HELPFUL HINT MORE ON CUTTING STEEL TUBING
By R. Sands, EAA 38949 Box 15, Temple, Pa.
When undertaking the construction of the fuselage for my Fokker DR.l replica, I cut one tubing joint with a hacksaw and file and immediately decided that there had to be a better way. I have a 10 in. lathe in my garage and decided to make use of it to cut the ends of tubing. A vise was made, with a horizontal "U" in it to accommodate any size of tubing. The vise is positioned on the lathe compound in a manner where the "U" centerline is on the same horizontal centerline of the lathe. By chucking end mills of various sizes in the lathe, you can cut the ends of the tubing for a perfect 100 percent fit against adjacent parts.
If the longeron is
7
,s in. O.D., use a TK in. O.D.
cutter. If the upright is at an angle to the longeron, simply locate the compound to the desired angle. I use a tube cutter for cutting tubing; this results in a perfect cut in a few minutes. This method of cutting and shaping the tubing permitted the fuselage to go together in
two weeks. Photo No. 1 shows 1 Vt in. O.D. tubing being cut with a IVi in. O.D. cutter. It is best not to plunge on the cutter as shown in the photo, but to "drill" from the ends, taking
about 1/16 in. depth with each cut. Photo No. 2 shows the perfect fit before welding. ®
BUMP COWLING . . . (Continued from page 37)
cowling where the bumps are was then made up separately and welded to the forward section. Making the bumps was accomplished by use of a concrete mold with locating pins in it to keep the bumps on different pieces in proper relationship. The concrete mold was filled with epoxy and an old bump cowl, coated with parting agent, was pressed into the epoxy and held there until the epoxy hardened.
Holes were drilled in the front section of the new cowl at proper locations to mate with the pins set in the female form. The "skirt" section was set in position and the slow, careful work of pounding the bumps was begun. Since hammering tended to work-harden the aluminum, it was necessary to have the cowl assembly heattreated from time to time to anneal the metal. Rubber hammers and wooden formers were used to form the bumps as smoothly as possible. After all forming work was done, the cowl's surface
was filled with body putty and sanded smooth. Dope, rubbing compound and elbow grease completed the job. ® 38
JANUARY 1969
Emulating the old Curtiss P-6E markings of the 17th Pursuit Group is this Smith "Miniplane", N-160F, built by Dan Sisco of 2115 Wood Rd., Fulton, Calif. Named "Rancho", the little biplane carries dummy exhaust ports, dummy
guns in troughs alongside the engine, extra air scoop on top of the cowl, and older-type windshield. With this added gingerbread, plus a 125 hp Lycoming 0-290-G and Aeromatic propeller, it will only top 115 mph and cruise at 105. It also boasts hand-tooled leather interior, and extralarge wheels and pants.
