Popular Woodworking 2001-02 № 120, страница 19

Ingenious Jigs

stock into thin strips and plane it so the thickness is even. The thickness of the strips depends to a large extent on the radius of the curve. The tighter the radius,

the thinner the strips. I use this chart as a jumping-off point:

• 2" to 4" radius — ³/32" thick

• 4" to 8" radius — V thick

• 8" to 12" radius — ³/l6" thick

• 12" radius or larger — ^1/4" thick

There are other factors to consider: the

species of wood, the slope of the grain (as it runs between the faces of the strips), the strength you want, and the amount of springback you can tolerate. For maximum strength and minimum springback, we decided to glue up the ribs from ^1/8"-thick strips, although the radius of the curve was nowhere near 8".

Stack the strips as you will glue them together. If you use strips that were all re-sawn from the same board, flip every other strip end for end to reverse the grain slope. Spread a thin layer of glue on the face of one strip, lay the next strip on top of it, spread more glue and repeat. If you're laminating a large number of strips, you may want to choose an adhesive with an extended working time.

Before the glue sets, clamp the laminated strip in the bending form. Let the glue set up for its full clamp time. If you're not sure of the clamp time, wait a full day before you remove the assembly from the bending form. As you release the clamps, there will be a small amount of springback. If the curve is critical (as it was for our glider ribs) make the curves in the bending form slightly tighter to compensate.

Making a Cold Bending Form

Pretty simple, huh? The only real trick to cold bending is in making a form that will apply an even clamping pressure all along the laminated assembly. Traditional bending forms consist of two parts, the form (the positive shape) and the press (the negative shape). Both of these parts are normally cut from the same stock. Begin by drawing the curve you want on the face of the stock. Cut the curve with a band saw, separating the stock into two parts. On the negative part, mark the thickness of the bent wood part. (Tip: Use a compass like a calipers, set it to the desired thickness. Follow the curve with the point of the compass, marking the thickness with the scribe.) Cut away the thickness on the band saw — this will create the press.

The trouble with this traditional bending form is that the press doesn't compensate for small variations in the thickness of the laminated stock or a band saw blade

HELP KIDS BUILD A WRIGHT FLYER

The most exciting woodworking project in 100 years.

The year 2003 will mark the 100th anniversary of the first controlled, sustained flight. On Dec. 17,1903, Wilbur and Orville Wright flew their first powered aircraft,called simply the Flyer, 852 feet across the sands of Kitty Hawk, North Carolina.This coming anniversary presents a unique opportunity to get young people all across America excited about avia-

A replica of the Wright Brothers' 1900 Glider that Nick Engler built and got airborne at Kitty Hawk, N.C., in late October.

tion — and woodworking!

The Wright brothers built the gliders and airplanes in their workshop in Dayton, Ohio.These machines were largely made of wood: spruce for the straight parts,ash for the bent parts and a little boxwood for the pulleys.The end result of these labors was that the Wrights, by virtue of their ingenuity and craftsmanship, achieved the age-old dream of flight. The story of their woodworking projects has become one of the most inspiring stories in American history.

That said, it is becoming harder and harder for young people to acquire the woodworking skills that gave us the airplane and a thousand other useful and beautiful innovations. High school shop programs are becoming a thing of the past. Vocational schools train students for industry, which relies more and more on computer-aided manufacturing. The old manual machine setups — what we use every time we make a cut or drill a hole — are no longer being taught on a wide scale,and our craft will suffer if we don't find other ways to introduce young people to the joys of woodworking.

Popular Woodworking has lent its support to a unique program of the Wright Brothers Aeroplane

Company (WBAC) of Dayton, Ohio, that addresses these concerns direct-ly.The WBAC is a non-profit educational organization of craftsmen, historians and aviators who are building replicas ofWright aircraft, including the 1903 Wright Flyer.They will build the Flyer with the involvement of young people across America!

Here's how it works:The WBAC has scripted a learning experience for kids ages 10 to 18 during which they learn a little aviation, a little history and a little woodworking. During this experience, which takes just a few hours of a morning or an afternoon, the kids build !/<l-scale ribs of the Flyer that they can take home.Then the whole class comes together to build a full-scale rib.The kids sign it and send it to the WBAC in Dayton, Ohio.There, more kids under the supervision of accomplished craftsmen, will assemble the ribs in a replica Flyer, that's 40 feet from wingtip to wingtip.

And that's not all. Each of the kids who works on a rib gets to sign it.The WBAC also invites each young person to make a prediction about what the next 100 years of aviation will bring.All the signatures will be preserved on the replica Flyer, and the predictions will be edited and assembled into a large book.The completed kid-built Flyer and the book will be unveiled at the Dayton International Airport on December 17,2002 (a year before the centennial anniver-sary),where it will serve as a milepost in both aviation and craftsmanship, pointing 100 years back and looking 100 years forward.

We're looking for woodworkers to serve as teachers and mentors to help conduct these learning experiences and to communicate the thrill of building something wonderful to children.The WBAC will send you information on these experiences if you'll just raise your hand and say "I'll do it."You can contact them through the Internet a www.wright-brothers.org, or write Wright Brothers Aeroplane Company, Kids Build a Flyer!, P.O. Box 204,West Milton,OH 45383.

Meanwhile,we'll continue to report on this exciting woodworking project as it progresses. PW

28 Popular Woodworking February 2001