tech treatment.
By Steve Baxter
As settlers trickled into the Great Plains during the mid and late 1800s, their first act of homesteading was often to build a rough shack out of cottonwood lumber — or to move into one abandoned by others. In a time and place where trees were few and far between, cottonwood was relatively plentiful and for the taking along the river bottoms there.
The accommodations were poor. As one homesteader put it, the cottonwood sheathing on his home warped so badly you could “throw a cat” clear through the structure.
Today, cottonwood is still plentiful, and it still warps. But down in Lubbock, TX, for more than a decade the O’Hair family has been using the lumber to build, of all things, fine interior shutters.
These are not the cute little louvers on the kitchen window, common years ago. Rather, they are typically large, sometimes very large, frames with narrow 2-inch stiles and tall spans between the top and bottom rails. Captive within the frames, the wide but thin louvers span as much as 36 inches of panel width. A twist or bow in any one member can render a shutter useless.
Actually, the O’Hair family has been building window treatments since 1939, and shutters, at first of Ponderosa pine, since the mid-60s. The conversion to cottonwood has required a Texas-sized commitment in brainpower, technology, legal tender and persistence if not hardheadedness.
What is remarkable is that O’Hair Shutters Inc. began the project about the same time it became a debt-free company — which it remains today, even after building a new 175,000-square-foot facility on its 40-acre expansion site.
“The new plant now includes a stack yard of several acres, lumber drying, rough mill, an engineering shop, priming and components,” says T. Brant O’Hair, marketing director. “All that’s left at the old (80,000-square-foot) facility is assembly, shipping and offices.
The Pesky Details
“Hopefully some time next year we’ll break ground on the final construction phase,” he says. It will consist of two more buildings totaling about 100,000 square feet to house the operations that have yet to be moved to the new site, O’Hair says.
Currently, the company’s 230 employees produce more than 1,000 shutter panels per day. Customers are woodworking/finishing shops across the country which sell the jobs to interior designers and homeowners, buy the unfinished or pre-primed panels, size those panels and build the perimeter framing to accommodate them, finish the works, apply the hardware, and do the installation. The O’Hair people call their woodworking customers “customizers.”
In addition to rectangular shutter panels with four different louver sizes (movable or fixed), O’Hair Shutters produces sunburst shutters (with radial louvers) for quarter-, half- and full-circle windows, as well as perimeter mouldings for use in the aforementioned framing.
For all of these products, O’Hair starts with rough green cottonwood brought in by rail from mills along the Mississippi and its tributaries. Although the company at first used lumber dried by others, its willingness to invest in dry kilns and experiment with drying techniques has been critical to achieving success with the specie.
“We’ve been drying cottonwood for probably seven or eight years now, and even in the last year we’ve continued to improve the drying process,” O’Hair says. “We recently had our dried lumber re-graded by an NHLA (National Hardwood Lumber Assn.) grader and we’re getting fewer drying defects than the grader had ever seen with cottonwood.”
The problem with purchasing pre-dried lumber is that “the lumber industry has a hard time justifying the necessary drying procedures, cottonwood not being a high-margin item,” O’Hair says. “It must be dried more gently, and that spells a more expensive drying process.
“As a purchaser of the rough green lumber, we are a problem solver for some mills who really don’t want to mess with cottonwood but have to take what they get alongside the ash and oak and other more profitable species,” O’Hair says. The green lumber weighs twice what it will when kiln dried to 9 percent moisture content, at which point it’s ready for the rough mill. It turns out that if you know how to dry it properly, cottonwood is not such a beast,” he says.
The Rough Mill
Next is the second critical cottonwood-specific processing step. Each piece of cut stock is re-ripped on Weinig Profimat moulders into “glue-up modules” approximately 1-1/4 inches square.
“Even after a state-of-the-art drying process and then all the work on the rough-mill cut line, the stock will still have some bow and camber to it. Every step of the way we’re trying to straighten it,” O’Hair says.
The modules are then turned 90 degrees and reglued to one another, face-grain to face-grain, original edges form the new face. The glued-up modules are cured in presses using radio frequency. O’Hair calls this “edge gluing in an edge-grain orientation.
“It’s an expensive process, but again, absolutely critical. It’s the only conceivable way to make shutters out of cottonwood,” he says.
The next stop is the moulding department, where the blanks are machined into the various profiles: end- and mid-rails, stiles, tilt-bars, perimeters, and so on.
One of the Weinig moulders there, a Unimat, is dedicated to processing louver blanks. “We surface the top and bottom of the blanks smooth and then we put a triple radius on the sides,” O’Hair explains. The five-head moulder has two additional vertical spindles at the end featuring Super Thin Saw saw blades, which slice apart each blank into three louvers.
An Extra Critical Step
“We follow up with Timesavers finishing sanders” featuring an orbital unit after the conventional wide sanding belts, he says. Then the louver radii are edge-sanded on Delle Vedove edge sanders.
At this point more than 70 percent of the panel mouldings are diverted into the priming department. (See “Beyond Sanding: A Primer” page 46.) They will meet up with the unfinished mouldings again in the components department, after being cut to finished length on another Barr Mullin optimizer line.
The “backbone” of the component operation is a group of four-axis CNC machining centers, O’Hair says. “We use CMS PF102’s and PF112’s for tenoning louvers and rails and to produce sunburst components.
“Our CNC machines utilize parametric programming rather than specific-part programs,” O’Hair says. Rather than relying a specific set of instructions for each different part in every size and configuration, such machines use parametric formulas to write new instructions for each type of part as the variables are changed. Thus there is no need to download the specific-part programs from the office computer’s files.
