Drilling VS bolt holes

Tonight I drilled most of the bolt holes that attach the VS to the aft-most fuselage bulkhead. I used my drill block, which worked well, but was initially too long to fit within the confined space on the aft bulkhead. A quick trim of material on the block and it worked fine. For the 1/4 inch holes at the bottom, I stepped up drill sizes, starting with #30, then #12, then finally 1/4 inch, all done with a drill block to keep things aligned. This worked well and I’m happy with the results.

Vertical stabilizer clamped and aligned ready to drill

I did run into a problem with the 1/4 inch holes, which I attributed to a blunt drill bit. The 3 holes at the bottom of the VS spar are drilled to 1/4 inch. They go through two steel plates, with aluminum sandwiched in the middle. The drill bit struggled to make progress on the steel, even when running at the appropriately lower RPM. I got 1 of 3 holes drilled, and half of another one before stopping. It’s frustrating to not be able to finish this step tonight, but worth waiting for a new bit so I get the best possible result. I contemplated sharpening the drill bit myself, but didn’t feel like experimenting when these are such critical holes. So I ordered some new bits from Aircraft spruce, and will wait for them to arrive before continuing this step.

First hole drilled and bolt inserted (bottom, just above tailwheel mount). This turned out to be the easiest hole, there is only one piece of steel to drill through on the inside

I have plenty more work to do, so I’m not worried about the delay on this particular step.

One thought on “Drilling VS bolt holes

  1. Good to see your progress Neal
    Make sure that there is absolutely no trace of steel drilling’s anywhere near the aluminium

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