QB wing conduit

How have you all managed to open up the tooling holes for conduit or snap bushings? With my unibit I can reach all ribs except number 2 & 3 (the two most inner on the wing walk). The unibits I have go up to 1/2" and 3/4" and the drill bit extensions all have at least a 0.6" head to them.

So far I've drilled the holes up to 1/2" (would like 5/8") using the unibit and 12" 1/2" drill bit (worked fairly well). I installed snap bushings with 3/8" ID. However I'd like to take the holes bigger but I can't come up with a tooling solution.

The other thought I had was to make another set of 1/2" holes for another set of snap bushings. These wings are getting pretty busy with pitot heat, nav/strobes, pitot/aoa lines, and autopilot! What have you all done about getting the holes bigger in a QB wing?

Thanks,
Scott

Grind down the unibit extension

I had the same problem when I ran the lines for my AOA. What I did was drill one hole, move the bit to the next rib, slide the newly reduced unibit through the hole, attached the unibit and drilled the next hole. I repeated that until I got through the wing walk ribs.

Bill

Drilling conduit holes in QB

I got this idea from some other website along the way. Not the only way to do this I'm sure.....might help.

My conduit tools photo.

I used the right angle drill for the open ribs and then the extensions for the ribs that are covered in the QB. First I made a template to mark where I wanted to drill the ribs then I started from the inboard end of the wing. The unibit that I have goes to 7/8 so I had to stop at every rib and remove the bit and put it back on the extension while still in the end of the wing. Real fun! I made 3/4" holes. I'm using Van's flex conduit.

Conduit from outboard view. The bottom of the wing is facing up in this picture.

View of conduit in open ribs.

I'm then using RTV silicone at each rib to hopefully prevent vibration from causing holes in the conduit. The location for holes is suggested buy Vans in a pdf file here.

Pete

I used a Unibit extension from http://www.fly-gbi.com/main.htm. Worked well , but a bit awkward as you needed to remove and repalce the unibit on the extension between consecutive holes.

Let me know if you need any more info.

QB Wing Conduit

I used the following items which made it easy to change out the step drill between ribs:

12' Quick Change Extension - $3.99
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=91056

Quick Change Step Drills -$14.99
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=91616

Good luck

It's pretty easy to make your own unibit extension. You need a length of 3/8" all-thread, a 3/8" coupler and some set screws. Drill out the threads on one end of the coupler, for the unibit. Then drill and tap the holes for the set screws.

drilling holes for snap bushings

I used a countersink bit, the manual deburring tool, and two one-foot extensions. Worked fine, but in retrospect, could have used the countersink bit, the two extensions, screwed into the Avery right angle drill attachment, and a pneumatic drill.
Mark Andrews N598X