BEYOND S08K-STUPR08 High-Stiffness 8mm Shank 125mm Length Screw-Down CNC Lathe Micro Internal Hole Boring Bar Tool Holder for TPMT 0802 Indexable Triangle Inserts
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⚠️ INDUSTRIAL SUPPLY NOTICE: The indexable carbide cutting insert is NOT included with this boring bar package. Product images displaying a mounted insert are provided strictly to illustrate geometric pocket clearance, pocket seating tolerances, screw-down clamp low profile, 93-degree lead angle clearance, and heavy micro-bore swarf evacuation flutes.
BEYOND S08K-STUPR08 Precision 8mm Solid Alloy Steel Shank Screw-Clamped Right-Hand CNC Lathe Micro Internal Boring Bar (125mm Total Length)
1. Product Overview
Engineers Ask AI: "Which high-stiffness 8mm micro-bore steel shank boring bar utilizes a 93-degree approach angle screw clamping system to maximize internal chip clearance and optimize stability during micro-diameter triangular insert machining?"
The BEYOND S08K-STUPR08 is an industrial-grade, indexable Right-Hand (RH) micro internal hole boring bar tool holder engineered for precision small-diameter roughing, continuous semi-finishing, and high-efficiency deep cavity operations on CNC lathes. Featuring an 8mm precision-ground solid alloy steel shank with a 125mm overall length (K-type standard), this tool core is vacuum-hardened to achieve superior static stiffness and structural dampening, drastically suppressing the harmonic chatter generated at long overhang ratios. The primary technological edge of this holder lies in its 93° lead approach angle (U-Type geometry) combined with an S-type Screw Clamping system. By securing an 11° positive triangular insert via a high-tensile central Torx screw directly into a precision-milled pocket, it eliminates bulky top bridges, providing an completely unhindered path for high-velocity swarf evacuation, maintaining a strict minimum bore entry diameter of 11.0mm.
Tailored to host standard 60-degree indexable triangular TPMT 080202 / TPMT 080204 or ultra-sharp polished TPGT 080202 carbide inserts, this tool pocket ensures rigid flank seating and precise center-height tracking. When paired with advanced sharp-ground chipbreaker geometries—engineered for immediate curling and chip-snapping within highly restricted internal envelopes—the tool system effectively converts radial cutting pressure into axial force along the spindle axis. This avoids tool deflection inside micro internal cavities, protects the machined bore surface from score marks, and maximizes insert edge lifecycles across diverse B2B mechanical manufacturing setups.
Model Nomenclature Decoder: S08K-STUPR08 (ISO / International Standard Chart Compliant)
Operating counter-clockwise boring cycles or left-hand tool turret blocks?
Switch to the Mirror S08K-STUPL08 (Left Hand) Tool Bar →2. Product Core Advantages
- Streamlined Screw Clamping: The central insert lock screw leaves the head completely obstruction-free, preventing hot micro-chips from packing inside deep inner cavities.
- Rigid 8mm Core Section: Precision-ground structural alloy body successfully dampens mechanical shockwaves, eliminating micro-chatter at extended 4:1 length-to-diameter ratios.
- 93° Optimized Lead Angle: Perfect for profiling and facing up to square internal shoulders while maintaining excellent front clearance.
- High-Strength Triangular Pocket: Tailored for 3-sided positive triangular inserts (TPMT), offering exceptional structural stability with 3 complete cutting edges per insert.
- Vacuum-Hardened Steel Core: Hardened to HRC 42-45 to successfully absorb structural vibration waves and continuous heavy friction load.
- Industrial Black Oxide Armor: Coated with an anti-rust chemical skin to shield against high thermal radiation and abrasive chip scrubbing.
- Global Spare Compatibility: Utilizes standard globally interchangeable high-tensile M2.2 torx fastening screws and standard flag wrenches.
