® Spiral Mill - Thread Inserts UN 1 2 Insert Size Fig. PitchTPIExt./ Int. UN UNC UNF UNS Ordering code Toolholder 16 Int. 1 15/16 - 2 1/2 2 1/16 - 2 H45 I 16 UN 12 Int. 1 15/16 - 2 5/8 H45 I 12 UN H45 2 8 Int. 2 1/8- 2 5/86Int.2 1/8- 2 3/4 H45 I 8 UNH45 I6UNSRH45... 4.5 Int. 2 1/4 H45 I 4.5 UN 4 Int. 2 1/2- 2 3/4 H45 I 4 UN 16 Int. ≥2 5/8 H63 I 16 UN 12 Int. ≥2 3/4 H63 I 12 UN H63 2 8 Int. ≥2 3/4 H63 I 8 UN SRH63... 6 Int. ≥2 7/8 H63 I 6 UN 4 Int. ≥3 H63 I 4 UN Whitworth Same insert for internal and external thread 1 2 Insert Size Fig. PitchTPI Ordering code Thread Size Toolholder H13 1 19 H13- 19 W G 3/8 SRH13... H15 1 14 H15- 14 W G 1/2 SRH15... H17 1 1411 H17- 14 WH17- 11 W G 1/2 - 5/8G ≥ 1” SRH17... H19 1 1411 H19- 14 WH19- 11 W G 3/4 - 7/8G ≥ 1” SRH19... H23 2 14 H23-14 W Int. G 7/8”Ext. ≥ G 1/2” SRH23... 11 H23-11 W ≥ G1" 14 H32-14 W Ext. ≥ G 1/2” H32 2 11 H32-11 W Int. ≥ G 11/8” SRH32...Ext. ≥ G 1” H45 2 11 H45-11 W Int. ≥ G 13/4”Ext. ≥ G 1” SRH45... H63 2 11 H63-11 W Int. ≥ G 21/2”Ext. ≥ G 1” SRH63... B04-5