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156 MINSTAC Preparation and Installation Procedures

Boss Preparation


Boss Preparation Tools

Combination Boss Drill TTTA9500227A
Plug Tap TTTA6201627A
Bottoming Tap TTTA6201727A


  1. Drill a 0.096" (2.44 mm) diameter pilot hole in the desired boss location.

  2. Insert the front of the Lee Combination Boss Drill (Part Number TTTA9500227A) into the pilot hole and drill down until the 0.311" (7.90 mm) diameter spotface cleans up the surface of the boss. All diameters should be concentric within 0.006" (0.15 mm) T.I.R. The sealing surface should be smooth with no burrs or tool marks.

  3. Tap the 0.250-28 unfinished threads using the Lee Plug Tap (Part Number TTTA6201627A) first and the Lee Bottoming Tap (Part Number 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.

Unless otherwise specified, dimensions are in inches [mm].

Tubing Preparation and Coupling Assembly

Tubing Preparation and Coupling Assembly Tools

Coupling Assembly Tool TTTA9500127A


  1. Cut the tubing reasonably square to the desired length.

  2. Hold the tubing with the Tubing Grip. Slide the center drill end of Lee Coupling Assembly Tool (Part Number TTTA9500127A) onto the tubing. Hand twist the tool clockwise to form a chamfered lip seal. The resulting chamfer should extend to the O.D. of the tubing.

  3. Slip the Ferrule (Part Number TMBA9501910Z) onto pin of the Coupling Assembly Tool. (Click here for 1/4-28 Flat Bottom Ferrule).

  4. Slide internally unthreaded end of the Collet Sleeve (Part Number TMCA9501950Z) over the Ferrule until it snaps in place.

    NOTE: Collet should protrude approximately 0.10" (2.5 mm from tool end).

  5. Thread the Coupling Screw (Part Number TMAA9501079Z) over the Collet Sleeve until it bottoms on the Collet Sleeve.

    NOTE: The Coupling Screw should protrude approximately 0.21" (5.3 mm from the end of tool).

  6. Thread the tool/coupling assembly counterclockwise onto the chamfered tubing with the Tubing Grip, applying slight force until resistance is felt after approximately 5 turns.

  7. Unscrew the coupling from tool.

    Unless otherwise specified, dimensions are in inches [mm].

Coupling Installation


Coupling Installation Tools

Torque Wrench TTTA9500343A
Wrench TTTA9500427C


  1. Start threading the coupling assembly into a 156 MINSTAC boss using Spline Wrench (Part Number TTTA9500427C).

  2. Tighten the fitting between 7 to 21 ozf•in (0.05 to 0.15 N-m) by slipping the Lee Torque Wrench (Part Number TTTA9500343A) onto the knurled Coupling Screw. The minimum torque is achieved by pressing the shorter torque arm clockwise until it just contacts the longer arm. To check that maximum recommended torque is not exceeded, invert the Torque Wrench and press the longer torque arm clockwise until the Coupling Screw begins to move. This should occur before the torque arms make contact. After gaining a feel for the proper torque, use of the Torque Wrench may be discontinued.

    Minimum recommended torque: 7 ozf•in (0.05 N-m)
    Maximum recommended torque: 21 ozf•in (0.15 N-m)
    Torque values based on fittings threaded into PEEK bosses.