Glue triangular stock on the leading edge.  Get perfect vs all the time.

Henry

Is there a sure fire way to sand a perfect V in the leading edges of flaps and elevators ?? If your flaps or elevators are let say 3/8" at the leading edge do you go 3/16" on the surface to the C/L of the leading edge ? I always manage to not get mine perfect the first time and have to go back and correct, doing it right the first time all the time is what I want.  Thanks

Leester,

I like your criteria...."...right the first time, all the time..."    Have I got a deal for you....here's a technique that fullfiles that criteria.

First...
    To Crist.....respectfully....you must have clearance on one of the surfaces or you will get interference when the surface moves, if you are using a pinned hinge....cloth hinges will be okay, as would be having a very large gap, which is not desired.

Let me mention, that the device on the left side of the photo did NOT work.   It was simply two blocks of wood glued together at 90 degrees, and covered with sandpaper.  Theoretically, you should be able to sand your 90 degrees "vee" in one step, but regardless of how careful one is, or how frequently you swap ends, the control surface would always end up with a "bow" being sanded in to it (plan view).....don't understand why ??


So, on to the technique that does work "...right the first time, all the time..."  Using this set up, I can sand the "vee" edge of a typical elevator half, in 60 seconds.....I kid you not.

Start out by drawing a center  line down the part to be sanded.  Using a ball point pen, you can do a satisfactory job just by eye, if you are careful.   Now is the best time to create your slots for the pinned style hinges.   Doing it after the "vee" is created is much more difficult and more error prone (yes, I did it incorrectly in this photo, but I learned from doing that).

A piece of 3/4" Melamine board works well for creating a platform on which to do the sanding.  A soft piece of 1/8"-1/4" foam protects the balsa and reduces skidding.

You will want a rather long sanding block, similar to what is in the photo.  In my case, I had sandpaper around the edges of the block, so the edge that is down against the work surface is covered with masking tape so that the work surface is not damaged.

Usually one is looking for a 45 degree bevel, and after doing this a few times, I got smart, and glued a 45 degree "guide foot" onto the edge of the sanding block.   That works extremely well, and avoids constant measuring.

Holding your workpiece slightly over the edge of the Melamine board, proceed to do your sanding, reversing the side of your control surface occasional.  Stop sanding just before you remove the ball point line.

There you have it....it's that simple.  As if often the case, it takes longer to describe the process than to actually do it !!   Once you have the setup and have done the process a couple of times, it becomes fun and works  ...."...right the first time, all the time...".

Cheers,

Warren Wagner

I've used the triangle stock method on a couple of RC planes; works great, and it's easy.  Make sure to use isosceles stock; not the equilateral.  Glen

Dremel Router table, 45 deg chamfer bit,  About 2 minutes setting the height, perfect tapers on the flaps and elevators.

Dave

I agree with Chris. I have found it is easier to fit a round edge rather than a pointed edge and I have don both. It is easier to make a 45 degree or rounding sanding tool to do the edge either round or or pointed. If you will notice Paul Walker Impact it has rounded edges. Rounded edges ar easier to finish also.