I've had enough experience with using hinges in airframe construction that I know they are very hard to get right. I want the cowl to go on and come off without a lot of hinge binding. Everyone I talk to has had problems with installing hinges that don't bind. So I decided to take my time with this exercise to see if I could do a better job than what I've done in the past. It seems to me that the primary problem with getting hinges attached properly lies in keeping them as straight as possible during the assembly process. There is significant play in the hinge pins. I decided to remove the play by using shims in the gaps within the hinge during drilling and assembly to keep the hinges as straight as possible. I set the fuselage side hinge half using clecos and the edge of the fuselage. I drilled holes in the hinges and the spacers to mount this hinge. During riveting however, I assembled the other half to the hinge using the hinge pin and forced a .030 shim in the gap between the shim halves. This takes out any variation that might occur while setting the rivets. After the rivets were set, I removed the shims and found the hinges to work very freely. To set the other half, I first predrilled holes in the second hinge half. I then assembled the hinge again and put the shims back in the holes to expand the hinge halves. I then taped up the bottom cowl and removed the top cowl. I could then drill down through the hinge through the cowl. I clecoed the front half of the hinge as I went. This seemed to work very well. Once I was done with both sides, I was able to insert and remove the hinge pins with no binding at all. Next step is to do the side hinge pins.