This technological approach is important because of the large variety of parts that are processed. O’Hair makes panels in 29 different widths ranging from 9 to 37 inches.
“What we’ve done so far has involved fairly simple parametric programs. We’re only dealing with one variable on louvers and rails and that’s the panel width they go into,” O’Hair says. “Our sunburst product has a couple of variables — the radius and the number of louvers into which that the quarter-circle is divided.”
But parametric programming is soon to assume a greater importance. Currently, stiles are machined with a simple dado that not only accepts the rail tenons but also “retaining strips” notched to create pivot holes for the different louver spacings. The strips are cut to length to accept whatever number of louvers and inserted in the dadoes, leaving spaces for the rails.
A New Design
“On this upcoming project there will be many more variables,” O’Hair says. “There will be the panel height (which ranges between 20 and 121 inches), the height of rail top and bottom, the location of any divider rails and the louver spacing with the number of louvers. Parametric programming will be indispensable, because there’ll be literally hundreds of thousands of permutations of those variables,” he says.
Down the road, O’Hair wants to use the same technology and machinery to process otherwise ordinary panels featuring radiused tops as well as individual eyebrow-shaped units on radius increments of 116 inch. “The potential to do things that heretofore have been too custom is just fascinating,” O’Hair says.
The technology makes it feasible to build one-of-a-kind items by automating the setup and standardizing all the various elements that define that custom item. “I love that kind of development work,” he says.
But it’s more than just a cerebral challenge. Homebuilders these days appear to have a love affair going with arched windows. “If a house has a few arches and we can provide contoured panels for them at a reasonable price, we’re going to get the rest of rectangular windows as well,” he says.
On even the simplest of these machining-center operations, O’Hair says, the nature of the various components-to-be necessitates specialized fixtures to secure and position them on the machine table.
“It’s not like we’re laying a big, flat sheet on the table with a spoil board underneath,” he says. “We try to use vacuum chucks to clear the way for the cutter tooling. Some applications require mechanical clamps or pneumatic clamps, though.” The stile- processing operation will utilize a fixture with its own servo or stepper motor to reorient the parts in 90 degree increments.
Training the Customizers
O’Hair operates a training program at its Lubbock plant for members of both groups. Even the most sawdust-encrusted woodworking veterans benefit, O’Hair says, especially from instruction on finishing techniques. Spraying shutters is a little more involved than finishing cabinet doors and other solid pieces, he says.
In another effort to aid its customers, O’Hair is developing a software program called The Customizer. Loaded into a notebook computer, the software is intended to accompany the shutter customizer on job calls. After measurements and design elements are input and tweaked, the program will draw and display the shutter installation in any number of configurations, among which the homeowner can choose.
Additionally, the program will perform a material take-off which the customizer can e-mail from his cell phone. In the future orders will automatically be fed into O’Hair’s computer system. There the job will be broken down into components and seamlessly fed right into the CNC controls in the component department.
“You get software in the home, you get parametric programming in the machine — it’s inevitable that people are going to start connecting the two,” O’Hair says.
Beyond Sanding: A Primer
O’Hair Shutters spent $1 million on machinery for its priming operation, then spent an entire year learning the best ways to set it up and run it before ever going into production.
“We had to work through a lot of issues,” Brant O’Hair, marketing director, says. One reason is that the operation is designed to do more than just pre-coat and sand the various mouldings that go into the company’s shutter panels, though that certainly is a great convenience for its customers.
That edge-gluing process, so critical to attaining straight and stable shutter members, has one pesky downside. It leaves at least one open glue line on the face of each component. No amount of curing time or acclimatization will prevent at least some of those joints from sinking ever so slightly. When they do, they can “telegraph” through paint finishes, especially on louvers “because they’re back-lit by the sun, the most intense inspection light there is,” says O’Hair.
So the first part of the priming operation is a flat line manufactured by Superfici which uses roll coaters to level any glue-joint indentations.
“Roller coating is an old technology,” O’Hair says. “My dad operated a roller coater as a kid back in 1939, applying solvent coatings to wood blinds. But it is still a very efficient way to apply UV coatings,” he says.
The UV-cured primer is “100 percent solids, which means that there’s no solvent or water in it,” O’Hair says. “It’s a liquid, but nothing evaporates. One mil wet becomes one mil dry.” Which is a good thing, because “the coating is very expensive on a per-gallon price basis,” he says.
A chemical component called photoinitiator is set off by the UV energy and commences the curing process. Photoinitiators are the expensive part of UV chemistry, O’Hair says.
After exiting the curing tunnel with its UV lamps, the mouldings go through a Timesavers single-head, widebelt sander running very fine grit. They are then flipped and primed on the opposite face.
Line Number Two
In this operation the primer is also UV cured and 100 percent solids, but with a lower viscosity than that used for the roller. Each of the UV coatings is supplied by Mirotone Pty. Ltd. of Sydney, Australia.
“Imagine a small box filled with coating and a slightly oversized opening on either side in the same shape as the profile,” O’Hair says. “You run the profiles through the box via these openings. Vacuum keeps the coating in the box.
“As the profiles exit the box, air being sucked in around their perimeters squeegees off the excess coating,” he says. “The amount of vacuum applied to the box thus controls the wet film thickness.
“All this is happening pretty fast,” he says. “We run over 100 feet a minute.”
From the vacuum box the mouldings enter a UV curing tunnel (the bottoms are cured first, so they can then be supported within the tunnel), and then finally a profile sander.
“All in one motion we’re coating, curing, and sanding,” O’Hair says. He adds that the line stretches 120 feet long.
— Steve Baxter
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