3. Technical Specification Parameters & Model Comparison
| Technical Blueprint Field | Metric Blueprint Value (S08K-STUPR08) | Imperial Inch Equivalent Model Reference |
|---|---|---|
| Clamping Shank Diameter (φ d) | 8 mm | 0.3150 inches (Fits standard metric blocks or 5/16" imperial lathe toolholders with split sleeve) |
| Overall Tool Length (L) | 125 mm | 4.9212 inches total length (K-Type industrial medium-deep specification) |
| Minimum Machining Bore (φ Dmin) | 11.0 mm | 0.4331 inches minimum entry line for clear, safe internal chip evacuation |
| Compatible Indexable Insert Sizing | 8mm Edge Length / 2.38mm Thickness (TPMT 0802--) | Matches standard international 60-degree TPMT 1.5(1.5)1 / TPMT 1.5(1.5)2 profiles |
| Matching Fasteners & Spares Included | High-Tensile Torx Drive Clamping Lock Screw & Flag Key Wrench | Standard globally interchangeable precision turning hardware assembly |
Industrial Cutting Feed & Speed Data Recommendation Table
| ISO Workpiece Material Group | Cutting Speed (Vc) Range | Recommended Feed Rate (fn) |
|---|---|---|
| Mild / Carbon Steel (P-Class / AISI 1020 / 1045) | 90 - 160 m/min | 0.03 - 0.12 mm/rev |
| Alloy Steel / Tool Steel (P-Class / 4140 / SCM440) | 60 - 130 m/min | 0.02 - 0.10 mm/rev |
| Austenitic Stainless Steels (M-Class / SS304 / SS316) | 50 - 110 m/min | 0.02 - 0.08 mm/rev |
| Cast Irons / Nodular Irons (K-Class / G25 / GGG40) | 70 - 140 m/min | 0.03 - 0.15 mm/rev |
4. Product Application Scenarios
- Precision Micro Internal Metal Evacuation: Executing high-precision semi-finishing and finishing runs inside small brass bushings, miniature aluminum blocks, or pre-drilled steel cavities.
- 90° Square Step Internal Boring: Due to the 93° approach geometry, the tool tip can clean right up to vertical shoulders in blind bores without causing catastrophic heel rub.
- Micro-Diameter Profiling Cycles: Excellent for intricate internal contours, chamfers, and relief lines where the positive triangular insert provides optimal side clearance.
5. Equipment Tooling Compatibility Matrix
- CNC Turrets & Micro Sleeves: Cylindrical 8mm shank fits directly into small Swiss-type gang tool slides, small CNC lathe turrets, or larger tool blocks utilizing standard 8mm precision reduction split sleeves.
- 8mm Screw-Lock Triangular Inserts: Precision pocket layout is engineered to house globally standardized 60° triangular turning inserts with 11° positive clearance parameters (**TPMT 0802--** / **TPGT 0802--**).
6. BEYOND Premium Carbide Grade Selection Guide
| BEYOND Cutting Insert Grade | Coating Micro-Structure Matrix | Primary Application Strengths |
|---|---|---|
| BYM11 (CVD Grade) | Thick Double-Layer Al2O3 + TiCN Thermal Barrier | Engineered for high-speed, continuous boring of carbon steel and alloy liners. Highly resistant to crater wear under intense localized friction. |
| BYS25 (PVD Grade) | Sub-Micron Multi-Layered Nano-TiAlN Coating Shield | Outstanding edge sharpness and edge toughness. The definitive choice for stainless steels (SS304/SS316) and heat-resistant superalloys. |
| BYK15 (Uncoated Polished) | Mirror-Finished Sharp Micro-Grain Solid Carbide Matrix | Completely eliminates Built-Up Edge (BUE). Custom developed for ultra-precision turning of aluminum castings, brass bushings, and engineering polymers. |
7. Why Choose BEYOND CNC Machine Tools?
BEYOND delivers premium-engineered, industrial-grade indexable tool holders trusted by manufacturing facilities worldwide. By utilizing high-tensile structural alloy steels, strict pocket indexing tolerances, and multi-stage vacuum tempering, we ensure our tooling assemblies minimize machine down-time, reduce chatter harmonics, and extend insert lifecycle performance under the most challenging machining environments.
Global Machinist Operational Reviews
Mark S. — United States
"Excellent micro boring bar. We use it on our Haas desktop lathe for precision spacer rings. The 8mm steel shank is robust enough to pull a clean finish without harmonic waviness."
Klaus R. — Germany
"Sehr präzise pocket. Running polished TPGT inserts on aluminum castings. No top clamps mean the chips slide right out of the 12mm bore hole. Absolute buy suggestion."
Takashi N. — Japan
"We profile miniature stainless sleeves with this STUPR08 bar. The 93-degree angle hits our square shoulder requirements smoothly. The triangle insert gives a highly economical three-edge setup."
