Knurled surfaces
Specify knurl pattern, pitch basis, process and finished envelope without confusing tool pitch with surface finish.
Tags: parts-and-design, knurling, machining, surface-features
On this page
Define the surface and its function
Specify the knurl pattern, dimensional condition and function. A visual pattern alone leaves the contact and fit requirements unresolved. Accu-Trak general knurling information
Under Accu-Trak’s diametral-pitch model, 96 DP on a 0.750-inch blank gives 72 teeth. A 73-tooth candidate implies a 0.7604167-inch blank. This checks nominal tracking geometry. Tooth wear and first-revolution penetration still affect tracking, and the model does not determine finished crest diameter.
Forming and cutting are different processes. Dorian describes forming heads as displacing material and increasing the part diameter, while cutting heads remove material to create the pattern. Do not carry a forming blank-size allowance into a cut-knurl process without review. Neither process name establishes a friction coefficient, grip force or interference-fit capacity for the finished part. Dorian modular knurling tools
Information to put on the drawing
Treat the following as a proposed handoff checklist, with the accepted tooling specification controlling detailed definitions:
| Field | Intent to resolve |
|---|---|
| Pattern | Straight, diagonal or diamond; direction and included/helix angle where relevant |
| Spacing | Numerical pitch, units and normal versus transverse measurement basis |
| Envelope | Finished crest diameter and limits, knurled length and location |
| Boundaries | Entry/exit, shoulder clearance, chamfers and allowed runout region |
| Acceptance | Complete pattern, tooth condition, fit/grip requirement and inspection stage |
Identify the material and condition, chosen process and finishing sequence. Keep a manufacturing blank diameter separate from a finished crest diameter. If the knurl engages another part, define the mating interface and acceptance independently of its decorative appearance.
Pitch is not a single interchangeable number
Accu-Trak distinguishes circular pitch, teeth per inch (TPI), metric pitch and diametral pitch (DP). For diagonal/diamond wheels, spacing is normally measured perpendicular to the teeth; the company notes legacy transverse-pitch exceptions for 14, 21 and 33 TPI. It also says “coarse,” “medium” and “fine” lack exact definitions. Use the actual tooling designation and measurement direction rather than translating those words into a guessed pitch. Accu-Trak pitch definitions and exceptions
Do not compare TPI and DP as though the numbers described the same quantity. Accu-Trak gives the DP blank relationship blank diameter in inches = number of teeth on the part / DP. Its page cites the historical ANSI B94.6-1984 system; that citation is not independent confirmation of the latest governing standard. Accu-Trak diametral-pitch explanation
Bounded tooth-count calculation
Using that supplier's DP relationship, a hypothetical 96 DP operation on a 0.750-inch blank corresponds to 96 × 0.750 = 72 teeth around the part. A 73-tooth candidate gives 73/96 = 0.7604167 inch, or about 19.3146 mm, compared with 19.0500 mm for the 72-tooth candidate. The diameter increment is 1/96 inch = 0.2645833 mm.
This is original arithmetic applying the stated DP model. It does not determine the finished crest diameter or establish a successful process. Accu-Trak explicitly warns that tooth sharpness, wear and first-revolution penetration can change tracking even when the nominal formula is followed. Confirm the actual blank and tool through the selected process. Accu-Trak DP limitations
Tracking, loads and process review
Double tracking is an unwanted extra impression pattern, not an alternative specified pitch. Accu-Trak identifies material hardness, wheel-crest sharpness, knurl width, initial infeed and spindle speed as influences on initial tracking. Its suggested corrections depend on whether the setup uses bump/cut knurling or end feeding. Do not turn one correction into a universal feed or depth instruction. Accu-Trak speeds, feeds and tracking guidance
The same guidance describes part/holder flex under rolling pressure and different setup procedures for single-wheel and straddle holders. Review the actual support, thin sections, tool approach and shoulder access with the machinist. A successful tooth-count calculation does not assess workpiece deflection or machine loading. Accu-Trak holder and infeed guidance
Avoid assigning a cutting speed from this reference alone. Select data for the actual tooling, material, holder and operation, and qualify the resulting pattern and dimensions.
Finished-part inspection
As proposed acceptance checks, verify pattern and spacing against the agreed reference, measure the specified finished envelope, inspect coverage at entry/exit and shoulders, and check damaged teeth, loose material or unacceptable sharp edges. State the inspection method: a diameter measurement across tooth crests does not by itself establish pitch, profile or functional grip.
Where coating or another finishing operation follows knurling, agree when dimensions and fit are accepted. For a pressed, torque-transmitting or retained interface, evaluate the actual mating geometry, material and service loads. A visible diamond pattern is not a load rating.
Related reference
Source scope
The cited live Accu-Trak and Dorian pages were reviewed on the date above; no technical revision dates were verified. Their process guidance and historical standard references are bounded as stated. Calculations and handoff/inspection checks are editorial guidance, not normative drawing requirements.