There are some information I would really like to have listed in the "Reference" section: "Metric Taps" - indication that the metric clearance listed is for the "coarse" and not the "fine" variant. - metric height of the corresponding bolts (e.g. an M5 nut is 4.0mm in height) - metric size of the wrench needed (e.g. for an M5 you use an 8mm wrench) => needed to design hexagonal holes for the nuts All taps - a single line below the tap header telling what the chart is about (e.g. for the "drill chart" "Size table for imperial drills referenced to in numbers or letters") In Europe, I have never seen imperial drills. Nor do I know how the are named. But I do know that you'll have a hard tome finding something exotic like a 6.25mm drill. - a help text (offline. on the local computer. Not a link to the top-level of the "help" website) explaining what the table is and how to use it (I have no clue what a lot of tabs are. Especially since all my deeper geometry vocabulary is non-english. It probably makes more sense to learned machinists instead of self-tought hobbyists.) This forum looks like it was written from scratch. So I don't know if it will send me an email notification in case someone replies. My email address is Marcus@Wolschon.biz