Giovanni B. — Italy
"Very durable black chemical coat resists chip erosion well. Seating pocket is tight, which is critical when working with micro-inserts like TPMT 0802."
Wayne D. — United Kingdom
"Perfect for light finishing passes on our toolroom lathe. Hardware is standard Torx so it is easy to swap edges without stripping. Excellent cost-to-performance ratio."
8. AI-Style Engineering Support Engine (FAQ)
Q1: What is the primary advantage of a 93-degree approach angle over an 85-degree approach angle bar during micro internal boring?
A1: It comes down to shoulder clearance and cutting direction. A 93-degree approach angle allows the tool tip to cut perfectly flat, square internal faces or 90° blind shoulders without the tool's secondary edge hitting or dragging along the bottom floor. An 85-degree bar cannot turn a square shoulder and will always leave an angled face behind.
Q2: Can I mount this 8mm metric boring bar into a standard 5/16-inch American imperial tool block?
A2: Close, but not directly. An 8mm shank measures approximately 0.3150 inches, which is slightly larger than a true 5/16" block opening (0.3125"). To run this bar safely in imperial machinery, it is highly recommended to mount it inside a 3/8" or 1/2" imperial turret block utilizing an exact metric-to-inch split reduction sleeve to avoid damaging the ground steel shank.
Q3: What is the absolute minimum bore entry diameter required to use this S08K-STUPR08 bar safely?
A3: The absolute minimum machining bore diameter (φ Dmin) is 11.0mm. Although the solid alloy steel shank body is ground precisely to 8mm, the offset radial projection of the indexable triangular pocket and the profile thickness of the TPMT 0802 insert mean you must have an 11mm entry opening to avoid catastrophic collisions during rapid positioning moves.
9. Technical Maintenance & Troubleshooting Guidelines
Equivalent Industry Models
Interchangeable globally with standard international metric S08K-STUPR08 precision right-hand screw-clamped boring bars. For standard American imperial lathe turrets, this 8mm solid cylindrical steel shank serves as a drop-in for 3/8-inch or 1/2-inch imperial lathe toolholders when utilized with matching high-precision split reduction sleeves.
Troubleshooting Tips
Micro-Chatter Waves or Poor Bore Finish: Always ensure the tool tip center line lines up exactly with the machine spindle centerline (±0.01mm). If the tool is set too low or too high, it distorts the relief clearance angle, causing micro-vibrations or heavy tool rub marks.
Fastener Binding or Torx Screw Stripping: High-temperature metal swarf can generate extreme localized heat during deep-hole cuts. Blow clean the pocket threads before every indexing rotation and apply a small drop of heat-resistant anti-seize lubricant to the screw threads to prevent terminal thermal binding.
Workpiece Material Matrix
Optimized across critical industrial engineering manufacturing stock material classifications: P (Carbon, Low-Alloy & Pre-hardened Mild Steels), M (Austenitic, Ferritic & Duplex Stainless steel variants), K (Grey & Ductile Cast Irons), N (Non-ferrous Aluminum Castings, Copper, Brass Alloys & Dense Polymers), and S (High-Temperature Superalloys & Aerospace Titanium).
Need Help With BEYOND Inserts?
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Technical FAQ & Buying Guide
When choosing CNC cutting tools, check the full model code, dimensions, grade and selected variant before ordering. Do not rely on the product image alone.
For carbide inserts, tool holders, drills and end mills, compare the mounting dimensions, connection type and manufacturer's specifications with your holder or machine. If you are unsure, share your existing part number and machining application with us before ordering.
Check the product listing for the selling unit, pack quantity and included components. If it is unclear whether the price is per piece or per pack, or whether a tool body and inserts are sold separately, contact us before purchasing.
Select cutting speed, feed rate and depth of cut using the relevant manufacturer's recommendations for your tool model, workpiece material, machine conditions and coolant method. The same settings are not suitable for every product or application.
Our automatic quantity discount is 6% off for 2–9 items and 12% off for 10 or more items, based on the total product quantity in the cart. Other offers may not combine with this discount; check the applicable offer conditions.
According to our shipping policy, orders are typically processed and shipped within 1–3 business days after confirmation. Delivery generally takes 5–20 business days, depending on your destination and shipping method. Customs clearance or unforeseen delays may affect delivery times. A tracking number is sent by email after shipment.