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Drilling the elevator horn

blueflyer

blueflyer

Well Known Member
Im sure others have done this before me, but it has worked so well in a few places in the construction of my emp, I thought I would post it. This trick helped me to drill the elevator horns perfectly. Once I got the counterweight flush with the surface of the stabilizer, I put a little of my daughter's paint on the end of my bolt.
paintedbolt.jpg

Then I stuck the bold thru the hole and touched it to the elevator horn.
boltthruhole.jpg

And voila, it showed me where to drill.
paintonhorn.jpg

Then I just drilled a #40 pilot hole in the center of the paint mark, then drilled to size. The placement was perfect.
 
That is a good idea. Were you able to align the trailing edges of the elevators with one another and get the counterweights flush with the stabilizer?
 
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That is a good idea, JR. I hadn't seen it done that way! I followed the lead of others who used a drill bushing for this task. McMaster-Carr has a 1/4" bushing with a 3/32" hole in the middle that's perfect for this job and it will keep the drill bit from wandering off the mark:

100_7873%20(Small).JPG


I had a 12" long #40 bit handy that was just the right one for this job. Once you have a #40 hole drilled through the horn, remove the elevator and enlarge the pilot hole to size. Then, use the bushing again and drill the other side.

100_7874%20(Small).JPG


These big wood clamps are perfect for clamping the elevators in neutral position while you drill:

100_7847%20(Small).JPG
 
I think you got a little lucky here. I've found that match drilling (like what BSwayze describes) practically forces perfect alignment. Meanwhile, marking and drilling into the mark can be less perfect... Drill bit not quite perfectly centered, wanders, etc.

Glad it worked for you. :)
 
Centering your pilot hole and not letting your "drill to size" drilling operation wander is critical. The elevators ended up in trail and they matched each other to boot.

I will add that if I had the bushing that Bruce described handy, I would have used it.
 
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For me, a challenge would be the "centering your pilot hole". The paint on the tip of a bolt may not be perfectly circular and I don't have micrometer eyes that can center a drill in a circle to a few thousands of an inch. :)

On a side note... a general question for all: Is drilling a pilot hole to full size pretty much guaranteed to ensure each stage of larger hole is still perfectly centered? I've always worried that simply following the pilot hole with larger bits would cause the holes to drift one way or the other.

So whenever I can, I match drill, even after I have pilot holes, like in the rod end bearing attach holes on the elevator horn (not the center hinge bearing hole mentioned in this thread). The manual says to make the original holes by drilling a #30 hole in both horns through a block that's been drilled perpendicularly on a drill press. I went ahead and drilled that block the final size as well, clamped it between the horns with spacers and match drilled the full size holes too. Paranoid?
 
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blueflyer said:
I will add that if I had the bushing that Bruce described handy, I would have used it.
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A small piece of 1/4" o.d. fuel line works perfectly here. (The 1/4" line will come with the wing kit.) Just select whatever size drill bit fits the i.d. A tiny error drilling this hole can lead to significant misalignment by the time you get out to the tip of the counterbalance arm. Thus, I'd recommend builders follow Van's instructions. Still sounds like it worked out for you though. Good luck with the rest of your build.
 
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grayforge said:
On a side note... a general question for all: Is drilling a pilot hole to full size pretty much guaranteed to ensure each stage of larger hole is still perfectly centered?
Click to expand...
Definitely not guaranteed! I can say that from experience. This is especially true when using a unibit.

I don't know exactly what they are called, but there are little drill-bit-like tools that have, say a #40 or #30 pilot tip but a larger shank. The pilot will guide the larger drill bit and keep everything centered. Not very expensive and good to have in the tool box. Somebody else may know what these are called.
 
Steve,

That sounds like the perfect tool to use to ensure holes stay where you want them as you drill them out further. I'll see if I can find some. :)

Thanks,
Russ
 
I think what you describe is called a "center drill" and I have one with a 3/16" shank. Not right for this application, but one with a 1/4" shank would work fine. They are used in lathes a lot, and I used one to make the bushing I used to drill my elevator horn. Bushings are the way to go, and a larger bit will allow less possible wander when enlarging than using a #40. IIRC, I used a #19.

Bob
 
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