topic Re: Tap drill size wrong (?) for 0.5625" UNF-18 in Fusion Support Forum

Tap drill size wrong (?) for 0.5625" UNF-18

WilliamLYJH9 — Fri, 31 Jul 2020 18:20:04 GMT

Hello,

Novice user here, but I don't think this is "operator error". The hole tool gives a tap hole size of 0.481" (see attached screen capture), but every published reference I have seen lists it on the order of 0.5156" (75% thread, alum). Am I missing something?

Regards,

Bill.

Re: Tap drill size wrong (?) for 0.5625" UNF-18

johnptc314159 — Fri, 31 Jul 2020 19:29:56 GMT

0.5156 is what i would use. i never paid much attention to the hole size 😞 there is a look up table for most thread info which can be modified in fusion 360.

Re: Tap drill size wrong (?) for 0.5625" UNF-18

HughesTooling — Sat, 01 Aug 2020 10:51:25 GMT

One problem is the dialog doesn't update the core diameter when you change the pitch. If you check the actual hole after creation you get this.

Mark