Lathe Tooling Reference
Quick Change Tool Post (QCTP) Sizes
| Size | Designation | Max Tool Shank | Typical Lathe Swing |
|---|
| AXA | 100 Series | 1/2" | 9–12" |
| BXA | 200 Series | 3/4" | 12–15" |
| CXA | 300 Series | 1" | 15–18" |
| CA | 400 Series | 1-1/4" | 18–24" |
| DA | 500 Series | 1-1/2" | 24"+ |
Common QCTP Holder Types
| Holder # | Type | Description |
|---|
| #1 | Turning & Facing | Standard holder for OD turning tools and insert holders |
| #2 | Boring Bar | Holds boring bars for internal operations |
| #4 | Heavy Turning | Oversized holder for heavy-duty roughing |
| #7 | Universal Parting | Holds parting/cut-off blades |
| #10 | Knurling | Holds knurling tools for surface texturing |
Lathe Chuck Types
| Type | Jaws | Self-Centering | Accuracy (TIR) | Use Case |
|---|
| 3-Jaw Scroll Chuck | 3 | Yes | 0.003–0.005" | General turning; round and hex stock |
| 4-Jaw Independent Chuck | 4 | No | 0.0005" (achievable) | Precision work; irregular or non-round shapes |
| 6-Jaw Chuck | 6 | Yes | 0.002–0.004" | Thin-wall parts; reduced distortion |
| 5C Collet Chuck | Collet | Yes | 0.0005" | High production; bar work; fast changeover |
| ER Collet Chuck | Collet | Yes | 0.0005–0.001" | Small lathes; sub-spindle; versatile range |
| Faceplate | N/A | No | Depends on setup | Large or irregular workpieces clamped with bolts |
| Magnetic Chuck | N/A | N/A | 0.001" | Thin discs; light finishing cuts only |
Turning Insert Holders
| Holder Style | Insert Shape | Lead / Approach Angle | Application |
|---|
| SCLCR/L | C (80° diamond) | 5° lead angle | General turning, facing, light profiling |
| SDJCR/L | D (55° diamond) | 93° approach | Profiling, copy turning, finishing |
| MTJNR/L | T (triangle) | 93° approach | Heavy turning, general purpose |
| MWLNR/L | W (80° trigon) | 95° approach | Roughing, heavy material removal |
| SVJBR/L | V (35° diamond) | 72.5° approach | Profiling, finish contouring |
| SRGCR/L | R (round) | N/A | Contouring, radius work, heavy roughing |
Boring Bar Sizes
| Bar Diameter | Min Bore Diameter | Max Overhang (Steel) | Max Overhang (Carbide) |
|---|
| 3/8" | 1/2" | 1-1/2" (4×) | 2-5/8" (7×) |
| 1/2" | 5/8" | 2" (4×) | 3-1/2" (7×) |
| 5/8" | 3/4" | 2-1/2" (4×) | 4-3/8" (7×) |
| 3/4" | 1" | 3" (4×) | 5-1/4" (7×) |
| 1" | 1-1/4" | 4" (4×) | 7" (7×) |
| 1-1/4" | 1-1/2" | 5" (4×) | 8-3/4" (7×) |
| 1-1/2" | 1-3/4" | 6" (4×) | 10-1/2" (7×) |
| 2" | 2-1/4" | 8" (4×) | 14" (7×) |
Overhang rules: Steel bars — max 4× diameter. Solid carbide — 6–7× diameter. Heavy-metal (tungsten) bars — up to 10× diameter. Shorter overhang always improves rigidity and finish quality.
Threading
Threading Methods
| Thread Type | Tool | Notes |
|---|
| External | Die | Quick for standard threads; limited to smaller sizes; manual or tailstock |
| External | Single-point (lathe) | Any thread form or pitch; requires G76 or manual compound; best finish |
| External | Thread mill (CNC) | Interpolated; one tool for multiple sizes; good for large diameters |
| Internal | Tap | Fast, standard sizes; risk of breakage in blind holes |
| Internal | Single-point (lathe) | Boring-bar style; any pitch/form; requires rigid setup |
| Internal | Thread mill (CNC) | Interpolated; less breakage risk than tapping; good for hard materials |
Common Thread Standards
| Standard | Designation Example | Description |
|---|
| UNC | 1/4-20 UNC | Unified National Coarse — general purpose, most common in US |
| UNF | 1/4-28 UNF | Unified National Fine — stronger in tension, vibration-resistant |
| NPT | 1/4-18 NPT | National Pipe Taper — tapered, seals with thread contact |
| Metric | M8×1.25 | ISO metric — diameter × pitch in mm |
| BSPP | G 1/4 | British Standard Pipe Parallel — straight thread, O-ring seal |
| ACME | 3/4-6 ACME | Trapezoidal — power screws, leadscrews, vises |
Lathe Centers
Live center: Rotates with the workpiece on bearings. Preferred for most turning — no friction heat, supports higher RPM. Mount in tailstock.
Dead center: Does not rotate; relies on lubrication. Used when higher precision is needed (no bearing play). Common in grinding and very precise turning. Requires center lubricant.
Both mount in the tailstock (or headstock) via Morse taper. Match the MT size to your machine's tailstock bore (typically MT2–MT4 for common lathes).
Center Drill Sizes
| Size # | Body Diameter (in) | Point Diameter (in) | Point Diameter (mm) |
|---|
| #0 | 1/8" | 0.031" | 0.8 |
| #1 | 1/8" | 3/64" (0.047") | 1.2 |
| #2 | 3/16" | 5/64" (0.078") | 2.0 |
| #3 | 1/4" | 7/64" (0.109") | 2.8 |
| #4 | 5/16" | 9/64" (0.141") | 3.6 |
| #5 | 7/16" | 3/16" (0.188") | 4.8 |