1st reply to your message is excellent. However; precision reamed holes in Aircraft parts also require some kind of fixturing or guide for the reaming. A portable guiding unit usually consists of a special "cup" with a removable guide bushing. Drill motor speeds have to be kept low and some kind of agent might have to be used to lubricate/cool the reamer, which should be frequently cleaned. These reamers have to be kept very sharp. A good check for a dull reamer is to slide your thumb along the edge of one of the flutes (Carefully) if it feels like its cutting YOU, or about to cut you, its in fairly good condition. If it feels smooth with no sharpness (Use a new reamer for comparison) it should be withdrawn from use. Most technicians will continue to use dull reamers, unless there are written instructions for quality assurance personnel to mandate involvement in the reamer checks. So make sure that if you have instructions, some kind of criteria for sharpness checks and stipulations that personnel not use the junk in their tool chests are also included. Also, as noted before, different types of interference fits need to be called out. These can be found in the Hilok manuals, or if your design or mod is Aircraft-type specific, you might want to call out the manufacturer's requirement for hole fit. Also remember that in some structural applications where cyclic fatigue plays a role, such as in main transverse floor beams, the quality of the holes has to be extremely high and will require a very specific inspection buyoff, AND will require a very specific type of Hilok fastener.
