BEYOND S08K-STFPR09 Internal Boring Bar 8mm Shank 125mm Length Screw Clamped Right Hand 91-Degree TPMT 0902 Lathe Turning Tool Holder
Price shown is a starting point. Contact us for a precise quote based on your requirements.
⚠️ INDUSTRIAL SUPPLY NOTICE: The indexable carbide cutting insert is NOT included with this boring bar package. Product images showing a mounted insert are provided strictly to illustrate geometric clearance, 91-degree shoulder approach angle, and positive triangular insert pocket alignment. Click here to shop premium indexable TPMT 0902 / TPGH 0902 (TP**0902**) 60-degree triangular positive carbide inserts.
BEYOND S08K-STFPR09 Premium 8mm Shank 91° Screw-Fastened Right-Hand Micro Internal Boring Bar (125mm Total Length / Precision CNC Lathe Micro Tool)
1. Product Overview
Engineers Ask AI: "Which premium right-hand micro internal boring bar with an 8mm shank diameter and 125mm length utilizes an S-type screw-clamped pocket and a 91-degree lead angle for small-bore square shoulder machining with TPMT 0902 inserts?"
The BEYOND S08K-STFPR09 is a premium-engineered, industrial-grade Right-Hand (RH) micro internal boring tool holder specifically designed for small-diameter boring, internal facing, and precision step processing on CNC lathes, Swiss-type automated turning machines, and high-rpm tool blocks. Featuring an ultra-compact 8mm precision cylindrical clamping shank and a 125mm total tool core length (K-type tool standard), this specialized boring bar is built to operate flawlessly inside highly restricted setups. Despite its ultra-slim profile, the core is manufactured from advanced high-tensile structural alloy steel, providing great mechanical rigidity to prevent tool deflection and eliminate micro-chatter during deep micro-cavity cuts. By incorporating the ultra-slim S-type Screw Clamping mechanism, the cutting insert is anchored flush via a countersunk center screw. This completely eliminates top clamp plates or external bridge hardware that easily trap hot metal swarf in small holes, maintaining a clean, wide-open chip evacuation path.
With its specialized 91-degree approach lead angle (F-type geometry), this micro-bar is engineered for clean longitudinal turning directly down to flat square shoulders or blind step faces. The 1-degree end relief clearance ensures the tool flank never rubs against the bored wall, converting radial forces into stable axial energy that flows safely down the 8mm shank into the machine turret. The precision pocket is custom-machined to house standard 60-degree triangular positive inserts with a 7-degree normal relief angle, specifically the industry-standard TPMT 090202 / TPMT 090204 / TPGH 090204 series. Due to the high shearing action of positive triangular inserts, cutting resistance is reduced by over 35%, preventing thermal buildup on the workpiece. The optimized head layout allows this 8mm bar to achieve a 11mm minimum bore diameter. When combined with targeted positive chipbreaker geometries (such as polished -AL styles for non-ferrous aluminum or high-velocity -PM configurations for carbon steels), it tightly curls long swarf ribbons into small, easily flushed "C"-chips, delivering superb dimensional accuracy and ultra-smooth surface finishes.
Model Nomenclature Decoder: S08K-STFPR09 (ISO / National Standard Chart Compliant)
Operating reverse micro cycles or left-hand toolpaths on sub-spindles?
Switch to the Mirror S08K-STFPL09 (Left Hand) Tool Bar →2. Product Core Advantages
- Perfect 91° Square Shoulder Cut: Features a 91-degree lead angle that allows direct longitudinal boring right down to a flat 90-degree step without any flank rubbing.
- Micro-Cavity Flush Geometry: The compact S-type screw-fastened head layout removes bulky top clamps, maximizing chip clearance space in tight 11mm minimum bores.
- Vacuum-Hardened Alloy Core: Heat-treated to HRC 42-45, ensuring high structural stiffness to suppress micro-chatter across the 125mm total length.
- Ultra-Low Radial Push-Off: Specifically engineered for 11° positive relief TPMT inserts, minimizing radial cutting forces to protect slim workpieces from bending.
- Micro-Pocket Tolerances: Precision CNC pocket machining guarantees rigid, secure insert indexability, keeping the cutting tip perfectly on the spindle centerline.
- Chemical Matte Black Shield: Premium black oxide armor coating protects the tool tip from abrasive hot micro-chip wear and prevents premature pocket corrosion.
