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4.5.4 Thumb insert type and size

4.5.4   thumb

Many bowlers use a thumb slug or thumb insert rather than a bare thumb hole. This page covers recording the thumb insert on the spec sheet. The physical installation (drilling the pilot hole, seating, adhesive, finishing) follows your shop's standard practice and the insert manufacturer's instructions — it is not covered here.

🎳 Recording the Thumb Insert

  • ✅ Record the thumb insert type on the sheet (for example, a switch-grip / interchangeable system, or a fixed slug).
  • ✅ Enter the O.D. (the pilot hole drilled in the ball) and the finished hole size (what the thumb sits in) — see 4.5.2.
  • ✅ For interchangeable thumbs, the relevant span type is Outer to Cut (O) — it lets you drill a new ball so the bowler simply locks in their own male inner sleeve, with no new thumb to drill. See 4.1.2.

⚠️ Verify with your Spectre team: confirm whether the thumb insert brand/model has a dedicated field or is recorded in Notes, and how the thumb insert O.D. and hole-size fields are labelled in the UI.

  • 4.5.2 — Entering thumb hole size
  • 4.5.3 — Entering vertical and lateral pitch for thumb
  • 4.1.2 — Span types (Outer to Cut for interchangeables)
  • 4.4.3 — STD vs. VACU (finger inserts)

Tip: For an interchangeable thumb, recording the setup with the Outer to Cut span means a returning bowler's next ball is ready without re-drilling the thumb — they show up, lock in their sleeve, and go.

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