I tried drilling for 1/4" threads, which is as big as i could comfortably go. But the holes are oblonged (dont know how to spell it) I guess i could do the brass insert thing, where would i go about finding that kind of stuff. I would like to put the ryobi in the plane im building now (kinda looks like a bellanca scout) but it will likely be hard to find the stuff to fix it, and i only have limited acess to an actual shop.