ASME B94.42-1972 — Carbide Blanks for Tipping Circular Saws

⚙️ ANSI/ASME B94.42-1972 is the American National Standard for the dimensional specifications and designations of carbide blanks used to tip (brace teeth onto) circular saws. Prepared by Technical Committee 1 (Carbide and Oxide Tools) of the ASME B94 Standards Committee on the basis of earlier work by the Cemented Carbide Producers Association standards committee, it is a revision and redesignation of B108.1-1966. Tipping consists of brazing sintered carbide teeth onto the saw body, which is the standard construction of woodworking circular saws, metal cold saws, and functionally similar cutters. The standardized blank sizes and designation codes guarantee geometric consistency and interchangeability across suppliers, making this document the fundamental procurement and manufacturing reference for carbide-tipped saw production.

1. Scope and Definitions 📌

This Standard covers dimensional specifications and designations for carbide blanks for tipping circular saws. Values stated in U.S. customary units are to be regarded as the standard. Two definitions anchor the document:

• Blank: an unground carbide solid.
• Carbide: a sintered combination of cobalt or other binder and refractory metals suitable as a cutting material.

Standard sizes and designations, intended primarily for tipping circular saws and functionally similar cutters, are given in Table 1. The predecessor B108.1 was developed from 1962 drafts, approved by the CCPA Standards Committee in 1963, submitted to the American Standards Association in 1963, recommended for revision by TC-1 in 1971, and approved/redesignated B94.42-1972 on August 8, 1972.

2. Designation System: Two-Letter Prefix + Four Digits 🔤

Blanks are designated by a two-letter prefix and a four-digit number:

• First letter W: identifies the shape and is descriptive of the principal application—woodworking saws.
• Second letter: designates the length (L) and thickness (T) group of the tip.
• Third-position digit (7 or 8): designates the style—”7″ for Style 1 and “8” for Style 2, illustrated in Fig. 1 (Style 1 has no side clearances).
• Last three digits: designate the nominal width (W) in thousandths of an inch.

Example: blank WA-7080 means W-shape blank, second letter A (0.250/0.260 in. long and 0.062/0.072 in. thick), Style 1 (digit 7), width 0.080/0.090 in. (080).

3. Sizes and Tolerances 📏

Table 1 lists nominal values and tolerances for length (L), thickness (T), and width (W) across all series. All dimensions carry the unilateral tolerance form +0.010 / −0.000 in. (+0.25 / −0.00 mm): blanks may only be oversize, never undersize, reserving grinding stock for the saw maker. Length and thickness are organized into letter groups:

Each series offers both Style 1 and Style 2 width sets—for example, the WA family includes WA-7065…WA-7160 (Style 1) and WA-8065…WA-8160 (Style 2). The user selects style and width from the saw’s tooth-seat geometry.

4. Style 1 versus Style 2 🔩

Fig. 1 illustrates the Style 1 and Style 2 blank profiles. The two styles share the same length, thickness, and width series but differ in the clearance geometry of the cutting tooth: Style 1 is the basic form (no side clearances), while Style 2 incorporates side relief so the tooth has lower lateral friction during sawing, suiting blades that need smoother chip clearance and lower heat generation. The choice follows the saw’s gullet shape and the intended cutting duty.

5. Engineering Practice Essentials 🛠️

• 🔍 Selection workflow: set saw parameters (diameter, pitch, tooth count) and duty (wood/metal, hard/soft) → pick the length/thickness group from the seat size (letter) → pick the style from the tooth form (7/8) → pick the width (three digits) → write the full code (e.g., WD-7180).
• 🔧 Brazing practice: carbide and steel have very different thermal expansion; control heating temperature and cooling rate during brazing to avoid cracks, then grind rake, clearance, and side faces within the blank envelope.
• 📊 Grinding management: grind carbide faces with diamond wheels; stock is limited by the +0.010/−0.000 tolerance, so measure each blank before grinding to prevent insufficient tooth height afterward.
• 📋 Procurement and inspection: order by full code and sample-check L/T/W and tolerances per lot; keep blanks from a single source per lot so grade and dimensions stay consistent.

6. Frequently Asked Questions ❓