After the hinge location are marked we'll need to mark the center line on the trailing edge of the wing. The center line doesn't need to be marked on the ailerons since the bevel on each aileron is the natural centerline. There are several ways to mark the centerline of the trailing edge, some are difficult and some are easy. I'm going to show a couple of the easier ways to do it. Before I describe the easy ways to mark the centerline I'll tell you about the hard way, and what's funny is the hard way is probably the way that most people will try right off the bat. What's so hard about this anyway? Don't you just measure the trailing edge and cut that in half? Sure, if the width of the trailing edge is a nice round number it's easy to mark half of that. But nine times out of ten the width is going to be some fraction that's really difficult to cut in half. Ok, try marking half of 19/32”. See what I mean? So here are a couple of ways to make it a bit easier to mark the centerline. The first way can be done with a standard ruler, and the second way requires a separate tool to be purchased.

The easy way to mark the center of the trailing edge with your ruler is to simply pick a measurement that you can divided in half easily. In picture #1 I used 1/2” as my reference. Now turn the ruler at an angle so that the two marks of your measurement are on the edges of the trailing edge, and then mark the center point of those two points. Use the same procedure to make a center mark on the other side of your hinge location, and then use your ruler to mark the centerline through the hinge location (picture #2). Neat and simple.

The second way involves buying an extra tool. I'm talking about [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXK262&P=7]Great Planes Precision Hinge Marking Tool [/link] . (Picture #3) It costs about $3, but if you keep an eye open sometimes Tower Hobbies will throw this tool in as an extra when you buy something else. This tool is really pretty simple. It consists of a plastic body that have two plastic feet on the bottom of it that are hinged, and on the center of the body there is a small pointed metal stud. This metal stud is what marks the center line. To use this tool you need to place it on the tailing edge of the plane and turn it so that both feet are firmly in contact with the top and bottom edges (picture #4), then push lightly down so the stud is indented enough in the wood to mark it and pull the tool down the tailing edge (picture #5). This will scribe a line in the center of the trailing and is fairly foolproof. If you can get this tool for free I'd say to go ahead and get it, but otherwise I'd say to just use a ruler and save the three buck.

So now we should have all of our hinge locations marked and ready to slot in order the install the CA hinges.

Pictures
1. Using a ruler to find the center of the trailing edge.
2. Marking the centerline of the trailing edge.
3. The Great Planes Precision Hinge Marking tool.
4. Placing the marking tool on the trailing edge.
5. Using the making tool to mark the center line.
6. The hinge location marked and ready to be slotted.


Until next time

Ken