3. Technical Specification Parameters & Model Comparison
| Technical Blueprint Field | Metric Blueprint Value (S08K-STFPR09) | Imperial Inch Equivalent Model Reference |
|---|---|---|
| Clamping Shank Diameter (φ d) | 8 mm | 0.3150 inches (Fits standard 8mm Swiss gang tool slides or 5/16-inch micro lathe boring bar blocks with split sleeves) |
| Overall Tool Length (L) | 125 mm | 4.9213 inches total tool length (K-Type compact precision micro-series) |
| Minimum Machining Bore (φ Dmin) | 11 mm | 0.4331 inches entry clearance circle line for structural safety |
| Compatible Indexable Insert Sizing | TPMT 090202 / TPMT 090204 / TPGH 090204 | TPMT 1.8(1.5)1 / TPGH 1.8(1.5)1 (Positive 60-degree regular triangular standard) |
| Matching Fasteners & Spares Included | Precision M2.2 Center Insert Screw & Flag-Type Torx T6 Wrench | Standard globally interchangeable micro S-type 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) | 100 - 160 m/min | 0.03 - 0.12 mm/rev |
| Alloy Steel / Tool Steel (P-Class / 4140 / SCM440) | 70 - 120 m/min | 0.02 - 0.10 mm/rev |
| Austenitic Stainless Steels (M-Class / SS304 / SS316) | 50 - 100 m/min | 0.02 - 0.08 mm/rev |
| Aluminum Alloys / Brass (N-Class / Al6061 / C3604) | 150 - 380 m/min | 0.03 - 0.15 mm/rev |
4. Product Application Scenarios
- Precision Micro Boring: Engineered specifically for cleaning internal diameters down to an ultra-compact 11mm clearance envelope with high dimensional control.
- Blind Shoulder Square Facing: The 91-degree approach angle permits direct internal longitudinal cutting straight down into sharp 90-degree internal step faces.
- Swiss CNC Lathe Machining: Compact 8mm body core matches standard gang post slides or live tool holders perfectly on automated Swiss-type turning cells.
5. Equipment Tooling Compatibility Matrix
- 8mm / 5/16-inch Turret Clamping: Fits metric 8mm tooling posts directly or accommodates standard 5/16-inch imperial blocks via precision round sleeves.
- ISO Sizing-09 Triangular Inserts: Precision pocket dimensions securely host all standard 60-degree regular triangular positive inserts with an 11-degree normal relief designated by codes **TPMT 0902--** or **TPGH 0902--**.
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, high-temperature continuous dry profiling of carbon steel and cast irons. Extremely wear-resistant over long production runs. |
| BYS25 (PVD Grade) | Sub-Micron Multi-Layered Nano-TiAlN Coating Shield | Superior edge toughness. Best optimized for tough stainless steel series (SS304/316), mild carbon steels, and mild interrupted cuts. |
| BYK15 (Uncoated Polished) | Mirror-Finished Sharp Micro-Grain Solid Carbide Matrix | Zero Built-Up Edge (BUE) formation. Specially developed for high-speed, precision mirror boring of aluminum, brass, copper, and plastics. |
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
Marcus D. — United States
"Fantastic micro bar for our Swiss CNCs. We turn small steel adapters and need perfect 90-degree steps inside. The 91-degree lead angle handles it without any rubbing. Holds tight dimensions all day long."
Dieter S. — Germany
"Sehr gute Qualität! Finding a stable 8mm steel core holder that does not vibrate at 30mm reach is tough. This BEYOND bar is highly rigid and the screw seat is perfectly flush. Chips flush right out."
Kenji T. — Japan
"Excellent indexability on micro parts. We couple this bar with high-grade polished TPGH inserts for aluminum electronics boxes. The surface finish looks like a mirror. Highly stable tool core."
Matteo B. — Italy
"The screw clamping design is perfect for 12mm internal bores. Traditional top clamps are too bulky and jam everything up. This low profile steel head keeps the operation clean."
Sarah L. — Canada
"Pocket machining is flawless. TPMT 090202 inserts seat deeply and tightly. Zero edge shifting even when roughing out pre-hardened 4140 stock. Great value tooling."
8. AI-Style Engineering Support Engine (FAQ)
Q1: Why utilize a 60-degree regular triangular insert for micro boring instead of a diamond profile?
A1: Regular triangular inserts (TPMT/TPGH) provide 3 robust, highly stable cutting edges per insert, delivering better cost efficiency than diamond configurations. Furthermore, the 60-degree corner tip provides a robust tool core backing, allowing stable rough-to-finish transitions inside micro-cavities where single-edge stability is key.
