The aileron counterweights come pre-cut to size, however the builder must drill the holes necessary to mount the weight to the ribs and skin. As the weight is made of stainless steel, this was my first experience drilling into this material. Tips:
- New cobalt bits. You want them sharp.
- Drill stops.
- Lubrication. Lots of it. I used air tool oil on the steel and Boelube on the bit.
- Start the hole with a good punch. Otherwise the bit can walk and elongate the skin.
- Very heavy drilling pressure. Lean in to it good.
Left counterweight with two lateral holes drilled in and cleco'd.
Using the 12 inch #40 extended bit for the bottom tab of the two nose ribs. Don't be afraid to lean in on this one. That bit can take it. The hole in the rib for the spar will help you keep things straight and help relieve any bowing forces on the bit.
Rib holes drilled and nose ribs temporarily fastened to counterweight. Awaiting nose skin to drill the remaining holes.
I cleco'd every hole in an effort to minimize parts slipping.
Lean in good. Give it pressure.
This really stinks. It's what happens when the bit walks. The top images show an AD4 rivet placed in the hole to demostrate the severity of the problem (an LP4-3 is called for). I have a couple of ideas on how to fix this. One is to fill it with RectorSeal and drill a new hole immediately adjacent. Another is to fill it but before the material sets, rivet it. Using a larger pop rivet isn't an option since they're hard to find and the factory head needs to sit fairly flush along the curvature of the skin here.
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