LN Valve Stem Creation

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Creation

1. Cut blanks from stock.
   1. Cut 2.7" blanks from 1/4 OD rod stock.

      Use micro table-saw to minimize kerf waste.

2. Machine stem tip.

   Machine the stem tips on the T-51 CNC lathe (LN VALVE STEM TIP).

3. Machine drive end.

   Machine the drive ends on the T-51 (LN VALVE STEM DRIVE END).

   Use the same 5C collet stop position as for the stem tips.

4. Machine port hole and position marker.
   1. Setup to clamp in mill vise on 1/8 inch parallel:
      1. Offset the parallel to the side so it rests fully on one of the ways, but only ~1/4" on the other.
      2. Shim the parallel 1/16 inch away from the fixed jaw.
      3. Use a leaf spring between moving jaw and parallel.
      4. Set vise stop at the end of the fixed jaw that the parallel does not reach.
   2. Drill 0.106 x 1/16 inch deep "funnel inlet" at passage location.

      0.578 inch back from tip.

   3. Drill 1/16 inch through passage.

      Slow the feed when approaching bottom to minimize the exit burr.

   4. Drill the position marker 1/16 x 0.020 (drill tip depth from surface).

      At 1.8 inch from passage hole.

   5. Gently begin deburring holes with sharp X-ACTO knife.
5. Hot form the drive end on the manual mill.

The side view of a collet fixture in a vise grip.

1. Insert the spline forming tool into a collet holder and clamp the assembly in the vise with the spline tool pointing up.

Tools needed for creating an LN valve stem

1. Center the spindle on the spline tool.
2. Insert the OD forming tool into the spindle with the mouth end down.

A front perspective of the collet fixture in a vise grip with the collet quill sticking out.

1. Adjust the table height so the maximum gap between the OD and spline tools is approximately 1/4 inch greater than the work piece.

   Two down strokes of the quill handle are required to fully lower the OD tool over the spline.

2. Set the quill stop so it stops the OD tool a few thou above where it would contact the acetal stop ring on the spline tool.
3. Turn the spindle on at 80 RPM.

Procedure

1. Insert a work-piece, passage-end up, partway into the OD tool.
2. Lower the quill so the OD tool captures the top half of the work-piece.
3. Reset the quill handle to the top of its range.
4. The drive end of work-piece should be resting on the top of the spline tool with the OD tool spinning slowly around the top half of it.
5. Start the work-piece rotating by using a handy length of scrap material to apply a gentle sideways pressure to the work-piece just beneath the OD tool.

   FEP tubing or rod works well for this step.

   The scrap avoids burning fingers in the next step.

6. Use the heat gun to warm the lowest approximately 1/4 inch of the rotating drive end until it becomes flexible.

   Approximately 10-15 seconds.

   The time is easily gauged by counting 13-20 rotations.

7. Set aside the heat gun and scrap "pusher".
8. Grasp the work-piece with the fingers and force the softened drive end down around and onto the spline tool use a twisting, orbital motion to ensure it is fully seated.
9. Immediately lower the OD tool completely over the drive end and allow several seconds for the work-piece to cool.
10. Fully raise the quill and pull the work-piece up to remove it from the spline tool.

Final Steps

1. The stem OD must have a smooth, effectively polished, surface.
   • If needed, finish stem OD:
     1. Snap the stem onto servo spline drill adapter (TL-SSDA) in drill.
     2. Dry-sand stem OD at 400, then 600 grit.
        1. Spin in both/alternating directions for each grit.
        2. Control the speed to avoid overheating the work-piece.
        3. Clean the sandpaper surface frequently with a sandpaper eraser and/or compressed air.
     3. Mark the hole near the stem with a black dot.