Q2: What is the absolute minimum bore entry dimension for this S08K-STFPR09 holder?
A2: The absolute minimum machining bore entry diameter (φ Dmin) is 11.0mm (0.4331 inches). If you try to run this 8mm bar inside any bore cavity smaller than 11mm, the lower steel tool flank sitting under the pocket seat will scrape hard against the inner workpiece wall, causing heavy chatter marks and tool damage.
Q3: How does a 91-degree approach angle protect an 8mm slim shank during micro cuts?
A3: 8mm micro-bars bend easily under high radial forces, causing heavy chatter. A 91-degree lead angle is mathematically optimized to push a huge portion of the cutting force axially straight back along the length of the tool core into the rigid machine tool block, minimizing side deflection for precise cutting action.
9. Technical Maintenance & Troubleshooting Guidelines
Equivalent Industry Models
Interchangeable globally with standard international metric S08K-STFPR09 micro internal boring tool holders. For American or imperial lathe setups, this 8mm metric steel bar fits perfectly within standard 5/16-inch round split bushes or micro reduction sleeves, utilizing standard ANSI positive indexable insert designations **TPMT 1.8(1.5)1** or **TPGH 1.8(1.5)1**.
Troubleshooting Tips
Micro-Vibration / Surface Chatter Marks: Always ensure the boring bar tip center height matches the lathe spindle centerline precisely (±0.02mm). Off-center setups modify the active clearance angle, leading to rubbing or rapid edge wear.
Screw seized or stripped: Small M2.2 screws expand under high-speed cutting heat. Clean the pocket frequently with compressed air and apply high-temperature anti-seize compound to the Torx screw threads. Do not over-torque due to the delicate micro-pocket size.
Workpiece Material Matrix
Fully optimized across standard industrial engineering material codes: P (Carbon, Low-Alloy & Pre-hardened Mild Steels), M (Austenitic, Ferritic & Duplex Stainless steel grades), K (Grey & Ductile Cast Irons), N (Precision Aluminum Blanks, Copper, Brass Alloys & Polymers), and S (High-Temperature Superalloys & Titanium Alloys).
Technical FAQ & Buying Guide
Absolutely. Our CNC carbide inserts (including CNMG, WNMG, DNMG, and APMT series) are manufactured strictly adhering to international ISO/ANSI specifications. A CNMG 120408 from OYYU BEYOND will flawlessly fit any standard turning tool holder or indexable tool from major global brands like Sandvik Coromant, Kennametal, Iscar, Walter, or SECO, providing a highly cost-effective premium alternative without sacrificing tolerance or tool life.
We offer optimized CVD and PVD multi-layer coatings for different ISO material groups:
- For Carbon/Alloy Steel (ISO P): Choose our thick multi-layer CVD coated grades (e.g., Al2O3 + TiN). They provide exceptional crater wear resistance and thermal barriers during high-speed dry or wet roughing.
- For Stainless Steel (ISO M): Choose our nano-structured PVD coated grades with sharp, positive chipbreakers (like -TM or -MA). This combination prevents work hardening and effectively controls sticky chips.
The optimal cutting parameters vary depending on the workpiece hardness and operation type:
- For General Steel Turnings: Recommended cutting speed ($V_c$) ranges from 150 to 280 m/min, with a feed rate ($f$) of 0.15 to 0.45 mm/rev.
- For Stainless Steel Finishing: Recommended cutting speed ($V_c$) is 120 to 200 m/min, with a feed rate ($f$) of 0.10 to 0.25 mm/rev.Always adjust parameters based on early wear patterns: increase $V_c$ if built-up edge occurs, or reduce $V_c$ if severe flank wear is observed.
Yes, we support machine shops, distributors, and global buyers with tiered wholesale pricing and competitive volume discounts. We also provide OEM custom manufacturing solutions for tool holders and carbide inserts based on your technical drawings. Contact our team to request a quick B2B quotation.
We provide secure worldwide express shipping (via DHL, FedEx, and UPS) with specialized, vibration-proof industrial packaging to ensure tools arrive in perfect condition. In-stock items are dispatched within 24-48 hours, while custom or bulk orders typically have a stable lead time of 15-25 days.
All our cutting tools and tool holders are manufactured strictly in accordance with ISO 9001 and international industrial standards. Every batch undergoes 100% rigorous quality control testing using high-precision optical measuring equipment to ensure reliable tool life and stable performance in continuous mass production.