December 2016 Project of the Month — By Jeff Nisley
This project is the first in a series of projects meant to aid in the pursuit of building model aircraft. I have included plans and instructions on how to build your own Dihedral Angle Sanding Jig for Model Aircraft Wings.
The purpose of a Dihedral Angle Sanding Jig is to accurately sand the edges of a model aircraft wing (mainly gliders) to the proper angle or pitch to create the wing’s dihedral angle. You will find that this jig was designed to do this job accurately and quickly.
To make this project, click on the above link to download and print a document that will give you instructions on how to determine the dihedral angle of your model aircraft, and a second link below that will give you a list of the materials and further information you need to complete this project.
This Sanding Jig can be made entirely from a piece of poplar 1/2″x 5-1/2″x 36″ purchased at the Home Depot. Be sure the cuts are square and at 90 degrees. A Table saw works well if you have one.
Needed in addition to the wood are two packages of pairs of 1″ hinges shown at left. You will also need to purchase about 14″ of Velcro. It’s best to get the “Velcro” brand as the generic brands won’t work as well for this application. I prefer black but it’s your call. HD sells a package of four 3-1/2” strips that are ideal for our purpose and is shown at right. My total for the wood, hinges and Velcro came to just under $14. Lastly I recommend a can of Rust-oleum clear Lacquer for a finish coat.
When pieces are cut, glue parts 6 and 7 back to back with carpenter’s glue to form the sanding block. The photo at left shows the finished sanding block with a 1″ x 4-1/2″ strip of sandpaper. The strip is attached only with double stick tape for easy replacement. Take the time now to sand all the pieces of the jig with 220 grit sandpaper. Round the edges slightly.
Line up pieces 1, 2, and 3 and tape together tightly so they are lined up and flat. Now using Duco cement, glue the hinges in place lining them up as perfectly as you can to the joints and set aside (see photo at left). When dry drill the 1/16″ starter holes and install the screws. When completed the platform slider should be perfectly aligned with the base. If not, use physical force to gently bend the structure to align the pieces so they slide in alignment with each other.
Next item to attach is the Slider Lifter shown at left. Notice several things about this piece. First it is set back from the edge 1/8″ to act as a finger hold when lifting it up from the Velcro. Second, that the tip is slightly sanded off as shown in the drawing on the Materials list. And thirdly, that it sports the “Hooks” side of the “Hook and Loop” components of the Velcro along its length. Attach with carpenter’s glue and clamp overnight if possible. Attach the Sanding Block Rest (4) using the same treatment and lastly glue the Platform Railing (8) to the Platform Slider (3). Round off the end of the rail near the sanding block as shown in the photo at right. If you don’t do this it will interfere with the sanding of the wing.
Lastly the Velcro and the Measurement Scale need to be added to the Jig. To aid in the alignment of these items, draw a thin pencil line 1″ from the wood’s end as a guide (see photo at left). Carefully cut out the Measurement Scale that is printed on the Materials List right up to the black border leaving no white paper edge. Seal this paper scale with a coat of clear lacquer and let dry. Now apply a thin coat of white glue to the back of the scale and apply to the Base (1) centering it and making sure the bottom border butts up perfectly to the 1″ guide line. Note: It is also possible to have a Kinko’s or Staples print a copy of the Measurement Scale on sticky backed paper to avoid the gluing process. I do recomend some sort of clear protective coating over the Scale to protect it in the future. Now all that is left to do is to apply the 4 velcro strips on either side of the scale. These will all be the “fuzzy” side of the Velcro.
One last note. I have found it convenient to keep the tools necessary for the jig in a handy 3 ring binder. The protractor I use and the sanding block fit neatly inside a vinyl pencil pouch as shown at right. Sheets of paper are stored to the left (If you look closely you will see a line that was drawn on the paper to determine the dihedral angle). Finally I have the printed Instruction Sheet for the sander placed inside the clear plastic sleeve on the front of the binder (not shown). This all makes it easy to keep all the parts of the sander together.
That should be it! Good luck finishing your Dihedral Angled Model Aircraft Wings!
Jeff Nisley is an editor of the website Flyhaffa.com and would like to hear from you if you have any comments or suggestions at firstname.lastname@example.org. Thanks