Robart makes a little jig that helps you drill your hinges in the center of whatever you are workin on then for the root part of the hinge where it is bigger you can make a little tool out of aluminum that sort of looks like a hinge with a bigger section wher the hinge is bigger and file it to shape...It takes a while but it lasts a long time and you poke it in the hinge hole and wiggle it around till you are satisfied that the hinge is fitting okay and you move on to the next hole...Thats what I have done for yrs and I have never had a hinge failure yet..One more thing I use ordinary yellow carpenters glue to stick them in...I just wipe the excess glue from the hinge and let it dry over nite...The next morning you go to move it and it is stuck solid...You give it a good twist and it goes " crack " and the glue breaks away from the plastic hinge and the hinge is as free as a bird....Even though the glue dosent really stick to plastic it has incased the hinge in a tough material that you would need a hammer to break.I sticks to the balsa and you will never pull it out ...Try just one hinge in a piece of balsa and you will see what I mean...