Designing a Giant Lathe to Build a Flagpole for Fort Snelling
Fort Snelling is an icon of Woodworkers Journal’s home state of Minnesota. Completed in 1825 in the midst of what was then a vast wilderness, Fort Snelling now stands in the middle of a major metropolitan area.
The Minnesota Historical Society has done a wonderful job restoring the fort and making it an amazing and educational place to visit. The most recent project has been the reconstruction of the historic fort’s 85-foot-tall flagpole.
[caption id="attachment_19059" align="aligncenter" width="350"] The lathe featured a "crawler" moving up the bed at four feet per hour 1/2" of wood as it traveled with a cutter similar to a dado head being used as the "lathe chisel."
The project began in 1986 as Steve Osman, former site manager at Fort Snelling, corresponded with National Park Service colleagues. Research showed that many flagpoles built in the 19th century shared characteristics with ships’ masts. Instead of looking for one monster tree that could be erected to achieve the height they wanted, builders made the poles in two pieces. The poles were stepped near the center of the assembly, with the smaller topmast overlapping the bottom mast. As in a sailing ship, shroud lines running through wooden cross spars help stabilize the upper section.
Robert Claybaugh of Claybaugh Preservation Architecture designed the new flagpole for Fort Snelling. Claybaugh created a pole 85 feet tall that maintained an accurate historical appearance, but incorporated modern materials (such as a lightning rod) to ensure longevity. But understanding how the flagpole was to be built was only the first step. Making it happen was next.
Although assembling the flagpole in two sections was simpler than using one large pole, finding the two sections proved difficult. The search began in the woods of northern Wisconsin, but the sawyer was unable to find trees that were large enough and free of insect damage. In the end, utility poles were the answer. The poles were delivered to Fort Snelling in November 2006. Mark Cutter, Charlie Nielsen and Dan Gates were hired to handle the project.
The next step involved turning the poles to the correct diameters. You don’t just walk into a store and buy a lathe capable of handling 4,000-pound Douglas fir utility poles ... so Dan built one. The 65-foot-long lathe consisted of I-beams, a hydraulic pump and motor, a variety of electrical components and a cutter-equipped “crawler” that worked its way up the I-beams, removing material from the spinning poles. When I asked Dan where the lathe material came from he said, “Aw, I just had it lying around.” I really want to see his garage.
The poles, spinning at 10 rpm, were turned true and to size. Lots of material had to be removed to hit the correct diameters. After some experimentation, it was found that a cutter similar to a stackable dado head worked the best. The crawler moved up the I-beam at four feet per hour, with the cutter taking off about 1/2" per pass. It was a long, slow process. Once shaped, the poles were sealed with a white acrylic stain.
Watching the crane hoist the assembled pole over the fort’s wall and thread it into its resting place was amazing! The pole was set into a massive steel pipe, which is in turn anchored into bedrock. Then, on Memorial Day 2007, a flag was hoisted up the flagpole for the first time at an impressive dedication ceremony.
With an eye toward historical accuracy and lots of “shade tree mechanic” ingenuity, the new Fort Snelling flagpole was conceived, created and erected. It’s a beautiful new addition to an historic old fort.