I'd have to agree with MinnFlyer, I posted a similar comment a while back. It's frustrating when you're trying to do a perfect job and taking pride in your aircraft and then you can't drill a straight hole for a control horn. Been there, done that. Try not to poke a hole in the covering and drill just far enough to see where the drill is trying to exit at and work it over closer to the hole in the horn. Use the clamping action to do the job. It's not ideal, but it works.