Splicing 1/4 inch wing spars And Leading edges

[Juan Valentin]

 
           I always had a hard time doing splicing of 1/4 inch spars and leading edges. Today I had an idea that I would like to share with you all. I took a piece of aluminum 1/2 inch thick ,1 inch wide and 3 inches long and milled a 1/4 inch slot in the center then I made a cut with a saw at a 20 degree angle to guide my exacto hand saw and now I`m able to cut perfect splices. After I cut them I glue them with 30 minute epoxy by using wax paper in the aluminum tool and sliding the two pieces together for aligment. Here are some pics.
                                                                                                                                                            Juan

[Paul Allen]

Juan
       Good work.
       Right tool for the job, makes life a bit easier.
Paul
In OZ

[Bob Reeves]

Xacto makes a small miter box for those that don't have a mill.

[FLOYD CARTER]

The Xacto mitre box only goes to 45 deg.  But that's enough glue area for our use.  Full scale spar splices must be 10-1, as I remember.

Floyd

[Brett Buck]

The Xacto mitre box only goes to 45 deg.  But that's enough glue area for our use.  Full scale spar splices must be 10-1, as I remember.

Floyd

     You can cut your own slots with a Zona saw. You want more than a 45 degree angle, more like 5 degrees (12:1 scarf joint). The only issue is that the Zona saw might not be long enough.

    It's easy to make your own mitre boxes, just glue them up from spruce stock and then cut the slots you need.

    Brett

[Jim Thomerson]

What I do is tack glue the two pieces of 1/4 square, or whatever, together with enough overlap.  Then I cut them apart with a Zona saw, and pop the glued on ends off.  As long as they are held steady and the saw doesn't bend, they will glue together perfectly. My recollection is that a proper scarf joint is supposed to be 12 to one.  Mine aren't that good.

[Motorman]

12:1 is desired but 10:1 is acceptable on full scale aircraft.

MM

[John Stiles]

Outstanding idea, I'll have my machinist son build me a couple of those. Thanks Juan for sharing your invention.

[Juan Valentin]

Hello John
                  Since you have a machinist son he can make this other tool for sanding the nose of the plane and get the right amount of clearance for your spinner. This Idea I got from an article on a magazine but can`t remember which one. I made it out of aluminum that I had laying around from doing something for my bike. The front disc is 2 inches in diameter for me that covers most of the .40 size planes I build. To use you bolt your engine with the amount right offset you want to the plane then you place sanding paper on the tools face and you slide it on the crankshaft and sand until you have the clearance you want from the spinner to the nose ring. Cover the engine inlet and exhaust,you can wrap it with cling wrap to stop dust and sandpaper particles. The pictures show the engine crutch for the Jetco Dolphin that I`m building.

[John Stiles]

Thanks Juan, I'm gonna show him that as well. Great stuff to have....makes a person's job building model airplanes a lot easier.

[Randy Ryan]

           I always had a hard time doing splicing of 1/4 inch spars and leading edges. Today I had an idea that I would like to share with you all. I took a piece of aluminum 1/2 inch thick ,1 inch wide and 3 inches long and milled a 1/4 inch slot in the center then I made a cut with a saw at a 20 degree angle to guide my exacto hand saw and now I`m able to cut perfect splices. After I cut them I glue them with 30 minute epoxy by using wax paper in the aluminum tool and sliding the two pieces together for aligment. Here are some pics.
                                                                                                                                                            Juan

The wise guy in me tells me to let you know this is called a plain "scarf" joint.