flickroll

flickroll

Well Known Member
How does one go about drilling a hole for a wire conduit in a closed wing? I have an RV-8 that I want to add some additional wires to the wing tip and the existing wire hole is too small. Looks to me like I need a long drill bit to enlarge the existing hole. Other ideas? Where would I get such a bit?

Thanks

Jim Shannon
 
Jim,

I had to drill a 2nd hole in the ribs for my AOA line after the wing was closed.

To do this I used two drill extensions and a uni-bit. I had to grind down the head of the bit extensions so they would fit through the holes but it worked out.

Granted, it was a pain to re-install the uni-bit and extension as I moved along but it wasn't difficult. Oh, I also used a Pneumatic angle drill to turn the bit when I got into wing.
 
I added an aluminum conduit using 1/2 x .035 6061-T6 tube Adel clamped to the ribs at the accessible root, tip and aileron bell crank mid section.

wingconduit2gq1.jpg


wingconduit1ux1.jpg


Jim Sharkey
RV6 - finishing up
 
Bill. how did you get the unibit in the extension? The shank of the unibit is way larger that the hole in the drill extension that I have.

Jim
 
unibit

I did this with several extensions and bought unibits from Harbor Freight, item 91616-9HZH, for $9.99 and then filled the base down until it fit in the extension. It worked and then I tossed the cheap unibit.
 
flickroll said:
Bill. how did you get the unibit in the extension? The shank of the unibit is way larger that the hole in the drill extension that I have.

Jim
Click to expand...
Jim,

My unibit fit the extensions w/o modification to anything other than the extensions.

Tommy's idea of using cheap bits sounds like a good one.
 
Two pieces of 1/4" threaded rod, two couplers, one drilled/tapped for a setscew. Put unibit in coupler and secure with setscrew. Use one rod and guide into existing small holes with free hand initially, then add second rod as you progress. Use low rpm obviously. Piece of cake.
dcp3043el6.jpg
 
I ground the drive end of my unibits into a hex (they come with only 3 flats) which lets you fit it into a socket. Get a hex-to-square adapter for the drill end, then you can mix and match socket extensions as needed.
 
Take your unibit to the Electrical tool section of Home Depot and match it's shank to one of the conduit bit extensions they will have there. One of these 36" flexible extension should do the trick.
 
The cheap Harbor Freight extensions (usually on sale for a set of 3 for $10) already have the 1/4" hex so no modifications are required to these.
 
Closed wing hole tool

1. 36" long 3/8" dia steel rod
2. Center drill one end for pilot drill bit
3. Cut threads on OD of same end. Thread size to match Rotobroach thread size. Make threads long enough to thread two nuts plus rotobroach on.
4. Thread on two nuts and tighten together. this will be the shoulder for the rotobroach cutter.
5. Purchase 5/8 dia and 3/4 dia rotobroach cutters from Avery Tools. Their part numbers are #17124 and #17128 respectively. On page 38 of my 2005 Avery Tool Catalog.

Rotobroach sheet metal cuttes are like a hollow end mill with an internally threaded ID. They make a very clean cut with almost no burr. You are essentially making a hole saw with a small enough mandrel to feed through the hole.

It would be nice if Van's would just put the 2 holes shown in their SB in the rib flat pattern before they formed it. Another example of the "revised 51% rule. Incidental for Van's (or for people with standard build kits who plan ahead, but a PITA for those of us with QBs who have to make the special tool. Perhaps some of you can get together and convince Bob Avery to offer a 3/8 rod with the center drilled hole and OD threaded. He sure has the equipment to do it and had an instant understanding of what I wanted to do when I discussed my idea with him.

Larry
 
Thanks everyone for their suggestions. I got a 5/8" hole drilled across the span for both the L&R wing panels (for a 1/2" id snap bushing). Was a real pita, but it's done. Oh yeah, both wing panels are off the airplane, would have been about impossible if the wings were on the fuselage. One more step in getting Jeff Jasinsky's very fine -8 back in the air.

Jim Shannon
N52VV
Charlottesville, VA
 
How do you debur the holes if you do it in the manners suggested? Do you debur them?
John Russell
 
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