125 MINSTAC - Boss Preparation

Boss Drawing

Boss Preparation Tools
Combination Boss Drill TTTA6201927A


Plug Tap TTTA6201627A


Bottoming Tap TTTA6201727A


125 MINSTAC Boss Preparation Procedure:
  1. Drill a 0.062" (1.67mm) diameter pilot hole in the desired boss location.
  2. Insert the front of the Lee Combination Boss Drill (part no. TTTA6201927A) into the pilot hole & drill down until the 0.312" (7.90 mm) dia. spotface cleans up the surface of the boss. All diameters should be concentric within .006" (0.15 mm) T.I.R. The sealing face should be smooth with no burrs or tool marks.
  3. Tap the 0.250-28 unfinished threads using the Lee Plug Tap (part no. TTTA6201627A) first & the Lee Bottoming Tap (part no. TTTA6201727A) second. These taps incorporate stops to avoid damaging the sealing surface.

NOTE: Care must be taken to ensure that the taps will follow true in the hole produced by the Combination Drill.
For more information, please send us your application information via our ASK LEE service. Or contact our application engineers in the USA at 1-800-LEE-PLUG or our representatives around the world.
Copyright 06/2002 by The Lee Company, USA
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